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2008 pipeline seminar - Bluewater/MCS audio Q&A

15.30-15.55 - Flexible Riser Integrity Management Experiences from the Uisge Gorm - Bluewater/MCS

‘Open Forum - Question and Answers’ session at the end of the presentation by Gus Chown of Bluewater

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Bluewater/MCS Q&A audio [5m14s - MP3 4.79MB]
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Douglas Souden – HSE (Seminar Chairman). Just before I throw it open to questions from the floor I just wondered if you had any view on the sort of resources it took to go through this assurance process and what was the period you know that it was out of service before you could get back into service just to reaffirm that sort of timeframe?

Gus Chown – Bluewater (Presenter). Well I mean in terms of people involved I mean MCS had what three or four people involved. All of the vendors were involved; probably a couple of people from NKT - two or three people from NKT. A couple of people in Coflexip and two or three people involved in Wellstream as well and basically in-house sort of three of us working on it - and obviously the client. I mean I worked closely with Glenn who’s here today, Glenn Wilson in Hess. It was basically a largish number of people working together and developing ideas as to how we could go about getting the thing back into production safely and timeframe wise basically August / September. It took us about two months to verify the ones that we selected. I mean the inspection process took place offshore and basically that took us about six weeks. We could then look at those of the risers that we think we could successfully reuse so we got into the detailed analysis and assurance process on those risers to at least have been able to get us back into injecting back to the reservoir and producing from it as well.

Meyrick Hadfield – HSE. Gus thank you very much. One comment and one question. The comment first of all. You mentioned making the I tubes bigger and access for inspection. This is a recommendation I hope to get in the Recommended Practice, RP17B through the FPT JIP that MCS is working on. Also other aspects about I tubes because they don’t figure in the ancillary equipment JIP. The main other aspect is should they be designed to cater for a failure of an I tube? If I have my way it will be in the Recommended Practice as matters to be considered at the design stage. My question is on the Flora Riser which was cracked I think?

Gus Chown – Bluewater (Presenter). Yes.

Meyrick Hadfield – HSE. Can you say any more about that. What caused it and why type of cracks they were?

Gus Chown – Bluewater (Presenter). I think to be honest the reason for that was probably that the hang off collars which were used during the construction phase were left on which that in itself I think blocks the vent path for the annulus vent so the construction guys when they left it, "well we don’t want it dropping down the hole so we’ll leave the hanger on it!" and that blocked the vent path. Consequently if you do, as you do, get permeation of gas, the pressure builds up and the sheath goes pop so that’s the moral. Take the hangers off.

Yeah it’s John Marsden from Flexlife. You mentioned that on the NKT pipe and the Technip pipe that both had breached out sheaths?

Gus Chown – Bluewater (Presenter). Yes.

John Marsden - Flexlife. Yeah one you condemned and the other you kept operating. What essentially was the difference between the two?

Gus Chown – Bluewater (Presenter). Basically the Flora riser was condemned because the cracks went right down to the water level so we had splash zone corrosion. The Coflexip A14 riser there was only a crack at the top from the end fitting down about two metres down the I tube which we could actually see to the bottom of. The rest of it was solid down to the bottom and from a fatigue analysis perspective the Coflexip riser was designed as a flooded riser so that it had no further impact on the design life and of course to be fair that only went in in 2001 so it had seen six years of service rather than eleven.

John Marsden - Flexlife. Thank you.

Gus Chown – Bluewater (Presenter). Ok cheers.

Glenn Wilson - Hess. Yes I mean from a Hess point of view and an observation from us was that the I tube sits in no-mans land. Sometimes it sits outwith - in a subsea team. Sometimes it sits with a facilities team and what we found in a lot of the analysis that we were doing and the findings and why have we missed this, somebody said they were doing it. So as an observation from an operator - is go back and check your own systems, do you have this gap? Do you have an ICP that goes and checks this? Is it a PMR? and is it a safety critical element because in some cases it should well be. So it’s you know, just an observation check.

Updated 2012-10-05