ASTM E432-91(2022)
(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 guide2 is intended to assist in the selection of a leak testing method.3 Fig. 1 is supplied as a simplified guide.
FIG. 1 Guide for Selection of Leakage Testing Method
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E432 − 91 (Reapproved 2022)
Standard Guide for
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 4.2 The various testing methods must be individually ex-
amined to determine their suitability for the particular system
1.1 Thisguide isintendedtoassistintheselectionofaleak
3 being tested. Only then can the appropriate method be chosen.
testing method. Fig. 1 is supplied as a simplified guide.
For example, radioactive gases are not generally employed as
1.2 The type of item to be tested or the test system and the
atracerforleaklocationbecauseofthehazardsassociatedwith
method considered for either leak measurement or location are
their use. However, such gases are employed in leakage
related in the order of increasing sensitivity.
detection equipment when they can be safely added to, and
1.3 This standard does not purport to address all of the removed from, a test chamber on a periodic basis.
safety concerns, if any, associated with its use. It is the
4.3 It is important to distinguish between the sensitivity
responsibility of the user of this standard to establish appro-
associated with the instrument employed to measure leakage
priate safety, health, and environmental practices and deter-
and the sensitivity of the test system followed using the
mine the applicability of regulatory limitations prior to use.
instrument. The sensitivity of the instrument influences the
1.4 This international standard was developed in accor-
sensitivity that can be attained in a specific test. The range of
dance with internationally recognized principles on standard-
temperatures or pressures, and the types of fluids involved,
ization established in the Decision on Principles for the
influence both the choice of instrument and the test system.
Development of International Standards, Guides and Recom-
4.4 The sensitivity of various test systems differ. For
mendations issued by the World Trade Organization Technical
example, a test utilizing a mass spectrometer leak detector
Barriers to Trade (TBT) Committee.
−15
normally has an ultimate sensitivity of 4.4×10 mol/s when
2. Referenced Documents the procedure involves the measurement of a steady-state gas
leakage rate.The sensitivity of the test may be increased under
2.1 ASTM Standards:
−19
special conditions to 4.4×10 mol/s by allowing an accu-
E1316Terminology for Nondestructive Examinations
mulation of the leakage to occur in a known volume before a
measurement of leakage is made. In the first case, the sensi-
3. Terminology
tivity of the test equals the sensitivity of the instrument;
3.1 Definitions—The definitions of terms relating to leak
whereas in the second case, the sensitivity of the test is 10
testing which appear in Terminology E1316 shall apply to the
times greater than that of the instrument. If the test system
terms in this guide.
utilizes a mass spectrometer operating in the detector-probe
2 4
mode, the sensitivity of the test can be 10 to 10 smaller than
4. Selection of System
that of the mass spectrometer itself.
4.1 The correct choice of a leak testing method optimizes
sensitivity, cost, and reliability of the test. One approach is to 5. Leakage Measurement
rank the various methods according to test system sensitivity.
5.1 In general, leakage measurement procedures involve
covering the whole of the suspected region with tracer gas,
while establishing a pressure differential across the system by
This guide is under the jurisdiction of ASTM Committee E07 on Nondestruc-
either pressurizing with a tracer gas or by evacuating the
tiveTestingandisthedirectresponsibilityofSubcommitteeE07.08onLeakTesting
Method.
opposite side. The presence and concentration of tracer gas on
CurrenteditionapprovedJune1,2022.PublishedJuly2022.Originallyapproved
the lower pressure side of the system are determined and then
ε1
in 1971. Last previous edition approved in 2017 as E432–91(2017) . DOI:
measured.
10.1520/E0432-91R22.
For ASME Boiler and Pressure Vessel Code applications, see related Recom-
5.2 Adynamic test method can be performed in the shortest
mended Guide SE-432 in the Code.
3 time. While static techniques increase the test sensitivity, the
Additional information may be obtained from Marr, J. W., Leakage Testing
Handbook, Report No. CR-952, NASA, Scientific and Technical Information time for testing is also increased.
Facility, P. O. Box 33, College Park, MD 20740 (Organizations registered with
5.3 Equipment or devices that are the object of leakage
NASA) or Clearing House for Federal, Scientific and Technical Information, Code
410.14, Port Royal Road, Springfield, VA 22151. measurementfallintotwocategories:(1)openunits,whichare
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E432 − 91 (2022)
FIG. 1 Guide for Selection of Leakage Testing Method
accessible on both sides, and (2) units that are sealed. The to the pump port. The amount of tracer gas that reaches the
second category is usually applied to mass-produced items detector may then be substantially reduced depending on the
including gas and vacuum tubes, transistors, integrated circuit location of the detector in the evacuated region.
modules, relays, ordnance units, and hermetically sealed in- (c)When no inherent tracer is available, the next approach
struments. should be to determine if there is a gage in the system that
5.3.1 Open or Single-Sealed Units—Either evacuation or
mightbeusedforleakagemeasurement.Thisgagemightbean
pressurization of one side of a unit that is accessible on both ionization gage or, in some fortunate circumstances, a mass
sides, may be employed to test for leakage across a unit. spectrometer in the system as part of the analytical instrumen-
5.3.1.1 Systems Leaking to Vacuum—Intheorderofincreas- tation.Considerationshouldbegivennotonlytogagesthatare
ing sensitivity for testing an evacuated system, the methods normally used for leak detection, but to any gas concentration
include: flow measurement, absolute pressure measurement, detectionequipmentthatmaybeusedforleakagemeasurement
the alkaline-ion diode halogen detector, and the helium mass ifithappenstobeavailable.Equipmentnotoriginallyintended
spectrometer leak detector. for pressure measurement may be used; for example, it is
(a)The first approach to the testing of units that may be possibletodetectthepressureriseinaleakingvacuumtubeby
evacuated is to determine if there is an inherent tracer in the operating the grid at a positive and an anode at a negative
system. This gas should be utilized if possible. potential, and noting an increase in
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.