[QUOTE=kwCharlie;38528]What do they say about the logic sequence, in the PLC, possible being changed and could that have prevented/delayed closure, or AMF/EDS failure, yet test OK in a normal BOP test?[/QUOTE]
kwCharlie – the ETs I’ve spoken to here have no knowledge of the PLC logic being changed, and I got the impression that they’d rather walk over broken glass than attempt something similar themselves. Could you point me to where I could find more information regarding the alleged changes?
Just going by my (non electrica)l gut, I don’t see how it would be possible. Before running the stack, you do a full EDS test with the BOP in the moon-pool and verify the correct sequence of functions, the times and gallon counts etc. You don’t have pipe in the BOP to shear and you don’t have any overpull to separate LMRP from BOP, but there are no by-passes or lock-outs or anything else different from an actual EDS. So if it works on surface using exactly the same electronic and hydraulic system you would use subsea, then you’d definitely expect it to work subsea.
Using the same logic, a ‘normal BOP test’ of any kind (function test) isn’t performed using some different system – the systems you use to test are the same systems you use when it’s for real. So if you had changes in the PLC logic that would cause a delay or failure, the delay/failure should have presented during testing.
That’s my instinct, but I’d appreciate if you could supply some info on what changes were supposed to have been made. Preferably in English and not pure Geek!