ASTM D6439-23

Standard Guide for Cleaning, Flushing, and Purification of Steam, Gas, and Hydroelectric Turbine Lubrication Systems

SIGNIFICANCE AND USE
4.1 This guide is intended to aid the equipment manufacturer, installer, service company, and turbine operator in coordinating their efforts to obtain and maintain clean lubrication and control systems.  
4.2 The flushing and cleaning philosophies stated in this guide are applicable to both large and small lubrication systems.  
4.3 Clean lubrication systems result from proper system design and good planning, execution, and communication by all involved during commissioning. No phase of these procedures should be undertaken without a thorough understanding of the possible effects of improper system preparation. The installation, cleaning, and flushing of the equipment should not be entrusted to persons lacking in experience.  
4.4 Because of the knowledge and specialized equipment that is required, the operator may wish to employ an outside specialist contractor for the system flushing. Review of this guide can provide guidelines for discussion with prospective contractors.
SCOPE
1.1 This guide covers types of contaminants, oil purification devices, contamination monitoring, contamination control during building or refurbishing of turbine systems, lubrication system flushing, and maintenance of pure lubrication oil.  
1.2 To obtain maximum operating life and reliability, or lubricants and system, it is vital that the turbine lubrication system has pure oil. This guide is intended to aid the equipment manufacturer, installer, and turbine operator in coordinating their efforts to obtain and maintain clean lubrication and control systems. These systems may be on land or marine turbine generators and propulsion and mechanical drive equipment. This guide is generalized due to variations in the type of equipment, builder's practices, and operating conditions.  
1.3 This guide primarily addresses petroleum based lubricating oil. For systems using nonpetroleum based fluids, this guide may not be appropriate. For nonpetroleum products, consult the equipment and fluid manufacturers.  
1.4 This guide is applicable to both large and small lubrication systems. Some equipment specified herein, however, may not be appropriate for all systems. Moreover, in situations where specific guidelines and procedures are provided by the equipment manufacturer, such procedures should take precedence over the recommendations of this guide.  
1.5 This standard does not purport to address the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 30-Jun-2023
• ICS: 75.100 - Lubricants, industrial oils and related products
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.C0.01 - Turbine Oil Monitoring, Problems and Systems

Relations

• Refers: ASTM D445-24 - Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
• Effective Date: 01-Apr-2024
• Refers: ASTM D4378-24 - Standard Practice for In-Service Monitoring of Mineral Turbine Oils for Steam, Gas, and Combined Cycle Turbines
• Effective Date: 01-Mar-2024
• Refers: ASTM D8112-24 - Standard Guide for Obtaining In-Service Samples of Turbine Operation Related Lubricating Fluid
• Effective Date: 01-Mar-2024
• Refers: ASTM D7546-24 - Standard Test Method for Determination of Moisture in New and In-Service Lubricating Oils and Additives by Relative Humidity Sensor
• Effective Date: 01-Feb-2024
• Refers: ASTM D7647-24 - Standard Test Method for Automatic Particle Counting of Lubricating and Hydraulic Fluids Using Dilution Techniques to Eliminate the Contribution of Water and Interfering Soft Particles by Light Extinction
• Effective Date: 01-Feb-2024
• Refers: ASTM D4175-23a - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 15-Dec-2023
• Refers: ASTM D4898-23 - Standard Test Method for Insoluble Contamination of Hydraulic Fluids by Gravimetric Analysis
• Effective Date: 01-Dec-2023
• Refers: ASTM D445-23 - Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
• Effective Date: 01-Nov-2023
• Refers: ASTM D4175-23e1 - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Jul-2023
• Refers: ASTM D7155-20 - Standard Practice for Evaluating Compatibility of Mixtures of Turbine Lubricating Oils
• Effective Date: 01-May-2020
• Refers: ASTM F311-08(2020) - Standard Practice for Processing Aerospace Liquid Samples for Particulate Contamination Analysis Using Membrane Filters
• Effective Date: 01-Apr-2020
• Refers: ASTM D7155-18 - Standard Practice for Evaluating Compatibility of Mixtures of Turbine Lubricating Oils
• Effective Date: 01-Jun-2018
• Refers: ASTM D664-11a(2017) - Standard Test Method for Acid Number of Petroleum Products by Potentiometric Titration
• Effective Date: 01-May-2017
• Refers: ASTM D445-16 - Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
• Effective Date: 15-Dec-2016
• Refers: ASTM D7843-16 - Standard Test Method for Measurement of Lubricant Generated Insoluble Color Bodies in In-Service Turbine Oils using Membrane Patch Colorimetry
• Effective Date: 01-Jun-2016

Overview

ASTM D6439-23 is the international standard guide for cleaning, flushing, and purification of steam, gas, and hydroelectric turbine lubrication systems. Developed by ASTM International, this guide assists manufacturers, service companies, installers, and turbine operators in establishing procedures and best practices for maintaining clean lubrication and control oil systems in both land-based and marine turbine generators as well as mechanical drive equipment.

Lubrication system cleanliness is essential for turbine reliability, minimizing wear, ensuring optimal performance, and extending equipment life. The guide covers types of contaminants, selection and use of oil purification devices, contamination control during system fabrication or refurbishment, and the maintenance of pure lubricating oil under a wide range of operational conditions.

Key Topics

• Contaminant Identification and Monitoring

  • Guidance on the types of contaminants found in turbine lubrication systems, including water, insoluble particulates, and soluble contaminants.
  • Recommendations for contamination monitoring methods and oil quality assessment to meet system cleanliness requirements.

• Cleaning and Flushing Procedures

  • Step-by-step recommendations for effective cleaning and flushing, including displacement flush, high-velocity flush, use of surface-active cleaning agents, and high-pressure water flushing.
  • Considerations for system design to facilitate thorough cleaning, such as access points for sampling and adequate filtration.
  • Emphasis on proper planning, execution, and experienced personnel.

• Contamination Control Strategies

  • Best practices during manufacturing, storage, installation, and refurbishment to minimize ingression of contaminants.
  • Detailed protocols for the protection and inspection of components like bearings, valves, coolers, tanks, and gear assemblies.
  • Addressing corrosion protection and compatibility of rust preventive and preservative oils.

• Oil Purification and Maintenance

  • Overview of oil purification devices such as filters, coalescers, centrifuges, and vacuum dehydrators.
  • Maintenance recommendations to ensure that lubricants remain pure and within manufacturer specifications throughout operational life.

Applications

• Commissioning of New Turbine Systems

  • Ensures that all contaminants introduced during manufacturing, assembly, and installation are removed prior to startup, preventing premature wear or damage.
  • Provides guidelines for collaboration between manufacturers, installers, and service providers.

• Routine and Preventive Maintenance

  • Assists operators in ongoing contamination monitoring and oil purification, helping to identify early signs of degradation and schedule maintenance before problems occur.
  • Reduces downtime and maintenance costs associated with oil contamination and system failures.

• Refurbishing and Overhaul

  • Offers stepwise processes for cleaning, flushing, and re-commissioning lubrication systems after major repairs or system rebuilds.
  • Tailors maintenance programs for both large-scale industrial turbines and smaller installations.

• Quality Assurance and Contractor Communication

  • Provides an authoritative reference for specifying cleanliness requirements and maintenance protocols in contracts and quality assurance documentation.

Related Standards

• ASTM D445: Kinematic Viscosity of Transparent and Opaque Liquids
• ASTM D4378: In-Service Monitoring of Mineral Turbine Oils
• ASTM D6304: Determination of Water in Petroleum Products
• ASTM D7155: Evaluating Compatibility of Mixtures of Turbine Lubricating Oils
• ISO 4406: Coding Level of Contamination by Solid Particles
• API 614: Lubrication Systems for Special Purpose Applications

