Water temperature is critical when hydrotesting
Agrawal Sunil (Mumbai -Stequ)
Maintenance Directors, This was not an incident at a Valero facility. This is another set of pictures telling a story that no one wants to be a character in. Many of you have already seen the tank with the blown roof but this pressure vessel failure is a new one I just received. The write-up immediately below was
by someone else but I thought it was worth including. The root cause of the incident is not mentioned but discernment says it was probably due to hydrotesting with 'very cold' water.
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Water temperature is critical when hydrotesting. The latest edition of
ASME
Section VIII, Division 1, which is our rule book for new pressure vessel
fabrication, RECOMMENDS that the metal temperature during hydrostatic or
pneumatic pressure testing be maintained at least 30 degrees F. above the
minimum design metal temperature, but need not exceed 120 degrees F., to
minimize the risk of brittle fracture.
The National Board of Boiler and Pressure Vessel Inspection Code, which is
our rule book for repairing boilers and pressure vessels, REQUIRES that
the
metal temperature for the pressure test shall be in accordance with the
original code of construction but not less than 60 degrees F.
unless...toughness characteristic information...indicating acceptability
of
lower test temperatures is made available. And again the max. metal
temperature allowed is 120 degrees F.
Please read the information that was sent with these pictures and then
pass
these on to anyone who ever gets involved with repair work and pressure
testing. Those of us involved with repairs and testing under our R stamp
program need to understand the risks associated with our work.
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(See attached file: P1010258.JPG)(See attached file: P1010248.JPG)(See
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