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What is a Three Piece Ball Valve?

Three piece ball valve, as the name suggests, the ball valve is composed of three parts: the valve body, cap, and cap. That’s right, the three-piece ball valve has two caps, which is the most significant difference from the two-piece ball valve. It is precisely because there are two caps for more options in choosing connection methods.

In addition to the most common threaded ends, there are also welded ends, sleeve welded ends, etc., because the cap is easier to process, and because the body and caps with different ports are combined, the connection types of the three piece ball valve are exceptionally abundant. You can click to view the technical drawings of our three-piece ball valve to see if they meet your needs. JINSON Fittings’ three piece ball valve is designed according to ASMEB 16.34, the temperature range is from minus 20°C to minus 180°C, and the material can be selected between austenitic stainless steel 304 and 316. Next, let’s look at the internal structure of the three piece ball valve.


The working principle of ball valve is that, it regulates, directs or controls the flow of a fluid (gases, liquids, fluidised solids, or slurries) by opening, closing, or partially obstructing various passageways by controlling a ball having a hole inside. Of course, the difference between the three piece ball valve and the two piece ball valve is the difference between one more valve cover and a big difference in the assembly. The two parts of the two-piece ball valve are threaded, which can be screwed to achieve the effect of community, but the three piece ball valve is different. Its body and two caps are three separate parts that need to be screwed.

As you can see in the picture, bolt holes are reserved on the periphery of the cap and body, and the three piece ball valve achieves a sealing effect through the cooperation of bolts, nuts and spring washers. As for the control part of the ball, there is no difference between the three-piece ball valve and the two-piece ball valve. The handle controls the centre shaft, and the centre shaft drives the ball to achieve a state of circulation and closure. And both the two-piece ball valve and the three-piece ball valve are full-bore ball valves.

A PTFE gasket connection is used between the two fittings for effective sealing. The maximum temperature that PTFE gaskets can withstand is 180°C, which also determines the temperature range of the two-piece ball valve. On the choice of handle: This kind of long handle with a lock is the most common on two-piece ball valves. You can lift the lock device and complete the opening or closing of the valve. After the operation, the lock device will automatically slide down to the lock position to prevent you from misoperation. Of course, there is also a version without a lock handle for you to choose from, except that there is no lock device, the version without a lock is the same as the version with a lock. Usually, the color of the handle cover is blue. If you need to customise the color you want on the handle or customize your logo, please get in touch with me.


As we emphasized in the previous paragraph, the body and cap are cast, like the 150lBS threaded fittings. After the body casting, process the threads according to your requirements, according to ISO7/1 or American standard NPT. After the threads are processed, the ball valves are assembled on the assembly line. The most important part of the entire processing link is the pressure tightness test. After assembly, we will strictly follow the API598 standard for testing, the ball valve is placed on the pressure apparatus for pressure seal test, clamped, pressurized to 5-7 bar, closed the valve, left to rest for 60 seconds to begin deflating, where there is gas emergence to prove that the ball valve is available. JINSON Fittings ensure that each ball valve you receive passes the rigorous pressure test. After completing all the tests, you will receive a perfect 3PC ball valve without any problems.


  • A three piece ball valve excels in applications where the end caps are welded or threaded into the pipeline. The centre section of the valve can be removed from the pipeline very easily and repaired as needed.
  • For processes that put heavy demands on valves, having a three piece ball valve is more convenient than one or two piece ball valves. When seats and seals need to be routinely replaced, having three pieces allows for easy disassembly, servicing and reassembly without having to do the major cutting on the pipe.
  • Three piece ball valves also allow for elastomers to be changed to accommodate different process conditions, temperatures, pressures and flows.


  • This type of valve is more expensive to manufacture than a two-piece ball valve.


Not sure how many pieces you should select for your ball valve application? Ask us about it! We gladly provide technical assistance to businesses.

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