Practical Value

Implementing ASTM D6439-23 ensures that steam, gas, and hydroelectric turbine lubrication systems meet industry-accepted cleanliness standards. This minimizes the risk of failures caused by contaminated oil and enhances the reliability, performance, and longevity of critical power generation equipment. By following this guide, organizations benefit from reduced operational risks, better lifecycle management of lubricating oils, and improved safety and compliance with international best practices.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D6439 − 23
Standard Guide for
Cleaning, Flushing, and Purification of Steam, Gas, and
Hydroelectric Turbine Lubrication Systems
This standard is issued under the fixed designation D6439; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Optimum turbine system reliability requires a well designed lubricating system and use of a good
lubricant that is free of contaminants. Achieving this requires use of proper purification methods to
ensure that the oil is free of detrimental contaminants. In addition, it requires an ongoing monitoring
program to ensure that the oil quality is within specifications and that corrective action is taken to
minimize contaminant generation and ingression. The benefits of purification of an operating
lubrication system can be significantly reduced if the lubricating systems are not initially cleaned to
a level that will prevent component damage on initial start up after manufacturing or rebuilding.
Care and thorough cleaning are required to minimize and remove contaminants during fabrication,
rebuilding, or installation, or combination thereof. Because contaminants will remain from these
processes, it is necessary to flush and purify the system to remove them prior to startup. Ongoing
purification is required to maintain pure oil during operation. In new systems, the emphasis is on the
removal of contaminants introduced during manufacture, storage, field fabrication, and installation. In
operational systems, the emphasis is on the removal of contaminants that are generated or carried in
during operation, and by malfunctions that occur during operation or contaminants that are introduced
during overhaul, or both.
1. Scope* 1.4 This guide is applicable to both large and small lubri-
cation systems. Some equipment specified herein, however,
1.1 This guide covers types of contaminants, oil purification
may not be appropriate for all systems. Moreover, in situations
devices, contamination monitoring, contamination control dur-
where specific guidelines and procedures are provided by the
ing building or refurbishing of turbine systems, lubrication
equipment manufacturer, such procedures should take prece-
system flushing, and maintenance of pure lubrication oil.
dence over the recommendations of this guide.
1.2 To obtain maximum operating life and reliability, or
1.5 This standard does not purport to address the safety
lubricants and system, it is vital that the turbine lubrication
concerns, if any, associated with its use. It is the responsibility
system has pure oil. This guide is intended to aid the equipment
of the user of this standard to establish appropriate safety,
manufacturer, installer, and turbine operator in coordinating
health, and environmental practices and determine the appli-
their efforts to obtain and maintain clean lubrication and
cability of regulatory limitations prior to use.
control systems. These systems may be on land or marine
1.6 This international standard was developed in accor-
turbine generators and propulsion and mechanical drive equip-
dance with internationally recognized principles on standard-
ment. This guide is generalized due to variations in the type of
ization established in the Decision on Principles for the
equipment, builder’s practices, and operating conditions.
Development of International Standards, Guides and Recom-
1.3 This guide primarily addresses petroleum based lubri-
mendations issued by the World Trade Organization Technical
cating oil. For systems using nonpetroleum based fluids, this
Barriers to Trade (TBT) Committee.
guide may not be appropriate. For nonpetroleum products,
2. Referenced Documents
consult the equipment and fluid manufacturers.
2.1 ASTM Standards:
This guide is under the jurisdiction of ASTM Committee D02 on Petroleum
Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcom-
mittee D02.C0.01 on Turbine Oil Monitoring, Problems and Systems. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved July 1, 2023. Published August 2023. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1999. Last previous edition approved in 2017 as D6439 – 11 (2017). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D6439-23. the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6439 − 23
D445 Test Method for Kinematic Viscosity of Transparent ISO 4406 Hydraulic Fluid Power—Fluids—Method for
and Opaque Liquids (and Calculation of Dynamic Viscos- Coding Level of Contamination by Solid Particles
ity) ISO 4572 Hydraulic Fluid Power—Filters—Multi-pass
D664 Test Method for Acid Number of Petroleum Products Method for Evaluating Filtration Performance
by Potentiometric Titration 5
2.3 API Standard:
D974 Test Method for Acid and Base Number by Color-
API 614 Lubrication, Shaft-Sealing, and Control-Oil Sys-
Indicator Titration
tems for Special Purpose Applications
D2272 Test Method for Oxidation Stability of Steam Tur-
bine Oils by Rotating Pressure Vessel
3. Terminology
D4175 Terminology Relating to Petroleum Products, Liquid
3.1 Definitions:
Fuels, and Lubricants
3.1.1 For definitions of terms used in this guide, refer to
D4241 Practice for Design of Gas Turbine Generator Lubri-
Terminology D4175.
cating Oil Systems (Withdrawn 2008)
3.2 Definitions of Terms Specific to This Standard:
D4248 Practice for Design of Steam Turbine Generator Oil
3.2.1 adsorption, n—removal of contaminants from oil by
Systems (Withdrawn 2008)
adhesion of the contaminant in an extremely thin layer of
D4378 Practice for In-Service Monitoring of Mineral Tur-
molecules to a fixed solid. The solid can be a fiber, a fine
bine Oils for Steam, Gas, and Combined Cycle Turbines
powder, or porous particles.
D4898 Test Method for Insoluble Contamination of Hydrau-
lic Fluids by Gravimetric Analysis
3.2.2 centrifugation, n—use of centrifugal force to separate
D6304 Test Method for Determination of Water in Petro-
contaminants from oils. Contaminants such as water and
leum Products, Lubricating Oils, and Additives by Cou-
particulate are generally more dense than the oil and migrate to
lometric Karl Fischer Titration
the outside of the centrifuge because of centrifugal force.
D6810 Test Method for Measurement of Hindered Phenolic
3.2.3 cleaning, v—direct removal of contaminant from any
Antioxidant Content in Non-Zinc Turbine Oils by Linear
part of the system, generally with the system shut down or
Sweep Voltammetry
offline.
D6971 Test Method for Measurement of Hindered Phenolic
and Aromatic Amine Antioxidant Content in Non-zinc 3.2.3.1 Discussion—Cleaning can include removal of con-
Turbine Oils by Linear Sweep Voltammetry
taminant by shoveling, sweeping, squeegee, vacuuming,
D7155 Practice for Evaluating Compatibility of Mixtures of wiping, displacing with clean, high pressure water blasting/
Turbine Lubricating Oils
jetting, dry compressed air; pressure steam and can be done
D7546 Test Method for Determination of Moisture in New with the aid of cleaning solutions.
and In-Service Lubricating Oils and Additives by Relative
3.2.4 cleaning solution, n—fluid used to aid in the removal
Humidity Sensor
of sludge and particulate matter in a system.
D7647 Test Method for Automatic Particle Counting of
3.2.4.1 Discussion—Cleaning solutions may be classified as
Lubricating and Hydraulic Fluids Using Dilution Tech-
surface active oil soluble cleaners, detergent-based, or water
niques to Eliminate the Contribution of Water and Inter-
based chemical cleaners.
fering Soft Particles by Light Extinction
3.2.5 coalescence, n—process of passing oil with free water
D7843 Test Method for Measurement of Lubricant Gener-
through a fiber sheet, generally in a cartridge form, to cause
ated Insoluble Color Bodies in In-Service Turbine Oils
smaller drops of water to join to form larger ones that can be
using Membrane Patch Colorimetry
more easily removed from the oil.
D8112 Guide for Obtaining In-Service Samples of Turbine
Operation Related Lubricating Fluid 3.2.6 coalescer, n—device that uses coalescence (e.g. the
F311 Practice for Processing Aerospace Liquid Samples for
aggregation of dispersed water to form sufficiently large
Particulate Contamination Analysis Using Membrane Fil- droplets so that they fall out of oil-phase suspension) to
ters
separate water from oil.
F312 Test Methods for Microscopical Sizing and Counting
3.2.6.1 Discussion—A coalescer generally consists of one or
Particles from Aerospace Fluids on Membrane Filters
more coalescing cartridge(s) that include a hydrophobic barrier
2.2 ISO Standards:
that hinders water from remaining dispersed in passing out
ISO 3722 Hydraulic Fluid Power—Fluid Sample
with the oil as it passes from the unit. It may also contain a
Containers—Qualifying and Controlling Cleaning Meth-
filter located upstream or downstream, or both, of the coalesc-
ods
ing cartridge(s).
ISO 4021 Hydraulic Fluid Power—Particulate Contamina-
3.2.7 displacement flush, n—system flush using on-board
tion Analysis—Extraction of Fluid Samples from Lines of
turbine pumps designed to remove unwanted materials from
an Operating System.
installation or repair.
The last approved version of this historical standard is referenced on
www.astm.org.
4 5
Available from American National Standards Institute (ANSI), 25 W. 43rd St., Available from American Petroleum Institute (API), 1220 L. St., NW,
4th Floor, New York, NY 10036, http://www.ansi.org. Washington, DC 20005-4070, http://www.api.org.
D6439 − 23
3.2.8 displacement oil, n—oil used to remove either a lighter specialist contractor for the system flushing. Review of this
grade flush oil or an oil that is highly contaminated with oil guide can provide guidelines for discussion with prospective
soluble material. contractors.
3.2.9 filter, n—device containing a screen or fiber depth
5. Contamination Control Overview
medium that removes particles from oil by physically trapping
5.1 Lubrication systems can become contaminated from a
them in or on the screen or mesh.
variety of sources. The main focus of this guide is on the
3.2.10 flushing, v—circulation of liquid through the lubrica-
minimization, monitoring, and control of contaminants: water
tion system or a component, when the turbine is not operating,
and both soluble and insoluble (stationary and suspended)
to remove contaminant.
contaminants. A more detailed discussion of these types of
3.2.11 high-pressure water cleaning, n—use of high-
contaminants is given in Appendix X1.
pressure water to remove heavy rust or fouling from lube
5.2 Contamination control is the complete program of
system internals and can be defined as hydroblasting,
obtaining and maintaining a clean lubricant and lubrication
hydrojetting, high pressure water cleaning – high pressure
system. This includes proper construction and maintenance
jetting, where water jets/streams penetrate the deposits to flush
practices, appropriate purification equipment, and regular
them out from the pipe and oil system components.
monitoring of contaminants. The contamination control pro-
3.2.12 high-velocity flush, n—system flush using external
gram must be capable of identifying and measuring contami-
pumps that generate three to four times normal operating
nants and controlling them at, or preferably below, component
system velocities and a Reynolds number over 4000.
tolerances. In particular, the sensitivity of bearings, gears,
3.2.13 operating oil, n—specific charge or chemistry of oil
seals, and proportional and servo valves should be reviewed.
to be used as the final fill oil after the flush.
As described in X2.7.1, cleanliness levels for various system
components are generally established by their manufacturers’
3.2.14 oxidation, n—chemical reaction of a lubricant at
specifications. These and recommendations of the fluid manu-
elevated temperatures between dissolved atmospheric oxygen
facturer must be considered when employing contamination
and the base oil.
control systems. In addition, there are insoluble contaminants
3.2.14.1 Discussion—Oxidation reaction will be accelerated
