MIL-DTL-17813H
the manufacturer to permit the manufacturer to recommend anchorage, guidance, alignment
requirements, and other recommendations for the specific application.
c. The life of a bellows expansion joint depends upon several variables of which the following are
a few examples: thickness of bellows material, size of the bellows, number of corrugations,
amount of motion, frequency of motion, temperature and pressure conditions. Therefore, no
life expectancy can be generally specified for all types of joints. The life requirement is best
specified by the number of complete cycles of movement which is anticipated for the period
the joint should last. This would be determined by the number of times the service would be
shut down over the required period, or by the number of times the temperature would vary
between certain limits during the period. Vibrational movement should be specified by
amplitude and frequency, as flexural stresses in the bellows under vibration should be within
the proportional limit of the material used. Cyclic endurance proof tests are expensive since
the joint under test is not suitable for use after the test. Such tests merely indicate suitability of
design and should only be specified where critical conditions warrant the extra time and
expense incurred.
6.4 Test pressure. EJMA Standards usually test their joints at 1-1/2 times rated pressure (see 6.2).
Joints can be manufactured for test at pressures higher than 1-1/2 times the rated pressure, but to do so
will usually force the design to be based on the test pressure rather than on the operating pressure. Such
practice would in most cases require an increase in thickness of the bellows material and a corresponding
increase in the number of corrugations to realize the cyclic endurance life. The characteristics of a
particular application should govern the decision to alter the test pressure requirements specified in 6.2.
6.5 First article. When a first article inspection is required, the item will be tested and should be a
first production item or it may be a standard production item from the contractor's current inventory as
specified in 4.5. The first article should consist of one expansion joint. The contracting officer should
include specific instructions in acquisition documents regarding arrangements for examination, test, and
approval of first article.
6.6 Environmentally preferable material. Environmentally preferable materials should be used to the
maximum extent possible to meet the requirements of this specification. As of the dating of this
document, the U.S. Environmental Protection Agency (EPA) is focusing efforts on reducing the 31 priority
chemicals. The list of chemicals and additional information is available on their website
https://www.epa.gov/osw/hazard/wastemin/priority.htm. Use of these materials should be minimized or
eliminated unless needed to meet the requirements specified herein (see section 3).
6.7 Subject term (key word) listing).
Axial movement
Corrugations
Diaphragm
Drain
Nickel
Rings
Sleeves
Valves
6.8 Changes for previous issue. Marginal notations are not used in this revision to identify changes
with respect to the previous issue due to the extensive change.
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