Subsea Revolution

When faced with the challenge of helping to create a product to boost safety and efficiency for offshore engagement, Trelleborg went above and beyond in developing a complete sealing solution to help its partner “revolutionize” the oil industry.

-By Fiona Bailey

WHEN THE QUESTION OF WHETHER it would be possible to create a large bore, high pressure hydraulically retractable coupler was first posed, one of the initial challenges that needed to be overcome was finding a seal that was up to the job. As a leading global supplier of polymer-based critical sealing solutions, Trelleborg Sealing Solutions was the natural choice to help Subsea Technologies Ltd (STL) create an innovative engineered solution to accelerate performance of its dynamic two inch Hydraulically Retractable Subsea Coupler.

IN SHORT

  • The new Hydraulically-Retractable Subsea Couplers from STL for its XR Connectors give radically improved vessel safety, reduce environmental risk and decrease costs by greatly boosting a vessel’s operating window.
  • STL required a custom-made seal which would work inside its pioneering product; scaling up to a large two inch bore posed a number of major challenges.
  • Trelleborg developed custom versions of its seals for the coupler.
  • The last round of testing is complete on the first coupler and further orders have been received.


The two inch Hydraulically Retractable Subsea Coupler was specifically designed for constant heavy duty operations and works with very small fluid volumes to ensure rapid movement

The two inch Hydraulically Retractable Subsea Coupler was specifically designed for constant heavy duty operations and works with very small fluid volumes to ensure rapid movement

A bigger challenge

STL, which specializes in providing reliable and cost effective products to solve complex subsea challenges, required a custom-made seal which would work inside the pioneering product. STL had previously developed small bore retractable couplers, used as sub-components in its unique XR Connector, however, scaling up to a large two inch bore to allow for choke and kill lines passing through the XR Connector posed a number of major challenges.

The hydraulically retractable couplers assist 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.

Turcon® Captive Glyd Ring® with XploR™ V9T82 elastomer material Find Out More

Working in harmony

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.

During the initial round of testing, STL discovered that the original hydraulic seals were extruding during the high temperature and high pressure phase of the test program. As the product development stage was so advanced, STL asked Trelleborg to propose a sealing solution that would address the issue of extrusion of the seal cap, without the need to change any of the existing hardware groove dimensions.

Issues overcome

Trelleborg 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 can be modified to facilitate installation.

Safety First

“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,” said Andrew Longdon, Technical Manager for Trelleborg Sealing Solutions in the UK. “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. We pride ourselves on innovation and relished this opportunity to work with STL in a bid to find a solution and ensure the two inch Hydraulically Retractable Subsea Coupler was working to its full capability.”

Not only does the coupler provide new opportunities for remote emergency release system designs for subsea applications, 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.

DRUMMOND LAWSON

DRUMMOND LAWSON

“Not only have they gone above and beyond in meeting expectations of the brief we outlined, but we were also impressed with the service we received throughout the process.”

- DRUMMOND LAWSON Managing Director of Subsea Technologies Ltd

Above and beyond

Subsea Technologies Ltd’s Managing Director Drummond Lawson said: “We knew Trelleborg – being a world-leader in sealing solutions – would be able to solve the challenge of finding a durable and robust seal to work in harmony with our product.

“Not only have they gone above and beyond in meeting expectations of the brief we outlined, but we were also impressed with the service we received throughout the process. We are by no means Trelleborg’s biggest client – but the support we received has been second to none. At every stage of the process a member of the Trelleborg team kept us fully informed from prototype development right through to bringing the product to market.

“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 can be used on subsea wellhead connectors, riser connectors, emergency disconnect packages, quick release stab plates and emergency disconnect points.

The coupler can be used on subsea wellhead connectors, riser connectors, emergency disconnect packages, quick release stab plates and emergency disconnect points.

An innovative subsea coupler

The two inch Hydraulically Retractable Subsea Coupler was specifically designed for constant heavy-duty operations and works with very small fluid volume s to ensure rapid movement. It is also more than capable of coping with solid-laden fluids such as drilling muds and well e ffluents. It is pressure balanced in both the extended and retracted positions, ensuring the coupler will remain in position in the event of hydraulic control system failure.

Additionally, it is possible to pressure test to full system working pressure against the retracted coupler without the need for an additional test cap. When retracted, the coupler stinger is flush with the coupler plate, preventing both dirt ingress and external impact on the retracted coupler from damaging the seals.

The coupler is fully Lloyds design verified and qualified to 3,000m (10,000ft) water depth, rated to 10,000psi hydraulic bore pressure and up to 5,000psi hydraulic function pressure. It can be used on subsea wellhead connectors, riser connectors, emergency disconnect packages, quick release stab plates and emergency disconnect points.

Further orders

Mr Lawson added: “We’ve only just completed the last round of testing and delivered the first coupler and already we have received further orders. Clearly other people can see the benefits that this cutting-edge product will create in their operations and service offerings, enabling our customers to deliver the latest safety and operability enhancements to their clients.”