ISO 19277:2018
(Main)Petroleum, petrochemical and natural gas industries — Qualification testing and acceptance criteria for protective coating systems under insulation
Petroleum, petrochemical and natural gas industries — Qualification testing and acceptance criteria for protective coating systems under insulation
This document describes various corrosion under insulation (CUI) environments in refineries and other related industries and environments, and establishes CUI environmental categories including operating temperature ranges from −45 °C to 204 °C for topside and aboveground service only. This document specifies both established and other test methods for the assessment of coatings used for prevention of CUI for each given environment. This document also provides acceptance criteria for each CUI environment. NOTE The test results and acceptance criteria can be considered an aid in the selection of suitable coating systems. For service or peak temperatures below −45 °C an optional cryogenic test can be incorporated and for over 204 °C testing acceptance criteria can be agreed between interested parties. Additional or other test and acceptance measures are possible, but require particular agreement between the interested parties. This document covers spray-applied coatings applied on new carbon and austenitic stainless steel for use in CUI service. This document does not cover testing of sacrificial coatings, such as inorganic zinc, as these coatings can be consumed quickly in wet environments. Developing accelerated corrosion testing for what can be continuous wet service with sacrificial coatings is beyond the scope of this document. "Non-through porosity" thermal spray aluminium coatings with greater than 250 µm dry film thickness can be tested and qualified in accordance with this document. This document does not cover tape and sheet applied products for use in preventing CUI. This document does not deal with other aspects of coating degradation, such as those caused by abrasion, erosion, ultraviolet degradation or other methods that can exist given specific environment and construction methods.
Industries du pétrole, de la pétrochimie et du gaz naturel — Essais de qualification des systèmes de revêtement protecteurs sous isolation
General Information
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 19277
First edition
2018-12
Petroleum, petrochemical and natural
gas industries — Qualification testing
and acceptance criteria for protective
coating systems under insulation
Industries du pétrole, de la pétrochimie et du gaz naturel — Essais de
qualification des systèmes de revêtement protecteurs sous isolation
Reference number
©
ISO 2018
© ISO 2018
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Published in Switzerland
ii © ISO 2018 – All rights reserved
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Performance testing design . 3
4.1 Relationship between artificial testing and natural exposure . 3
4.2 Laboratory tests . 3
4.3 Additional laboratory tests . 4
5 CUI classification environments . 4
6 Test samples . 4
6.1 Test panels . 4
6.2 Steel substrates . 4
6.3 Sampling of coatings . 5
6.4 Number of test panels . 5
6.5 Coating systems . 5
6.5.1 Coating application . 5
6.5.2 Dry film thickness . 5
6.5.3 Overcoating interval . 6
6.5.4 Conditioning . 6
6.5.5 Heat conditioning . 6
6.6 Scribe . 6
6.7 Reference system . 6
7 Test procedures and assessment . 6
7.1 Assessment and acceptance . 6
7.2 Assessment of adhesion and artificial ageing . 6
7.2.1 Adhesion testing before artificial ageing . 6
7.2.2 Artificial ageing . 7
7.2.3 Adhesion testing after artificial ageing . 7
7.3 Thermal cycling test . 8
7.4 Multi-phase CUI cyclic corrosion test . 8
7.4.1 Description of test. 8
7.4.2 Test equipment-apparatus . 8
7.4.3 Test set-up and preparation .11
7.4.4 Test procedure .11
7.4.5 Acceptance .12
8 Optional tests .13
8.1 Optional cryogenic cycling testing .13
8.1.1 General.13
8.1.2 Cryogenic test .13
8.1.3 Adhesion testing after cryogenic test aging .13
8.2 Optional vertical pipe test .14
8.2.1 Application .14
8.2.2 Description of test.14
8.2.3 Test equipment — Apparatus .14
8.2.4 Test process scope .16
8.2.5 Temperature profile calibration .16
8.2.6 Test equipment — Procedure .16
8.3 Additional performance tests .16
9 Test report .17
Annex A (informative) Corrosion testing of conditioned and heat conditioned test samples .18
Annex B (informative) Example of test report for CUI coating acceptance .19
Annex C (informative) Example of test report for cryogenic testing .23
Annex D (informative) Example of test report for optional vertical pipe test .24
Bibliography .27
iv © ISO 2018 – All rights reserved
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso
.org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 67, Materials, equipment and offshore
structures for petroleum, petrochemical and natural gas industries.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
Introduction
Unprotected carbon steel in insulated service with the presence of water and concentrating
contaminants from the atmosphere or surrounding sources can cause accelerated corrosion and lead
to severe metal loss. Additionally, unprotected austenitic and duplex stainless steels can suffer external
chloride-induced stress corrosion cracking if contaminates, such as chlorides from the atmosphere
and or the insulation, are present at the steel surface. Therefore, steel structures under insulation are
normally protected to prevent corrosion-related damage during the operational life required of the
equipment.