(oxidation precursors) that are below machine tolerances, but
by the presence of oxidation accelerators such as metallic
as their volume amasses they create a potential for sludge and
contaminants and water to result in the formation of insoluble
varnish creation as a normal consequence of oxidation reac-
soft contaminants, better known as varnish contamination.
tions.
3.2.15 pure oil, n—homogeneous lubricating oil containing
5.3 Contamination control considerations must begin with
stable additives and free of soluble or insoluble contaminants
system design and continue through the manufacture,
of concentrations that exceed the lubrication system specifica-
installation, flushing, cleaning, operation, and maintenance of
tions.
the system.
3.2.16 purification, v—removal of a contaminant present in
5.4 Design of the system must consider component con-
the oil through a separation process.
taminant sensitivity and provide points for sampling oil and
3.2.17 sacrificial flush oil, n—charge of oil that is used in
methods for controlling contaminants. Contamination monitor-
the flushing process and not used as the final operating oil.
ing is discussed in Appendix X2 and contamination control
3.2.18 surface active flush, n—system flush with the use of
methods in Appendix X3. Inclusion of filtration in steam and
surface active cleaners to remove varnish and sludge.
gas turbine lubrication systems is discussed in Practices D4248
and D4241 respectively.
4. Significance and Use
5.5 The manufacturer must minimize the amount of built-in
4.1 This guide is intended to aid the equipment
contaminant by minimizing ingression and by flushing com-
manufacturer, installer, service company, and turbine operator
ponents to achieve target cleanliness levels in the finished
in coordinating their efforts to obtain and maintain clean
component.
lubrication and control systems.
5.6 Contamination control during installation and major
4.2 The flushing and cleaning philosophies stated in this
maintenance of turbine systems is discussed in Section 6.
guide are applicable to both large and small lubrication
systems. 5.7 Proper heating is critical during flushing and routine
operation to minimize oil degradation. Heating is discussed in
4.3 Clean lubrication systems result from proper system
Appendix X4.
design and good planning, execution, and communication by
all involved during commissioning. No phase of these proce- 5.8 Removal of contamination by flushing is discussed in
dures should be undertaken without a thorough understanding Section 7.
of the possible effects of improper system preparation. The
5.9 Contamination control in operational systems and dur-
installation, cleaning, and flushing of the equipment should not
ing routine maintenance is discussed in Section 8. Properly
be entrusted to persons lacking in experience.
designed systems can normally control water and insoluble
4.4 Because of the knowledge and specialized equipment contaminants in operational systems. If, however, it is neces-
that is required, the operator may wish to employ an outside sary to remove soluble contaminants other than water, an oil
D6439 − 23
change and also possibly a flush may be required preceeded by been removed. For very compact system it is strongly recom-
an oil system surface cleaning. mended to check the preassembled system, with inspection for
example from the disassembly of flanges, valves etc. As these
6. Contamination Control When Installing and components are usually under the warranty of the manufacture,
Refurbishing Turbine Systems it will be critical to communicate this to the manufacture as of
part of control at delivery.
6.1 General:
6.2.1.3 Undercover storage is recommended. Monthly in-
6.1.1 Exclusion or removal of contaminant, or both, in
spections are recommended, and corrective steps must be taken
manufacturing or refurbishing, or both, are necessary for a
when necessary. Care must be taken during inspections to
subsequent successful flushing and cleaning. This process can
minimize disturbance of equipment protection.
be achieved only by the cooperation and diligence of many
parties.
6.2.2 Corrosion Protection:
6.1.2 Examples of Essential Precautions to Exclude or
6.2.2.1 The application of various types of rust preventives
Remove Contaminant, or Both:
is required to protect uncoated ferrous surfaces from corrosion
6.1.2.1 The system should be designed to allow successful
during the storage and installation phases. Most preservatives
cleaning.
today are oil soluble, and special procedures, such as hydraulic
6.1.2.2 The pipe and other equipment must be properly
lancing, are often used to preserve gear cases, sumps, and
cleaned and preserved.
tanks. The preservative compounds can normally be removed
6.1.2.3 All possible locations for the entrance of dirt (pipe
by flushing the system with regular lubrication oil or oil
ends) must be durably covered and secured for storage prior to
solvent, although hand cleaning of some components is also
shipment and loading. Shipment and unloading must take place
employed. If possible, however, the flush oil, operating oil, and
without damage to these covers.
preservative should be compatible to preclude foaming, the
6.1.2.4 Inspection of pipe at the turbine site must be
formation of emulsions, precipitates or the breakdown of
thorough to discover any damage or open covers and to have
lubrication oil additives. A system flush (displacement flush)
them repaired.
with a sacrificial flush oil is often recommended to minimize
6.1.2.5 Storage prior to installation must be in a sheltered
operating oil contamination which could result in reduced
location, especially if the storage is to be for a long duration.
performance. Product compatibility of the flush oil should be
6.1.2.6 Inspection immediately prior to installation must be
confirmed in accordance with Practice D7155 testing. Caution
thorough, and the pipe must be cleaned if excessive rust or dirt
should be exercised in this regard. Compatibilities and limita-
is discovered.
tions may generally be obtained from the oil suppliers. Corro-
6.1.2.7 Continuous monitoring of conditions during the
sion preventatives have the possibility to be removed by
complete turbine installation must take place to ensure that
flushing, however care should be taken to assure that all of
cleanliness related tasks are being accomplished. Dirt should
them have been removed. Consequently it is recommended to
not be introduced into the pipes and equipment.
check the oil quality after the displacement flush. Achieving oil
6.1.2.8 Great care must be taken to prevent contaminant
temperature between 55 °C to 60 °C and higher if possible
entry during any modifications.
plays a big role in removing the traces of these corrosion
6.1.2.9 The work area must be kept clean.
preventatives. The flushing shall be followed by a thorough oil
6.1.2.10 This list is not complete, but it does illustrate that
drain of the displacement oil and should be performed care-
the manufacturer, the shipper, the operator, and the installation
fully. Review with the equipment manufacturer may also be
contractor (service company) are all responsible for ensuring
beneficial. All oils added, including preservative oils, should be
that no contaminants enter the lubrication system. These efforts
filtered as discussed in 7.6.
to prevent the entrance of dirt will make the flushing procedure
6.2.2.2 Once the rust preventative is removed, the ferrous
easier, safer, and shorter, and thus less costly.
surfaces are subject to rust unless care is taken to keep all
6.2 On-Site Contamination Control:
surfaces oil-wetted. Corrosion of unwetted surfaces can be
6.2.1 General:
minimized by the use of vapor space inhibited oils to the
6.2.1.1 All components that are fabricated and assembled at
maximum extent possible. The general procedure for the use of
a manufacturer’s facility and received as a unit for installation
the vapor space inhibited oils is as follows:
in the system are defined as preassembled components.
(1) Wet all surfaces with vapor space inhibited oils after
6.2.1.2 The preassembled components should be inspected
cleaning.
upon receipt to determine condition and degree of protection.
(2) Do not drain; add sufficient oil to provide a reservoir of
All seals and caps intended to exclude moisture and dirt should
the oil in the assembly.
be checked for integrity and replaced as required. If the initial
(3) Seal the component to prevent loss of vapor phase
or a subsequent inspection discloses dirt or rusting, the item
protection and intrusion of contaminants.
should be immediately cleaned, represerved, and sealed, as
6.2.2.3 These vapor space inhibited oils may be fully
required. Because of the variety of equipment and materials,
compatible with regular lubricating oils and flushing oils, and
details for each case cannot be given here. For painted (coated)
components, the coating should be inspected for integrity and draining or removal may not be necessary. Compatibility
testing in accordance with Practice D7155 is recommended to
renewed as necessary. All components should be checked to
ensure that all tape and temporary supports or restraints have confirm compatibility. In addition, it has been shown that these
D6439 − 23
oils may provide some residual protection to the system and 6.2.4.3 Internal surfaces that cannot be reached should be
minimize corrosion after the oils have been drained or dis- flushed with an oil soluble cleaner or filtered petroleum
solvent. Alkaline or acid cleaners should not be used.
placed.
6.2.2.4 The vapor space inhibited oils are available in a
NOTE 1—Petroleum solvents are flammable; care must be taken to
range of viscosities. However, if an oil of significantly higher prevent fires. Precautions must also be taken to ensure that workers do not
inhale fumes from the solvent or come into contact with liquid solvents for
viscosity than the flushing oil is used, draining of the as-
prolonged periods. Filters can generate electric charges. Proper electrical
sembled system to limit the amount of the higher viscosity to
connection of all equipment prior to transferring fluids or starting flushing
10 % is recommended to prevent significantly increasing the
is required.
viscosity of the flushing oil.
6.2.4.4 After internal surfaces have been cleaned, they
6.2.3 Gear Assemblies:
should be sealed or put into service as soon as possible. If the
6.2.3.1 When shipping gears, additional braces and tapes internal surfaces cannot be effectively sealed or put into
are frequently used to prevent movement of the elements and service, they must be thoroughly air dried and coated imme-
diately by spraying them with filtered and compatible rust
damage to the teeth and bearings. Upon receipt of the as-
preventive oil. After all surfaces have been coated, the equip-
sembled gears at the installation point, an inspection should be
ment should be reassembled and all openings capped. This rust
conducted with the gear manufacturer’s representative to
preventative coating may require removal with flush oil prior to
determine whether any damage has occurred during shipment.
equipment use.
At this time the gears should be thoroughly inspected for
6.2.5 Sumps and Tanks—Sumps, reservoirs, or tanks should
contamination, and if any is found, the manufacturer’s recom-
be completely drained and thoroughly inspected. If present,
mendation should be followed for proper represervation. Peri-
rust, mill scale, weld spatter, loose paint, and so forth, should
odic inspections, careful to minimize vapor space inhibition
be manually removed. A coating of rust-preventive oil, or a
loss, should be made to ensure that proper preservation is
vapor space inhibitor oil, should be applied, and all openings
maintained until the gear assembly is placed into regular
should be sealed. This rust preventative coating may require
operation. Upon installation, all temporary restraints, including
removal with flush oil. Repainting is not recommended.
tape, must be removed.
6.2.6 Bearings—It is important that bearings be installed by
6.2.3.2 Speed reducers are normally shipped with a thin
qualified personnel. Extreme care should be taken to prevent
coating of preservatives applied to all internal machined
accidental contamination of, or damage to, the bearings and
surfaces that are in contact with lubrication oil, such as gear
journals. Bearing surfaces should be protected by rust-
