QUESTION: How do I select between 1-, 2-, or 3-piece ball valves for 2-way service?
This is a common question we are asked here at Midwest Valves. A ball valve is a type of quarter-turn valve. It uses a hollow, pivoting and perforated ball to control the flow of water, oil, or gas, or another medium.
Here is what you need to know:
Standard stainless steel ball valves are suitable for use for fluid temperatures up to 180°C and for cold working pressures of up to 6895kPa. These valves are investment cast for high-dimensional control.
What is the difference between 1-, 2-, and 3-piece lever-operated ball valves?
- The 1-piece ball valve has a reduced bore. This means the hole in the ball is smaller in diameter than the internal diameter of the pipe-work it occupies. It is the most affordable option and is used where flow turbulence and pressure drops are of no concern.
- The 2-piece ball valve design option has a ball which allows the full port volume to be used. It has, in most cases, PTFE (polytetrafluoroethylene) seats to allow a positive closure.
- The 3-piece ball valve design option is a full port design. This means the hole in the ball has the same diameter as the pipe. It is used where low flow resistance is required and for mixed liquids and solids. It has stainless steel bolts which hold the three pieces in place and this, in turn, allows seals to be replaced. Due to the competitive Australian market, however, and the replacement cost of an entire 3-piece ball valve, there are very few Australian valve suppliers who stock replacement seals for a 3-piece ball valve.
- There are Fire-Safe versions of the ball valve available. These feature a higher pressure rating than other ball valves (up to 2000psi for water, oil and gas (wog). For fire-safe valves of 25mm and less in size, working pressures of 3000psi apply.
- Lever-operated valves are lockable. This prevents the unauthorised use of the valve.
- Actuation (the mechanism of opening and closing the valve, or allowing intermediate positioning) of a valve allows more convenient control of the valves, depending on whether compressed air or electricity is available and within budget for the plant.
For ball valves that require actuation, manufacturers produce 3-piece stainless steel ball valves with actuator mounting pads to ISO 5211. This allows for direct mounting of pneumatic or electric actuators such as the one pictured above.
Midwest Valves is one of the leading valve suppliers in Australia.Contact Peter today for advice and guidance on your valve requirements, including for stainless steel screwed-end ball valves, and to discover our product range and to determine which products are right for your needs. We deliver all over Australia (depending on the size of freight consignment). Call (02) 6374 2808.