XYZ restraint design from individual shoe,guide, stop

Nowadays we find people choosing shoe, guide & stop standard design & assemble them in XYZ restraint. How the integral supporting arrangement like shoe is then is evaluated for the combined XYZ loading?
For standard XYZ restraints, what our forum members do, if no standard XYZ restraint is available in load rated status.

regards,
Sam

You have just discovered that there is more to Pipe Stress than creating Ceasar models and looking at stress values. Welded shoes can be designed for the actual loads acting on them by using the Kellogg method or WRC 107/297. Your analysis will mean nothing if your supports are unable to control the movement of the piping as you have modeled it in Caesar.

I couldn't have said it better myself! Good post Red Raider!

On the last project the lot went for FEA/FEM but then we were misusing CAESAR II by calculating duct dia 3000 with 8 mm wall...

If your pipe is at high temperature and especially in creep range standard calcs do not seem to work as we see a lot of problems with items welded to pipe.

ANC/XYZ is not ANC/XYZ if the steel or concrete goes with the support.

Yes, there is much more than the model.

All of you are right. We ourselves did design each anchor properly for nuke plants.

But, there safety ruled, nowadays profit motive does the same.

regards,

sam

Note that any sensible analysis of a pipe support design comes out the same whether safety or profit motive governs the design. Sample economic analysis for a shoe in a refinery:

Man-hours per support design: 4
Engineering billing rate for pipe stress analyst: $75 to $125
Cost of material: $2
Cost of installation labor: $35 to $60
Total cost: $337 to $562

Potential economic consequences of a support failure: $2 billion

Required design reliability: ($2 billion - $562)/($2 billion) = .9999997

Since guesswork is not going to produce a design to anywhere near that level of reliability, an engineer who understands risk analysis properly will engineer the support. And an owner who is investing $1 billion to build a (small) refinery will pay him for it.

Engineers who do not understand risk analysis usually end up working on less critical tasks.

Risk based approaches were not usually adopted in low probability fatal incident risks like pressure vessel/piping mechanical failures; prescriptive risk-avoidance codes and standards were thought to be sufficient to manage such risks. But, nowadays when engineering service has become a commodity, time has come to try other risk mitigation techniques.

Regular independent safety audit can discover the loopholes in the system in place. The very fact that work is being audited makes the A/E quality conscious!


Nowadays, everone is aware about consequences of accidents. But, due to job hierarchy and split responsibility in the work process, many don't take the needed steps to bell the cat.

regards,

sam

Agreed, Sam. I posted as I did to try to explain two things to newbies:

1. No matter how good you think you are at guessing, you're not good enough. Calculate it, get it checked, and file it, then if something goes wrong you can still sleep at night.

2. If you recommend that something be calculated, and management disagrees, you can whip what I posted above out of the third brain cell from the left and impress the hell out of them in about 30 seconds, using numbers appropriate to your particular problem. This sort of argument is almost foolproof in meetings - nobody wants to go on record as saying the ice is not too thin for skating. And as the piper, you're the only one with a ruler for that particular measurement.