teeth, bearings, journals, interior housing surfaces, and oil
preventive oil that is readily soluble in flushing oil or vapor
piping. The preservative is oil soluble and is normally removed
space inhibitor oil. All openings should be sealed.
by the flushing program. Gear cases, protected by vapor space
6.2.7 Control Devices—Installation and contamination pro-
inhibited lubricating oil, should be inspected upon receipt for
tection for oil-wetted control devices should be handled as
integrity of seals. Damaged seals should be replaced immedi-
carefully as that for bearings. Extreme care must also be taken
ately. If the oil has been lost, the gear case and the gears should
to prevent accidental contamination of the associated piping
be pressure sprayed through the inspection openings with
during installation.
filtered vapor space inhibited oil or rust preventive oil at 55 °C
6.2.8 Pumps—Prior to assembly and installation, pumps
to 57 °C (130 °F to 135 °F). Starting at the top of the case, the
should be inspected for the presence of hard film coatings or
gear case and the gears should be thoroughly flushed down.
contaminants. If any are present, the pumps should be thor-
After flushing, the oil level recommended by the gear manu-
oughly cleaned, coated with rust-preventive or vapor-space
facturer should be reestablished and the unit sealed.
inhibitor oil, and sealed.
6.2.4 Valves, Strainer, and Coolers:
7. Flushing
6.2.4.1 Valves and strainers, when received from the
manufacturer, should be inspected to determine if there is
7.1 If the equipment manufacturer has supplied detailed
contamination. If there is evidence of a hard film protective
flushing procedures, they should take precedence over these
coating or contamination, the unit should be dismantled and all recommendations.
the parts thoroughly cleaned with filtered petroleum solvent. In
7.2 Flushing Methods:
all cases, use clean, lintless cloths (not waste cloths), a
7.2.1 Displacement Flush—For new systems and systems
squeegee, or a vacuum cleaner.
with service hours that do not typically require surface active
6.2.4.2 Coolers should be verified clean from the manufac-
cleaning or the improved cleaning of a high-velocity flush, but
turer. A Borescope can be used prior to installation for
require lubricant ISO Cleanliness lowered to meet OEM
inspection. If any contamination is found within the cooler the
specification or replacement of current charge of lubricant.
system should be cleaned to meet the turbine manufacturer
7.2.1.1 For a unit that is field assembled, keeping the
cleanliness specification. Depending on the type of cooler (Fin
lubrication and hydraulic control system piping clean enough
Fan, Plate, Shell & Tube), metallurgy, and contamination found
so that flushing is not necessary is economically and practically
cleaning can consist of chemical cleaning and or oil flushing to impossible. Thus, it is generally recognized that an oil flush
expedite the process. Care should be taken to review cooler
must take place after the piping has been installed and just
pressure and flow restrictions. before the turbine and its driven equipment go into operation.
D6439 − 23
The success of this oil flush, however, depends to a large and return flow rates and protect critical surfaces from con-
degree on the success of the efforts to keep dirt out initially and taminants. System headers may be isolated to increase pipeline
the proper preparation and conduct of the flush. A successful velocity. The use of outside pumps is typically required to
flush means that clean pipe and system components are achieve this flow.
obtained in a minimum of time and with a minimum of effort.
7.2.3 Surface Active Oil Soluble or Detergent Based
7.2.1.2 The cleaning and flushing of both new and used Cleaner—Flushing for in-service systems with varnish or
systems are accomplished by essentially the same procedure. sludge that require a cleaning solution for effective deposit
In the new systems, the emphasis is on the removal of removal.
contaminants introduced during the manufacture, storage, sys-
NOTE 2—Using detergents, as surface tension acting products, in
tem temporary rust protection, field fabrication, and installa-
turbine lube oil systems can impact the lube oil characteristics such as air
tion. In used systems, the emphasis is on removal of contami-
release or demulsibility. When using detergents, it is strongly recom-
nants that are generated during operation or are introduced to
mended to perform additional flushing steps to remove the remaining
concentration of these detergents, and attach a lot of importance on the
the system during overhaul.
maximum drain of the flushing oil.
7.2.1.3 A displacement flush utilizes a displacement flush
oil of the same chemistry as the final operating oil. System 7.2.3.1 Some turbine and associated hydraulic systems may
pumps and flow channels are utilized to circulate the displace- require a surface active flush to clean inaccessible internal
ment flush oil. Side stream filtration is recommended to surfaces of varnish. The term varnish is being used to include
improve flush effectiveness. all internal deposits, including sludge. Flushing with a surface
active cleaner is typically reserved for gas turbines with
7.2.2 High-Velocity Flush—For new systems and systems
combined hydraulic and turbine oil reservoirs. Minor levels of
with service hours that may not require surface active cleaning
oil soluble cleaners or solvent cleaners may impact operating
and will benefit from enhanced flushing compared to displace-
oil demulsibility, required in steam turbine operation. A sub-
ment flushing. High velocity oil flush results typically in a
sequent displacement flush shall be conducted to effectively
higher cleaning efficiency and also in a flushing time that is
remove the surface active cleaning agent. Both the surface
significantly shortened. Moreover, high flow rates of oil initiate
active flushing fluid and the following displacement flush fluid
the removal of contaminants in most cases (apart from severe
should not be reused as they may impact the performance of
corrosion of oil aging agglomerates and varnish), whereas
the final system operating oil. Hydraulic system flushing can be
flushing with system pumps do not assure the contamination
improved with the use of flushing blocks that are used to
displacement from all corners, pipes, dead zones of the oil
bypass the system servo valves.
system.
7.2.3.2 Some hydraulic fouling deposits require water-based
7.2.2.1 It is important to review the flow path and verify that
cleaning agents, that is, chemical cleaning – degrease. This
no restrictions or dead spots are left while flushing activities
method should only be used in extreme fouling and oxidation
are taking place before performing a high-velocity flush. Low
applications. In the event that the lubricant oxidizes and carbon
or no, flow regions (dead spots) or “traps” will allow for
deposits cause filter plugging and hydraulic valve failure a
contaminates to gather and redistribute throughout the system
lubrication engineer and chemical service flushing expert
once the flush has concluded.
should be consulted to review the metallurgy of the system and
7.2.2.2 Lube oil lines that do not see continuous flow during
chemistry appropriate to clean the system. Water-based chemi-
normal operation often collect contaminates at valves and
cal cleaning will be followed by lube oil displacement or
orifices. These locations can be found on the outlet side of the
high-velocity oil flushing and vacuum dehydration to remove
system pumps, that is, pressure relief valves, and on units with
residual water and particulate contaminates.
fixed drain piping back to the lube oil reservoir. In these cases,
the lube oil flushing procedure should include opening and 7.2.4 High-pressure water flush for systems with service
hours that have developed significant rust or fouling to the
flushing out these lines.
extent that less aggressive flushing methods are ineffective.
7.2.2.3 Moreover, achieving the high oil velocities in return
Cleaning the surfaces with high pressure water stream/jets
headers is hardly achievable without additional distribution of
means that the water streams/jets at high pressure level
additional oil stream headed separately from the flushing skid.
effectively penetrates the soft and hard deposits (especially
The disproportion of supply/discharge header compared to
rust, welding slag and splatter, varnish agglomerates) that high
return header is the reason. High-velocity Oil Flushing is
oil velocities removes slowly, less effectively, if at all. Special
critical to removing contaminates left behind when foreign
care must be taken to remove all flush water at the completion
material can be introduced to the lube oil system and in cases
of this flush.
when welding activities are conducted in the field, that is,
precommissioning, pipe-modifications, major maintenance ac- 7.2.5 General Flushing Method Guidance:
tivities.
7.2.5.1 It may not be practical to flush through certain
7.2.2.4 The primary requirement for a successful oil flush is systems or devices that are assembled, cleaned, and sealed in
a high oil velocity at least three to four times normal system the factory before shipment. Such equipment should be care-
velocity, and a Reynolds number over 1000 within the system. fully protected against intrusion of contaminants, and in this
Wherever possible, turbulent flow should be achieved in flushing procedure, such equipment should be blanked off or
system pipes. Jumpers are installed around critical components bypassed until other systems are clean. This guidance also
such as bearings and control valves to elevate bearing supply applies to oil coolers, that are highly recommended to flush
D6439 − 23
separately first and avoid massive dirt ingress in other oil not to be flushed should be blanked off with the use of
system sections and piping. numbered blanks. Ensure that the flushing loop is contained
7.2.5.2 Even for assemblies that can be flushed through
with positive-closure valves; check valves are insufficient to
freely, the prescribed flushing procedure may not have the
protect equipment from high-velocity flush. The numbered
ability to flush out any and all conceivable kinds of contami-
blanks must be removed from the system and accounted for on
nants. Much adverse experience testifies to this. Therefore, it is
a checklist at the end of the flushing period. All items should be
clear that great care should be exercised during the entire
identified on flush flow path marked P&ID DWG’s and written
system installation to prevent unnecessary impurities from
procedures.
entering the oil systems that cannot be easily removed by
7.4.3 Despite all efforts, some particles large enough to
flushing. Such contamination, when dislodged by turbine
damage pumps may remain. In all systems, installing tempo-
vibration or system operational effects, could cause problems
rary strainers of 80 to 100 mesh on the suction side of the
in subsequent operations.
lubrication oil or flush pumps, or both, is recommended. In
7.2.5.3 The knowledge that a system flush will be per-
addition, install temporary fine mesh strainers on the discharge
formed before startup should not be allowed to lead to the
side of gravity and pressure systems. Customary marine
misconception that contaminants entering the oil system are
practice is to install these in the duplex strainers on the
not harmful because “they will all be removed by the flush.”
discharge side.
7.2.5.4 A written process and procedure should be devel-
oped for each flush regardless of OEM. The procedure should 7.4.4 Whenever possible, use of full flow filters during the
include OEM cleanliness guidelines, site specific standards,
flush is recommended. Auxiliary filters may be used to provide
owner requirements, deliverables, lubrication handling, and
higher filtered oil flow rates and finer filtration. All purification
timeline.
systems should be ready for operation as soon as the flushing
oil is installed. It is generally desirable to purify the reservoir,
7.3 General Guidelines for Flushing of Operational Systems
pump, and purification systems before beginning to flush the
to Remove Contaminant:
rest of the unit. This has the advantage of providing clean oil
7.3.1 Guidelines for when to remove used oil or flush an
operational system to reduce contaminant, or both, are given in to other parts of the system. In addition, when purified oil is
