ASTM E432-91(2011)

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.

General Information

• Status: Historical
• Publication Date: 30-Jun-2011
• ICS: 77.040.99 - Other methods of testing of metals
• Technical Committee: E07 - Nondestructive Testing
• Drafting Committee: E07.08 - Leak Testing Method

Relations

• Replaces: ASTM E432-91(2004) - Standard Guide for Selection of a Leak Testing Method
• Effective Date: 01-Jul-2011
• Referred By: ASTM E543-21 - Standard Specification for Agencies Performing Nondestructive Testing
• Effective Date: 01-Jul-2011
• Referred By: ASTM E2533-21 - Standard Guide for Nondestructive Examination of Polymer Matrix Composites Used in Aerospace Applications
• Effective Date: 01-Jul-2011
• Referred By: ASTM E1002-11(2022) - Standard Practice for Leaks Using Ultrasonics
• Effective Date: 01-Jul-2011
• Referred By: ASTM E2982-21 - Standard Guide for Nondestructive Examination of Thin-Walled Metallic Liners in Filament-Wound Pressure Vessels Used in Aerospace Applications
• Effective Date: 01-Jul-2011
• Referred By: ASTM F2391-22 - Standard Test Method for Measuring Package and Seal Integrity Using Helium as the Tracer Gas
• Effective Date: 01-Jul-2011

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E432 − 91 (Reapproved 2011)
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 For example, radioactive gases are not generally employed as
atracerforleaklocationbecauseofthehazardsassociatedwith
1.1 Thisguide isintendedtoassistintheselectionofaleak
3 their use. However, such gases are employed in leakage
testing method. Fig. 1 is supplied as a simplified guide.
detection equipment when they can be safely added to, and
1.2 The type of item to be tested or the test system and the
removed from, a test chamber on a periodic basis.
method considered for either leak measurement or location are
4.3 It is important to distinguish between the sensitivity
related in the order of increasing sensitivity.
associated with the instrument employed to measure leakage
1.3 This standard does not purport to address all of the
and the sensitivity of the test system followed using the
safety concerns, if any, associated with its use. It is the
instrument. The sensitivity of the instrument influences the
responsibility of the user of this standard to establish appro-
sensitivity that can be attained in a specific test. The range of
priate safety and health practices and determine the applica-
temperatures or pressures, and the types of fluids involved,
bility of regulatory limitations prior to use.
influence both the choice of instrument and the test system.
2. Referenced Documents
4.4 The sensitivity of various test systems differ. For
example, a test utilizing a mass spectrometer leak detector
2.1 ASTM Standards:
−15
normally has an ultimate sensitivity of 4.4×10 mol/s when
E425Definitions of Terms Relating to Leak Testing (With-
the procedure involves the measurement of a steady-state gas
drawn 1991)
leakage rate.The sensitivity of the test may be increased under
−19
3. Terminology special conditions to 4.4×10 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.
whereas in the second case, the sensitivity of the test is 10
times greater than that of the instrument. If the test system
4. Selection of 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,
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
opposite side. The presence and concentration of tracer gas on
Method.
the lower pressure side of the system are determined and then
CurrenteditionapprovedJuly1,2011.PublishedJuly2011.Originallyapproved
measured.
in 1971. Last previous edition approved in 2004 as E432-91 (2004). DOI:
10.1520/E0432-91R11.
2 5.2 Adynamic test method can be performed in the shortest
For ASME Boiler and Pressure Vessel Code applications see related Recom-
mended Guide SE-432 in the Code.
time. While static techniques increase the test sensitivity, the
Additional information may be obtained from Marr, J. W., Leakage Testing
time for testing is also increased.
Handbook, Report No. CR-952, NASA, Scientific and Technical Information
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
measurementfallintotwocategories:(1)openunits,whichare
410.14, Port Royal Road, Springfield, VA 22151.
accessible on both sides, and (2) units that are sealed. The
The last approved version of this historical standard is referenced on
www.astm.org. second category is usually applied to mass-produced items
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E432 − 91 (2011)
FIG. 1 Guide for Selection of Leakage Testing Method
including gas and vacuum tubes, transistors, integrated circuit (c)When no inherent tracer is available, the next approach
modules, relays, ordnance units, and hermetically sealed in- should be to determine if there is a gage in the system that
struments. mightbeusedforleakagemeasurement.Thisgagemightbean
5.3.1 Open or Single-Sealed Units—Either evacuation or ionization gage or, in some fortunate circumstances, a mass
pressurization of one side of a unit that is accessible on both spectrometer in the system as part of the analytical instrumen-
sides, may be employed to test for leakage across a unit. tation.Considerationshouldbegivennotonlytogagesthatare
5.3.1.1 Systems Leaking to Vacuum—Intheorderofincreas- normally used for leak detection, but to any gas concentration
ing sensitivity for testing an evacuated system, the methods detectionequipmentthatmaybeusedforleakagemeasurement
include: flow measurement, absolute pressure measurement, ifithappenstobeavailable.Equipmentnotoriginallyintended
the alkaline-ion diode halogen detector, and the helium mass for pressure measurement may be used; for example, it is
spectrometer leak detector. possibletodetectthepressureriseinaleakingvacuumtubeby
(a)The first approach to the testing of units that may be operating the grid at a positive and an anode at a negative
evacuated is to determine if there is an inherent tracer in the potential, and noting an increase in anode current with time.
system. This gas should be utilized if possible. (d)When there is no inherent tracer or gage within the
(b)When one side is evacuated, leakage of the tracer into system,astandardtestingmethodmustbechosenbasedonthe
the vacuum will reach the detector quickly if there is essen- sensitivity desired.
tially no stratification. However, evacuation does not always 5.3.1.2 Systems Leaking to Atmosphe
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