Pressure safety valve (PSV) removed by mistake
What happened?
During a pressure safety valve (PSV) campaign,
PSV-C was mistakenly broken into and removed
instead of PSV-D.
The valve was not isolated as per isolation
procedure so it was open to flare during the time
between breaking of containment until the time the
blank flanges were fitted and torqued (30 minutes).
The incorrect PSV was identified the next morning,
and the offshore installation manager (OIM) was
informed.
There was no damage to workers or the
environment.
The risks of being open to flare while the PSV was
removed are significant, with potential for
unplanned shutdowns, full blowdown initiation,
ignition at worksite, explosion and multiple
fatalities.
Why did it happen?
The workers did not check that the valve was the
correct one to be working on and did not notice
that PSV-D was not tagged.
Isolation integrity was not confirmed by the
production team before work started.
Weak isolation procedure, allowing work under an
unproven isolation.
No flange management system to ensure
identification, assembly, and torque/tension to
correct values.
The permit to work (PTW) did not require gas
check/monitoring for breaking containment and
there were no additional checks. Gas testing
requirements not understood.
There was no toolbox talk between all relevant
parties to confirm the full procedure.
Management were distracted with a prior work job
that prevented them giving full attention to this job.
What did they learn?
Review the isolation procedure and re-assess the
acceptability of flare and drain scopes against
single unproven valve isolation.
Plan high risk activities during day shifts where
there is higher control and scrutiny due larger
numbers of management on duty.
Confirm there are adequate gas testers, and the
equipment and process are understood by users.
Reinforce management’s accountability in the PTW
system.
Hold toolbox talks are required for every task.
Assess competence of issuing authorities (IA) and
performing authorities (PAs) – implement a formal
approval process.
Ask yourself or your crew
How can we prevent this from happening on our
site?
What were the risks of an open valve?
Do you/your colleagues stop and check for
isolation before beginning work?
Have you ever found management are distracted
by too many different projects? What can you do to
help?
During a Pressure Safety Valve (PSV) campaign, a PSV-C was mistakenly broken into and removed
instead of PSV-D.