stuarbc
Mechanical
- Dec 6, 2006
- 9
I have been asked to review a planned modification to a vessel.
The vessel currently has a 22" flange that is blinded off with a bolted 22" 300# flange. I can't find much data on 22" flange sizes as they are not a standard size.
They are planning to cut a hole in the center of the blind flange and insert a 10" pipe that will protrude into the nozzle. They are going to weld a flange onto the end of the pipe and install piping to it. (pretty much fabricating a nozzle and attaching it to the blind)
According Section VIII D1 UG-39(b)(1)....doing this is acceptable but requires a repad. There is an equation for the required cross sectional area of the repad......
My questions are:
1) The equation contains a variable (t), required thickness of blind flange. If the actual thickness of the blind flange is larger than the required....can this be taken into account? If so, how?
2) The calculation for the required thickness in UG-34 includes a variable (E), joint efficiency factor. What is the joint efficiency factor for a bolted structure?
3) I need dimensional info on the flange for the calculation...like the gasket moment arm....any idea where I can find dimension for 22" flanges...or do you think this was special fabrication?
The vessel currently has a 22" flange that is blinded off with a bolted 22" 300# flange. I can't find much data on 22" flange sizes as they are not a standard size.
They are planning to cut a hole in the center of the blind flange and insert a 10" pipe that will protrude into the nozzle. They are going to weld a flange onto the end of the pipe and install piping to it. (pretty much fabricating a nozzle and attaching it to the blind)
According Section VIII D1 UG-39(b)(1)....doing this is acceptable but requires a repad. There is an equation for the required cross sectional area of the repad......
My questions are:
1) The equation contains a variable (t), required thickness of blind flange. If the actual thickness of the blind flange is larger than the required....can this be taken into account? If so, how?
2) The calculation for the required thickness in UG-34 includes a variable (E), joint efficiency factor. What is the joint efficiency factor for a bolted structure?
3) I need dimensional info on the flange for the calculation...like the gasket moment arm....any idea where I can find dimension for 22" flanges...or do you think this was special fabrication?