pipe threading and fluid mechanics 1

[_Yoda_]

While removing gas hydrates. A vent pipe is connected by threads to a balon ball valve that is connected to the gas lift meter run. The vent pipe is vertical and is 69" with a 45 degree elbow at the end. Everything is schedule 80 steel 1" nominal. When the ball valve was opened all the way, the force coming out of the vent pipe at a 45 degree angle caused a rotational force in the opposite direction the pip end was facing, which caused the nipple of the vent pipe to fail and fly off. The static pressure in the line was 700 psi at the time. How could I figure out the force from the gas coming out of the 45 degree end? Also how Could i figure the stresses on the threads of the 1" x 4" nipple if the make up was only 3/8" or 4.3125 threads? Pitch= 0.08695

Any help would be greatly appreciated,
Thank you.

 

[bimr]

Another poster recently had the same question:

Link

 

[_Yoda_]

Thank you @bimr

 

[MJCronin]

Yoda,

Be careful when you are evaluating the strength of a threaded pipe connection.

Threads can get damaged and repeatedly cut into the pipe ..... to the point where the pipe has nearly no wall thickness left. The quality of the joint depends on the skill of the pipefitter.....

IMHO, this is a location where a socket welded fitting, or at least a seal welded threaded fitting would be a better choice

MJCronin
Sr. Process Engineer

 

[_Yoda_]

Appreciate that @MJCronin, I agree.

 

[oldestguy]

Fluid mechanics may have an answer. However, that force may be at your 700 psi times area of the fitting opening. Probably a lot more than that skinny pipe can handle, so you tested that already. Your three posts could all be done in this post. Read the rules here. You violated them.