1、Designation: G 20 88 (Reapproved 2002)Standard Test Method forChemical Resistance of Pipeline Coatings1This standard is issued under the fixed designation G 20; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revis
2、ion. A number in parentheses indicates the year of last reapproval. A superscriptepsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method is intended for evaluating the resis-tance of pipe coating materials when exposed to variousconcentrations of
3、reagents or suspected soil contaminants. Thetest serves as a guide to investigators wishing to compare therelative merits of pipe-coating materials in specific environ-ments. The choice of reagents, concentrations, duration ofimmersion, temperature of test, and properties to be reportedare necessari
4、ly arbitrary and should be chosen to reflectconditions known to exist along the pipeline right-of-way.1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concerns,
5、if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:D 543 Practices for Evaluating the Resistance
6、of Plastics toChemical Reagents2D 883 Terminology Relating to Plastics2G 8 Test Methods for Cathodic Disbonding of PipelineCoatings3G 12 Test Method for Nondestructive Measurement of FilmThickness of Pipeline Coatings on Steel3G 17 Test Method for Penetration Resistance of PipelineCoatings (Blunt Ro
7、d)33. Summary of Test Method3.1 This test method consists of an immersion-type test in aclosed container where coated pipe specimens are in long-termcontact with both the liquid and vapor phase of the test reagent.Specimens exposed in this manner are inspected for visiblesigns of chemical attack. Su
8、bsequent tests for cathodic dis-bonding in accordance with Test Method G 8, or penetrationunder load in accordance with Test Method G 17, may beapplied to determine if the specimens have undergone any lossof mechanical or bonding properties.4. Significance and Use4.1 The data obtained for short-term
9、 tests are of interestonly in eliminating the most unsuitable materials or forindicating a probable order of resistance in any particularmedia.4.2 Test conditions should take into account the manner andduration of immersion, the reagent, the temperature of thesystem, the area exposed above and below
10、 the liquid level, andother performance factors selected for the particular test.5. Apparatus5.1 Thickness Gage, capable of measuring the coatingthickness in the manner prescribed by Test Method G 12.5.2 Test ContainerA transparent closed container, sized tocompletely encase the pipe specimen and la
11、rge enough toprovide adequate exposure to both the liquid and vapor statesof reagent.NOTE 1For example, a 2-L (2.0-qt) capacity, Mason-type jar with a70-mm (2.75-in.) diameter neck has been found suitable for use with 2 in.pipe and is illustrated in Fig. 1.5.2.1 To avoid pressure build-up within the
12、 test containers,the threaded cup shall be replaced with a solid-rubber stopper.A positive venting device, such as a water seal, shall be usedwhen testing with volatile solvents at elevated temperatures.5.2.2 A separate container shall be used for each testspecimen.5.3 Oven or Constant-Temperature R
13、oom or BathTo en-sure uniformity of test results, the test cells and specimen shallbe maintained at the test temperature 65C (9F) over theduration of the test period.5.4 Auxiliary Testing DevicesSupplemental equipmentused to determine specific mechanical properties of specimensbefore and after immer
14、sion shall conform to the requirementsprescribed in the applicable ASTM test method.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.48 on Durability of Pipeline Coating and
15、 Linings.Current edition approved May 27, 1988. Published July 1988. Originallypublished as G 20 71 T. Last previous edition G 20 83.2Annual Book of ASTM Standards, Vol 08.01.3Annual Book of ASTM Standards, Vol 06.02.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocke
16、n, PA 19428-2959, United States.6. Reagents6.1 The reagents selected for coating-resistance tests shouldbe those anticipated to occur in the environment or in theproduct being carried in the pipeline at the temperatures and inthe concentrations expected. The numbers in parentheses referto the list o
17、f standard reagents given in Section 4 of PracticesD 543.6.1.1 Acetic Acid (5 %) (4.4.2).6.1.2 Acetone (4.4.3).6.1.3 Carbon Disulfide.6.1.4 Gasoline.6.1.5 Hydrochloric Acid (10 %) (4.4.23).6.1.6 Kerosine (4.4.28).6.1.7 Lime Water, Saturated.6.1.8 Methyl Alcohol (4.4.29).6.1.9 Methyl Ethyl Ketone.6.1
18、.10 Nitric Acid (10 %) (4.4.33).6.1.11 Sodium Carbonate Solution (20 %) (4.4.38).6.1.12 Sodium Chloride Solution (10 %) (4.4.40).6.1.13 Sodium Hydroxide Solution (10 %) (4.4.42).6.1.14 Sulfuric Acid (30 %) (4.4.46).6.1.15 Toluene (4.4.48).6.1.16 Transformer Oil (4.4.49).6.1.17 Trichlorethylene.6.1.1
