PRESSURE TESTING VENTURIS

[JACKSCREWS]

hi guys,could anybody outthere help me,im having alot of trouble sealing off fabricated venturis for pressure testing sizes are 36'' 900Lb, 48'' 6oolb test pressures 206bar and 120 bar using spiral wound graphite filled gasket onto scrolled faces, bolts are 2 1/2'' and 2 3/4''.
i am using hydraulic torque wrench to correct settings,am i using right type of gasket or should i be using some kind of sealant with them would appreciate your help/comments

 

[JACKSCREWS]

forgot to say they are carbon steel flanged raised face

 

[unclesyd]

Have you got enough flange for your size and pressure?
What is the code or standard?

On such a large flange I would be very careful if I was very near the allowables for a particular flange. It also get a little more interesting as a flange advances in diameter.
You should be using more than one hyd wrench at at time, a very minimum of 3.

Can you come back with more detail like torque on nuts and tightening secquence?

Number of bolts/studs and material?

 

[vesselfab]

On a large diameter like that, we have had problems with the spiral wound gaskets. What I prefer is a 1/16" thick carbon steel ring that is faced with .030" of graphite on both sides. It's real tender to handle but it doesnt't leak. Also, like unclesyd said, have you got enough flange? Especially large diameter like this that barely make appendix 2 calcs or b16.47. one hydraulic torque wrench at a time is hard to seal unless you go in extremely small increments. Are you useing the correct bolts with the correct lubrication on them for correct torque?

 

[JACKSCREWS]

HI GUYS,FLANGES ARE ASME B16.5 STANDARD ,TIGHTENING SEQUENCE IS 180° OPPOSITE AT 30% ,60%,100% 0F TORQUE.
MAX TORQUE FOR 2 3/4 '' bolts 10250Nm .BOLTS AND STUDS ARE B7 2H

 

[JACKSCREWS]

also using copperslip on threads to get max load on bolts.

 

[unclesyd]

Your torque number is low.

What bolt stress are you trying to achieve?

How many wrenches?

What is your design pressure and temp as your test pressure is near the max?

 

[JACKSCREWS]

1 wrench, design press 128 bar and 80 bar respectively,temp @ ambient 20°c but probably less in conditions,youre probably right unclesyd about more wrenches but conditions don't lend themselves to using more could it be a gasket issue like vessleflab says.torque settings came from gasket supplier.

 

[unclesyd]

I'm a little confused as to the flange and the bolting size. Not saying they are not made but I've never seen a 16.5 ASME flange above 24". Normally you would use ASME 16.47 Series B, A or MSS-SP44 for 26" and above. The stud call out for the 36" is 20-3 1/2" and for the 48" 24-4" studs.
As far as the gasket I don't think you have properly seated it to where it will hold.

I hate to ask but can you comeback with the number of studs and exactly which flange you have?