8.5. used for flushing, the increased contaminant observed in the oil
7.3.2 The remainder of Section 7 should be reviewed and when additional sections are flushed gives some measure of
the applicable sections decided upon, after consultation of the
flush effectiveness. If necessary, pipes and valves for recircu-
equipment user with the appropriate suppliers, based on the
lation to the reservoir should be installed. If this piping is
condition of the system and used oil.
temporary, valves at the reservoir and purification device
7.3.3 Sea water contamination requires special procedures.
should be provided to allow removal of the temporary piping.
After removal of excess salt water, corrosion inhibitors spe-
7.4.5 Frequently, sampling points installed for monitoring
cifically developed for this type of contamination might be
oil cleanliness during routine operation are not adequate to
used in the system.
monitor the cleanliness of components and the progress of the
7.4 Preparation of System for Flushing:
flush. Sampling points must be installed as necessary, as
7.4.1 Prior to the flushing operation, all accessible areas of
described in X2.2.2, and Guide D8112. If the lubricating oil
the lubricating oil system should be thoroughly inspected. If
heater has not been installed, or if it is inadequate, heat may be
significant contaminant is encountered, it should be manually
supplied to the flushing oil in several ways. The best method is
removed. Final inspection for welding splatter or materials that
to pass hot water through the cooler; this can be generated by
may break loose and contaminate the system with metallic
bubbling low-pressure steam through the water somewhere
particles should be made. If found they should be completely
outside the cooler. The cooler must be vented to the atmosphere
removed. As always, containment of oil within the powerhouse
to prevent pressure build up. Low pressure steam may also be
is important. Ensure that any service companies involved are
used; however, the cooler should be checked against the
aware of the responsibility to prevent oil from reaching the
manufacturer’s recommendation. Great care must be taken to
environment. For piping systems that are not typically exposed
ensure that not over 34 kPa (5 psig) steam is admitted to the
to the pressures and temperatures, (and vibrations, if appli-
cooler so that the cooler is not damaged and the flushing oil is
cable) being used during flushing, preparations must be made
not overheated. Electrical heaters may also be used. The
to quickly and effectively respond to any potential oil leaking
cautions outlined in Appendix X4 must be observed to avoid
from the system.
overheating the oil.
7.4.2 Any temporary humidity control devices (vacuum
7.4.6 A lance attached to a clean hose should be used for hot
dehydrators, coalescing filters) placed in the system must be
oil spraying of gearing or other hard to reach areas. It can be
removed. The state of cleanliness of the system at this time is
attached to the cooler (currently being used as a heater) or an
always questionable, and therefore, all lubricating oil mani-
oil pump discharge strainer. For safety, the hose, lance, and any
folds and leads to bearings must be blanked off as closely as
other fittings used must be pressure rated for the full flush
possible to the parts they serve. For high-velocity flushing,
pump outlet pressure. Precautions must also be taken to protect
jumpers may be installed to bypass all bearings, but they
personnel from the hot oil spray. Extreme fire and spark
should be so installed as to bypass as little of the piping and
flow passages as possible. All other areas in the system that are protection precautions must be taken. Even less hazardous
D6439 − 23
lubricants can ignite if heated and sprayed; conventional 7.5.4 Varnish Cleaner Selection—Removing varnish from
mineral oils may form explosive mixtures under such condi- lube oil system surfaces can be accomplished through the use
tions. of cleaners. This varnish is not removed from the system. Once
dispersed from surfaces, it remains suspended within the
7.4.7 A rotating nozzle (patent pending) is attached to a
lubricant. Cleaners are, therefore, to be used in accordance
flange and a clean hose for hot oil spraying of gearing or other
with the recommendations by the cleaner’s supplier or manu-
hard to reach areas. It can be supplied via temporary bypass
facturer.
line from system supply header line. The nozzle is mounted on
7.5.4.1 Surface Active Oil Soluble Cleaners—is added to the
1 150# flange and inserted inside of the area to be flushed. A
operating turbine at the supplier’s recommended percentage,
360º rotating nozzle sprays the flushing oil, and used for seal
mixed and circulated with in-service oil, and then drained with
oil tanks and larger gear box openings that allow for insertion
in-service oil during a maintenance outage. Selection of
of the mechanism.
surface-active oil soluble cleaner should take into account
7.5 Selection of Flushing Oil:
compatibility with in-service oil, cleaning time available prior
7.5.1 The oil selected for flushing of the system can be
to outage and by the supplier’s recommendation, and cleaning
either the system operating oil or flushing oil that is compatible efficiency.
with the operating oil . In cases where residual flush oil may be
7.5.4.2 Detergent-Based Cleaners—used for cleaning tur-
of sufficient quantity as to impact system operating oil bine reservoirs during maintenance outages, often performed
performance, similar viscosity flushing oil should be used. In
by third party flushing companies using auxiliary filtration.
some cases there may be a benefit to using a very low viscosity Sacrificial rinses are required to remove any residual cleaner as
oil (~15 cSt) for high-velocity flushing, then performing a this will interfere with performance of the new turbine oil.
displacement flushing step with in-service oil which will be 7.5.4.3 Water-Based Chemical Cleaners—used for cleaning
discarded, prior to bringing the system back into normal turbine reservoirs during maintenance outages, often per-
operation. In all cases, the selection of the type of flushing oil formed by third party flushing companies. Water and a chemi-
to be used should be based on the judgment of experienced cal cleaner are added to a drained lube oil reservoir, circulated
personnel after thorough inspection of the lubricating system. at high velocity throughout the system and then drained. The
To minimize oil contamination, delivery should only be made system is then dried prior to filling with new turbine oil.
in clean containers with clean or flushed hoses, pumps and
7.6 Supplying Flushing Oil to Reservoir—When filling the
manifolds. For large quantities, use of stainless steel or
turbine lubricating sys
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D6439 − 11 (Reapproved 2017) D6439 − 23
Standard Guide for
Cleaning, Flushing, and Purification of Steam, Gas, and
Hydroelectric Turbine Lubrication Systems
This standard is issued under the fixed designation D6439; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Optimum turbine system reliability requires a well designed lubricating system and use of a good
lubricant that is free of contaminants. Achieving this requires use of proper purification methods to
ensure that the oil is free of detrimental contaminants. In addition, it requires an ongoing monitoring
program to ensure that the oil quality is within specifications and that corrective action is taken to
minimize contaminant generation and ingression. The benefits of purification of an operating
lubrication system can be significantly reduced if the lubricating systems are not initially cleaned to
a level that will prevent component damage on initial start up after manufacturing or rebuilding.
Care and thorough cleaning are required to minimize and remove contaminants during fabrication,
rebuilding, or installation, or combination thereof. Because contaminants will remain from these
processes, it is necessary to flush and purify the system to remove them prior to startup. Ongoing
purification is required to maintain pure oil during operation. In new systems, the emphasis is on the
removal of contaminants introduced during manufacture, storage, field fabrication, and installation. In
operational systems, the emphasis is on the removal of contaminants that are generated or carried in
during operation, and by malfunctions that occur during operation or contaminants that are introduced
during overhaul, or both.
1. Scope Scope*
1.1 This guide covers types of contaminants, oil purification devices, contamination monitoring, contamination control during
building or refurbishing of turbine systems, lubrication system flushing, and maintenance of pure lubrication oil.
1.2 To obtain maximum operating life and reliability, or lubricants and system, it is vital that the turbine lubrication system has
pure oil. This guide is intended to aid the equipment manufacturer, installer, and turbine operator in coordinating their efforts to
obtain and maintain clean lubrication and control systems. These systems may be on land or marine turbine generators and
propulsion and mechanical drive equipment. This guide is generalized due to variations in the type of equipment, builder’s
practices, and operating conditions.
1.3 This guide primarily addresses petroleum based lubricating oil. For systems using nonpetroleum based fluids, this guide may
not be appropriate. For nonpetroleum products, consult the equipment and fluid manufacturers.
1.4 This guide is applicable to both large and small lubrication systems. Some equipment specified herein, however, may not be
This guide is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.C0.01 on Turbine Oil Monitoring, Problems and Systems.
Current edition approved May 1, 2017July 1, 2023. Published July 2017August 2023. Originally approved in 1999. Last previous edition approved in 20112017 as
D6439 – 11.D6439 – 11 (2017). DOI: 10.1520/D6439-11R17. 10.1520/D6439-23.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6439 − 23
appropriate for all systems. Moreover, in situations where specific guidelines and procedures are provided by the equipment
manufacturer, such procedures should take precedence over the recommendations of this guide.
1.5 This standard does not purport to address the safety concerns, if any, associated with its use. It is the responsibility of the
user of this standard to establish appropriate safety and healthsafety, health, and environmental practices and determine the
applicability of regulatory limitations prior to use.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D445 Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
D664 Test Method for Acid Number of Petroleum Products by Potentiometric Titration
D974 Test Method for Acid and Base Number by Color-Indicator Titration
D2272 Test Method for Oxidation Stability of Steam Turbine Oils by Rotating Pressure Vessel
D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
D4241 Practice for Design of Gas Turbine Generator Lubricating Oil Systems (Withdrawn 2008)
D4248 Practice for Design of Steam Turbine Generator Oil Systems (Withdrawn 2008)
D4378 Practice for In-Service Monitoring of Mineral Turbine Oils for Steam, Gas, and Combined Cycle Turbines
D4898 Test Method for Insoluble Contamination of Hydraulic Fluids by Gravimetric Analysis
D6304 Test Method for Determination of Water in Petroleum Products, Lubricating Oils, and Additives by Coulometric Karl
Fischer Titration
D6810 Test Method for Measurement of Hindered Phenolic Antioxidant Content in Non-Zinc Turbine Oils by Linear Sweep
Voltammetry
D6971 Test Method for Measurement of Hindered Phenolic and Aromatic Amine Antioxidant Content in Non-zinc Turbine Oils
by Linear Sweep Voltammetry
D7155 Practice for Evaluating Compatibility of Mixtures of Turbine Lubricating Oils
D7546 Test Method for Determination of Moisture in New and In-Service Lubricating Oils and Additives by Relative Humidity
Sensor
D7647 Test Method for Automatic Particle Counting of Lubricating and Hydraulic Fluids Using Dilution Techniques to
Eliminate the Contribution of Water and Interfering Soft Particles by Light Extinction
D7843 Test Method for Measurement of Lubricant Generated Insoluble Color Bodies in In-Service Turbine Oils using
Membrane Patch Colorimetry
D8112 Guide for Obtaining In-Service Samples of Turbine Operation Related Lubricating Fluid
