1、Designation: C1785 16aStandard 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 f
3、ilm 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 elect
4、rically 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 con
5、cerns, 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 I
6、nsulationC1729 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 testa
8、reas 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 pla
9、s-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
10、barriertypically 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 sing
11、le 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
13、audiblealarm 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 a
14、nd Moisture.Current edition approved Sept. 1, 2016. Published September 2016. Originallyapproved in 2013. Last previous edition approved in 2016 as C1785 16. DOI:10.1520/C1785-16A.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org
15、. For 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 met
16、al jacketing 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 for
17、mation 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 j
18、acketing.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
19、 barrier 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 equipme
20、nt shall 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 On
21、e lead 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
22、size capable of touching the moisture barrierof 2 6116 by 2 6116 in. (50.8 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 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.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 w
28、aterwithout allowing a wet connection to form between the wettedareas and any 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 topreven
29、t contact of the electrolyte with the bare metal edgeswhen testing these types.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 o
30、nthe 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 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 circu
31、it which will be signaled by the test equipmentas an audible alarm.8.3.7 During 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
32、size of the marked continuous pinholedetection areas in inches squared (millimeters squared) andnote this value.8.3.9 Repeat steps 8.3.1 through 8.3.8 for each of theremaining nine test areas.8.4 Alternative Testing Procedure:NOTE 3This alternative testing procedure is more time-consumingduring samp
33、le preparation but is useful on those specimens where thereare many irregularly shaped relatively small areas of continuous pinholedetection. See X1.2.4 for further information.C1785 16a28.4.1 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 b
34、y 2.5 ft(610 by 762 mm) is recommended.8.4.2 Using a permanent marker, draw 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 ex
35、ample of a test area marked in the mannerdescribed in 8.4.1 and 8.4.2. Note 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
36、any bare metal edge of the jacketing. Do not flood themoisture barrier surface 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 t
37、ypes.8.4.5 Allow 5 min after wetting for the water to permeatethe moisture 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
38、to the other lead andtouch this sponge with light pressure to each of the 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 al
39、arm.8.4.9 During the testing of the 180 squares in the test area,count the 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
40、 the sponge overthe entire test area.NOTE 4If the number of squares exhibiting 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
41、work because thesurface of the moisture barrier is wet.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 collectively in all ten test area
42、s. 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 squaredFIG. 1 Example of Marking and Pinhole Detections Using the Alternative
43、 Testing Procedure in 8.4C1785 16a3(millimeters squared). 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 collectively in all ten test areas. Call this amount P3.10
44、. 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 detections (value P3 from section 9.3) per50 ft2(4.
45、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 BiasNo information can be presented on the bias ofth
46、e 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; lagging; moisturebarrier; moisture retarder; pinhole
47、; pinhole detections; thermalinsulationAPPENDIX(Nonmandatory Information)X1. DESCRIPTIONS OF PATTERNS IN PINHOLE DETECTIONS ENCOUNTERED AND RECOMMENDED TEST PROTO-COLS FOR EACH PATTERNX1.1 BackgroundX1.1.1 In past testing of pinhole detections using TestMethod C1785 including testing done in an atte
48、mpted inter-laboratory study, various types of patterns in pinhole detectionswere observed. It was found that certain test protocols weremore effective and efficient in measuring the number of pinholedetections for the various patterns observed.X1.2 Patterns in Pinhole DetectionsX1.2.1 There are thr
49、ee types of patterns to the pinholedetections that have been observed in past testing.X1.2.2 A relatively small number of discreet pinhole detec-tions. These are easily counted as the test sponge is moved overthe test area such that all portions of the test area are testedonce. The key to this pattern is not the number of pinholeFIG. X1.1 The Three Patterns of Pinhole DetectionsC1785 16a4detections but, rather, that they are discreet and countable witha clear separation between the incidents of pinhole detection.The left drawing in Fig. X1.1 shows an example of
