ASTM E432-91(2004)
(Guide)Standard Guide for Selection of a Leak Testing Method
Standard Guide for Selection of a Leak Testing Method
ABSTRACT
This guide deals with the selection of the appropriate leak testing method for either leak measurement or location for a particular system being tested (test system), which may consist either of open units or sealed units. The leak testing method may either be dynamic or static, with the dynamic test method requiring shorter time but lesser sensitivity as compared to static techniques. The choice of the appropriate leak testing method shall involve most importantly the optimization of the sensitivity, cost, and reliability of the test. In the case where various testing methods are available for a particular test system, each shall be examined separately and then ranked according to test system sensitivity. However, when determining the sensitivity, it is important to be able to differentiate the sensitivity associated with the instrument used to measure leakage from the sensitivity of the test system followed using the instrument. While the sensitivity of a specific test is dependent on the sensitivity of the instrument used, the choice of instrument and the test system are both influenced by the range of temperatures or pressures and the kinds of fluids involved.
SCOPE
1.1 This guide is intended to assist in the selection of a leak testing method. is supplied as a simplified guide.
1.2 The type of item to be tested or the test system and the method considered for either leak measurement or location are related in the order of increasing sensitivity.
1.3 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.
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Designation:E432–91 (Reapproved 2004)
Standard Guide for
1
Selection of a Leak Testing Method
This standard is issued under the fixed designation E432; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope atracerforleaklocationbecauseofthehazardsassociatedwith
2 their use. However, such gases are employed in leakage
1.1 Thisguide isintendedtoassistintheselectionofaleak
3
detection equipment when they can be safely added to, and
testing method. Fig. 1 is supplied as a simplified guide.
removed from, a test chamber on a periodic basis.
1.2 The type of item to be tested or the test system and the
4.3 It is important to distinguish between the sensitivity
method considered for either leak measurement or location are
associated with the instrument employed to measure leakage
related in the order of increasing sensitivity.
and the sensitivity of the test system followed using the
1.3 This standard does not purport to address all of the
instrument. The sensitivity of the instrument influences the
safety concerns, if any, associated with its use. It is the
sensitivity that can be attained in a specific test. The range of
responsibility of the user of this standard to establish appro-
temperatures or pressures, and the types of fluids involved,
priate safety and health practices and determine the applica-
influence both the choice of instrument and the test system.
bility of regulatory limitations prior to use.
4.4 The sensitivity of various test systems differ. For ex-
2. Referenced Documents
ample, a test utilizing a mass spectrometer leak detector
−15
normallyhasanultimatesensitivityof4.4 310 mol/swhen
2.1 ASTM Standards:
4
the procedure involves the measurement of a steady-state gas
E425 Terminology Relating to Leak Testing
leakage rate.The sensitivity of the test may be increased under
−19
3. Terminology
special conditions to 4.4 310 mol/s by allowing an accu-
mulation of the leakage to occur in a known volume before a
3.1 Definitions—The definitions of terms relating to leak
measurement of leakage is made. In the first case, the sensi-
testing which appear in Terminology E425 shall apply to the
tivity of the test equals the sensitivity of the instrument;
terms in this guide.
4
whereas in the second case, the sensitivity of the test is 10
4. Selection of System
times greater than that of the instrument. If the test system
utilizes a mass spectrometer operating in the detector-probe
4.1 The correct choice of a leak testing method optimizes
2 4
mode, the sensitivity of the test can be 10 to 10 smaller than
sensitivity, cost, and reliability of the test. One approach is to
that of the mass spectrometer itself.
rank the various methods according to test system sensitivity.
4.2 The various testing methods must be individually ex-
5. Leakage Measurement
amined to determine their suitability for the particular system
5.1 In general, leakage measurement procedures involve
being tested. Only then can the appropriate method be chosen.
covering the whole of the suspected region with tracer gas,
For example, radioactive gases are not generally employed as
while establishing a pressure differential across the system by
either pressurizing with a tracer gas or by evacuating the
1
This guide is under the jurisdiction of ASTM Committee E07 on Nondestruc-
opposite side. The presence and concentration of tracer gas on
tive Testing and is the direct responsibility of Subcommittee E07.08 on Leak
the lower pressure side of the system are determined and then
Testing.
measured.
Current edition approved May 1, 2004. Published June 2004. Originally
approvedin1971.Lastpreviouseditionapprovedin1997asE432-91(1997).DOI:
5.2 Adynamic test method can be performed in the shortest
10.1520/E0432-91R04.
time. While static techniques increase the test sensitivity, the
2
For ASME Boiler and Pressure Vessel Code applications see related Recom-
time for testing is also increased.
mended Guide SE-432 in the Code.
3
Additional information may be obtained from Marr, J. W., Leakage Testing 5.3 Equipment or devices that are the object of leakage
Handbook, Report No. CR-952, NASA, Scientific and Technical Information
measurementfallintotwocategories:(1)openunits,whichare
Facility, P. O. Box 33, College Park, MD 20740 (Organizations registered with
accessible on both sides, and (2) units that are sealed. The
NASA) or Clearing House for Federal, Scientific and Technical Information, Code
second category is usually applied to mass-produced items
410.14, Port Royal Road, Springfield, VA 22151.
4
Withdrawn. Replaced by Terminology E1316.
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