F311 Practice for Processing Aerospace Liquid Samples for Particulate Contamination Analysis Using Membrane Filters
F312 Test Methods for Microscopical Sizing and Counting Particles from Aerospace Fluids on Membrane Filters
2.2 ISO Standards:
ISO 3722 Hydraulic Fluid Power—Fluid Sample Containers—Qualifying and Controlling Cleaning Methods
ISO 4021 Hydraulic Fluid Power—Particulate Contamination Analysis—Extraction of Fluid Samples from Lines of an
Operating System.
ISO 4406 Hydraulic Fluid Power—Fluids—Method for Coding Level of Contamination by Solid Particles
ISO 4572 Hydraulic Fluid Power—Filters—Multi-pass Method for Evaluating Filtration Performance
2.3 API Standard:
API 614 Lubrication, Shaft-Sealing, and Control-Oil Systems for Special Purpose Applications
3. Terminology
3.1 Definitions:
3.1.1 For definitions of terms used in this guide, refer to Terminology D4175.
3.2 Definitions of Terms Specific to This Standard:
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
Available from American Petroleum Institute (API), 1220 L. St., NW, Washington, DC 20005-4070, http://www.api.org.
D6439 − 23
3.2.1 adsorption, n—removal of contaminants from oil by adhesion of the contaminant in an extremely thin layer of molecules
to a fixed solid. The solid can be a fiber, a fine powder, or porous particles.
3.2.2 centrifugation, n—use of centrifugal force to separate contaminants from oils. Contaminants such as water and particulate
are generally more dense than the oil and migrate to the outside of the centrifuge because of centrifugal force.
3.2.3 cleaning, v—direct removal of contaminant from any part of the system, generally with the system shut down or offline.
Cleaning can include removal of contaminant by shoveling, sweeping, squeegee, vacuuming, wiping, displacing with clean, dry
compressed air and can be done with the aid of cleaning solutions.
3.2.3.1 Discussion—
Cleaning can include removal of contaminant by shoveling, sweeping, squeegee, vacuuming, wiping, displacing with clean, high
pressure water blasting/jetting, dry compressed air; pressure steam and can be done with the aid of cleaning solutions.
3.2.4 cleaning solution, n—fluid used to aid in the removal of sludge and particulate matter in a system. Cleaning solutions may
be classified as chemical cleaners, solvent cleaners, or oil soluble cleaners.
3.2.4.1 Discussion—
Cleaning solutions may be classified as surface active oil soluble cleaners, detergent-based, or water based chemical cleaners.
3.2.5 coalescence, n—process of passing oil with free water through a fiber sheet, generally in a cartridge form, to cause smaller
drops of water to join to form larger ones that can be more easily removed from the oil.
3.2.6 coalescer, n—device that uses coalescence to separate water from oil. A coalescer generally consists of a coalescing
cartridge(s) and a hydrophobic barrier that hinders water from passing out with the oil. It may also contain a filter located upstream
or downstream, or both, of the coalescing cartridge(s).(e.g. the aggregation of dispersed water to form sufficiently large droplets
so that they fall out of oil-phase suspension) to separate water from oil.
3.2.6.1 Discussion—
A coalescer generally consists of one or more coalescing cartridge(s) that include a hydrophobic barrier that hinders water from
remaining dispersed in passing out with the oil as it passes from the unit. It may also contain a filter located upstream or
downstream, or both, of the coalescing cartridge(s).
3.2.7 displacement flush, n—system flush using on-board turbine pumps designed to remove unwanted materials from installation
or repair.
3.2.8 displacement oil, n—oil used to remove either a lighter grade flush oil or an oil that is highly contaminated with oil soluble
material.
3.2.9 filter, n—device containing a screen or fiber depth medium that removes particles from oil by physically trapping them in
or on the screen or mesh.
3.2.10 flushing, v—circulation of liquid through the lubrication system or a component, when the turbine is not operating, to
remove contaminant.
3.2.11 high-pressure water flush,cleaning, n—use of high-pressure water to remove heavy rust or fouling from lube system
internals.internals and can be defined as hydroblasting, hydrojetting, high pressure water cleaning – high pressure jetting, where
water jets/streams penetrate the deposits to flush them out from the pipe and oil system components.
3.2.12 high-velocity flush, n—system flush using external pumps that generate three to four times normal operating system
velocities and a Reynolds number over 4000.
3.2.13 operating oil, n—specific charge or chemistry of oil to be used as the final fill oil after the flush.
3.2.14 oxidation, n—chemical reaction of a lubricant at elevated temperatures between dissolved atmospheric oxygen and the base
oil. Oxidation reaction will be accelerated by the presence of oxidation accelerators such as metallic contaminants and water.
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3.2.14.1 Discussion—
Oxidation reaction will be accelerated by the presence of oxidation accelerators such as metallic contaminants and water to result
in the formation of insoluble soft contaminants, better known as varnish contamination.
3.2.15 pure oil, n—homogeneous lubricating oil containing stable additives and free of soluble or insoluble contaminants of
concentrations that exceed the lubrication system specifications.
3.2.16 purification, v—removal of a contaminant present in the oil through a separation process.
3.2.17 sacrificial flush oil, n—charge of oil that is used in the flushing process and not used as the final operating oil.
3.2.18 surface active flush, n—system flush with the use of surface active cleaners to remove varnish and sludge.
4. Significance and Use
4.1 This guide is intended to aid the equipment manufacturer, installer, service company, and turbine operator in coordinating their
efforts to obtain and maintain clean lubrication and control systems.
4.2 The flushing and cleaning philosophies stated in this guide are applicable to both large and small lubrication systems.
4.3 Clean lubrication systems result from proper system design and good planning, execution, and communication by all involved
during commissioning. No phase of these procedures should be undertaken without a thorough understanding of the possible
effects of improper system preparation. The installation, cleaning, and flushing of the equipment should not be entrusted to persons
lacking in experience.
4.4 Because of the knowledge and specialized equipment that is required, the operator may wish to employ an outside specialist
contractor for the system flushing. Review of this guide can provide guidelines for discussion with prospective contractors.
5. Contamination Control Overview
5.1 Lubrication systems can become contaminated from a variety of sources. The main focus of this guide is on the minimization,
monitoring, and control of contaminants: water and both soluble and insoluble (stationary and suspended) contaminants. A more
detailed discussion of these types of contaminants is given in Appendix X1.
5.2 Contamination control is the complete program of obtaining and maintaining a clean lubricant and lubrication system. This
includes proper construction and maintenance practices, appropriate purification equipment, and regular monitoring of
contaminants. The contamination control program must be capable of identifying and measuring contaminants and controlling
them at, or preferably below, component tolerances. In particular, the sensitivity of bearings, gears, seals, and proportional and
servo valves should be reviewed. As described in X2.7.1, cleanliness levels for various system components are generally
established by their manufacturers’ specifications. These and recommendations of the fluid manufacturer must be considered when
employing contamination control systems. In addition, there are insoluble contaminants (oxidation precursors) that are below
machine tolerances, but as their volume amasses they create a potential for sludge and varnish creation as a normal consequence
of oxidation reactions.
5.3 Contamination control considerations must begin with system design and continue through the manufacture, installation,
flushing, cleaning, operation, and maintenance of the system.
5.4 Design of the system must consider component contaminant sensitivity and provide points for sampling oil and methods for
controlling contaminants. Contamination monitoring is discussed in Appendix X2 and contamination control methods in Appendix
X3. Inclusion of filtration in steam and gas turbine lubrication systems is discussed in Practices D4248 and D4241 respectively.
5.5 The manufacturer must minimize the amount of built-in contaminant by minimizing ingression and by flushing components
to achieve target cleanliness levels in the finished component.
5.6 Contamination control during installation and major maintenance of turbine systems is discussed in Section 6.
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5.7 Proper heating is critical during flushing and routine operation to minimize oil degradation. Heating is discussed in Appendix
X4.
5.8 Removal of contamination by flushing is discussed in Section 7.
5.9 Contamination control in operational systems and during routine maintenance is discussed in Section 8. Properly designed
systems can normally control water and insoluble contaminants in operational systems. If, however, it is necessary to remove
soluble contaminants other than water, an oil change and also possibly a flush may be required.required preceeded by an oil system
surface cleaning.
6. Contamination Control When Installing and Refurbishing Turbine Systems
6.1 General:
6.1.1 Exclusion or removal of contaminant, or both, in manufacturing or refurbishing, or both, are necessary for a subsequent
successful flush and flushing and cleaning. This process can be achieved only by the cooperation and diligence of many parties.
6.1.2 Examples of Essential Precautions to Exclude or Remove Contaminant, or Both:
6.1.2.1 The system should be designed to allow successful cleaning.
6.1.2.2 The pipe and other equipment must be properly cleaned and preserved.
6.1.2.3 All possible locations for the entrance of dirt (pipe ends) must be durably covered and secured for storage prior to shipment
and loading. Shipment and unloading must take place without damage to these covers.
6.1.2.4 Inspection of pipe at the turbine site must be thorough to discover any damage or open covers and to have them repaired.
6.1.2.5 Storage prior to installation must be in a sheltered location, especially if the storage is to be for a long duration.
6.1.2.6 Inspection immediately prior to installation must be thorough, and the pipe must be cleaned if excessive rust or dirt is
discovered.
6.1.2.7 Continuous monitoring of conditions during the complete turbine installation must take place to ensure that cleanliness
related tasks are being accomplished. Dirt should not be introduced into the pipes and equipment.
6.1.2.8 Great care must be taken to prevent contaminant entry during any modifications.
6.1.2.9 The work area must be kept clean.
6.1.2.10 This list is not complete, but it does illustrate that the manufacturer, the shipper, the operator, and the installation
contractor (service company) are all responsible for ensuring that no contaminants enter the lubrication system. These efforts to
prevent the entrance of dirt will make the flushing procedure easier, safer, and shorter, and thus less costly.
6.2 On-Site Contamination Control:
6.2.1 General:
6.2.1.1 All components that are fabricated and assembled at a manufacturer’s facility and received as a unit for installation in the
system are defined as preassembled components.
6.2.1.2 The preassembled components should be inspected upon receipt to determine condition and degree of protection. All seals
and caps intended to exclude moisture and dirt should be checked for integrity and replaced as required. If the initial or a
subsequent inspection discloses dirt or rusting, the item should be immediately cleaned, represerved, and sealed, as required.
Because of the variety of equipment and materials, details for each case cannot be given here. For painted (coated) components,
the coating should be inspected for integrity and renewed as necessary. All components should be checked to ensure that all tape