19、8 Other selected environments.7. Hazards7.1 Take safety precautions to avoid personal contact, toeliminate toxic vapors, and to guard against explosion hazardsin accordance with the hazardous nature of the particularreagents being used.8. Test Specimen8.1 The test specimen shall be prepared with its
20、 surfacepreparation and coating procedures equivalent to that of coatedpipe. A control specimen shall be retained for comparison.8.2 In order to utilize the test container specified in 4.2, thepipe specimen, with end caps, shall be restricted to a maximumoverall length of 180 mm (7.0 in.) and a diam
21、eter of 65 mm(2.5 in.).8.3 Both ends of the pipe specimens shall be plugged withinert stoppers and coated with an epoxy-base coating material.8.4 Specimens with Holidays:8.4.1 A holiday shall be made in the surface of the coatedpipe specimen at a point 25 % of the distance between the endcaps. It sh
22、all be made by drilling a radial hole through thecoating so that the angular cone point of the drill will fullyenter the steel where the cylindrical portion of the drill meetsthe steel surface. The drill diameter shall not be less than threetimes the coating thickness, but it shall never be smaller
23、than 6mm (0.25 in.) in diameter. The steel wall of the pipe shall notbe perforated.8.4.2 A second identical holiday shall be drilled into thecoating surface at a point 25 % of the distance between the endcaps of the specimen (see Fig. 1). Both holidays should lie inthe same pipe axis.8.5 Specimens w
24、ithout intentional holidays shall also beprepared for testing.NOTE 2Intentional holidays shall be made in only those specimensfor which a comparison of disbonding properties is desired. Other samplesused for supplemental mechanical testing shall be run without holidays.9. Procedure9.1 Place a single
25、 specimen in a vertical position in each testcontainer.9.2 Fill the container with the selected reagent so that theliquid level covers one half of the coated pipe specimen up toa point midway between the two intentional holidays. Stopperthe 704 Container to prevent evaporation of the reagent andagai
26、nst contamination.9.3 Maintain the reagent level at the original level.9.4 The basic immersion test for a particular coating mate-rial shall consist of twelve specimens, six with holidays and sixwithout, each in an individual test cell. Remove duplicatesamples of each from the test at 30, 60, and 90
27、 day intervals.Additional investigations of pre- and post immersion mechani-cal properties will require additional specimens. It is recom-mended that in all cases provisions be made for duplicate testspecimens.9.5 Remove the specimen after 30, 60, and 90 days ofimmersion. Wash with running water all
28、 specimens removedfrom acid, alkali, or other aqueous solutions and wipe them drywith a soft, clean, cotton cloth or paper tissue. Specimensremoved from volatile solvents such as acetone, alcohol, etc.,need no rinsing before wiping dry.9.6 Observe and report before, immediately after, and 2 hlater t
29、he appearance of specimen after exposure to reagent onthe basis of visual examination for evidence of loss of gloss,developed texture, decomposition, discoloration, softening,swelling, injury, bubbling, blistering, cracking, solubility, etc.as defined in Terminology D 883.9.7 Mechanically probe each
30、 of the intentional holidays inaccordance with Section 8.3.3 of Test Method G 8 to see ifthere has been any loss of coating bond during the test period.DimensionsA70 mm (2.75 in.) Jar OpeningB45 mm (1.75 in.) Holiday LocationC90 mm (7.00 in.) Length of Pipe SpecimenNOTE 1Dimensions shown for 2 in. I
31、PS pipe.FIG. 1 Chemical Immersion Test Schematic of Test CellG 20 88 (2002)29.8 Perform other planned mechanical tests to determine ifany degradation of coating properties has occurred throughreagent exposure.10. Report10.1 The report shall include the following:10.1.1 Complete identification of the
32、 material tested, includ-ing type, source, manufacturers code, and previous history,10.1.2 Method of preparing test specimen,10.1.3 Temperature of test,10.1.4 Description of media, including ASTM designation,10.1.5 Duration of immersion,10.1.6 Outside diameter of test specimen,10.1.7 Initial thickne
33、ss of coating,10.1.8 General appearance of specimen after immersion,10.1.9 Immersion area in square millimetres (squareinches),10.1.10 Vapor phase area in square millimetres (squareinches), and10.1.11 Disbonded area after immersion in square millime-tres (square inches).11. Precision and Bias11.1 As
34、 there are no direct measurements involved with thistest method, no precision and bias statement is necessary.Measurements made by procedures for other test methodsshould refer to the precision and bias statements therein.12. Keywords12.1 chemical resistance; pipeline coatingsASTM International take
35、s no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own res
36、ponsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be address
37、ed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the
38、 address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).G 20 88 (2002)3
