Mooring Failure Monitoring

Questions to FPSO Operators:

How would you know if you had a mooring failure?

How confident are you that you are presently operating with all lines intact?

For FPSOs with external turrets or spread mooring system, you’re probably pretty confident in your ability and time frame for detecting a failed line whether it be an in-air load cell or visual check of line angles.

But what about FPSOs with internal or external submerged turrets, which represent roughly half of all FPSOs worldwide? When posing these questions to operators, the common response is: “Yes, but we’re designed to operate with one failed line.”

Welaptega’s response: “Your mooring system was actually designed to operate without any line failures for the life of field.  So, if you have a line failure, how confident are you that the remaining lines aren’t similarly degraded—especially considering that they’re now picking up the added load from the failed line?”

The fact of the matter is, the majority of the world’s FPSOs with submerged turrets have no means of detecting a failure and, quite often, regularly scheduled underwater inspections provide the first indication of trouble. But with as many as 1-3 years between inspections, this is an unacceptable time frame for operating with one line down.

A DGPS system is a pretty good, relatively low-cost option. But this also requires quite a sophisticated excursion watch circle to identify an abnormal turret offset under normal operating conditions. Ideally, you’d be able to identify a line failure under benign conditions rather than when you’re in the middle of a significant storm.

There are options available for failure and tension monitoring, but the predominant feedback from the minority of operators using them is high cost and issues with reliability—not to mention the difficultly of integrating them into mooring systems currently in operation.

There’s a need in the industry for an economical, robust failure detection system that can be installed on new mooring systems or retrofitted to existing ones. And this is precisely what Welaptega is currently developing. Email for more details or stay tuned to the blog for updates.

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