1、Designation: C1785 16aC1785 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 revis
2、ion, the 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 concentration of pinhole detections in a moisture ba
3、rrier film or coatingthat is applied to the interior surface of metal jacketing.1.2 Since this method relies on the completion through the metal jacketing of an electrical circuit, this method is only applicableto jacketing that is electrically conductive and has a moisture barrier applied which is
4、not electrically conductive.1.3 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information only and are not considered standard.1.4 This standard does not purport to address all of th
5、e safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitations prior to use.1.5 This international standard was develop
6、ed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents
7、2.1 ASTM Standards:2C168 Terminology Relating to Thermal InsulationC1729 Specification for Aluminum Jacketing for InsulationC1767 Specification for Stainless Steel Jacketing for InsulationE177 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE691 Practice for Conducting an Interl
8、aboratory Study to Determine the Precision of a Test Method3. Terminology3.1 DefinitionsDefinitions in Terminology C168 apply to terms used in this specification.3.2 Definitions of Terms Specific to This Standard:3.2.1 continuous pinhole detectionwhile the test is being conducted, a continuous sound
9、ing of the audible test equipmentalarm over an area larger than the contact area of the cellulose sponge.3.2.1.1 DiscussionIn some cases, large portions of one or more of the test areas (see 8.2.1) or even all of one or more test areas will yield a continuouspinhole detection. This concept of a cont
10、inuous pinhole detection and the area yielding this performance is necessary to quantifythe number of pinhole detections in a sample exhibiting this phenomenon (see 9.2 and 9.3)1 This test method is under the jurisdiction ofASTM Committee C16 on Thermal Insulation and is the direct responsibility of
11、 Subcommittee C16.33 on Insulation Finishesand Moisture.Current edition approved Sept. 1, 2016Sept. 1, 2017. Published September 2016October 2017. Originally approved in 2013. Last previous edition approved in 2016 asC1785 16.C1785 16a. DOI: 10.1520/C1785-16A.10.1520/C1785-17.2 For referencedASTM st
12、andards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an
13、 ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as publis
14、hed by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.2 moisture barrier (moisture retarder)a layer of plastic film or other material applied to the inner side of metal jacketingto i
15、nhibit jacket corrosion by interfering with the formation of a galvanic cell between the dissimilar metals of the pipe and jacketor by preventing crevice or pitting corrosion.3.2.3 pinholea hole completely through a moisture barrier typically too small to be seen by the eye.3.2.4 pinhole detectiona
16、single sounding of the audible test equipment alarm while the test is being conducted.3.2.4.1 DiscussionBecause pinholes are very small and the dampened cellulose sponge contacts the moisture barrier in an area larger than a singlepinhole (see 6.4), it is theoretically possible that multiple pinhole
17、s in close proximity to each other would register as a singledetection. For this reason, this test method measures the concentration of pinhole detections rather than pinholes.3.2.5 holidaysynonymous with pinhole.4. Summary of Test Method4.1 Avoltage is applied across the nonconductive moisture barr
18、ier on metal jacketing using an electrode consisting of a cellulosesponge dampened with an electrically conductive liquid such as tap water. Holes in the moisture barrier lead to completion of anelectrical circuit which triggers an audible alarm in the test equipment. The number of pinhole detection
19、s collectively in tenspecified test areas is determined and reported.5. Significance and Use5.1 Corrosion on the interior surface of metal jacketing can be caused by the formation of a galvanic cell between the dissimilarmetals of the pipe and jacket or by crevice or pitting corrosion.5.2 The applic
20、ation of a moisture barrier to the interior surface of the metal jacketing inhibits this corrosion by interfering withthe galvanic cell formation or by preventing water from contacting the interior metal surface.5.3 Holes in the moisture barrier decrease its effectiveness in preventing corrosion. La