There are different ways of protecting steel structures from corrosion under insulation. This document
deals with protection by use of coating when used as part of a system, including insulation and cladding
materials, which can work together to prevent corrosion under insulation (CUI). All components of the
corrosion prevention system are important in achieving adequate corrosion protection. This document
only deals with the coating part of the corrosion protection system with focus on typical CUI coating
environments. Further, this document focuses on accelerated testing protocols and acceptance criteria,
so that interested parties can make informed decisions.
In order to ensure effective corrosion protection of steel structures and equipment, it is necessary for
owners of such structures, planners, consultants, companies carrying out corrosion protection work,
inspectors of protective coatings and manufacturers of coating materials to have at their disposal state-
of-the-art information in a concise form on corrosion protection by coating systems. Such information
has to be as complete as possible, unambiguous and easily understandable to avoid difficulties and
misunderstandings between the interested parties with the practical implementation of protection work.
This document is intended to give the abovementioned information to people who have some technical
knowledge of coatings and the process operations of the equipment. It is assumed that the user of this
document is familiar with other relevant International Standards, in particular those dealing with
surface preparation, inspection/testing of coatings, and relevant regulations.
Future parts of this document are planned to be developed and can include other subjects like higher
temperature, cyclic and intermittent service, testing of coatings for maintenance and repair, tape-
applied coating materials, etc.
vi © ISO 2018 – All rights reserved
INTERNATIONAL STANDARD ISO 19277:2018(E)
Petroleum, petrochemical and natural gas industries —
Qualification testing and acceptance criteria for protective
coating systems under insulation
1 Scope
This document describes various corrosion under insulation (CUI) environments in refineries and
other related industries and environments, and establishes CUI environmental categories including
operating temperature ranges from −45 °C to 204 °C for topside and aboveground service only. This
document specifies both established and other test methods for the assessment of coatings used for
prevention of CUI for each given environment. This document also provides acceptance criteria for each
CUI environment.
NOTE The test results and acceptance criteria can be considered an aid in the selection of suitable coating
systems. For service or peak temperatures below −45 °C an optional cryogenic test can be incorporated and for
over 204 °C testing acceptance criteria can be agreed between interested parties. Additional or other test and
acceptance measures are possible, but require particular agreement between the interested parties.
This document covers spray-applied coatings applied on new carbon and austenitic stainless steel for
use in CUI service. This document does not cover testing of sacrificial coatings, such as inorganic zinc, as
these coatings can be consumed quickly in wet environments. Developing accelerated corrosion testing
for what can be continuous wet service with sacrificial coatings is beyond the scope of this document.
“Non-through porosity” thermal spray aluminium coatings with greater than 250 µm dry film thickness
can be tested and qualified in accordance with this document. This document does not cover tape and
sheet applied products for use in preventing CUI.
