ASTM C1785-16

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Designation: C1785 − 15 C1785 − 16
Standard Test Method for
Concentration of Pinhole Detections in Moisture Barriers on
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Metal Jacketing
This standard is issued under the fixed designation C1785; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers the determination of the concentration of pinhole detections in a moisture barrier film or coating
that 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 applicable
to jacketing that is electrically conductive and has a moisture barrier applied which is not electrically conductive.
1.3 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions 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 the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
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2.1 ASTM Standards:
C168 Terminology Relating to Thermal Insulation
C1729 Specification for Aluminum Jacketing for Insulation
C1767 Specification for Stainless Steel Jacketing for Insulation
3. Terminology
3.1 Definitions—Definitions in Terminology C168 apply to terms used in this specification.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 continuous pinhole detection—while the test is being conducted, a continuous sounding of the audible test equipment
alarm over an area larger than the contact area of the cellulose sponge.
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This test method is under the jurisdiction of ASTM Committee C16 on Thermal Insulation and is the direct responsibility of Subcommittee C16.33 on Insulation Finishes
and Moisture.
Current edition approved Nov. 1, 2015March 1, 2016. Published November 2015March 2016. Originally approved in 2013. Last previous edition approved in 20132015
as C1785C1785 – 15.-13. DOI: 10.1520/C1785-15.10.1520/C1785-16.
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For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3.2.1.1 Discussion—
In 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 continuous
pinhole detection. This concept of a continuous pinhole detection and the area yielding this performance is necessary to quantify
the number of pinhole detections in a sample exhibiting this phenomenon (see 9.2 and 9.3)
3.2.2 moisture barrier (moisture retarder)—a layer of plastic film or other material applied to the inner side of metal jacketing
to inhibit jacket corrosion by interfering with the formation of a galvanic cell between the dissimilar metals of the pipe and jacket
or by preventing crevice or pitting corrosion.
3.2.3 pinhole—a hole completely through a moisture barrier typically too small to be seen by the eye.
3.2.4 pinhole detection—a single sounding of the audible test equipment alarm while the test is being conducted.
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C1785 − 16
3.2.4.1 Discussion—
Because pinholes are very small and the dampened cellulose sponge contacts the moisture barrier in an area larger than a single
pinhole (see 6.4), it is theoretically possible that multiple pinholes in close proximity to each other would register as a single
detection. For this reason, this test method measures the concentration of pinhole detections rather than pinholes.
3.2.5 holiday—synonymous with pinhole.
4. Summary of Test Method
4.1 A voltage is applied across the nonconductive moisture barrier on metal jacketing using an electrode consisting of a cellulose
sponge dampened with an electrically conductive liquid such as tap water. Holes in the moisture barrier lead to completion of an
electrical circuit which triggers an audible alarm in the test equipment. The number o
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