21、rge holes, scratches, or tears in themoisture barrier visible to the naked eye are easily discerned and are cause for rejection of the metal jacketing.5.4 Small holes called pinholes or holidays that are not visible to the naked eye but are large enough to allow corrosion are asignificant concern an
22、d should be avoided to the extent possible.5.5 This test method is used to quantify the concentration of pinhole detections present in a moisture barrier for the purpose ofquality control on metal jacketing with an applied moisture barrier.5.6 Examples of standards which have specific requirements f
23、or the maximum allowable concentration of pinhole detections inthe moisture barrier are Specifications C1729 and C1767.6. Apparatus6.1 Test equipment shall be a pinhole or holiday detector with an output voltage of 65 to 75 volts DC that emits an audible signalwhen a connection between the two leads
24、 is detected.NOTE 1These instruments can be found by performing a web search for “wet sponge pinhole detector” or “wet sponge holiday detector”.6.2 One lead of the pinhole detector shall have a spring tensioned metal clamp capable of being attached to the metal jacketing.6.3 The other lead of the pi
25、nhole detector shall have a metal clamp capable of securing a cellulose sponge.6.4 The cellulose sponge clamped to the pinhole detector lead shall have a size capable of touching the moisture barrier of 26 116 by 2 6 116 in. (50.8 6 1.6 by 50.8 6 1.6 mm).6.5 Test equipment shall have its test voltag
26、e and operability validated on a regular basis.7. Test Specimens7.1 Specimens tested are metal jacketing rolls or metal jacketing sheets.7.2 Any width that can be conveniently placed on a table can be tested but the typical width of metal jacketing is 3 ft (0.91 m)or, rarely, 4 ft (1.22 m).7.3 For r
27、olls, 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 the approximately 30 ft (9.1 m) long testing surface.8. Procedure8.1 Sample Preparation:8.1.1 Place specimen(s) on a reasonably flat, level, and clean surface with the moisture barrier facing up.
28、C1785 1728.1.2 If necessary, secure the jacketing to the test surface so that it is reasonably flat and does not curl up during testing. Thiscan be done with weights or with clamps. Assure that the securement method does not scratch or damage the moisture barrier.8.1.3 The moisture barrier must not
29、come in contact with dirt or grit, for example, by walking on the surface, as this is likelyto 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 to 0.48 m2) in each of ten successive 3 lineal ft (0.91 m) long sectionsof the test
30、specimen. This yields 10 approximately evenly spaced and evenly sized test areas.8.2.2 For sheet jacketing, select one or more 4.8 to 5.2 ft2 (0.45 to 0.48 m2) sections per sheet. Test enough sheets to yield 10approximately evenly spaced and evenly sized test areas.NOTE 2For both roll and sheet jack
31、eting, a series of ten rectangular test 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 water without allowing a wet connection to form between the wetted areasand any bare metal edge of the jacketing. Do not
32、 flood the moisture barrier surface with electrolyte.8.3.2 Water tends to run freely on the surface of painted and plastic film moisture barriers so special care must be taken toprevent contact of the electrolyte with the bare metal edges when testing these types.8.3.3 Allow 5 min after wetting for
33、the water to permeate the moisture barrier.8.3.4 Test for pinhole detections between five and ten minutes after initial wetting.8.3.5 Attach one lead of the pinhole tester to bare metal on the jacketing piece being tested.8.3.6 Wet the cellulose sponge attached to the other lead and move this sponge
34、 over the test area such that all portions of thetest area are tested once. The presence of one or more pinholes in the area covered by the sponge allows the completion of anelectrical circuit which will be signaled by the test equipment as an audible alarm.8.3.7 During the test, note the number of
35、discrete soundings of the audible alarm in the test area.8.3.8 If one or more portions of the test area yield a continuous pinhole detection (see 3.2.1), mark these areas.8.3.8.1 Determine the size of the marked continuous pinhole detection areas in inches squared (millimeters squared) and notethis