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and temporary supports or restraints have been removed. For very compact system it is strongly recommended to check the
preassembled system, with inspection for example from the disassembly of flanges, valves etc. As these components are usually
under the warranty of the manufacture, it will be critical to communicate this to the manufacture as of part of control at delivery.
6.2.1.3 Undercover storage is recommended. Monthly inspections are recommended, and corrective steps must be taken when
necessary. Care must be taken during inspections to minimize disturbance of equipment protection.
6.2.2 Corrosion Protection:
6.2.2.1 The application of various types of rust preventives is required to protect uncoated ferrous surfaces from corrosion during
the storage and installation phases. Most preservatives today are oil soluble, and special procedures, such as hydraulic lancing, are
often used to preserve gear cases, sumps, and tanks. The preservative compounds can normally be removed by flushing the system
with regular lubrication oil or oil solvent, although hand cleaning of some components is also employed. If possible, however, the
flush oil, operating oil, and preservative should be compatible to preclude foaming, the formation of emulsions, precipitates or the
breakdown of lubrication oil additives. A system flush (displacement flush) with a sacrificial flush oil is often recommended to
minimize operating oil contamination which could result in reduced performance. Product compatibility of the flush oil should be
confirmed in accordance with Practice D7155 testing. Caution should be exercised in this regard. Compatibilities and limitations
may generally be obtained from the oil suppliers. It is strongly recommended that preservative oil removal and preservative oil
solubility in, and compatibility with, all subsequent oils, including the system oil, be reviewed at every step of subsequent
processes. Corrosion preventatives have the possibility to be removed by flushing, however care should be taken to assure that all
of them have been removed. Consequently it is recommended to check the oil quality after the displacement flush. Achieving oil
temperature between 55 °C to 60 °C and higher if possible plays a big role in removing the traces of these corrosion preventatives.
The flushing shall be followed by a thorough oil drain of the displacement oil and should be performed carefully. Review with the
equipment manufacturer may also be beneficial. All oils added, including preservative oils, should be filtered as discussed in 7.6.
6.2.2.2 Once the rust preventative is removed, the ferrous surfaces are subject to rust unless care is taken to keep all surfaces
oil-wetted. Corrosion of unwetted surfaces can be minimized by the use of vapor space inhibited oils to the maximum extent
possible. The general procedure for the use of the vapor space inhibited oils is as follows:
(1) Wet all surfaces with vapor space inhibited oils after cleaning.
(2) Do not drain; add sufficient oil to provide a reservoir of the oil in the assembly.
(3) Seal the component to prevent loss of vapor phase protection and intrusion of contaminants.
6.2.2.3 These vapor space inhibited oils may be fully compatible with regular lubricating oils and flushing oils, and draining or
removal may not be necessary. Compatibility testing in accordance with Practice D7155 is recommended to confirm compatibility.
In addition, it has been shown that these oils may provide some residual protection to the system and minimize corrosion after the
oils have been drained or displaced.
6.2.2.4 The vapor space inhibited oils are available in a range of viscosities. However, if an oil of significantly higher viscosity
than the flushing oil is used, draining of the assembled system to limit the amount of the higher viscosity to 10 % is recommended
to prevent significantly increasing the viscosity of the flushing oil.
6.2.3 Gear Assemblies:
6.2.3.1 When shipping gears, additional braces and tapes are frequently used to prevent movement of the elements and damage
to the teeth and bearings. Upon receipt of the assembled gears at the installation point, an inspection should be conducted with
the gear manufacturer’s representative to determine whether any damage has occurred during shipment. At this time the gears
should be thoroughly inspected for contamination, and if any is found, the manufacturer’s recommendation should be followed for
proper represervation. Periodic inspections, careful to minimize vapor space inhibition loss, should be made to ensure that proper
preservation is maintained until the gear assembly is placed into regular operation. Upon installation, all temporary restraints,
including tape, must be removed.
6.2.3.2 Speed reducers are normally shipped with a thin coating of preservatives applied to all internal machined surfaces that are
in contact with lubrication oil, such as gear teeth, bearings, journals, interior housing surfaces, and oil piping. The preservative is
oil soluble and is normally removed by the flushing program. Gear cases, protected by vapor space inhibited lubricating oil, should
be inspected upon receipt for integrity of seals. Damaged seals should be replaced immediately. If the oil has been lost, the gear
case and the gears should be pressure sprayed through the inspection openings with filtered vapor space inhibited oil or rust
preventive oil at 55 °C to 57 °C (130 °F to 135 °F). Starting at the top of the case, the gear case and the gears should be thoroughly
flushed down. After flushing, the oil level recommended by the gear manufacturer should be reestablished and the unit sealed.
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6.2.4 Valves, Strainer, and Coolers:
6.2.4.1 Valves, strainers, and coolers,Valves and strainers, when received from the manufacturer, should be inspected to determine
if there is contamination. If there is evidence of a hard film protective coating or contamination, the unit should be dismantled and
all the parts thoroughly cleaned with filtered petroleum solvent. In all cases, use clean, lintless cloths (not waste cloths), a squeegee,
or a vacuum cleaner.
6.2.4.2 Coolers should be verified clean from the manufacturer. A Borescope can be used prior to installation for inspection. If any
contamination is found within the cooler the system should be cleaned to meet the turbine manufacturer cleanliness specification.
Depending on the type of cooler (Fin Fan, Plate, Shell & Tube), metallurgy, and contamination found cleaning can consist of
chemical cleaning and or oil flushing to expedite the process. Care should be taken to review cooler pressure and flow restrictions.
6.2.4.3 Internal surfaces that cannot be reached should be flushed with an oil soluble cleaner or filtered petroleum solvent. Alkaline
or acid cleaners should not be used.
NOTE 1—Petroleum solvents are flammable; care must be taken to prevent fires. Precautions must also be taken to ensure that workers do not inhale fumes
from the solvent or come into contact with liquid solvents for prolonged periods. Filters can generate electric charges. Proper electrical connection of all
equipment prior to transferring fluids or starting flushing is required.
6.2.4.4 After internal surfaces have been cleaned, they should be sealed or put into service as soon as possible. If the internal
surfaces cannot be effectively sealed or put into service, they must be thoroughly air dried and coated immediately by spraying
them with filtered and compatible rust preventive oil. After all surfaces have been coated, the equipment should be reassembled
and all openings capped. This rust preventative coating may require removal with flush oil prior to equipment use.
6.2.5 Sumps and Tanks—Sumps, reservoirs, or tanks should be completely drained and thoroughly inspected. If present, rust, mill
scale, weld spatter, loose paint, and so forth, should be manually removed. A coating of rust-preventive oil, or a vapor space
inhibitor oil, should be applied, and all openings should be sealed. This rust preventative coating may require removal with flush
oil. Repainting is not recommended.
6.2.6 Bearings—It is important that bearings be installed by qualified personnel. Extreme care should be taken to prevent
accidental contamination of, or damage to, the bearings and journals. Bearing surfaces should be protected by rust-preventive oil
that is readily soluble in flushing oil or vapor space inhibitor oil. All openings should be sealed.
6.2.7 Control Devices—Installation and contamination protection for oil-wetted control devices should be handled as carefully as
that for bearings. Extreme care must also be taken to prevent accidental contamination of the associated piping during installation.
6.2.8 Pumps—Prior to assembly and installation, pumps should be inspected for the presence of hard film coatings or
contaminants. If any are present, the pumps should be thoroughly cleaned, coated with rust-preventive or vapor-space inhibitor oil,
and sealed.
7. Flushing
7.1 If the equipment manufacturer has supplied detailed flushing procedures, they should take precedence over these
recommendations.
7.2 Flushing Methods:
7.2.1 Displacement Flush—For new systems and systems with service hours that do not typically require surface active cleaning
or the improved cleaning of a high-velocity flush.flush, but require lubricant ISO Cleanliness lowered to meet OEM specification
or replacement of current charge of lubricant.
7.2.1.1 For a unit that is field assembled, keeping the lubrication and hydraulic control system piping clean enough so that flushing
is not necessary is economically and practically impossible. Thus, it is generally recognized that an oil flush must take place after
the piping has been installed and just before the turbine and its driven equipment go into operation. The success of this oil flush,
however, depends to a large degree on the success of the efforts to keep dirt out initially and the proper preparation and conduct
of the flush. A successful flush means that clean pipe and system components are obtained in a minimum of time and with a
minimum of effort.
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7.2.1.2 The cleaning and flushing of both new and used systems are accomplished by essentially the same procedure. In the new
systems, the emphasis is on the removal of contaminants introduced during the manufacture, storage, system temporary rust
protection, field fabrication, and installation. In used systems, the emphasis is on removal of contaminants that are generated during
operation or are introduced to the system during overhaul.
7.2.1.3 A displacement flush utilizes a displacement flush oil of the same chemistry as the final operating oil. System pumps and
flow channels are utilized to circulate the displacement flush oil. Side stream filtration is recommended to improve flush
effectiveness.
7.2.2 High-Velocity Flush—For new systems and systems with service hours that may not require surface active cleaning and will
benefit from enhanced flushing compared to displacement flushing. High-velocity flushing provides improved cleaning of typically
non-wetted surface areas like the lube oil return header.High velocity oil flush results typically in a higher cleaning efficiency and
also in a flushing time that is significantly shortened. Moreover, high flow rates of oil initiate the removal of contaminants in most
cases (apart from severe corrosion of oil aging agglomerates and varnish), whereas flushing with system pumps do not assure the
contamination displacement from all corners, pipes, dead zones of the oil system.
7.2.2.1 It is important to review the flow path and verify that no restrictions or dead spots are left while flushing activities are
taking place before performing a high-velocity flush. Low or no, flow regions (dead spots) or “traps” will allow for contaminates
to gather and redistribute throughout the system once the flush has concluded.
7.2.2.2 Lube oil lines that do not see continuous flow during normal operation often collect contaminates at valves and orifices.
These locations can be found on the outlet side of the system pumps, that is, pressure relief valves, and on units with fixed drain
piping back to the lube oil reservoir. In these cases, the lube oil flushing procedure should include opening and flushing out these
lines.
7.2.2.3 Moreover, achieving the high oil velocities in return headers is hardly achievable without additional distribution of
