1、Designation: G55 07 (Reapproved 2013)Standard Test Method forEvaluating Pipeline Coating Patch Materials1This standard is issued under the fixed designation G55; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revi
2、sion.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method provides an accelerated means ofdetermining the relative sealing abilities of pipeline patchingmaterials that are
3、used to seal holidays in pipeline coatings onsteel pipe. This test method is intended for utilization ofspecimens of pipeline coatings on small-diameter pipe, forrepresenting coatings used for buried or submerged service,and where the purpose of the coating is to provide an electricalbarrier between
4、 the steel pipe and its environment.1.2 This test method is not intended for evaluating patchmaterials that are overlapped upon themselves.1.3 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.4 This standard does not purport t
5、o address all of thesafety concerns, 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. Summary of Test Method2.1 Patched pipeline coati
6、ng specimens are suspended in anaqueous, alkaline, low-resistivity electrolyte. The specimensare individually connected to a magnesium anode or rectifier ata point external to the electrolyte. The coated, patched pipelinespecimens are sealed at the base and at all other areas exceptthe patch boundar
7、ies, such that the only paths for current floware at the boundaries of the patches. Current flow in each patcharea is averaged from monthly readings taken for one year.3. Significance and Use3.1 Holidays in pipeline coatings may be repaired bycircumferential wrapping with a suitable pipe wrap tape.H
8、owever, this technique is not always practicable and patchingmay be required. The effectiveness of a patch material dependsupon its adhesion to the original pipeline coating to effectsealing.3.2 The results of this accelerated test have been found toyield comparative data useful for the selection of
9、 patchingmaterials. The user is cautioned against the use of this methodfor absolute material properties characterization.3.3 This procedure provides an accelerated method byexposing the patch to a severe radius of curvature on small-diameter pipe. The specimen is also exposed to a stress voltagein
10、the presence of a highly conductive electrolyte.4. Apparatus4.1 Test VesselA cylindrical glass battery jar (orequivalent), approximately 300 mm (12 in.) in diameter and300 mm in height. One magnesium anode shall be contained ineach battery jar, with a maximum of eight pipe specimens, andwith each sp
11、ecimen measuring about 25 mm (1 in.) in diameterby approximately 300 mm in length of coated pipe. (See 4.3and Fig. 1 and Fig. 2.)4.2 SuspensionThe suspension ring for supporting thepipe specimens shall be an electrically nonconductive circulardisk, measuring approximately 300 mm (12 in.) in diameter
12、and approximately 5 mm (316 in.) in thickness. (See 6.4.) Drilla 15-mm (12-in.) diameter hole through the center of the ringfor external extension of the anode lead wire. Drill eightsuspension holes, about 45 mm (134 in.) in diameter, throughthe suspension ring for the pipe specimens; these holes sh
13、all becentered 110 mm (412 in.) from the center of the suspensionring and evenly spaced around the ring at 45 increments asmeasured from the center of the suspension ring.4.3 PotentialA high-purity magnesium anode shall beused, weighing approximately 2.3 kg (5 lb), and having anopen-circuit potentia
14、l of approximately 1.7 d-c V relative to acopper-copper sulfate electrode, and complete with a factory-sealed lead wire. The magnesium anode may be replaced by acontrolled d-c voltage from a rectifier, and then maintaining thepotential between the specimen having the least current flowand a copper-c
15、opper sulfate reference cell (with the cell beingproperly immersed in the electrolyte) at 1.50 6 0.05 d-c V.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applicationsand is the direct responsibility ofSubcommittee D01.48 on Durability
16、of Pipeline Coating and Linings.Current edition approved June 1, 2013. Published June 2013. Originallyapproved in 1977. Last previous edition approved in 2007 as G55 07. DOI:10.1520/G0055-07R13.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United
17、 States1(See Note 1.) The anode should be composed of a suitablenonconsumable material.2This option will avoid the precipi-tation of magnesium salts on the specimens.NOTE 1The potential of the magnesium anode will approximate thisrange over the life of the test. If a calomel electrode is used for th
18、ereference cell, the potential should be 1.43 6 0.05 d-c V.4.4 ElectrolyteUse 1 % each by weight of anhydrous puregrades of sodium chloride, sodium sulfate, and sodiumcarbonate, dissolved in either distilled water or demineralizedwater. This electrolyte shall never be less alkaline thanpH = 10.0 and
