Bolt Torque Values for Spiral Wound Gasketed Joints
Bolt Torque Values for Spiral Wound Gasketed Joints
(OP)
I have read recently that spiral wound gaskets designed in accordance with ANSI B16.20 are suppose to compress to 0.125-0.135 with a uniform bolt stress of 30,000 psi. This means that torque tables should only depend on the bolt size. Yet many tables are set up by pressure class/fitting size. The SWG manufacturers typically say the torque is the users reponsibility. Suppliers usually fall back on gasket stress.
Does anyone have any ideas on what should be used?
Thanks
Does anyone have any ideas on what should be used?
Thanks





RE: Bolt Torque Values for Spiral Wound Gasketed Joints
The graphite-impregnated gaskets work VERY well, sealing better at lower crush amounts.
RE: Bolt Torque Values for Spiral Wound Gasketed Joints
RE: Bolt Torque Values for Spiral Wound Gasketed Joints
RE: Bolt Torque Values for Spiral Wound Gasketed Joints
RE: Bolt Torque Values for Spiral Wound Gasketed Joints
Unless the fill material has been improperly selected and/or there's an extremely poor fit-up, there are very few field problems with spiral wound gaskets. And from a maintenance standpoint, there's no spending 2 hours with an old wood chisel trying to scrape old gasket material from flange faces that you can only get an inch apart. The spiral wound ones just drop out when the bolts are undone, or they stick to one flange or another, and just pop off with a little push from a screwdriver.
If design engineers want to check things about flanges, go after the idiots that install class 125 flanges instead of the 150s they should use. Check the SAE grade fasteners that are ROUTINELY used in place of B7 studs and 2H nuts. There are FAR bigger issues that need to be addressed. Really.
And if you're really going to specify torque, then get out into the field, and CHECK THAT IT GETS DONE. Good contractors will price this into their quotes, then lose the job to the low-bid short cut artists who WON'T DO IT because they figure that nobody will ever check. And you know what? They're right.
RE: Bolt Torque Values for Spiral Wound Gasketed Joints
Nuclear power plants require a controlled method for making up all joints. For most joints this means using a calibrated torque wrench, as well as a specified sequence for tightening the bolts. There are reasons for this ostensibly crazy approach but they would take too long to explain.
As for the contractor problem, I agree that is real...too real. I have seen 10-15% joint leakage after an outage directly linked to contract help.
I agree that SWG joints if made up properly will just keep on tickin'.
Thanks