This document does not deal with other aspects of coating degradation, such as those caused by
abrasion, erosion, ultraviolet degradation or other methods that can exist given specific environment
and construction methods.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 554, Standard atmospheres for conditioning and/or testing — Specifications
ISO 1513, Coatings and varnishes — Examination and preparation of samples for testing
ISO 2409, Coatings and varnishes — Cross-cut test
ISO 2812-2, Coatings and varnishes — Determination of resistance to liquids — Part 2: Water
immersion method
ISO 4624, Coatings and varnishes — Pull-off test for adhesion
ISO 4628-2, Coatings and varnishes — Evaluation of degradation of coating coatings — Designation of
intensity, quantity and size of common types of defect — Part 2: Designation of degree of blistering
ISO 4628-3, Coatings and varnishes — Evaluation of degradation of coating coatings — Designation of
intensity, quantity and size of common types of defect — Part 3: Designation of degree of rusting
ISO 4628-4, Coatings and varnishes — Evaluation of degradation of coating coatings — Designation of
intensity, quantity and size of common types of defect — Part 4: Designation of degree of cracking
ISO 4628-5, Coatings and varnishes — Evaluation of degradation of coating coatings — Designation of
intensity, quantity and size of common types of defect — Part 5: Designation of degree of flaking
ISO 4628-8, Paints and varnishes — Evaluation of degradation of coatings — Designation of quantity
and size of defects, and of intensity of uniform changes in appearance — Part 8: Assessment of degree of
delamination and corrosion around a scribe
ISO 7384, Corrosion tests in artificial atmospheres — General requirements
ISO 9227, Corrosion tests in artificial atmospheres — Salt spray tests
ISO 12944-6, Paints and varnishes — Corrosion protection of steel structures by protective paint systems —
Part 6: Laboratory performance test methods and associated assessment criteria
ISO 15528, Paints, varnishes and raw materials for paints and varnishes — Sampling
ISO 19840, Paints and varnishes — Corrosion protection of steel structures by protective paint systems —
Measurements of, and acceptance criteria for, the thickness of dry films on rough surfaces
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at https: //www .electropedia .org/
3.1
artificial ageing
procedure designed to accelerate the ageing of a coating system, i.e. to reduce the corrosion-protective
efficiency more rapidly than by natural weathering
[SOURCE: ISO 12944-6:1998, 3.1, modified — ‘paint system’ has been changed to ‘coating system’.]
3.2
corrosion under insulation
CUI
corrosion that is a result of the effect of moisture and contaminants, on the steel surfaces under thermal
insulation
3.3
dry film thickness
DFT
thickness of a coating remaining on the surface when the coating has hardened
3.4
durability
expected life of a protective coating system to the first major maintenance coating
[SOURCE: ISO 12944-8:2017, 3.3, modified — ‘paint system’ has been changed to ‘coating system’ and
‘maintenance painting’ has been changed to ‘maintenance coating’.]
3.5
nominal dry film thickness
NDFT
dry film thickness specified for each coat or for the whole coating system
2 © ISO 2018 – All rights reserved
3.6
peak temperature
maximum temperature for the designed system, including possible upsets and temperature reached as
a result of maintenance efforts such as steam cleaning
3.7
sacrificial coating
coating that provides corrosion protection by sacrificing or being consumed in the act of protecting the
substrate
4 Performance testing design
4.1 Relationship between artificial testing and natural exposure
The selection of a coating system for specific conditions should preferably be based on experience from
the use of the system in similar cases. The reason is that the durability of a CUI coating system depends
on many external factors, such as the environment, the design of the structure, the insulation material,
the weather proofing (cladding), the surface preparation, the application, drying procedures, service
temperature, thermal shock, thermal cycling, peak temperature, amount of moisture, contaminants
and other variables.
The durability is also linked to the chemical and physical characteristics of the system, e.g. the type
of binder, the dry film thickness. These CUI related performance characteristics can be evaluated by
artificial tests. Resistance to water or moisture, boiling water, steam interface, electrolytes in the
system, thermal exposure, thermal shock, and thermal cycling are of primary interest.
Artificial tests and durations specified in this document have been selected to help ensure that potential
coating systems will have the characteristics needed for the durability required in the intended service.
Results from artificial tests should be used with caution, because artificial testing will not necessarily
have the same effect as natural exposure. Many factors have an influence on the progress of degradation
and, in the laboratory, it is not possible to accelerate all of them using the most effective method. It is
therefore difficult to make a reliable ranking of coating systems of very different compositions from
artificial tests in the laboratory. This can sometimes lead to efficient protective coating systems being
rejected because they cannot pass these tests.
4.2 Laboratory tests
As CUI environments are very specific and have special requirements, several tests are included so that
coating products can exhibit performance in harsh environments typical of CUI exposure. These include
thermal performance, boiling water, thermal shock, thermal cycling, peak temperature performance,
and long term isothermal conditions. In addition, these coating products shall provide corrosion
protection for long periods of time at ambient conditions, and in possibly wet conditions related to
initial coating application prior to process start up, time associated with process shutdowns, and short
term mothballing of the facility.
Standard weathering testing procedures shall be used to establish ambient related corrosion control
test procedures and acceptance criteria. Both air dried and conditioned test samples and heat conditions
test samples shall be evaluated.
