Most piping stress analysis for FRP and other nonmetallic piping systems are based on flexibility. This seems fine for most above ground piping installations. But bow would you design a piping system and perform stress analysis on a piping system that could not be flexible? For example a piping system that was on a skid, an offshore platform, a vessel or ship, and a process piping system inside a plant, both horizontal and vertical.

I am not clear about your question.

As far as understand, all the piping systems are flexible. Even the piping on skid, on offshore platform, piping on ship or in process plant are analysed in the same manner as per usual codes & standards. The basis of stress analysis is the same for all the piping systems.

For FRP, refractory piping , it is slightly different.

Please be more clear about the query.

There is no room for the piping to flex when installed on a skid, an offshore platform, a vesel or ship, and an inside process piping system. There is not enough length between direction changes and branch lines for flexibility. Therefore how do you install the piping (supports, guides, and anchors)? You cannot design a piping system using flexible analysis when there is no flex, can you?

How do you know where to place supports, anchors, and guides? Should an analysis of the piping tell you that bending moments on changes in direction and branches exceed the allowables? For example you cannot place an anchor far enough from a change in direction to accommodate the allowable bending moment? or can you?

Can CAESAR II be used to help design a piping system that must be restrained? Can CAESAR II help to properly locate a support, or guide, or anchor? Can CAESAR II be used to tell if a support or anchor or guide is improperly placed due to excessive stress on the piping?

I think you should first understand that software is to be utilized to validate engineering judgement. You should not work other way round. (Sorry to be sounded blunt, but softwares work on the principle of "Garbage in garbage out"). If you start looking in software to get solutions to your problems then you may land up in difficulties.

Regarding flexibility of piping systems, believe me, all the piping systems are flexible, they can bend / twist. So you just have to follow basic engineering (routing & supporting) and then check flexibility in CAESAR-II.

CAESAR II is one of several "piping flexibility and stress analysis" programs. These are analysis tools used to determine the structural response to applied loads (that's the flexibility reference) in terms of load and deflections and "code-defined" stresses. You layout the pipe, CAESAR II evaluates your layout. You design the system, CAESAR II analyzes your design.

Piping installed in confined spaces is still flexible. The deflections may be very small, though. CAESAR II (or any other software program) can calculate the magnitude of the expansion (and other) forces, the deflections, and the resulting stresses.

You appear to be confusing the concept of "I know this leg is too short to flex adequately and will therefore produce high forces and moments on its end points," with "this piping is rigid." Nothing in the physical world that we know of is perfectly rigid, and FRP pipe is not high on the list of contenders.

Most FRP pipe has a low enough Young's modulus that it CAN be restrained very tightly without generating unacceptable forces and moments on the steel terminal points. You may fatigue it with enough thermal cycles, but you'll probably not damage anything you connect it to. But of course you need to do the analysis to make sure that my generalities apply to your specific problem.

The biggest problem with FRP pipe is modeling the joints. Mechanical joints (threaded or clamped) have inherent flexibility at the joint. Lapped butt joints are stiffer than the surrounding pipe, although not necessarily stronger. And you can get into really funky situations.

You are probably best off to get the system vendor to do the stress analysis - he should have more experience with his particular product than anyone. But you may well be too late in the procurement cycle to make this happen. (We put this responsibility on FRP vendors as a matter of course, up front in the bid process.)

This, I guess, is a long-winded way of saying that I agree with the other posters here. Design the piping, model it, run it, and see what happens.

Thank you all very much. I understand now. Most FRP systems if not properly anchored and supported from the effects of expansion and contraction due to pressure surge and temperature, will fail at the fitting due to excessive bending load. A piping flexibility and stress analysis program would calculate the loads based on the input of an anchor, support, or guide location at the fitting (change of direction or branch). The output calculation(s) would be compared to the allowable bending moment. Is this correct? Do you have to make the comparison manually? You enter the type of support (anchor, guide, or support) and the distances away from changes in direction and branch lines.

You design the installation of the piping and then use a piping flexibility and stress analysis program to calculate the bending moments to see if they are within the allowable.

FRP and other nonmetallic piping systems can be fully restrained. This is practical because the lower elastic modulus results in anchor loads that are not unreasonably high. By fully retrained, I mean with more than one anchor in a straight run of pipe. This is even recommended by some over flexible installations to limit piping movements and resulting issues at support locations.

The default B31.3 stress calculations will not include the stress due to axial loads in the thermal expansion case, which should of course be considered in a fully restrained system. If you use the Appendix P rules, the stress due to axial loads caused by restrained thermal expansion will be included.

In an FRP system, you must know the details of the specific sytem you are designing, including the possibility that the joints may be weak spots with the loads on them limited accordingly.

what is software to be used for FRP PIPING FOR SEA WATER LINE OF SIZE: 20" FRP PIPING JOINING TO 66" CS CEMENT LINED PIPE AND PLATE HEAT EXCHANGERS.

ANALYSIS DONE BY ISO-14692 IS ACCEPTBALE OR NOT.

PLS GUIDE US.

ISO 14692 Part 3 is recommended if one is looking at performing a stress analysis of FRP piping system. I found it very useful and is a good guide.

Eventually the FRP supplier's guidelines have to be considered.

Have your supplier supply the allowable stress envelope before you start your analysis based on ISO 14692. For typical stress envelope again Part3 of ISO14692 should be of a help.

If possible ,you may consider the analysis of the FRP portion by your supplier's engineering dept and review it.