Trunnion Ball Valve

In a trunnion design the ball is anchored on shafts — trunnions — at top and bottom, rather than floating between the seats. Line pressure is carried by the trunnions instead of pushing the ball into the downstream seat, so operating torque stays manageable no matter how large or how highly rated the valve is. Spring-loaded seats press against the ball to seal. This is the standard construction for large diameter and high pressure ball valves.

Body and closure in ASTM A105, A350 LF2, A182 F304/F316, A352 LCB or A216 WCB. Ball in A182 F316, F304, F51, ENP coated or hardfaced. Stem in A182 F6a, F304, F316 or Monel. Seat inserts in PTFE, RTFE, Devlon, nylon, PEEK or metal; seals and gaskets in PTFE, graphite or spiral wound; fasteners ASTM A193 B7/B8M with A194 2H/8M nuts. A350 LF2 and A352 LCB are the low-temperature options.

2″ to 24″ with larger sizes on request, in Class 150# to 2500#. Designed to API 6D and tested to API 598 / API 6D, with face-to-face per ASME B16.10 and end connections per ASME B16.5 flanged or ASME B16.25 butt weld. Fire safe design to API 607 / API 6FA is available. Operation is manual, gear, pneumatic or electric.

A floating ball valve, such as the two piece or three piece designs, is simpler and cheaper and works well up to moderate sizes and Class 300. Above about 6″, or above Class 300, the force line pressure puts on a floating ball makes it very hard to turn and wears the downstream seat. A trunnion valve removes that load, which is why pipeline and high-pressure service uses it almost exclusively.

MVS is a manufacturer — building valves at its own works since 1978, ISO 9001:2015 certified — and exports across several continents. The minimum order quantity is 20 pieces. Sizes above 24″, fire safe construction, low-temperature materials and gear or actuated assemblies are built to order.