Additional CUI and high temperature related tests shall also be used in order to verify the ability of a
coating to work under insulation at the prescribed conditions.
Inorganic zinc primers or other sacrificial coatings are no longer recommended in CUI environments
due to the accelerated corrosion related to wet environments. If testing and acceptance is required,
additional testing, as agreed between the interested parties, can be performed. However, long term
wet environments are difficult to accelerate and as such the specifier/owner should be careful with any
acceptance criteria for sacrificial coatings.
4.3 Additional laboratory tests
Other test methods may also be used by agreement between interested parties.
5 CUI classification environments
Table 1 provides a list of CUI classification environments including the minimum and maximum
temperatures for all environments. These descriptions include both isothermal and cyclic conditions.
Table 1 — CUI classification environments
Classification Minimum temperature Peak temperature
CUI-1 −45 °C to 60 °C
CUI-2 −45 °C 60 °C to 150 °C
CUI-3 −45 °C 150 °C to 204 °C
Further, each coating should be qualified for each specific CUI classification where it is intended to
be used. A coating that meets the requirements of a CUI-1 classification does not necessarily meet
the requirements of a CUI-3 classification, and a coating that meets the requirements of a CUI-3
classification does not necessarily meet the requirements of a CUI-1 classification. By consolidating
testing some tests can be used for more than one classification.
For insulated service for temperatures above 204 °C, additional testing may be performed as agreed by
interested parties.
An optional classification for cryogenic cycling exposure (“-Cryo”) may be added to each of the
classifications in Table 1, when cryogenic testing and acceptance are included. In such cases the
classifications as presented in Table 2 are appropriate.
Table 2 — CUI classification cryogenic environments
Classification Minimum temperature Peak temperature
CUI-1-Cryo −196 °C to 60 °C
CUI-2-Cryo −196 °C 60 °C to 150 °C
CUI-3-Cryo −196 °C 150 °C to 204 °C
6 Test samples
6.1 Test panels
This document requires the use of test panels and other testing surfaces that are available as standard
shapes typically available on the market place. Both A-36 or S275 carbon steel and 316 (316L) austenitic
stainless steel test panels shall be incorporated in testing and also shapes as described in 6.2 to 6.7.
6.2 Steel substrates
Test panels will be as follows unless otherwise agreed to and documented.
6.2.1 Carbon steel test panels shall be made of A-36 or S275 carbon steel. The minimum panel size
shall be 3 mm × 150 mm × 70 mm or as agreed and documented by the parties. The thickness of the test
panels shall not allow for bending as a result of heating and quenching. Unless otherwise agreed, the
panel surface shall be prepared by abrasive blast-cleaning to meet the requirements of the corresponding
technical product data sheet as per the coating manufacturer’s instructions. In all other respects, test
panels shall comply with ISO 7384.
4 © ISO 2018 – All rights reserved
6.2.2 Austenitic stainless steel test panels shall be used when stainless steel panels are specified. The
grade shall be 316 or 316L stainless steel or as agreed and documented by the parties. The minimum
panel size shall be 3 mm × 150 mm × 75 mm. Unless otherwise agreed, the panel surface shall be prepared
by abrasive blast-cleaning to meet the requirements of the corresponding technical product data sheet as
per the coating manufacturer’s instructions. In all other respects, test panels shall comply with ISO 7384.
6.2.3 Square carbon steel tubing (A-36, ASTM A-500, or S275) ASIC standard shape HSS4X4X1/4
measuring approximately 101,4 mm by 101,4 mm, 406,3 mm long with a wall thickness of 6,35 mm shall
be used for the multi-phase CUI cyclic test. Each coating sample area shall be a minimum of 101,4 mm
long, on all four sides of the square tube with just the front face scribed with an X-cut. Each tube shall
have an endcap welded on each end with a 25,4 mm pipe 101,5 mm long with a threaded connector. The
two pipes shall be centred horizontally and shall be vertically attached with a centre 25,4 mm down from
the top of the square tube. The completed tube should be tested to ensure that the welds do not leak.
Figure 2 provides a general layout (see 7.4.2). Unless otherwise agreed, the tube’s exterior surfaces shall
be prepared by abrasive blast-cleaning to meet the requirements of the corresponding technical product
data sheet as per the coating manufacturer’s instructions.
