Thrust Support In Re-Heater Safety Valve

All a matter of strength versus potential thrust forces. Supports are used on pipelines where required.

thanks for your answer.thrust support is essential where any thrust load comes into picture.but particularly thrust support is used only in re-heater safety valve support.y we are not using this kind of supports in other safety valves like main steam pipeline safety valve etc...

How big is it?

You dont say how long the outlet pipe is from the safety valve. The main reason for support is that most outlet pipes ( after the relief) are a horizontal length and an elbow upwards or downwards. When the relief/safety vents, a force is setup in the bend, tending to straighten the bend. This may damage equipment or worse, people. If the horizontal portion is kept very short, basically ±400 mm the straightening forces are much less. Main pipe lines are typically supported at both ends, which provide a flexing/give effect to other safety valves in the lines. (the valve is not rigidly held, as it is directly on the header)