1、Designation: C1785 16Standard 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 and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C168 Terminology Relating to Thermal In
6、sulationC1729 Specification for Aluminum Jacketing for InsulationC1767 Specification for Stainless Steel Jacketing for Insula-tion3. 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
7、pinhole detectionwhile the test is beingconducted, a continuous sounding of the audible test 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 testar
8、eas will yield a continuous pinhole detection. This concept ofa continuous pinhole detection 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
9、-tic film or other material applied to the inner side of metaljacketing to inhibit jacket corrosion 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 b
10、arriertypically too small to be seen by the eye.3.2.4 pinhole detectiona single sounding of 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 singl
11、e pinhole (see 6.4), it is theoreticallypossible that multiple pinholes in close proximity to 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
12、Method4.1 A voltage is applied across the nonconductive moisturebarrier on metal jacketing using an electrode consisting of acellulose sponge dampened with an electrically conductiveliquid such as tap water. Holes in the moisture barrier lead tocompletion of an electrical circuit which triggers an a
13、udiblealarm in the test equipment. The number of pinhole detectionscollectively in ten specified test areas is determined andreported.1This test method is under the jurisdiction ofASTM Committee C16 on ThermalInsulation and is the direct responsibility of Subcommittee C16.33 on InsulationFinishes an
14、d Moisture.Current edition approved March 1, 2016. Published March 2016. Originallyapproved in 2013. Last previous edition approved in 2015 as C1785 15. DOI:10.1520/C1785-16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For
15、Annual Book of ASTMStandards volume information, 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 States15. Significance and Use5.1 Corrosion on the interior surface of metal jac
16、keting canbe caused by the formation of a galvanic cell between thedissimilar 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
17、 or by preventingwater from contacting the interior metal surface.5.3 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 jacketi
18、ng.5.4 Small holes called pinholes or holidays that are notvisible to 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 barri
19、er for the purposeof quality control on metal jacketing with an applied 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 sha
20、ll be a pinhole or holiday detectorwith an output voltage of 65 to 75 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
21、 of the pinhole detector shall have a springtensioned metal clamp capable 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 c
22、apable of touching the moisture barrierof 2 6116 in. by 2 6116 in. (50.8 6 1.6 mm by 50.8 6 1.6mm).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 ca
23、n be conveniently placed on a tablecan 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 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.
24、 Procedure8.1 Sample Preparation:8.1.1 Place specimen(s) on a reasonably flat, 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 wi
25、th clamps. Assure that thesecurement method does not scratch or damage the 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 jac
26、keting, select about 4.8 to 5.2 ft2(0.45 to0.48 m2) in each of ten successive 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.
27、 Test enough sheets toyield 10 approximately evenly spaced and evenly sized testareas.8.3 Testing:8.3.1 Wet a 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
28、rface 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 types.8.3.3 Allow five minutes after wetting for the water topermeate the
29、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 to the other lead andmove this sponge over the test area such that
30、 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 During the test, note the number of discrete soundingsof the audibl
31、e 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 in.2(mm2) and note this value.8.3.9 Repeat steps 8.3.1 through 8.3.8 for each of the
32、remaining nine 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 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.
33、Call this sum A1.C1785 1629.2.1 Divide areaA1 in in.2(mm2) by the contact area of thesponge in in.2(mm2). See 6.4. The 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 collective
34、ly 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 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 det
35、ections (value P3 from section 9.3) per50 ft2(4.65 m2).11. Precision and Bias11.1 PrecisionThe precision information (repeatabilityand reproducibility) of this test method will be determined viaan inter-laboratory study once it is approved and will beavailable on or before December 1, 2014.11.2 Bias
36、No information can be presented on the bias ofthe procedure in this test method for measuring the concentra-tion of pinhole detections in moisture barriers on metaljacketing because no material having an accepted referencevalue is available.12. Keywords12.1 cladding; holiday; jacket; jacketing; lagg
37、ing; moisturebarrier; moisture retarder; pinhole; pinhole detections; thermalinsulationASTM International takes 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
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