6.2.4 A standard black carbon steel pipe (A-36 or S275), approximately 600 mm long, with 50 mm
outside diameter with typical wall thickness of 5 mm shall be used for the optional vertical insulation
pipe test. Unless otherwise agreed, the test surface shall be prepared by abrasive blast-cleaning to
surface preparation to meet the requirements of the corresponding technical product data sheet as per
the coating manufacturer’s instructions.
6.3 Sampling of coatings
A representative sample of the product to be tested (or of each product in the case of a multi-coat
system) shall be taken in accordance with ISO 15528. Each sample for testing shall be examined and
prepared in accordance with ISO 1513.
6.4 Number of test panels
At least three panels shall be prepared for each test, unless otherwise specified. Each tube shall have
the coating applied three times with the fourth space for a control coating.
6.5 Coating systems
6.5.1 Coating application
The test panels/surfaces shall be dry and free of dust, grease and any other foreign matter, immediately
prior to coating application and in keeping with the coating manufacturer’s recommendations. The
test panels/surfaces shall be coated (preferably by spraying), air dried and cured in strict accordance
with the coating manufacturer's recommendations. Each coat shall be homogenous in thickness and
appearance and free from runs, sags, misses, pinholes, wrinkling, gloss variation, cissing, particle
inclusions, dry overspray and blistering. If the manufacturer's drying requirements are in conflict
with 6.5.4, the requirements of 6.5.4 shall take precedence, unless agreed to by all parties. Appropriate
protection shall be applied to the edges and back side of test panels.
6.5.2 Dry film thickness
The method and procedure for checking dry film thickness shall be in accordance with ISO 19840 for
rough surfaces. After each coat is sufficiently hardened, the dry film thickness of the applied coating
shall be measured on the test surface of the test panel/surface at five locations (in the centre and
each corner, at least 15 mm to 20 mm from the panel edge or rounded surface of the square tube) and
these measurements shall be recorded as the minimum, arithmetic mean and maximum. The dry film
thickness shall be within the range of the manufacturer’s specifications and shall not exceed 20 % of
the specified value.
6.5.3 Overcoating interval
For each layer of coating application, the overcoating interval shall comply with the coating
manufacturer's recommendations.
6.5.4 Conditioning
Unless otherwise agreed, the coated test samples shall be conditioned for three weeks in a standard
atmosphere of 23 °C ± 2 °C with 50 % ± 5 % relative humidity or 20 °C ± 2 °C with 65 % ± 5 % relative
humidity, as defined in ISO 554, before testing, and in accordance with the requirements of the
corresponding technical product data sheet as per the coating manufacturer’s recommendations.
6.5.5 Heat conditioning
Heat conditioning of the test samples shall be performed on applied and conditioned test samples. Heat
conditioning shall consist of heating the conditioned test panels to the maximum temperature of the
classification for 20 h in a muffler oven or other similar device. The test panels shall then be removed
and air cooled for 4 h. This process shall be repeated a total of 5 times, providing for a total of 100 h
exposure at maximum temperature of the classification and 20 h of air cooling time.
6.6 Scribe
If a scribe is required for testing of coatings on steel substrates, the scribe shall be in accordance with
ISO 12944-6. Special care should be taken to ensure that potentially hot and small metal fragments do
not affect the sample. Individual test procedures will indicate the need of a scribe for testing.
6.7 Reference system
It is recommended to use a coating system that has been in successful use for years on site and whose
performance as indicated by laboratory testing is well known, as a reference system. This system
shall be as similar as possible in composition and/or generic type and dry film thickness to the coating
system being tested.
7 Test procedures and assessment
7.1 Assessment and acceptance
All tests shall be conducted in triplicate. At least two of the three tests shall comply with the
requirements specified in this document. Triplicate for the multiphase CUI cycle test shall be three
separate tubes run in three separate test cycles. Triplicate for the optional vertical pipe test shall be
three separate tubes.
7.2 Assessment of adhesion and artificial ageing
7.2.1 Adhesion testing before artificial ageing
The applied and conditioned coating sample panels and the heat conditioned coating sample panels
shall be tested for adhesion. This includes both the carbon steel test panels and the stainless steel test
panels. Table 3 provides list of testing and acceptance criteria.
