ABERDEEN, UK -- iicorr has completed a caissons integrity study involving 20 offshore platform operators/integrity management contractors.
The survey covered three types of caissons:
* Pump caissons – stilling tubes to pump seawater up to the production areas for injection, cooling, or firewater uses
* Discharge caissons – for storing or draining fluids into the sea, such as water produced during production processes
* Carrier caissons – structural conduits for risers, umbilicals, cables, etc. to provide protection.
Questionnaires returned to iicorr contained information on more than 200 caissons on 80 platforms.
Respondents identified fifty-nine recorded integrity problems, the biggest of which was internal corrosion leading to holes forming in the caissons. The most common inspection technique applied was external visual inspection, which does not detect pre-failure indications of internal corrosion, iicorr says.
The study uncovered 29 reported incidents over the last five years, ranging from out-of-service caissons to those requiring complete replacement. The total estimated costs of the 29 incidents is in excess of $11.1 million, while the average cost of the 59 integrity problems was estimated at $160,000 each.
“The caissons research is the first in a planned series of specialist surveys we will complete through our Centre of Excellence,” says Mark Wilson, iicorr’s technical director. “These studies will address particular issues and challenges our business units are working to overcome. The first report highlights very clearly the high cost of integrity issues and the savings that can be generated by stopping problems from happening in the first place.’’
The report is available on www.centreofexcellence.com
iicorr completes caissons integrity study
iicorr has completed a caissons integrity study involving 20 offshore platform operators/integrity management contractors.