Screwed Fittings

1
04/95

Committed to
Safety

Screwed Fittings Background Screwed piping
connections can have unseen dangers due to the
risk of crevice corrosion of the threads. Crevice
corrosion of piping threads can result in a loss
of strength and integrity along the threads.
Leaking fittings should not be tightened under
pressure as the connection may fail
completely. It is important that all production
operators, maintenance crews and their
supervisors are aware of the dangers of screwed
piping fittings. Pressurised systems transferring
corrosive gases are particularly
dangerous. Recommendations Equipment with a
leaking screwed fitting should be shut-down and
depressurised. The fitting should be removed and
inspected. Re-tightening under pressure could be
dangerous as the condition of the fitting is
unknown. Learning Points There are a number of
screwed piping connections in PDO in many
locations. It is important to inform personnel of
the hazards and to alert them of the dangers of
tightening screwed fittings that are
pressurised. For more information on this topic,
please contact AOS/4 at 67-7867.