ASTM G158-98
(Guide)Standard Guide for Three Methods of Assessing Buried Steel Tanks
Standard Guide for Three Methods of Assessing Buried Steel Tanks
SCOPE
1.1 This guide covers procedures to be implemented prior to the application of cathodic protection for evaluating the suitability of a tank for upgrading by cathodic protection alone.
1.2 Three procedures are described and identified as Methods A, B, and C.
1.2.1 Method A- Noninvasive with primary emphasis on statistical and electrochemical analysis of external site environment corrosion data.
1.2.2 Method B- Invasive ultrasonic thickness testing with external corrosion evaluation.
1.2.3 Method C- Invasive permanently recorded visual inspection and evaluation including external corrosion assessment.
1.3 This guide presents the methodology and the procedures utilizing site and tank specific data for determining a tank's condition and the suitability for such tanks to be upgraded with cathodic protection.
1.4 The tank's condition shall be assessed using Method A, B, or C. Prior to assessing the tank, a preliminary site survey shall be performed pursuant to Section 8 and the tank shall be tightness tested pursuant to 5.2 to establish that the tank is not leaking.
1.5 While this guide provides minimum procedures for assessing a tank's condition, this guide does not provide minimum installation procedures or requirements for upgrades of the tank by cathodic protection.
1.6 The values stated in inch-pound units are to be regarded as the standard. The SI units given in parentheses are provided for information only.
1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: G 158 – 98
Standard Guide for
Three Methods of Assessing Buried Steel Tanks
This standard is issued under the fixed designation G 158; 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 (e) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
The purpose of this guide is to provide three methods of inspecting and assessing buried steel
tank(s) for corrosion damage and determining the suitability of these tanks prior to application of
cathodic protection.
1. Scope priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
1.1 This guide covers procedures to be implemented prior to
the application of cathodic protection for evaluating the suit-
2. Referenced Documents
ability of a tank for upgrading by cathodic protection alone.
2.1 The most recent version of the following documents
1.2 Three procedures are described and identified as Meth-
should be consulted as references by those using this guide:
ods A, B, and C.
2.2 ASTM Standards:
1.2.1 Method A—Noninvasive with primary emphasis on
D 2216 Test Methods for a Laboratory Determination of
statistical and electrochemical analysis of external site envi-
Water (Moisture) Content of Soil and Rock
ronment corrosion data.
E 114 Practice for Ultrasonic Pulse-Echo Straight-Beam
1.2.2 Method B—Invasive ultrasonic thickness testing with
Examination by the Contact Method
external corrosion evaluation.
E 797 Practice for Measuring Thickness by Manual Ultra-
1.2.3 Method C—Invasive permanently recorded visual in-
sonic Pulse-Echo Contact Method
spection and evaluation including external corrosion assess-
E 1323 Guide for Evaluating Laboratory Measurement
ment.
Practices and the Statistical Analysis of the Resulting Data
1.3 This guide presents the methodology and the procedures
E 1526 Practice for Evaluating the Performance of Release
utilizing site and tank specific data for determining a tank’s
Detection Systems for Underground Storage Tank Sys-
condition and the suitability for such tanks to be upgraded with
tems
cathodic protection.
G 51 Test Method for pH of Soil for Use in Corrosion
1.4 The tank’s condition shall be assessed using Method A,
Testing
B, or C. Prior to assessing the tank, a preliminary site survey
G 57 Test Methods for Field Measurement of Soil Resistiv-
shall be performed pursuant to Section 8 and the tank shall be
,
6 6
ity Using the Wenner Four-Electrode Method
tightness tested pursuant to 5.2 to establish that the tank is not
2.3 American Society for Nondestructive Testing Stan-
leaking.
dard:
1.5 While this guide provides minimum procedures for
ASNT SNT-TC-1A Personnel Qualification and Certifica-
assessing a tank’s condition, this guide does not provide
tion in Nondestructive Testing
minimum installation procedures or requirements for upgrades
2.4 NACE International Standards:
of the tank by cathodic protection.
RP-0169 Standard Recommended Practice-Control on Ex-
1.6 The values stated in inch-pound units are to be regarded
ternal Corrosion on Underground or Submerged Metallic
as the standard. The SI units given in parentheses are provided
Piping Systems
for information only.
1.7 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
Annual Book of ASTM Standards, Vol. 04.08.
responsibility of the user of this standard to establish appro- 3
Annual Book of ASTM Standards, Vol. 03.03.
Annual Book of ASTM Standards, Vol.14.02.
Annual Book of ASTM Standards, Vol.11.04.
Annual Book of ASTM Standards, Vol. 03.02.
1 7
This guide is under the jurisdiction of ASTM Committee G-1 on Corrosion of Available from American Society for Nondestructive Testing, 1711 Arlingate
Metals and is the direct responsibility of Subcommittee G01.10 on Corrosion in Plaza, P.O. Box 28518, Columbus, OH 43228-0518.
