Good day folks,
We are re-writing our Well Integrity Management Standard at the moment and this is a "journey" ;)
We have been aligning mostly on ISO 16530-1:2017 (this is what we chose initially) and there are a few areas where this could potentially be improved (we have been sending feed-back to the revision committee... and hope to see a revision soon, which would ideally include / cover some fundamentally different definitions in the new NORSOK D-010... but that's a separate topic)
On to the main reason for this message - a consultation of closing time for old subsea systems... I thought it would have been covered in the past so I did a search on the forum but this returned nothing so I'm creating a new thread.
API14C defines clearly performance criteria to be expected for surface systems: all actuated valves should close in 45s or less. This part is clear, and by default we are treating all valves connected to our ESD systems as Safety Critical Elements (SCE).
For subsea systems the picture is much less clear - and since we are having to operate legacy systems with old direct-hydraulic systems our position is that a standard closing time cannot (and should not) be applied. Rather, depending on the expected (or original) closing performance... our job should really be to 1- make sure that closing times don't create unsafe conditions (for instance creating unwanted HC inventory) and are acceptable, and then 2- are stable over time.
For instance if the original closing time was 2min45s when the system was commissioned (let's say hypothetically in 1997) then if this is still 2min45s today this should not necessarily raise concerns... On the other hand if this original closing time of 2min45s appears to be gradually increasing and would now have drifted to 3min15s, this should raise concerns and prompt: 1- a review of potential consequences (increased HC inventory or higher pressures downstream) and 2- investigation on this trend and how to address it (prevent further degradation)
Has this previously been discussed in the section? Any thoughts or comments? I'm less familiar with API17... but assume this would not contradict the philosophy.
Cheers.