Testing Large Butterfly Valves 1

[dblcrona]

We have a new product line of butterfly valves. I have designed and built fixtures for testing all sizes 2" - 10" that will run on our existing test stands. None of our test stands had the required ram force to hydro-test our 12"-16" sizes at 400 psi. Since these are low volume we decided not to invest in a new test stand. Instead, I had one of our sister companies design special blind flanges to bolt to either side of these valves for testing. When I ran a test on the 12" I blew out my 90A Urethane seal immediately. I know that 400psi in a 12" valve exerts a force in excess of 45000 lbs. How can I calculate the force that these bolts are putting on the valve when torques to 125 ft lbs? Also, Are there ant calculations for the elongation of Nitronic 60 studs under load? These would help me to make sure I am putting enough pressure on the seals. Any other tips you can provide on testing butterfly valves of this size would be appreciated.

Thanks

 

[cranekiran]

Hi dblcrona,

I have few suggestions and some queries for you.

1)Is your valve double flanged?
2)If your valve is a flanged one then what standard is the flange based on? for eg:- ANSI,JIS,BS etc.
3)You have to use the same bolts in your testing to what you would be fastening the valve with a pipeline in actual operating conditions.
4)400 p.s.i is not that high a pressure for a butterfly valve.There are Butterfly valves operating at 750 psi's and are being tested successfully in house.
5)Does the swing radius of the disc stays inside the body or does it come out of the body face to face dim.?
6)If the swing radius is coming out,Then your Two test flanges (One at top,One at bottom & the valve in the middle tightly fastened to both the flanges)should be designed similar to a bowler's hat,The rim of the hat is your flange and the dome shape above the flange accomodates the emerging disc.
7)The thickness of your flange is no rocket science.you have to refer your flange standard to get it,It is as simple as that.
8)There should be an inlet given to the bottom flange and an outlet provided on the top flange(assuming water is the media.)
9)you should select a appropriate N.R.V and a appropriate pressure switch for the testing.
10)Do you have a gear box mounted on your valve?
11)Is your gear box properly designed?
12)Is your valve electrically operated?
13) if it is electrically operated then what actuator are you using?
14)The most important part in any testing is deciding on what standard you should test the valve.If it is a cycle test then you can refer AWWA C-504 which gives a in-depth but easy to understand steps.

Cheers!