The actual two offset dimensions are normally determined by 3D CAD design. Lots of factors to consider. One important item is to ensure the disc will not hit the valve ID or pipe when opening. API-609 has an equation which helps you calculate if this is going to happen. Other contributing facotrs are the valve face to face length, shaft diameter, seat and disc diameters, and how much clearance you need between the seat and disc when the valve is fully open. In the end, it is a real challenge to fit all the parts witin the industry standard face to face length. Design is best accomplished using 3D CAD.
thanx alot bcd..
i am new to this and i am trying to understand triple offset valve design.
so i started with double offset valve design.
i will go through api 609 and will try to design a valve in 3D CAD
but can u tell me how the values of 1st and 2nd offset will affect the design.because all those factors disc should not hit pipi or valve id is important while deciding 1st offset.but what about 2nd offset ? .i mean while deciding 2nd offset should i keep it as less as possible or some other logic is there ?
You are asking the crux of designing a valve and you expect people will answer your query on such forum?
My advise - Hire a triple offset valve design consultant and get the things in right place.
