I'm having trouble modeling this steam pipe connection to some equipment. Attached is a sketch as well as some results from my attempts at modeling a functional hangar solution. The equipment is connected at node 1, modeled as an anchor and the pipe clamp, 3.625" below it is at node 2 (case 1) or 5.625" at node 3 (case 2-4). The expansion (at 700 F) is causing a lot of force at "1". I'm trying to model the eq. connection as an anchor w/ a gap to represent gasket compression. Is this a good idea? Why won't node 1 move when there is a gap and force present?

Forgive my ignorance on the issue. Training has been arranged, but time is not on my side. Advice is appreciated.

1. The force exerted as a result of thermal expansion in a rigid system is going to be E*A*alpha*delta T regardless of the distances involved. You should know that. It's the zeroth theorem of pipe stress analysis; until you have absorbed this you are in over your head; it's what we are fighting against continually.

2. Try calculating the stiffness of the structure for your support and entering that. Even if it's very stiff, it's not likely to be anywhere near the magnitude of the stiffness term E*A in the above equation. for instance, if you have a couple of rod hangers you can figure the spring constant for the rods (remember to use the root area if they're all-thread). Or if its a cantilever beam, you can handle that I hope.

3. Most spiral wound gasket vendors will tell you that E for their gasket is less than about 450,000 psi. You can put a 1/8" thick gasket element into your model and calculate an axial stiffness for it based on this E, a 1/8" thickness, and the contact area (from Sect VIII Div 1 Appx 2). Warning - flaunting this knowledge in the face of an uninformed supervisor can get you into a world of trouble.

4. Modeling the gasket compression as a gap is pure fiction - gasket compression is caused by the bolts holding the flange to the valve, and the gap is essentially closed before the system is started up. Normal bolt loads flatten the spiral element until there is some contact with the retaining ring. Usually, operating pressures will cause the bolts to stretch and the flange to cup so that a gap is created (that's why there are two load cases to calculate in Sect. VII Div 1 Appx 2). You probably can argue that this gap creates some "give" in a flanged joint (but not with the uninformed supervisor of (3.) above), but I recommend 2. as a first pass at solving your problem. (Numerous other people have also recommended (2.) to posts here as a first pass at dealing with minute lift-off of rigid supports at risers in a rack, but somehow this advice keeps flying by the readers.) USE THE SEARCH FUNCTION, GUYS AND GALS!!!!

5. I'm glad to hear that your employer understands that outside training is appropriate where no capable supervision is available. If more employers had this mindset, there would be a lot fewer posts to this board, and a lot more good pipe stress analysts around.

The real issue is that the force on the eqp. is too high. Expansion is small and I'm trying to find a way to allow it rathar than create force at the equipment. Since defining the clamp is a bit difficult, I'd hoped the gasket would relieve the problem. Lift off does not seem to be a problem as the reaction force at the eqp. is pushing down on the clamp.

I will solve this problem by defining the hangar by engineering fiot and requiring the guys to either move conflicts or provide better field drawings.

Apparently an experienced analyst could see how other answers on this forum (and the others I searched) apply to my problem. The information you've provided has been unique and valuable.

Thank you for your response.