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Trelleborg creates seal for STL

Written by  OE Staff Wednesday, 05 July 2017 08:10

Trelleborg has created a seal that works inside a new product, which was developed by Subsea Technologies Ltd. (STL), the 2in Hydraulically Retractable Subsea Coupler.

Image from Trelleborg.

The seal assists in creating the XR Connector’s unequalled high-angle release capability, which has no maximum riser angle limit. It was designed to deliver radically improved vessel safety, reduce environmental risk and decrease costs by greatly boosting a vessel’s operating window.

STL had previously developed small bore retractable couplers, used as sub-components in its unique XR Connector, however, scaling up to a large 2in bore to allow for choke and kill lines passing through the XR Connector, posed a number of major challenges. 

In order for the full potential and functionality of the two-inch coupler to work, it needed a seal to be developed that would work in harmony with the coupler, the world’s first of that size with a hydraulically retractable element.

Trelleborg said it immediately set about overcoming the issue and developed custom versions of its Turcon Captive Glyd Ring with XploR V9T82 elastomer material and Turcon Stepseal 2A CR with PEEK corner reinforcement rings.

The Stepseal 2A CR is the new standard corner reinforced rod/piston seal for single-acting use and has many advantages, such as its anti-tilt design and that the dimensions of the seal body and CR-Ring which can be modified to facilitate installation.

Andrew Longdon, Technical Manager for Trelleborg Sealing Solutions in the UK, said: “Throughout the process we constantly had to think about the safety issues and challenges that are frequently faced when working with heavy duty engagement of subsea equipment.

“We worked with STL as the team conducted a very lengthy test program including a full PR-2 temperature and pressure cycling program along with endurance cycle testing on the products in accordance with the ISO 10423 standard. 

“STL also conducted two disconnects with 10,000 psi bore pressure. This was all completed with one set of seals which I think is some achievement.”

Not only does the coupler provide new opportunities for remote emergency release system designs for subsea applications, Trelleborg says it also enables people to be removed from stab plate engagement functions on the surface. By being hydraulically retractable, it allows the heavy duty engagement of equipment both on surface and subsea to be separated from the comparatively delicate engagement of control system interfaces.

Subsea Technologies Ltd’s Managing Director Drummond Lawson said: “This was no easy challenge and without Trelleborg, we would not have been able to produce what we believe to be the first coupler of this size ever to be made with a hydraulically retractable element, which we are certain will create opportunities for our clients beyond just its use in our XR Connector.”
The coupler is fully Lloyds design verified and qualified to 3000m (10,000ft) water depth, rated to 10,000 psi hydraulic bore pressure and up to 5,000 psi hydraulic function pressure.

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