1、Designation: C1785 17Standard Test Method forConcentration of Pinhole Detections in Moisture Barriers onMetal Jacketing1This standard is issued under the fixed designation C1785; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the
2、year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the con-centration of pinhole detections in a moisture barrier fi
3、lm orcoating that is applied to the interior surface of metal jacketing.1.2 Since this method relies on the completion through themetal jacketing of an electrical circuit, this method is onlyapplicable to jacketing that is electrically conductive and has amoisture barrier applied which is not electr
4、ically conductive.1.3 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.4 This standard does not purport to address all of thesafety conc
5、erns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accor-dance with
6、internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2
7、C168 Terminology Relating to Thermal InsulationC1729 Specification for Aluminum Jacketing for InsulationC1767 Specification for Stainless Steel Jacketing for Insula-tionE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDe
8、termine the Precision of a Test Method3. Terminology3.1 DefinitionsDefinitions in Terminology C168 apply toterms used in this specification.3.2 Definitions of Terms Specific to This Standard:3.2.1 continuous pinhole detectionwhile the test is beingconducted, a continuous sounding of the audible test
9、 equip-ment alarm over an area larger than the contact area of thecellulose sponge.3.2.1.1 DiscussionIn some cases, large portions of one ormore of the test areas (see 8.2.1) or even all of one or more testareas will yield a continuous pinhole detection. This concept ofa continuous pinhole detection
10、 and the area yielding thisperformance is necessary to quantify the number of pinholedetections in a sample exhibiting this phenomenon (see 9.2 and9.3)3.2.2 moisture barrier (moisture retarder)a layer of plas-tic film or other material applied to the inner side of metaljacketing to inhibit jacket co
11、rrosion by interfering with theformation of a galvanic cell between the dissimilar metals ofthe pipe and jacket or by preventing crevice or pittingcorrosion.3.2.3 pinholea hole completely through a moisture barriertypically too small to be seen by the eye.3.2.4 pinhole detectiona single sounding of
12、the audibletest equipment alarm while the test is being conducted.3.2.4.1 DiscussionBecause pinholes are very small andthe dampened cellulose sponge contacts the moisture barrier inan area larger than a single pinhole (see 6.4), it is theoreticallypossible that multiple pinholes in close proximity t
13、o each otherwould register as a single detection. For this reason, this testmethod measures the concentration of pinhole detections ratherthan pinholes.3.2.5 holidaysynonymous with pinhole.4. Summary of Test Method4.1 A voltage is applied across the nonconductive moisturebarrier on metal jacketing u
14、sing an electrode consisting of acellulose sponge dampened with an electrically conductive1This test method is under the jurisdiction ofASTM Committee C16 on ThermalInsulation and is the direct responsibility of Subcommittee C16.33 on InsulationFinishes and Moisture.Current edition approved Sept. 1,
15、 2017. Published October 2017. Originallyapproved in 2013. Last previous edition approved in 2016 as C1785 16a. DOI:10.1520/C1785-17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume infor
16、mation, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardizati
17、on established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.137 liquid such as tap water. Holes in the moisture barrier lead tocompletion of an electrical cir
18、cuit which triggers an audiblealarm in the test equipment. The number of pinhole detectionscollectively in ten specified test areas is determined andreported.5. Significance and Use5.1 Corrosion on the interior surface of metal jacketing canbe caused by the formation of a galvanic cell between thedi
19、ssimilar metals of the pipe and jacket or by crevice or pittingcorrosion.5.2 The application of a moisture barrier to the interiorsurface of the metal jacketing inhibits this corrosion byinterfering with the galvanic cell formation or by preventingwater from contacting the interior metal surface.5.3
20、 Holes in the moisture barrier decrease its effectivenessin preventing corrosion. Large holes, scratches, or tears in themoisture barrier visible to the naked eye are easily discernedand are cause for rejection of the metal jacketing.5.4 Small holes called pinholes or holidays that are notvisible to