6 © ISO 2018 – All rights reserved
Table 3 — Adhesion assessment before artificial ageing for carbon steel and stainless steel
test panels
Assessment Requirement Conditions
method
ISO 2409 Classification 0 to 2 If the dry film thickness of the coating system is
less than or equal to 250 µm.
In case of cross cut value of 2, a pull-off test in
accordance with ISO 4624 shall be conducted
ISO 4624 No adhesive break between steel and the
primer (first coat) (unless pull-off values are
5 MPa or more)
7.2.2 Artificial ageing
Table 4 provides test methods and durations as required for each classification. Table 5 provides
acceptance criteria for these tests. Annex A provides a rationale for the testing of ambient and heat
conditioned test panels.
Table 4 — Ambient test methods and duration for carbon steel test panels
ISO 9227 ISO 2812-2
(neutral salt spray) (water immersion)
Duration Duration
Classification
Scribed Scribed
Applied and Applied and
Heat conditioned Heat conditioned
conditioned conditioned
CUI-1 720 hours 480 hours 3 000 hours 2 000 hours
CUI-2 720 hours 480 hours 3 000 hours 2 000 hours
CUI-3 720 hours 480 hours 3 000 hours 2 000 hours
Table 5 — Ambient corrosion test acceptance criteria
Test method Classifications ISO 4628-2 ISO 4628-3 ISO 4628-4 ISO 4628-5 ISO 4628-8
ISO 9227 CUI-1 CUI-2 CUI-3 0 (S0) Ri 0 0 (S0) 0 (S0) 2/3
ISO 2812-2 CUI-1 CUI-2 CUI-3 0 (S0) Ri 0 0 (S0) 0 (S0) 2/3
Time of assessment (after end of test) Immediately <8 h
7.2.3 Adhesion testing after artificial ageing
The artificially aged test panels shall be tested for adhesion after the prescribed duration (time of
assessment) in the standard atmosphere in accordance with ISO 554. This includes only the carbon
steel test panels. Table 6 provides a list of testing and acceptance criteria.
Table 6 — Adhesion assessment after ambient corrosion testing for carbon steel test panels
Assessment Requirements Time of assessment Conditions/Remarks
method
ISO 2409 Classification 0 to 2 Assessment after 12 d in If the dry film thickness of the
standard atmosphere as de- coating system is less than or
fined in ISO 554 equal to 250 µm.
In case of cross cut value of 2, a
pull-off test in accordance with
ISO 4624 shall be conducted
ISO 4624 No adhesive break between Assessment after 12 d in
steel and the primer (first standard atmosphere as de-
coat) (unless pull-off values fined in ISO 554
are 5 MPa or more)
7.3 Thermal cycling test
The test panel is then placed in the oven and heated. When the test panel reaches the maximum
temperature of the classification, it shall immediately be dipped/quenched into ice water covering at
least 3/4 of the test panel and left immersed until the temperature of the test sample metal temperature
is reduced to <15 °C. This shall be repeated for the number of cycles required. The coated surface shall
then be evaluated. Minimum and maximum thermal cycling temperatures and the number of cycles are
provided for each CUI classification in Table 7. Acceptance criteria are provided in Table 8.
Table 7 — Thermal cycling test for carbons steel test panels
Classification Minimum temperature Maximum temperature Cycles
CUI-1 5 °C 60 °C 20
CUI-2 5 °C 150 °C 20
CUI-3 5 °C 204 °C 20
Table 8 — Thermal cycling acceptance criteria
Classifications ISO 4628-2 ISO 4628-3 ISO 4628-4 ISO 4628-5
CUI-1 0 (S0) Ri 0 0 (S0) 0 (S0)
CUI-2 0 (S0) Ri 0 0 (S0) 0 (S0)
CUI-3 0 (S0) Ri 0 0 (S0) 0 (S0)
7.4 Multi-phase CUI cyclic corrosion test
7.4.1 Description of test
The multi-phase CUI cyclic corrosion test process is used to test the ability of the coating to work in
typical environments where CUI occurs. This test process includes dry heat, thermal shock, immersion,
boiling water, steam interface, and shut down time. This test takes six weeks and does not consider the
effect related to individual insulation materials. This test process is used for CUI-2 and CUI 3, as these
CUI coatings extend into the boiling water range.
