Trelleborg Sealing Solutions helps develop cutting-edge subsea product

26 September, 2017

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 an established global supplier of polymer-based critical sealing solutions, Trelleborg Sealing Solutions was a natural choice to help Subsea Technologies Ltd (STL) create an innovative engineered solution to accelerate performance of its dynamic 2 inch hydraulically retractable subsea coupler.

STL, which specialises 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 2-inch bore to allow for choke and kill lines passing through the XR Connector, posed a number of major challenges.

Improved vessel safety, reduced environmental risk and decreased costs

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.

In order for the full potential and functionality of the 2-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 programme.

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.

Trelleborg 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 programme including a full PR-2 temperature and pressure cycling programme along with endurance cycle testing on the products in accordance with the ISO 10423 standard.