19、 should be within a resistivity range from 20 to35 cm.4.5 Instruments:4.5.1 Resistivity Meter, capable of measuring 20 to 40cmin an aqueous solution.4.5.2 pH meter, capable of measuring 0 to 14 pH.4.5.3 Thermometer, ASTM Type 17C or equivalent, 19 to27C.4.5.4 Microammeters, d-c, 0 to 100-A and 0 to
20、500-A.4.5.5 Voltmeter, for direct current, having an internal resis-tance of not less than 10 M and having a range from 0.01 to5.0 V.4.5.6 Full-Wave Rectifier, optional, 0 to 0.05 % ripple,capable of maintaining 1.50 6 0.05 d-c V relative to acopper-copper sulfate cell, and having a capacity for at
21、least 10A of direct current.5. Test Specimens5.1 DimensionsThe specimen shall be steel pipe approxi-mately 25 mm (1 in.) in diameter, approximately 300 mm (12in.) in length, and previously coated with the desired originalpipeline coating.5.2 Circuit TapA 5-mm (316-in.) diameter hole shall bedrilled
22、or tapped (or a self-tapping screw may be used) at apoint 13 mm (12 in.) below the top of each specimen. This tapis for a machine screw anode lead wire connection.5.3 Pipe Suspension Support HolesA6-mm (14-in.) diam-eter hole shall be drilled completely through both walls of thecoated pipe specimen
23、at a point 20 mm (34 in.) from the top endof the specimen and located vertically beneath the circuit taphole. A short length of wooden dowel pin about 5 mm (316 in.)in diameter shall be used as an insertion through the suspensionholes to support and level the pipe specimen on the circularsuspension
24、ring when the suspension ring is mounted on thebattery jar.5.4 Intentional HolidaysA 4-fluted 13-mm (12-in.) diam-eter facing bit shall be used to drill intentional holidays throughthe original pipeline coating to the metal. Drilling suchholidays shall be practiced on scrap pieces of small-diameterc
25、oated pipe, prior to drilling the holidays in the test specimens.Drilling shall not be any deeper than necessary into the metalof the pipe. Three holidays shall be prepared on each specimenin a vertical line directly underneath the circuit tap to corre-spond to electrolyte immersions of 38 mm (112 i
26、n.), 114 mm(412 in.), and 190 mm (712 in.), as measured from the top of theholiday to the surface of the electrolyte. The thickness of thesuspension ring shall be considered for its effect in elevatingthe pipe specimens in the electrolyte.5.5 PatchesA square patch configuration of 25 by 25 mm(1 by 1
27、 in.), evenly centered about the holiday, shall be lightlymarked. This will provide a minimum patch overlap of 6 mm(14 in.) as measured perpendicular to the center of each patchedge to the circumference of the holiday. The top and bottomedges of each patch shall be in the horizontal plane. Eachmarke
28、d patch area shall be lightly buffed with 120-grit sand-paper. A primer shall be applied using clean cotton on a stickto extend the primer to the edges of the marked patch areawhen specified by the manufacturer of the patch. The manu-facturers specified drying time shall be used for primers beforeap
29、plication of the patch. Scissors or a knife shall be used to cuttape patches to size; tape patches shall be applied by a firmpressure of the thumb. Wax patches shall be applied bydripping or pouring the melted wax on the patch area to thedesired patch thickness. Each mastic patch or each liquid patc
30、hshall be applied with a new, clean brush. The number of coatsapplied shall be recorded and the patch thickness shall be2The sole source of supply of a nonconsumable anode, Durachlor 51 anode,Type B, 18-in. with cable, known to the committee at this time is Duriron Co., P.O.Box 1145, Dayton, OH 4540
31、1. If you are aware of alternative suppliers, pleaseprovide this information to ASTM International Headquarters. Your comments willreceive careful consideration at a meeting of the responsible technical committee,1which you may attend.FIG. 1 Test Assembly for Evaluating Pipeline Coating Patch Ma-ter
32、ialsG55 07 (2013)2indicated. The balance of the circumferential band that is notcovered by a patch is then covered either with the patchmaterial under test or with another material that has beendemonstrated to maintain an effective seal with the originalpipeline coating. The base of each specimen sh
33、all be sealedwith a material capable of preventing current flow at the baseof the specimen.All prepared specimens shall be conditioned aminimum of 48 hours at room temperature prior to immersionin the electrolyte. Current leakage at the base seal shall belimited to not more than 1 A.5.6 WiringIndivi
34、dual 150-mm (6-in.) lengths of 18-gageinsulated copper wire and small alligator clips shall be used forthe electrical connection from the machine screw of thespecimen to the lead wire of the anode.6. Procedure6.1 Place the anode in the bottom of the battery jar. Extendthe anode lead wire vertically
