Good evening all,
I am racking my brain over something that I believe should be fairly straight forward. I have a inlet control valve with an O-ring that mates to the top of compressor via four socket head cap screws and I am trying to determine the proper bolt torque for those four screws. Please see below if I am over complicating this or if i am on the right track.
Design Parameters:
Design pressure: 2 PSI
O-RING SIZE:
.139" C.S
3.387" OD
70 DURO
Mounting bolt size and quantity as determined by the compressor.
M8 X 1.25 X 20 Qty: 4
So based off the above, my calculations are as follows.
ASME BPVC VIII Appendix 2
Hydrostatic force due to pressure is:
W=(PI/4)(G^2)(P) + (Gasket factor is zero to self energizing seal)
W=(PI/4)(3.387^2)(2)
W= 18 lbs
Parker O-Ring handbook:
Compressive force required to properly squeeze the O-Ring:
Squeeze % from interpolation: 24%
Compression load force based off Cross Section / DURO / Squeeze
50 Pounds per inch of O-ring circumference
Which gives me a load of 162 lbs to compress the O-ring to 24%
So if i am thinking about this correctly I need to develop a total clamping load of 180 lbs with the four M8 screws.
F=(180/4) =45 lbs per screw
T=cDF
c=.2
D=0.314961"
F=45
T=3 Ft-lbs.....
And this is where I am at a loss. Do I torque the bolts to 3 Ft-lbs based off the above loads or do I follow ASME PCC-1 and torque them based off of yield strength?
Thank you all in advance.
I am racking my brain over something that I believe should be fairly straight forward. I have a inlet control valve with an O-ring that mates to the top of compressor via four socket head cap screws and I am trying to determine the proper bolt torque for those four screws. Please see below if I am over complicating this or if i am on the right track.
Design Parameters:
Design pressure: 2 PSI
O-RING SIZE:
.139" C.S
3.387" OD
70 DURO
Mounting bolt size and quantity as determined by the compressor.
M8 X 1.25 X 20 Qty: 4
So based off the above, my calculations are as follows.
ASME BPVC VIII Appendix 2
Hydrostatic force due to pressure is:
W=(PI/4)(G^2)(P) + (Gasket factor is zero to self energizing seal)
W=(PI/4)(3.387^2)(2)
W= 18 lbs
Parker O-Ring handbook:
Compressive force required to properly squeeze the O-Ring:
Squeeze % from interpolation: 24%
Compression load force based off Cross Section / DURO / Squeeze
50 Pounds per inch of O-ring circumference
Which gives me a load of 162 lbs to compress the O-ring to 24%
So if i am thinking about this correctly I need to develop a total clamping load of 180 lbs with the four M8 screws.
F=(180/4) =45 lbs per screw
T=cDF
c=.2
D=0.314961"
F=45
T=3 Ft-lbs.....
And this is where I am at a loss. Do I torque the bolts to 3 Ft-lbs based off the above loads or do I follow ASME PCC-1 and torque them based off of yield strength?
Thank you all in advance.
