An isolation valve for a waste water treatment plant. Our inlet pipe is above the level of the treatment plant, so on power failure of the plant, I would like to isolate the inlet flow so:

We are looking for a 6" (DN 150) PN 250 ball valve for a test stand (pure water). Valve shall be electrically driven plus option manually actuated.

Facing the challenge of finding a way to weld fully welded body Ball Valve.The matter is that, ones the valve is opened and the seat replaced, the body must be welded again without damaging the seats

Assume the resistance torque on the ball is known as T, a constant, how much axial force F needed on the piston or two pins to drive the ball rotation?

I'm sizing a relief valve for a gas-liquid separator, which belongs to a petroleum production field.

Field sketches that instead of showing the standard call out for valves (i.e. 150# etc) what I'm getting; for example, 275WP or 275WOP and 275WOG. What is up with WOP and WOG?

A closed loop chilled water system that runs at a differential pressure of 30 psi.

3 way diverter, 1/4" Max pressure 10 Bar,Temperature: 500 Degree Celcius.