Do you get basic load or ASME Load Combinations reactions from your pipe stress guys?

[seenote2]

My pipe stress guys always gives the piping loads based on pipping load combinations instead of basic loads. I've asked for basic loads but they've refused to do it. So I've just ran with what I've got and used the largest and smallest (uplift) loads. I was wondering if this is a normal thing to not get basic loads or if I'm not understanding I should be applying the pipe stress loads. They've also state that they can't run basic loads and that I can't manipulate the load combination reactions to get basic loads because Ceaser II runs iterations or some sort. Which to me doesn't makes sense as the Load Combination Reactions should be the addition of the basic load reaction. I'm still new to the industry so any insight would be appreciated.

 

[1503-44]

Stress guys are interested in stress, not loads. Usually they calculate only dead + thermal loads, sometimes combined with internal pressure loads. If there are significant loads (greater than some preagreed defined minimum) at a given point, especially where they have pipe anchors, they should advise you. Otherwise you should use a generally adequate load, something like 40psf for piped areas, such as for pipe loads within a pipe rack and check pipe layout drawings for large pipe which may give loads above that threshold.

Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[mronlinetutor]

The pipe has two failure modes: 1. rupture by ring pressure, 2. rupture by bending stress along the longitudinal direction. Note, Pipe behaves differently from plates or beams because the pipe circumference is usually thin. So it is a thin shell or membrane and the failure stress along the pipe's longitudinal depends on the failure shear stress and bending moment. The stress unit cube of the combined stress is different from the top to the bottom of the pipe. So you have to do all the calculations to find the correct answer. The pipe might collapse due to its own weight where there is no ring pressure and the upper half of the pipe and lower half of the pipe behave like an arch and you have to consider an unbalanced half load. The construction technicians might drop the pipe so you have to include unexpected impact load due to gravity. Finally, you have to consider the thermal load due to weather and the temperature of the transportation of gas or liquid. The pipe is a real problem in the artic. Watch out for bending corners and stress for stoppers. As the gas and liquid in transportation changes direction, the pipe will have a side kick load which has to be interpreted as stress.

disclaimer: all calculations and comments must be checked by senior engineers before they are taken to be acceptable.