21、 the naked eye but are large enough to allow corrosionare a significant concern and should be avoided to the extentpossible.5.5 This test method is used to quantify the concentration ofpinhole detections present in a moisture barrier for the purposeof quality control on metal jacketing with an appli
22、ed moisturebarrier.5.6 Examples of standards which have specific requirementsfor the maximum allowable concentration of pinhole detectionsin the moisture barrier are Specifications C1729 and C1767.6. Apparatus6.1 Test equipment shall be a pinhole or holiday detectorwith an output voltage of 65 to 75
23、 volts DC that emits anaudible signal when a connection between the two leads isdetected.NOTE 1These instruments can be found by performing a web searchfor “wet sponge pinhole detector” or “wet sponge holiday detector”.6.2 One lead of the pinhole detector shall have a springtensioned metal clamp cap
24、able of being attached to the metaljacketing.6.3 The other lead of the pinhole detector shall have a metalclamp capable of securing a cellulose sponge.6.4 The cellulose sponge clamped to the pinhole detectorlead shall have a size capable of touching the moisture barrierof 2 6116 by 2 6116 in. (50.8
25、6 1.6 by 50.8 6 1.6 mm).6.5 Test equipment shall have its test voltage and operabilityvalidated on a regular basis.7. Test Specimens7.1 Specimens tested are metal jacketing rolls or metaljacketing sheets.7.2 Any width that can be conveniently placed on a tablecan be tested but the typical width of m
26、etal jacketing is 3 ft(0.91 m) or, rarely, 4 ft (1.22 m).7.3 For rolls, a length of 30 ft (9.1 m) is required.7.4 For sheets, test as many sheets at a time as will fit on theapproximately 30 ft (9.1 m) long testing surface.8. Procedure8.1 Sample Preparation:8.1.1 Place specimen(s) on a reasonably fl
27、at, level, andclean surface with the moisture barrier facing up.8.1.2 If necessary, secure the jacketing to the test surface sothat it is reasonably flat and does not curl up during testing.This can be done with weights or with clamps. Assure that thesecurement method does not scratch or damage the
28、moisturebarrier.8.1.3 The moisture barrier must not come in contact withdirt or grit, for example, by walking on the surface, as this islikely to cause damage to the moisture barrier.8.2 Test Area Selection:8.2.1 For roll jacketing, select about 4.8 to 5.2 ft2(0.45 to0.48 m2) in each of ten successi
29、ve 3 lineal ft (0.91 m) longsections of the test specimen. This yields 10 approximatelyevenly spaced and evenly sized test areas.8.2.2 For sheet jacketing, select one or more 4.8 to 5.2ft2(0.45 to 0.48 m2) sections per sheet. Test enough sheets toyield 10 approximately evenly spaced and evenly sized
30、 testareas.NOTE 2For both roll and sheet jacketing, a series of ten rectangulartest areas of size 2 by 2.5 ft (610 by 762 mm) is recommended.8.3 Normal Testing Procedure:8.3.1 Wet a test area with an electrolyte such as tap waterwithout allowing a wet connection to form between the wettedareas and a
31、ny bare metal edge of the jacketing. Do not flood themoisture barrier surface with electrolyte.8.3.2 Water tends to run freely on the surface of painted andplastic film moisture barriers so special care must be taken toprevent contact of the electrolyte with the bare metal edgeswhen testing these ty
32、pes.8.3.3 Allow 5 min after wetting for the water to permeatethe moisture barrier.8.3.4 Test for pinhole detections between five and tenminutes after initial wetting.8.3.5 Attach one lead of the pinhole tester to bare metal onthe jacketing piece being tested.8.3.6 Wet the cellulose sponge attached t
33、o the other lead andmove this sponge over the test area such that all portions of thetest area are tested once. The presence of one or more pinholesin the area covered by the sponge allows the completion of anelectrical circuit which will be signaled by the test equipmentas an audible alarm.8.3.7 Du
34、ring the test, note the number of discrete soundingsof the audible alarm in the test area.8.3.8 If one or more portions of the test area yield acontinuous pinhole detection (see 3.2.1), mark these areas.8.3.8.1 Determine the size of the marked continuous pinholedetection areas in inches squared (mil
35、limeters squared) andnote this value.8.3.9 Repeat steps 8.3.1 through 8.3.8 for each of theremaining nine test areas.C1785 17237 8.4 Alternative Testing Procedure:NOTE 3This alternative testing procedure is more time-consumingduring sample preparation but is useful on those specimens where thereare