additional oil stream headed separately from the flushing skid. The disproportion of supply/discharge header compared to return
header is the reason. High-velocity Oil Flushing is critical to removing contaminates left behind when foreign material can be
introduced to the lube oil system and in cases when welding activities are conducted in the field, that is, precommissioning,
pipe-modifications, major maintenance activities.
7.2.2.4 The primary requirement for a successful oil flush is a high oil velocity at least three to four times normal system velocity,
and a Reynolds number over 40001000 within the system. Wherever possible, turbulent flow should be achieved in system pipes.
Bearing jumpers are installed Jumpers are installed around critical components such as bearings and control valves to elevate
bearing supply and return flow rates and protect bearingcritical surfaces from contaminants. System headers may be isolated to
increase pipeline velocity. The use of outside pumps is typically required to achieve this flow.
7.2.3 Surface Active Oil Soluble or Detergent Based Cleaner—Flushing for in-service systems with varnish or sludge that require
a cleaning solution for effective deposit removal.
NOTE 2—Using detergents, as surface tension acting products, in turbine lube oil systems can impact the lube oil characteristics such as air release or
demulsibility. When using detergents, it is strongly recommended to perform additional flushing steps to remove the remaining concentration of these
detergents, and attach a lot of importance on the maximum drain of the flushing oil.
7.2.3.1 Some turbine and associated hydraulic systems may require a surface active flush to clean inaccessible internal surfaces
of varnish. The term varnish is being used to include all internal deposits, including sludge. Flushing with a surface active cleaner
is typically reserved for gas turbines with combined hydraulic and turbine oil reservoirs. Minor levels of oil soluble cleaners or
solvent cleaners may impact operating oil demulsibility, required in steam turbine operation. A subsequent displacement flush shall
be conducted to effectively remove the surface active cleaning agent. Both the surface active flushing fluid and the following
displacement flush fluid should not be reused as they may impact the performance of the final system operating oil. Hydraulic
system flushing can be improved with the use of flushing blocks that are used to bypass the system servo valves.
7.2.3.2 Some hydraulic fouling deposits require water-based cleaning agents, that is, chemical cleaning – degrease. This method
should only be used in extreme fouling and oxidation applications. In the event that the lubricant oxidizes and carbon deposits
cause filter plugging and hydraulic valve failure a lubrication engineer and chemical service flushing expert should be consulted
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to review the metallurgy of the system and chemistry appropriate to clean the system. Water-based chemical cleaning will be
followed by lube oil displacement or high-velocity oil flushing and vacuum dehydration to remove residual water and particulate
contaminates.
7.2.4 High-pressure water flush for systems with service hours that have developed significant rust or fouling to the extent that
less aggressive flushing methods are ineffective. High-pressure water is locally directed at fouled areas. Cleaning the surfaces with
high pressure water stream/jets means that the water streams/jets at high pressure level effectively penetrates the soft and hard
deposits (especially rust, welding slag and splatter, varnish agglomerates) that high oil velocities removes slowly, less effectively,
if at all. Special care must be taken to remove all flush water at the completion of this flush.
7.2.5 General Flushing Method Guidance:
7.2.5.1 It may not be practical to flush through certain systems or devices that are assembled, cleaned, and sealed in the factory
before shipment. Such equipment should be carefully protected against intrusion of contaminants, and in this flushing procedure,
such equipment should be blanked off or bypassed until other systems are clean. This guidance also applies to oil coolers, that are
highly recommended to flush separately first and avoid massive dirt ingress in other oil system sections and piping.
7.2.5.2 Even for assemblies that can be flushed through freely, the prescribed flushing procedure may not have the ability to flush
out any and all conceivable kinds of contaminants. Much adverse experience testifies to this. Therefore, it is clear that great care
should be exercised during the entire system installation to prevent unnecessary impurities from entering the oil systems that
cannot be easily removed by flushing. Such contamination, when dislodged by turbine vibration or system operational effects,
could cause problems in subsequent operations.
7.2.5.3 The knowledge that a system flush will be performed before startup should not be allowed to lead to the misconception
that contaminants entering the oil system are not harmful because “they will all be removed by the flush.”
7.2.5.4 A written process and procedure should be developed for each flush regardless of OEM. The procedure should include
OEM cleanliness guidelines, site specific standards, owner requirements, deliverables, lubrication handling, and timeline.
7.3 General Guidelines for Flushing of Operational Systems to Remove Contaminant:
7.3.1 Guidelines for when to remove used oil or flush an operational system to reduce contaminant, or both, are given in 8.5.
7.3.2 The remainder of Section 7 should be reviewed and the applicable sections decided upon, after consultation of the equipment
user with the appropriate suppliers, based on the condition of the system and used oil.
7.3.3 Sea water contamination requires special procedures. After removal of excess salt water, corrosion inhibitors specifically
developed for this type of contamination might be used in the system.
7.4 Preparation of System for Flushing:
7.4.1 Prior to the flushing operation, all accessible areas of the lubricating oil system should be thoroughly inspected. If significant
contaminant is encountered, it should be manually removed. Final inspection for welding splatter or materials that may break loose
and contaminate the system with metallic particles should be made. If found they should be completely removed. As always,
containment of oil within the powerhouse is important. Ensure that any service companies involved are aware of the responsibility
to prevent oil from reaching the environment. For piping systems that are not typically exposed to the pressures and temperatures,
(and vibrations, if applicable) being used during flushing, preparations must be made to quickly and effectively respond to any
potential oil leaking from the system.
7.4.2 Any temporary humidity control devices (vacuum dehydrators, coalescing filters) placed in the system must be removed. The
state of cleanliness of the system at this time is always questionable, and therefore, all lubricating oil manifolds and leads to
bearings must be blanked off as closely as possible to the parts they serve. For high-velocity flushing, jumpers may be installed
to bypass all bearings, but they should be so installed as to bypass as little of the piping and flow passages as possible. All other
areas in the system that are not to be flushed should be blanked off with the use of numbered blanks. Ensure that the flushing loop
is contained with positive-closure valves; check valves are insufficient to protect equipment from high-velocity flush. The
numbered blanks must be removed from the system and accounted for on a checklist at the end of the flushing period. All items
should be identified on flush flow path marked P&ID DWG’s and written procedures.
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7.4.3 Despite all efforts, some particles large enough to damage pumps may remain. In all systems, installing temporary strainers
of 80 to 100 mesh on the suction side of the lubrication oil or flush pumps, or both, is recommended. In addition, install temporary
fine mesh strainers on the discharge side of gravity and pressure systems. Fine screens of 100 mesh or finer should be installed
at the inlet of all feed lines to the bearing pedestal. They should also be installed on the inlet headers of gear sets. Lintless bags,
if available, may be used temporarily on the inside of the existing lubricating oil system strainers during the flushing period.
Magnetic separating elements may be installed in the existing lubricating oil system strainers. Customary marine practice is to
install these in the duplex strainers on the discharge side.
7.4.4 Whenever possible, use of full flow filters during the flush is recommended. Auxiliary filters may be used to provide higher
filtered oil flow rates and finer filtration. All purification systems should be ready for operation as soon as the flushing oil is
installed. It is generally desirable to purify the reservoir, pump, and purification systems before beginning to flush the rest of the
unit. This has the advantage of providing clean oil to other parts of the system. In addition, when purified oil is used for flushing,
the increased contaminant observed in the oil when additional sections are flushed gives some measure of flush effectiveness. If
necessary, pipes and valves for recirculation to the reservoir should be installed. If this piping is temporary, valves at the reservoir
and purification device should be provided to allow removal of the temporary piping.
7.4.5 Frequently, sampling points installed for monitoring oil cleanliness during routine operation are not adequate to monitor the
cleanliness of components and the progress of the flush. Sampling points must be installed as necessary, as described in X2.2.2,
and Guide D8112. If the lubricating oil heater has not been installed, or if it is inadequate, heat may be supplied to the flushing
oil in several ways. The best method is to pass hot water through the cooler; this can be generated by bubbling low-pressure steam
through the water somewhere outside the cooler. The cooler must be vented to the atmosphere to prevent pressure build up. Low
pressure steam may also be used; however, the cooler should be checked against the manufacturer’s recommendation. Great care
must be taken to ensure that not over 34 kPa (5 psig) steam is admitted to the cooler so that the cooler is not damaged and the
flushing oil is not overheated. Electrical heaters may also be used. The cautions outlined in Appendix X4 must be observed to avoid
overheating the oil.
7.4.6 A lance attached to a clean hose should be used for hot oil spraying of gearing or other hard to reach areas. It can be attached
to the cooler (currently being used as a heater) or an oil pump discharge strainer. For safety, the hose, lance, and any other fittings
used must be pressure rated for the full flush pump outlet pressure. Precautions must also be taken to protect personnel from the
hot oil spray. Extreme fire and spark protection precautions must be taken. Even less hazardous lubricants can ignite if heated and
sprayed; conventional mineral oils may form explosive mixtures under such conditions.
7.4.7 A rotating nozzle (patent pending) is attached to a flange and a clean hose for hot oil spraying of gearing or other hard to
reach areas. It can be supplied via temporary bypass line from system supply header line. The nozzle is mounted on 1 150# flange
and inserted inside of the area to be flushed. A 360º rotating nozzle sprays the flushing oil, and used for seal oil tanks and larger
gear box openings that allow for insertion of the mechanism.
7.5 Selection of Flushing Oil:
7.5.1 The oil selected for flushing of the system can be either the system operating oil or flushing oil that is compatible with the
operating oil and of similar viscosity. The . In cases where residual flush oil may be of sufficient quantity as to impact system
operating oil performance, similar viscosity flushing oil should be used. In some cases there may be a benefit to using a very low
viscosity oil (~15 cSt) for high-velocity flushing, then performing a displacement flushing step with in-service oil which will be
discarded, prior to bringing the system back into normal operation. In all cases, the selection of the type of flushing oil
...