Blowout Preventers

Tripling safety margin with duel-material seals

The failed blowout preventer (BOP) on the Deepwater Horizon sent shock waves through the drilling industry, signaling that no link in the safety chain is impervious to catastrophic disaster. So, when a major BOP manufacturer in Houston experienced issues with piston-and-rod seals on its BOPs, engineers grew concerned and investigated the problem.

They discovered the existing D-shaped nitrile seals were deforming under high pressure, sometimes rolling inside their grooves. In rare instances, they extruded altogether. Tests showed that the soft nitrile fitted in an unusually wide extrusion gap failed to withstand the extreme 10,000 PSI.

Throughout testing, the existing seals continued to deform, despite repeated efforts to redesign, reformulate and improve the material. The company turned to System Seals, which has extensive experience with high-pressure sealing issues.

System Seals’ research led to the creation of 132 and 232 seals. Both are dual-material designs with a soft HNBR element, protected by two thermal plastic backup rings. Combining soft and hard materials into a single seal maximizes sealing capabilities, while resisting the potential for rolling and extrusion.

A prominent Gulf oil-and-gas company began testing System Seals products in its BOPs. They compared results to the current D-seals from the previous provider. To maintain a clear margin of safety, each seal needed to endure 250 cycles before experiencing any issues at all, spanning a six-month test period.

After extensive testing with the System Seals’ products, the seal cycled 750 times – three times the benchmark of 250 – before engineers had seen enough and stopped the tests. Since then, the company has never experienced issues with the new System Seals’ products.

The customer replaced its rod-and-piston seals with new System Seals’ products in all new BOPs. They also recalled the faulty seals in existing BOPs. System Seals is now working with the manufacturer to improve other areas of their equipment.