Cross Metal Valve Seals - When the Pressure’s on

The operating temperature and application determine the selection of Cross metal seals in valves. (Photo with kind permission from Koso Kent Introl Ltd.)

Metal seal rings are typically used in valves operating at temperatures above 250ºC.(Photo with kind permission from Koso Kent Introl Ltd.)

As concerns over climate change intensify, the pressure on industries to curb fugitive emissions continues to increase. Embracing innovative technologies, adopting best practices in maintenance and operation and prioritising regulatory compliance are key to addressing the challenges. Within this scenario metallic sealing solutions can provide significant benefits for valve manufacturers and valve users alike.

In a typical petrochemical or chemical plant, 60% of fugitive emissions are caused by leaking valves, with nearly 80% released at valve stems. Leaks at the bonnets, flanges and seats also contribute to valve failures. As industrial operating conditions continue to subject valves to more extreme temperatures and pressures, effective sealing cannot be met with traditional materials and methods.

As a result, metal seals are now used where other materials are unacceptable, particularly in environmentally hazardous areas.  Manufactured in a wide range of sizes, often from specialised alloys, they deliver long-term sealing performance, improved efficiency and reduced maintenance.

Metal stem seals for rotary, rising stem and linear valves provide full metal-to-metal contact, leak tightness and accommodation of axial stem movement. Special rings that control fugitive emissions and withstand the severe service conditions in chemical, petrochemical and nuclear facilities are available for sealing valve stems.

Metal-to-metal seals are also used in other valve applications, including body-bonnet connections, seats, pressure-balanced plugs and back-seat sealing. High service temperatures and other requirements such as fire safety, extended lifetime cycles, chemical resistance and high sealing performance are being met by metal seals, including those used in butterfly valves. High-pressure, triple-offset butterfly valve seats are often sealed with machined metal seals for critical bidirectional applications, whilst double-offset butterfly valve seats can also be fitted with metal seals for high-pressure service.

Sealing pressure-balanced plugs in globe valves involves dynamic seals that move with the plug.  Manufactured with equalising pressure gaps, the plugs reduce torque requirements, enabling the use of smaller actuators, but also introduce secondary leak paths. For valves in high-temperature service, a dynamic metal seal can be installed on top of the plug to prevent leakage to the external environment.

Other applications involve back-seat sealing of metal-seated, trunnion-mounted ball valves where, depending on the amount of seat movement required, metal seals can be successfully used.

To meet these challenges Cross Manufacturing’s environmentally efficient technologies – backed by comprehensive technical support and R&D facilities – deliver precision and strength, with regular production encompasses diameters from 12mm up to 2,000mm for high pressure applications in temperatures up to 1,000°C to suit valves of virtually any size and design.

Tel:               +44 (0)3301 224 400

Email:           contact@crossmanufacturing.com

Website:       Flow Control Sealing Solutions | Cross Manufacturing

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