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Pipeline Pigging Incident
Dave Shepherd
Aug, 2005
© Chevron 2005
DOC ID
What is a Pipeline Pig?
Used to clean or inspect pipelines
that are in service.
Commonly used for:
 Paraffin removal
 Corrosion Inhibition
 Pipeline Suspension
© Chevron 2005
DOC ID
2
Background
 Two workers were attempting to remove a pig from a line
that was launched the previous day.
 Found pig was stuck in reducer section but cleared block
valve so valve could be closed.
 After depressuring pig receiver and opening it to
atmosphere, both workers believed energy had been
removed. Pig had to be pulled into pig receiver through
the reducer to remove so they fashioned a hook from
some ss tubing.
Open to Atmosphere
Receiver
© Chevron 2005
DOC ID
Reducer
Ball Valve
3
Incident
 When worker hooked onto pig, the pig shot out and
struck him in the nose resulting in major facial
injuries.
 Apparently, part of the pig created a seal with a
weld in the reducer section, which created a
pressure trap behind the pig.
© Chevron 2005
DOC ID
4
Injured Worker
July 27, 2005
© Chevron 2005
DOC ID
August 1, 2005
5
Facial Reconstruction
 8 hour procedure
 7 plates (Titanium and Stainless Steel) used to
reconstruct nose, eye sockets, and cheekbones.
 Held together with 39 screws.
 Jaw wired shut 2 – 4 weeks.
 Expected to make full recovery.
© Chevron 2005
DOC ID
6
Other Factors
 Safety glasses were not damaged but covered in oil and
water. Likely prevented any chemical damage to eyes.
 Trapped pressure was just high enough to create a seal
but too low to move pig on its own. If pressure was
lower or higher, incident would not have occurred.
 Root cause was in hazard recognition. Neither worker
considered any pressure existed since the pipe was open
to atmosphere.
© Chevron 2005
DOC ID
7
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