PDPumpGuy
Mechanical
- Oct 3, 2005
- 8
I have recently experienced two different fatigue failure on a large diameter studs used on reciprocating mud pumps. When examining the failure, we found a very unusual thread profile that we first thought was a manufacturing defect, however we have now learned it was by design. The pumps were made in China, and they call this thread profile a Zig-Zag, or Hackle profile over there. It's basically a normal angle on one side of the thread, but the other side is flat. It's apparently used when loads are applied in only one direction to help prevent vibrations from loosening the threads. Both the stud and the nut have a similiar profile.
Has anyone heard of this, and if you have any information about where I can learn more about it I'd very much appreaciate it. I'm trying to understand how this profile might affect the load carrying properties of the joint (as compared with a more standard thread profile), and how to best determine how to preload it.
Has anyone heard of this, and if you have any information about where I can learn more about it I'd very much appreaciate it. I'm trying to understand how this profile might affect the load carrying properties of the joint (as compared with a more standard thread profile), and how to best determine how to preload it.