Engineering evaluation of misfit at piping closure points

If due to any reason the piping fit-up mismatchs in welding/flange closure points are overcome by piping distortion with pull or heating, how can we consider whether the same is acceptable in engineering evaluation using Caesar-II beforehand ? I have noted one in LANL B 31.3 piping guide App-F.

As essentially these are cold pulls, isn't it proper to evaluate the same using Caesar-II for strain-sensitive eqpts, when in doubt?

Although the cold pull loads are secondary loads, self limiting, this can be reason for non-catastropic events like progrssive failure by local fatigue cracks, seal/bearing failures of rotating equipments.

Rather, the effect of the construction oversights connected with high primary loads like the unaccounted pressure thrust in tied expansion joints due to non-availability of tightened nuts in both sides of plates on the tie rods or locked/topped-out/bottomed-out spring hangers in the field can be more serious.

regards,

sam

If you know this type of problem exists, do the work to check out its effects. Often we don't hear about it until a failure actually occurs.

You might check with passengers of, for instance the early Comet aircraft whether "progressive failure by local fatigue cracks" is really a "non-catastropic event"....

Dear MoverZ,

Just to know where the real problem of this kind exist, screening checks like one suggested in LANL B 31.3 piping guide App-F comes to help. Then, the engineering evaluation of the suspect case where alignment fit-up tolerance is exceeded can be performed with Caesar-II on piping & NozzlePro for vessel/nozzle interface.

It's like carrying out T3/T4/TSH blood test on every newborn yields 1 in 2400 suspect case for thyroid problems; then the detailed treatment on the really affected can be done.

For piping connected with strain-sensitive equipments or having leak-prone flanges carrying flamable or catagory-M fluids, careful installation is warrented. Even for a very sharp eye of a walk-down auditor,distortions due to cover-up of alignment mismatch is difficult without opening up of flanges after installation of piping.

regards,

sam