Ball valve seats of Devlon® V-API are now widely specified for oil and gas applications where operating conditions are stringent.
Devlon V-API has many advantages over nylon and PTFE, with one material replacing several thermoplastics over a wide range of operating pressures and temperatures. In comparison with virgin or glass-filled PTFE, Devlon V-API has similar friction values at low and high temperatures, with the benefit of superior dimensional stability.
It also has a considerable cost advantage over PTFE and PEEK, and can be manufactured up to 2.25m (88.6-inch) diameter.
For many years the industry trend was to use several thermoplastics to cover the required operating range for ball valve seats and inserts.
However, by specifying filled-PTFE or nylon as the soft seat material, manufacturers were restricting the design of their valves, and creating ambiguity as to the precise operational capabilities.
Working closely with valve manufacturers, James Walker Devol developed Devlon V-API as a superior seat material that would overcome the individual shortcomings of all the other material grades. Its operating temperature range is -193°C to +200°C (-315°F to +392°F), and it handles a pressure of 414bar (6000psi) at +176°C (350°F).
Devlon V-API is currently approved by operators including Shell and BP, and is specified by over 20 of the world's leading valve companies.
Photo caption: Valve seat and insert of bright yellow Devlon® V-API in a floating ball valve. Image by courtesy of KVC (UK) Ltd.
18 February 2009