Bolt Pre-Load
Bolt Pre-Load
(OP)
I have a question on bolt preload and have been getting confused. I am trying to calculate the bolt preload for an end plate so we are able to pressure test the motor. Do I set the bolt pre-load to what will hold the end plate in place without fluid leaking so the bolt does not pass its yield point when under pressure? Or is the expected pressure seen per bolt also required to be taken up by the preload.
I believe it is the first method, so the bolt does not stretch and will return to its starting dimensions, thus maintianing the seal. However, some of the mechanics believe they should tighten it to near yield point.
Thanks for your help.
I believe it is the first method, so the bolt does not stretch and will return to its starting dimensions, thus maintianing the seal. However, some of the mechanics believe they should tighten it to near yield point.
Thanks for your help.





RE: Bolt Pre-Load
RE: Bolt Pre-Load
RE: Bolt Pre-Load
What I have seen many mechanics do is over-torlque bolts "if 55 is good, 100 is twice as good" and cause them to yield. A bolt that has started to yield is starting to fail. It is necking down, and providing much less preload. And when there is a leak, the mechanic will tell you that you gave him "bad bolts".
RE: Bolt Pre-Load
RE: Bolt Pre-Load