Sealing Success for an API 10,000 Choke Valve

A leading manufacturer of control and choke valves approached M Seals seeking a solution to a critical sealing challenge. The customer was looking to reduce manufacturing costs and shorten lead times by eliminating the subcontracted surface grinding and polishing processes traditionally used during valve production.

While this change delivered efficiencies, it also created a significant problem. The existing sealing arrangement, designed to operate on highly polished surfaces, could no longer achieve the required performance on the newly machined components.

Engineering Assessment

The valve was specified to API 10,000 and required operation within a temperature range of -29°C to +121°C. In addition, it was necessary to achieve PR2 qualification testing using nitrogen gas in accordance with API 6A Annex F (20th Edition).

The removal of the grinding and polishing stages resulted in metal surface finishes changing from a finely polished 0.1-0.2 Ra to a machined finish of less than 0.4 Ra. The customer's existing PTFE lip seal arrangement was unable to tolerate the increased surface roughness, leading to sealing failure under gas testing conditions.

Bespoke Sealing Solution

M Seals developed a custom-engineered packing set for the stem sealing arrangement. The design incorporated a high-deflection PTFE lip seal supported by multiple PTFE and rapid gas decompression (RGD) resistant elastomeric V-segments. This provided enhanced sealing integrity and redundancy, while a virgin PEEK anti-extrusion ring protected against seal extrusion under high pressure and temperature conditions.

For the seat seal, the existing design was replaced with an RGD-resistant elastomeric P-seal, again supported by a virgin PEEK anti-extrusion ring. All sealing materials were independently tested and qualified to API 6A / ISO 10423 F.1.13 Class FF/HH requirements.

Proven Performance

Following installation, the valve was mounted vertically and subjected to full PR2 qualification testing using nitrogen gas in accordance with API 6A Annex F (20th Edition).

The bespoke sealing solution successfully met all test requirements, enabling the valve to achieve full API 6A compliance and receive official witness certification. As a result, the customer was able to maintain performance, reduce production costs and significantly improve time-to-market without compromising reliability.

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