Our experience indicates that a BOP in good condition
can function satisfactorily for decades. Everything depends on the
maintenance and the availability of parts.
Only 3 brands of BOP's have a long history. These
brands: Cameron, Shaffer and Hydril have parts available for BOP's made
as long ago as the 1960's.
Welding and subsequent stress relief provides the
main factor that limits life. Stress relief after welding has a
cumulative affect that continues the tempering process that occurred
during original manufacturing. Continued maintenance should minimize
welding, and hardness testing before welding and after stress relief
will indicate if the mechanical properties have degraded as a result of
these processes. Hardnesses of all pressure containing parts of BOP's
should meet the minimum hardnesses of the applicable API Spec used at
the time of manufacture of the equipment.
If you know
you have to weld on equipment, take your hardnesses before you do any
welding. That will protect you from wasting time and money.
After any repair that requires welding and stress
relief, the BOP should receive a body shell test just as it would
receive as new manufactured equipment.
See
http://www.woodcousa.com/Pressure_Test.htm for more about
testing. You may also find related information you may use at
http://www.woodcousa.com/NDT.htm .