Soils. Available from National Association of Corrosion Engineers (NACE) Interna-
Current edition approved Sept. 10, 1998. Published September 1998. tional, P.O. Box 218340, Houston, TX 77218-8340.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
G 158
RP-0187 Standard Recommended Practice-Design Consid- 3.1.7 pH—the numerical value of the negative logarithm of
erations for Corrosion Control of Reinforcing Steel in the hydrogen ion concentration in moles per litre in an
Concrete electrolyte.
3.1.8 tank tightness test—a method capable of detecting a
RP-0285 Standard Recommended Practice-Corrosion Con-
0.1 gal/h leak rate, while accounting for any applicable effects
trol of Underground Storage Tank Systems by Cathodic
of thermal expansion or contraction of the product, of vapor
Protection
pockets, of tank deformation, of evaporation or condensation,
2.5 Environmental Protection Agency Methods:
and of the location of the water table. The method must be
EPA SW 846 Test Methods for Evaluating Solid Waste
capable of detecting a 0.1 gal/h leak rate with a probability of
EPA 371.1 Measurement of Sulfate Reducing Bacteria
detection of at least 0.95 and a probability of false alarm of at
2.6 National Fire Protection Association (NFPA)
most 0.05 or in accordance with NFPA 329.
NFPA 329 Recommended Practice for Handling Under-
3.1.9 underground storage tank (UST)—any one or combi-
ground Releases of Flammable and Combustible Liquids
nation of tanks (including connected underground piping), the
2.7 Underwriters Laboratories Inc.
volume of which is 10 % or more beneath the surface of the
UL 58 Steel Underground Tanks for Flammable and Com-
ground.
bustible Liquids
3.1.10 upgrade—the addition to or retrofit of UST systems
using approaches including,but not limited to, cathodic protec-
3. Terminology
tion to improve the ability of a UST system to prevent a
3.1 Definitions of Terms Specific to This Standard:
release.
3.1.1 buried—to be placed in the ground and covered with
3.1.11 unconditional probability of corrosion failure—the
earth.
probability of corrosion failure which includes a determination
3.1.2 cathodic protection—an applied technique to prevent
of whether localized, pitting, or general corrosion is occurring.
further corrosion of a metal surface by making that surface the
3.1.12 UST—see underground storage tank (see 3.1.9).
cathode of an electrochemical cell. For example, a tank system
3.1.13 redox potential—potential of platinized platinum
can be cathodically protected through the application of either
electrode in a redox environment (reversable system). The
galvanic anodes or impressed current.
value of redox potential depends on whether the system is in
3.1.3 corrosion specialist/cathodic protection specialist—a
the oxidized, partially oxidized, partially reduced, or reduced
competent person who by reason of knowledge of the physical
state.
sciences and the principles of engineering and mathematics,
3.2 limitations—The user of this guide is encouraged to
acquired by education and related practical experience, is
review any available third party verification information pro-
qualified to engage in the practice of corrosion control on
vided as part of the vendor selection process.
buried or submerged metallic piping systems and metallic
3.3 vendor provided information—The user is referred to
tanks. Such persons shall be registered professional engineers
Annex A1 for a specific form and format of information which
or persons recognized as corrosion specialists or cathodic
must be provided by a vendor. This information consists of
protection specialists by NACE, if their professional activities
historic performance data on a method and is mandated as part
include suitable experiences in external corrosion control on
of the guide.
buried or submerged metallic piping and tanks.
3.1.4 corrosion technician—a person possessing basic
4. Significance and Use
knowledge of corrosion and corrosion control, who is capable
4.1 This guide provides three methods for determining the
of performing routine, well defined work under the supervision
suitability of a buried steel tank to be upgraded with cathodic
of the corrosion specialist/cathodic protection specialist.
protection.
3.1.5 invasive procedure—a method of determining the
4.2 This guide may be used to assess any UST, including
corrosion status of a tank by assessing the tank from the inside
non-regulated USTs.
as part of the upgrade procedure. Further, for the purposes of
this guide, it does not require manned entry into the tank. (See 4.3 This guide provides three alternative methods but does
non-invasive.) not recommend any specific method or application. The
3.1.6 noninvasive procedure—a method of determining the responsibility for selection of a method rests with the user.
corrosion status of a tank from the characteristics of its
4.4 This guide has specific requirements for vendor pro-
surroundings with minimal entry into the tank. Further, for the
vided information which should be requested and reviewed by
purposes of this guide, it does not require manned entry into
the user.
the tank. (See invasive.)
5. Permits, Plans and Tank Leak Testing
5.1 Prior to engaging in any activities relating to the
9 alteration, repair, or upgrade of any UST system, consult all
Available from Underwriters Laboratories Inc., 333 Pfingsten Rd., Northbrook,
IL 60062-2096. necessary authorities to obtain any required permits.
