Oil and Gas

Low Pressure Ball Valves generally rely on Teflon based materials, either in its ‘Virgin’ form or filled with most commonly Glass Fibre, Carbon or Graphite. At higher pressures Nylon based or PEEK materials are most common.

For O’Ring seals, depending upon service conditions, NBR, FKM and FFKM materials are the most used. At higher pressure gas service above around 100 BARg, Anti-Explosive Decompression (AED) grades should be specified.

These advanced seats (common in trunnion designs) use differential pressure across both upstream and downstream faces to enhance sealing force bidirectionally without relying solely on springs or line pressure. Unlike single piston effect (SPE) seats that relieve via one side, double piston effect (DPE) maintains cavity isolation until overpressure forces relief, combining tight shutoff with automatic safety venting for severe service.

Ball valves are fire tested by putting a pressurised valve through a controlled, standardised fire to see how much it leaks and whether it still works afterwards. This is meant to mimic a serious plant fire in a repeatable laboratory setup, so different valves can be compared fairly.

First, the valve is mounted on a test rig, connected to pipework and pressurised with water or gas, typically to a large percentage of its rated working pressure. It is normally closed, because the key question is whether it can still shut off flow when exposed to fire. The valve is then surrounded by high‑temperature flames, often in the 750–1000 °C range, for around half an hour. During this burn period, instruments continuously measure internal leakage past the ball and external leakage to atmosphere.

When the burn time is over, the flames are shut off and the valve is rapidly cooled, for example with water spray, to represent firefighting conditions. Leakage is still monitored because temperature shocks can open up gaps or damage seals. Finally, while still pressurised, the valve is operated (opened and closed) and checked for acceptable leakage and basic structural integrity against limits defined in fire‑test standards such as API 607 or API 6FA.

Upstream production uses valves built for high pressure, erosive fluids, and simple, reliable shut‑ Typical upstream valves are gate or ball valves on the wellhead, choke valves to control well flow and pressure, full‑bore ball or gate valves for pipeline isolation, and check valves to prevent backflow. Downstream refining operates with more stable, controlled conditions and focuses on tight process control and equipment isolation. Refineries mainly use globe‑type control valves for accurate flow and pressure regulation, along with gate, ball, butterfly, check, and relief valves for isolation and over‑pressure protection.

Floating Ball: The ball “floats” axially between two seats, sealing via line pressure pushing it against the downstream seat. Cavity relief typically uses a drilled hole (e.g., 3mm) in the ball connecting the cavity to the upstream pipeline side, venting excess pressure there per specs like Shell MESC 77/170. Alternatively, self-relieving seats or body bypass holes equalize cavity pressure with the line port, but this requires careful flow direction orientation and avoids venting to atmosphere.

Trunnion Mounted: The ball is fixed on trunnions (upper/lower stems), handling higher pressures with seats providing the seal. Cavity relief relies on seat design rather than ball holes; rising cavity pressure pushes the seat away from the ball against its spring, automatically relieving into the pipeline (often downstream). This works even in open positions where cavity pressure differs from line pressure.

Cavity relief in ball valves prevents dangerous pressure buildup in the body cavity (the space between the ball and seats) when the valve is closed and trapped media expands due to temperature changes, such as in oil & gas pipelines exposed to heat.

Certainly with Ball and Butterfly valves this is normally possible with the addition of a simple interface and drive adaption to suit the valve and actuator, make sure that you specify that all such valves are supplied with an ISO mounting flange.
Standard Gate and Globe Valves are more difficult to retrospectively actuator, and this MUST be specified when enquiring or buying these products.