7.4.2 Test equipment-apparatus
The multi-phase cyclic CUI test method is designed to provide an overall test procedure for coatings
for elevated temperature insulated service. It includes cyclic testing methods providing dry heat,
intermittent boiling water for an extended period of time, a steam interface, and an ambient state
where there is no heating.
8 © ISO 2018 – All rights reserved
This test process does not take into account the effect of any possible detrimental chemicals given off
by specific insulation materials. The immersion and boiling water portion of this test utilizes water
with 5 % NaCl (m/v).
To understand the effect of any chemicals associated with the use of any particular insulation, a specific
solution can be agreed between the interested parties. Any change of solution shall be documented in
the final report.
Figure 1 provides an overall schematic diagram of the equipment and guidance as to the test set up.
Key
1 sample tube 6 solution chamber
2 steam port 7 auxiliary heater
3 view port 8 peristaltic pump
4 chamber lid 9 solution chamber
5 closed loop oil heater or other alternate heating mechanism
Figure 1 — Schematic presentation of multi-phase CUI cyclic corrosion test
The apparatus includes the following items.
a) Closed-loop oil heater with piping of approximately 2,54 mm internal diameter connecting to the
CUI sample tube. The heating unit should be capable of keeping the circulating heating oil at the
specified testing temperature. The heater is typically three phase with 6 kW heating capacity.
Alternate heating systems are acceptable, if the temperature of the surface of the sample tubes is
maintained with ±5 °C.
b) Closed-loop heat transfer fluid/oil for operating to the maximum temperature of the test in the
range of 150 °C to 175 °C can be used.
c) CUI sample tube, coatings applied and conditioned in accordance with 6.5.4. Figure 2 provides a
schematic presentation of the CUI sample tube. Each coating tested shall have a least a 100 mm
wide continuous application on all four sides of the tube.
d) Solution chamber and lid with view port and with four 6,35 mm ports: three for steam release and
one for tubing connection from the peristaltic pump. Figure 3 provides a schematic presentation of
the solution chamber.
e) Peristaltic pump for pumping the solution to the solution chamber with tubing for transfer of the
solution.
f) Auxiliary hot plate heater typically two heater 220 V – 240 V, 5 kW, with approximate dimension
375 mm × 625 mm.
Key
a
Centred.
Figure 2 — Schematic presentation of sample tube (square pipe)
10 © ISO 2018 – All rights reserved
Key
A loose fit hole for 25,4 mm (1 inch) pipe fitting centred on both ends
B solution chamber lid weldment
C solution chamber weldment
D tabs for centring lid on chamber
NOTE Components are weldments made using 3,175 mm non-rusting material suitable for temperature of
test protocol. Water tight welds with loose fit between solution chamber and lid.
Figure 3 — Schematic presentation of solution chamber
7.4.3 Test set-up and preparation
The applied and conditioned CUI sample coated tube shall be scribed in accordance with 6.6 on the face
of the square tube as depicted in Figure 2. Note that the pipe fittings are welded offset in one direction.
The CUI sample tube should be piped to the closed-loop oil heater using a section of flexible (typically
flexible for ease of assembly) stainless tubing to each side of the CUI sample tube.
The solution chamber shall be placed on the auxiliary heater. The CUI sample tube should be placed in
the solution chamber with the offset hanging down, so that during the immersion phase the solution
will reach the midpoint of the scribe face/side. The CUI sample tube should not be in contact with the
bottom or sides or top of the solution chamber. The solution chamber lid shall be placed within the clips
of the solution chamber.
The peristaltic pump shall be connected with one of the four steam vents to allow a predetermined
amount of solution into the solution chamber.
7.4.4 Test procedure
The test procedure shall be in accordance with the following cycle.
1) The tube shall be heated, internally, to the test temperature by heating the oil in the closed-loop
oil heater to a temperature that results in the surface of the coated tube reaching 150 °C ± 5 °C or
177 °C ± 5 °C, depending on requirement. The surface temperature of the coatings samples on the
square tube will reach test temperature within 30 min to 60 min.
2) The oil temperature shall remain at set temperature throughout the heating process, which shall
last for 120 h each week. The initial heating process each week will take 30 min to 40 min depending
on test temperature requirements. The oil heater will be initially set to 93 °C and once it comes to
temperature, left to stabilize for 10 min. The temperature setting is then increas
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