Floating ball and trunnion ball valves

Ball valve characteristics

Ball valves are widely used in fluid-handling systems for flow control. These types of quarter turn valves are suitable for non-corrosive and corrosive pipe line systems. In general, ball valves offer many advantages when contrasted with other valve types. Ball valves provide high flow capacities with very low pressure loss, compared to other kind of valves. Additionally, the design of the regulating element allows the valve to function without the complications of side loads, typical of butterfly or globe valves,

Several types of ball valves are available from different manufacturers including:

Side entry, top entry, fully welded

The difference is in the way that ball is mounted and the possibilities for service and seat changes, where top entry ball valves are enabling change of ball seats without removing the valve from the line. Fully welded ball valves are actually maintenance free, which means in the event of valve malfunction, it has to be removed and replaced. Side entry ball valves can be serviced by removing the valve from the line.

Floating ball, trunnion mounted ball

Floating ball valves are using the forces from fluid pressure to additionally reinforce the sealing of ball seats, while trunnion mounted ball valves are used in the situation where valve size and the weight of ball together with applied pressure is to high for soft seats to resist the forces. In trunnion ball valve, the ball is fixed.

One piece, two pieces, three pieces body

Generally, small ball valves up to DN25 can be made as one piece and floating ball valves are made as two pices body valves. Trunnion ball valves are commonly made as three pieces body ball valves.

Above ground, bellow ground installation

Depending on the position of pipe line, ball valves are made for above ground, or bellow ground mounting position, so appropriate corrosion protection is applied.

Wrench operated, gear operated and motor operated

For ball valves, generally smaller than DN100, the wrench operated ball valves can be used. For valves where hand force for operation exceeds 350 kN, use of actuators is required. Also, if remote control over the functionality of valves is needed, acturators should be used.

Flanged connections, threaded connection, butt weld connection

Technical data

For proper ball valve selection, except flow capacity in terms of K_g, K_v or C_v, several more technical informations are required:

Materials

Commonly used materials for ball valves working with natural gas and LPG, as non corrosive medium, are carbon steel with RPTFE for seats and sealings, like one example given bellow:

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