Available from US Environmental Protection Agency, Office of Underground
5.2 Tank Leak Testing:
Storage Tanks, 401 “M” St. SW, Washington, DC 20460.
5.2.1 To establish that tanks are not leaking prior to assess-
Available from National Fire Protection Assoc., Batterymarch Park, Quincy,
MA 02169. ment, they shall be assessed by a leak detection system. This
G 158
leak detection assessment alone is not sufficient to determine priate to the method of assessment of the suitability of tanks for
that a tank is suitable for upgrading with cathodic protection upgrading with cathodic protection:
under this guide. 8.1.3.1 Stray d-c current sources,
5.2.2 A tightness test or another release detection system in 8.1.3.2 Existing cathodic protection systems,
accordance with NFPA 329 shall be used. Any release detection 8.1.3.3 Steel product and vent piping and fittings, and
must be capable of detecting a leak from any portion of the 8.1.3.4 Adjacent subsurface metallic/steel-reinforced con-
tank that routinely contains product, and be independently crete structures.
evaluated and certified in accordance with Practice E 1526 or 8.2 Preliminary Evaluation—Prior to assessing the tank, a
the equivalent. Leak detection results shall be provided to the preliminary site survey must be performed pursuant to Section
corrosion specialist/cathodic protection specialist. 8 and a tightness test must be performed pursuant to 5.2 to
5.2.3 This testing shall be accomplished within six months establish that the tank is not leaking.
prior to performing any of the assessment procedures.
9. Method A—Noninvasive with Primary Emphasis on
Statistical and Electrochemical Analysis of External
6. Required Approvals and Certifications
Site Environment Corrosion Data (1,2)
6.1 The corrosion assessment work carried out under this
9.1 Field and Laboratory Testing—Noninvasive with Pri-
guide shall be performed under the responsible direction of a
mary Emphasis on Statistical and Electrochemical Analysis of
corrosion specialist/cathodic protection specialist as defined in
External Site Environment Corrosion Data.
3.1.3.
9.1.1 Tests shall be conducted by, or as directed by a
6.2 The corrosion specialist/cathodic protection specialist
corrosion specialist/cathodic protection specialist.
shall certify to the tank owner or operator that the personnel
9.1.2 Field Testing Procedures—Tests to be performed shall
performing the assessment work on the tank are knowledgeable
include, but are not limited to, the following:
of all the applicable procedures in this guide.
9.1.2.1 Stray Currents—Perform tests to detect the presence
6.3 The corrosion specialist/cathodic protection specialist
of stray currents at each tank site. This test shall consist of
shall certify to the tank owner or operator that all work was
measuring structure-to-soil potentials at right angles at a
performed in strict accordance with this guide.
minimum of two locations within the tank facilities and
observing the measurements for not less than2hata time
7. General Safety Requirements
when such influences are most likely to occur. The monitor
7.1 All personnel shall comply with applicable federal,
shall consist of a field data acquisition unit, with a minimum of
state, and local health and safety codes and regulations.
10-MV input impedance, used in conjunction with a stable
reference cell(s) placed in contact with the soil in the vicinity
8. Preliminary Site Survey
of the tank. The instrument shall measure and store structure-
8.1 A corrosion technician, under the responsible direction to-electrolyte potential (voltage) data at least every 5 s through-
of the corrosion specialist/cathodic protection specialist, shall out the entire duration of field investigation at the site or for 2
obtain tank site specific information as appropriate to the h, whichever is greater. If variations of 650 mV or greater are
method of assessment to be used. measured during the test period, make 24-h recording measure-
8.1.1 Facility Information: ments to confirm stray current effects.
8.1.1.1 Address or location, and 9.1.2.2 Tank Information:
8.1.1.2 Name and telephone number of owner and operator (a) Locate all tanks and confirm materials of construction,
contact personnel. age, capacity, and dimensions. Produce detailed site sketches
8.1.2 Tank and Piping Details: describing the layout of the UST system and above grade
8.1.2.1 Number and capacity, pertinent details for each site.
8.1.2.2 Location and dimensions, (b) Determine the presence and extent of internal corrosion
8.1.2.3 Age, immediately below the fill riser. If the depth of corrosion
8.1.2.4 Material of construction,
penetration in the tank shell exceeds 50 % of the tank wall
8.1.2.5 Electrical isolation, thickness, the UST shall be declared to have failed the test and
8.1.2.6 Type of product stored, the procedure.
8.1.2.7 Names of site contact personnel, (c) Determine if the tanks and piping are electrically
8.1.2.8 Backfill material, continuous.
8.1.2.9 Coatings and linings, 9.1.2.3 Bore Hole Tests:
8.1.2.10 Leak history, (a) Determine locations for soil borings in the field. Make
8.1.2.1
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