36、many irregularly shaped relatively small areas of continuous pinholedetection. See X1.2.4 for further information.8.4.1 Outline a rectangular 4.8 to 5.2 ft2(0.45 to 0.48 m2)test area with a permanent marker. An area of size 2 by 2.5 ft(610 by 762 mm) is recommended.8.4.2 Using a permanent marker, dr
37、aw a series of lines 2 in.(51 mm) apart roughly parallel to both sides of the rectangulartest area identified and marked per 8.4.1. This will yield 180marked boxes of size 4 in.2(2581 mm2). The left drawing inFig. 1 shows an example of a test area marked in the mannerdescribed in 8.4.1 and 8.4.2. No
38、te that the size of each markedbox is about the same as the size of the sponge specified in 6.4.8.4.3 Wet the test area with an electrolyte such as tap waterwithout allowing a wet connection to form between the wettedareas and any bare metal edge of the jacketing. Do not flood themoisture barrier su
39、rface with electrolyte.8.4.4 Water tends to run freely on the surface of painted andplastic film moisture barriers so special care must be taken toprevent contact of the electrolyte with the bare metal edgeswhen testing these types.8.4.5 Allow 5 min after wetting for the water to permeatethe moistur
40、e barrier.8.4.6 Test for pinhole detections between five and tenminutes after initial wetting.8.4.7 Attach one lead of the pinhole tester to bare metal onthe jacketing piece being tested.8.4.8 Wet the cellulose sponge attached to the other lead andtouch this sponge with light pressure to each of the
41、 180 squaresmarked in the test area (see 8.4.2). The presence of one or morepinholes in the area covered by the sponge allows the comple-tion of an electrical circuit which will be signaled by the testequipment as an audible alarm.8.4.9 During the testing of the 180 squares in the test area,count th
42、e number of discreet soundings of the audible alarm inthe test area and note this number. This technique differs fromthat in 8.3.6 because each of the 180 marked squares in the testarea is tested individually rather than moving the sponge overthe entire test area.NOTE 4If the number of squares exhib
43、iting a pinhole detection islarge, it is easier to mark each square in which a pinhole detection occursand then later count the number of marked squares. A grease pencil isrecommended for this since a permanent marker will not work because thesurface of the moisture barrier is wet.FIG. 1 Example of
44、Marking and Pinhole Detections Using the Alternative Testing Procedure in 8.4C1785 17337 8.4.10 Repeat steps 8.4.1 8.4.9 for each of the remainingnine test areas.9. Calculations9.1 Sum the number of discrete pinhole detections in eachof the ten test areas to yield a total number of pinholedetections
45、 collectively in all ten test areas. Call this sum P1.9.2 Sum the sizes of the marked continuous pinhole detec-tion areas from 8.3.8.1. Call this sum A1.9.2.1 Divide area A1 in inches squared (millimeterssquared) by the contact area of the sponge in inches squared(millimeters squared). See 6.4. The
46、result is the number ofpinhole detections assigned to the continuous pinhole detectionareas. Call this P2.9.3 Sum P1 and P2 to yield the total number of pinholedetections collectively in all ten test areas. Call this amount P3.10. Report10.1 Report the following information:10.1.1 Identification of
47、the material tested including type ofmetal jacketing and type of moisture barrier.10.1.2 Date of testing.10.1.3 Concentration of pinhole detections as the totalnumber of pinhole detections (value P3 from section 9.3) per50 ft2(4.65 m2).11. Precision and Bias311.1 The precision of this test method is
48、 based on aninterlaboratory study of Test Method C1785 conducted in2016. Four laboratories participated in this study. Each of thelabs reported three replicate test results for three differentmoisture barriers. Every “test result” reported represents anindividual determination. Except for the use of
49、 only fourlaboratories, Practice E691 was followed for the design andanalysis of the data.11.1.1 Repeatability (r)The difference between repetitiveresults obtained by the same operator in a given laboratoryapplying the same test method with the same apparatus underconstant operating conditions on identical test material withinshort intervals of time would in the long run, in the normal andcorrect operation of the test method, exceed the followingvalues only in one case in 20.11.1.1.1 Repeatability can be interpreted as the maximumdifference between
