Hi, i have come across some bid documents for refinery units where the PMC has put the following requirement.
" Separate support standard shall be provided for High Pressure piping".
I could not find any specific requirements in 31.3 Ch. IX for special support design for such piping.
Any body having experience in this can throw some light?
Regards
Siv

CAESAR II does not addres B31.3 Chapter IX.

Generally, high pressure piping produces support loads and operating case displacements that require engineered (one-of-a-kind) supports rather than simply using shoes and the usual hardware that goes with them on the more usual piping systems. This is because the weight per unit length and stiffness of all of the components used for high pressure piping is far outsinde the values for common off-the-shelf support hardware.

1. Relief valve thrust loads are huge, although not normally applied to the pipe.
2. Piping is extremely stiff, so there is more interaction between adjacent supports.
3. The piping routinely approaches or exceeds yield near the bore during normal operation, so the local effects of support loads now must be considered when checking hoop stress.

Thanks Craig B for your advise.
Can you please elaborate on point2.
For point 3 would it be better to use clamped shoes instead of welded ones?
Do you generally use FEM software for checking the local effect of supports for high pressure lines.

Some more queries.

1. Chapter IX is not exclusively for greater than 2500# rating. Suppose we have a 2500# rating line. If we classify it as high pressure than we need a separate engineered support and if we don't (apply chapter 2 rules) than we can use standard supports?
2. Is preparation of such engineered supports purview of a stress analysis engineer or shall it be done by specialised support manufacturer. What is the normal industry practise.?
Regards
Siv

"Piping is extremely stiff" - the assumption that a steel I-beam is "rigid" may not be valid when compared to an 8" pipe with a 2" wall. So you may need to go to the trouble of calculating a stiffness for every beam that supports your pipe.

Clamped supports are much better than welded ones for this sort of application.

My experience with corporate pipe support standards is that they are generally not worth the trouble above Class 300 or 600. Usually, the support loads for piping at Class 600 or 900 get to the point where you are above the rated load for "standard" supports. If your company's standards can handle more load, by all means use them.

Most of us design a couple of hundred pipe supports a year. Most support vendors can handle simple spring stanchions (cans) or spring hangers, but trapeze hangers with springs, axial line stops, riser supports, and the like usually are best done by the analyst. Capabilities of vendors vary from continent to continent, also. In North America, we are fortunate to have a lot of capable vendors. I wouldn't be so charmed about blindly using a local vendor's design in some other parts of the world.