35、through the center of thesuspension ring; then center the suspension ring on the batteryjar.6.2 Mount each patched pipe specimen through one of thelarge holes in the suspension ring, with patches facing out, untilthe wooden dowel pin in the suspension hole of the specimenis supported by the suspensi
36、on ring. When all specimens havebeen suspended into the battery jar, pour the room temperatureelectrolyte into the battery jar to a point 32 mm (114 in.) abovethe topmost patch. The electrolyte will then be the requiredheight above each patched holiday. Mark and maintain thisFIG. 2 Alternative Test
37、Assembly for Evaluating Pipeline Coating Patch MaterialsG55 07 (2013)3level of electrolyte by additions of distilled water or deminer-alized water. Maintain the assembly at room temperature forthe entire test.6.3 WiringUse alligator clips to connect the 150-mm(6-in.) length of 18-gage insulated copp
38、er wire from themachine screw in the patched specimen to the lead wire of theanode.6.4 DataSee the suggested report (Fig. 3) for the collec-tion of data. Record the data at the start of the test exposure as0 month test duration. Record the data (microamperes ofcurrent flow, pipe to electrolyte poten
39、tial relative to a copper-copper sulfate reference cell, and the electrolyte with respect topH, resistivity, and temperature) each month for 12 consecutivemonths. Select a date for taking data within 62 calendar daysof the day of the month that the initial data were recorded (forexample, a test begi
40、nning on the 19th day of a particular monthshould have successive monthly data taken between the 17thand 21st days of the next 12 months).6.5 Current Flows:6.5.1 Determine current flows by temporarily disconnectingthe 18-gage insulated wire from the anode, connecting thepositive lead froma0to100micr
41、oammeter (d-c) to thepatched specimen, and connecting the negative lead to the wirefrom the anode, external to the battery jar. If there is ameasurable current flow for a patched specimen (1 A ormore), remove that specimen from the battery jar, taking carenot to allow the specimen to contact the edg
42、e of the hole in thesuspension ring. Gently rinse the specimen with either demin-eralized water or distilled water (at room temperature) toremove all traces of electrolyte. Then, with the microammeterconnected in series from the patched specimen to the anode,slowly lower the patched specimen into th
43、e electrolyte and notethe current flow just below, and then just above, each patch.The difference in microamperes is the amount of current flowthat is being transmitted by that particular patch.6.5.2 Record only 100 A when the current flow for a patchexceeds 100 A. When 100 A has been recorded for t
44、woconsecutive readings, remove the patch, clean the patch area,and then permanently patch the area with a material capable ofsealing the holiday for the remainder of the test. The currentflow data for the original patch is assumed to continue at themaximum value of 100 A for the remainder of the tes
45、t. Theresealing will permit the continuance of accurate readings ofthe current flows for the remaining test patches on that pipespecimen. The 0 to 500 d-c microammeter can be used asnecessary during the first month of failure of one or morepatches on a pipe specimen, when the total current flow of a
46、pipe specimen exceeds 100 A.FIG. 3 Suggested Form for Collecting and Summarizing DataG55 07 (2013)47. Report7.1 The report shall be a copy of the data collection form(Fig. 3) with all computations completed. The averages areobtained by adding all of the numbers accumulated in a column(initial readin
47、g plus 12 monthly readings), and dividing thesummation by 13. Determine average values for the microam-peres of current flow for each patch, the pipe to electrolytepotential, and for the pH, resistivity, and temperature of theelectrolyte. The summary section also provides space for alisting of the a
48、verage current flow for each set of three patches.8. Precision and Bias8.1 Precision data are limited to the comparison of the threesamples of any one patch material sealing the holidays on anyone original pipeline coating. These data are based on limitedinformation, but statistically have been show
49、n, by round-robintesting by four laboratories, to provide a reasonable basis forcomparing the sealing abilities of various patching materialsand various pipeline coatings.8.2 The average values of triplicate samples of the samematerials, excluding values of 0 A, by the same worker shouldnot be considered suspect unless they differ by more than afactor of 2. For example, an average value of 20 Afor one setrequires a second set of the same materials to be between 10 to40 A for the same worker.8.3 The average values of triplicate sa
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