Hi everyone. Liftoff has been one of the sticky topic here but I would like to start a new discussion...

I have encountered several times in my calculations that pipe support lift off less than 1mm which makes liftoff non-existent and of no concern to hot sustained stress. The problem with that sometimes is that even a 0.05mm would make the support load zero and transfer 100% of loads to adjacent support and it is especially problematic when it is the first support from the nozzle which would result to nozzle overloading. The solution is to move the location of support. Incorporating nozzle stiffness in the model sometimes solve the problem.

I'm wondering what other stress engineer do with such cases. Sometimes it's just playing with numbers. Modifying the layout or support location to pass nozzle loads because of non-existent liftoff (let's say <1mm)is not practical and convincing client to modify it is really difficult.

Any thoughts?