MIL-STD-1622B(SH)
being cleaned in the event of a pump failure or stoppage. It shall be compatible with the cleaning agent.
(d)Gages, flowmeters, and thermometers as required which are compatible with the cleaning solvent.
(e)Equipment to perform the applicable analyses of 5.14.
5.7.3.2 Preliminary tightness test. A preliminary tightness test shall be performed on the system before introducing the cleaning solvent into the system piping. The preliminary joint tightness test shall be performed with nitrogen to a minimum of 75 lb/in2 or the maximum system operating pressure if lower. All accessible mechanical joints, seal welds, and disturbed welded joints shall be tightness tested as specified in 5.10.
5.7.3.3 Hydrostatic. Hydrostatic testing as specified in 5.10 should normally be accomplished before the final flush.
5.7.3.4 Flush. Flushing shall be accomplished as follows:
(a)The piping shall be flushed with cleaning solvent at not less than
3 ft/sec for not less than 30 minutes. If the flushing circuit is
through parallel paths, if necessary, the flow paths shall be
isolated as necessary to ensure that each path is flushed with
full flow for at least 5 minutes followed by a 30 minute flush of
the entire system without full flow required in each leg.
(b)Obtain a sample of the cleaning solvent from all sampling
locations. For critical applications, verify organic cleanliness
by analyzing for hydrocarbons or NVR as specified in MIL-STD-1330,
or approved EPA Oil and Grease and Total Hydrocarbon test methods
such as EPA Method 1664, or equal. The acceptance criteria is 15
ppm. For all applications, verify particulate cleanliness as
specified in 5.14.3.1. If any of the analyses fail, replace the
solvent and repeat the flush.
(c)After acceptable samples are obtained, the cleaning solvent shall
be removed by draining and then purging with low pressure
nitrogen. A vacuum pump may be used in the final stages of solvent removal. Heat (200oF maximum) may be applied to the external surfaces of the piping to facilitate removal of the cleaning solvent. The nitrogen exhaust shall be checked for
traces of the cleaning solvent with a halide leak detector. Evacuating and purging shall be continued until no trace of the solvent is detectable.
(d)The piping shall be pressurized with nitrogen to a minimum of 75 lb/in2 or the maximum system operating pressure, whichever is less. Samples of nitrogen under pressure shall be taken after a period of no less than 1 hour and analyzed for solvent content.
Samples shall be analyzed by gas chromatography or equivalent methods. The solvent content shall not exceed 10 ppm. If this limit is exceeded, the piping shall be purged with nitrogen until acceptable samples are obtained.
5.7.3.5 Dry, reassemble and package. The piping shall be reassembled or packaged as specified in 5.16.1 to maintain cleanliness. To maintain the piping dry, the piping should be pressurized with no less than 10 lb/in2 of nitrogen, or the maximum system operating pressure if lower, until the piping is restored to normal service. If the pressure should drop below 10 lb/in2 before being restored to normal service, the responsible authority should investigate to ensure that moisture has not entered the piping. If excessive moisture is detected in the piping, remove moisture by purging with nitrogen, or other appropriate method, to the applicable cryogenic specification.
30
For Parts Inquires submit RFQ to Parts Hangar, Inc.
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business