24 July 2003
including Change 1, Jan 2004 and Change 2, March 2005
result of hydrostatic pressure tests or from normal operating pressures, make repairs
only after it has first been definitely determined that such repairs are practicable and
economical. After approved repairs of this nature have been completed, recalculate the
maximum allowable working pressure of the vessel or boiler according to the
requirements of Chapter 10. Prior to returning the vessel or boiler to service, perform a
hydrostatic test, based on the recalculated maximum allowable working pressure.
Gaskets. Replace manhole and handhole gaskets after performing the
hydrostatic strength test unless a non-compressible metal gasket is used.
PNEUMATIC TESTS. Perform a pneumatic test only in extreme cases,
when a hydrostatic test is not permissible. Do not perform pneumatic tests without the
written approval of the NAVFACENGCOM Boiler Inspection Certification Board. This
approval can be granted by submitting a request in writing to NAVFACENGCOM via the
respective NAVFAC Senior Boiler Inspector. Include the proposed pneumatic test
procedures for each particular test in the request. Pneumatic test procedures for each
particular test are in UG-100 for Section VIII Division 1 vessels, and in Article T-4 for
Section VIII Division 2 vessels. The pneumatic test pressure will be 1.25 times the
MAWP for Division 1 vessels and 1.15 times the MAWP for Division 2 vessels. A
pneumatic test may be used in lieu of the hydrostatic test prescribed in paragraph 6-1 of
this Chapter, with NAVFACENGCOM approval as follows:
For vessels that are so designed and/or supported that they cannot safely
be filled with water.
For vessels not readily dried that are to be used in services where traces
of the testing liquid cannot be tolerated and the parts of which have, where
possible, been previously tested by hydrostatic test pressure.
PRESSURE TEST RESULTS
Yielding During Test. If yielding occurs, and examination shows the
vessel is in satisfactory condition, establish the MAWP as 50 percent of the pressure at
No Yielding During Test. If yielding does not occur, increase the
pressure step by step until the required test pressure has been reached. Then hold the
pressure for a sufficient time to permit inspection of the vessel for leaks or signs of
Inspection Under Pressure. If permanent deformation occurs, replace or
repair the vessel. If permanent deformation occurs in a vessel not constructed to the
ASME Boiler and Pressure Vessel Code, drill and discard the vessel.