36、value.8.3.9 Repeat steps 8.3.1 through 8.3.8 for each of the remaining nine test areas.8.4 Alternative Testing Procedure:NOTE 3This alternative testing procedure is more time-consuming during sample preparation but is useful on those specimens where there are manyirregularly shaped relatively small
37、areas of continuous pinhole detection. 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 (610by 762 mm) is recommended.8.4.2 Using a permanent marker, draw a series of lines 2 in. (51 mm) apa
38、rt roughly parallel to both sides of the rectangular testarea identified and marked per 8.4.1. This will yield 180 marked boxes of size 4 in.2 (2581 mm2). The left drawing in Fig. 1 showsan example of a test area marked in the manner described in 8.4.1 and 8.4.2. Note that the size of each marked bo
39、x is about thesame as the size of the sponge specified in 6.4.8.4.3 Wet the test area with an electrolyte such as tap water without allowing a wet connection to form between the wetted areasand any bare metal edge of the jacketing. Do not flood the moisture barrier surface with electrolyte.8.4.4 Wat
40、er tends to run freely on the surface of painted and plastic film moisture barriers so special care must be taken toprevent contact of the electrolyte with the bare metal edges when testing these types.8.4.5 Allow 5 min after wetting for the water to permeate the moisture barrier.8.4.6 Test for pinh
41、ole detections between five and ten minutes after initial wetting.8.4.7 Attach one lead of the pinhole tester to bare metal on the jacketing piece being tested.8.4.8 Wet the cellulose sponge attached to the other lead and touch this sponge with light pressure to each of the 180 squaresmarked in the
42、test area (see 8.4.2). The presence of one or more pinholes in the area covered by the sponge allows the completionof an electrical circuit which will be signaled by the test equipment as an audible alarm.8.4.9 During the testing of the 180 squares in the test area, count the number of discreet soun
43、dings of the audible alarm in thetest area and note this number. This technique differs from that in 8.3.6 because each of the 180 marked squares in the test areais tested individually rather than moving the sponge over the entire test area.NOTE 4If the number of squares exhibiting a pinhole detecti
44、on is large, it is easier to mark each square in which a pinhole detection occurs and thenlater count the number of marked squares. A grease pencil is recommended for this since a permanent marker will not work because the surface of themoisture barrier is wet.8.4.10 Repeat steps 8.4.1 8.4.9 for eac
45、h of the remaining nine test areas.9. Calculations9.1 Sum the number of discrete pinhole detections in each of the ten test areas to yield a total number of pinhole detectionscollectively in all ten test areas. Call this sum P1.C1785 1739.2 Sum the sizes of the marked continuous pinhole detection ar
46、eas from 8.3.8.1. Call this sum A1.9.2.1 Divide area A1 in inches squared (millimeters squared) by the contact area of the sponge in inches squared (millimeterssquared). See 6.4. The result is the number of pinhole detections assigned to the continuous pinhole detection areas. Call this P2.9.3 Sum P
47、1 and P2 to yield the total number of pinhole detections collectively in all ten test areas. Call this amount P3.10. Report10.1 Report the following information:10.1.1 Identification of the material tested including type of metal jacketing and type of moisture barrier.10.1.2 Date of testing.10.1.3 C
48、oncentration of pinhole detections as the total number of pinhole detections (value P3 from section 9.3) per 50 ft2 (4.65m2).FIG. 1 Example of Marking and Pinhole Detections Using the Alternative Testing Procedure in 8.4TABLE 1 Pinholes DetectedMaterial AverageARepeatabilityStandardDeviationReproduc
49、ibilityStandardDeviationRepeatabilityLimitReproducibilityLimitx Sr SR r RStucco embossed metalwith polykraft moisturebarrier1793 9 12 25 33Smooth metal with poly-film moisture barrier 8 8 8 22 24Smooth metal withpainted moisture barrier 1559 66 420 186 1176A The average of the laboratories calculated averages.C1785 17411. Precision and Bias311.1 PrecisionThe precision information (repeatability and reproducibility) of this test method will be determined via aninter-laboratory study once it is approvedis based on an interlaboratory study of Test Method C178
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