Most floating design two piece of ball valve goes throu […]
Most floating design two piece of ball valve goes through the hydro shell test which is 1.5 times the ANSI rated pressure. The valve soft seat test is at either 80 or 100psi in the closed position.
(Note: It is important not to test the ball valve higher than the operating pressure in the closed position. For system pressure tests higher than expected operating pressures, it is important to leave the ball valves in the open position.)
Most all smaller sizes (1/4” – 3”) floating ball valves with either weld-end or threaded-end connections have pressure ratings of WOG (water, oil or gas) or MAWP (maximum allowable working pressure). The MAWP or WOG pressure ratings are considered a do-not-exceed pressure at normal ambient temperatures.
In most soft-seated valves, there is a pressure-temperature curve, maximum pressure at ambient and maximum pressure at the highest temperature rating of the seat. The stress levels of the valve seat and its ability to thermal cycle over these limits determine this. The valve seat must be strong enough and thick enough to take fluid dynamic effects without folding over or deforming.
Each valve seat design varies per its applications, material strength, and physical compounds. The pressure-temperature curves and the torque curves vary with the seat materials and design of the individual valves.
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