Hello Ashish,

Your clad pipe system may not closely resemble "most other" clad pipe systems. Yours is a relatively large diameter pipe with a significant cladding thickness.

Clad pipe is stiffer than common or "unclad" pipe. How much stiffer is open to debate. IF (and this is a big IF) the cladding is bonded to the pipe ID continuously it might have the effect of simply adding (in your case 1/8 inch) to the total wall thickness. If this were the case the effect would be predictable (we could calculate the resulting pipe section modulus "Z").

If the cladding is not tightly bonded to the pipe ID but is attached to the pipe only at the butt welds the pipe would be stiffer by "some amount". The "pipe-within-a-pipe" effect might be similar to "double containment" systems or "jacketed" systems. The section modulus, "Z", will be still be increased, but by how much.

The stiffer the pipe is the more load will be transferred from the piping system to the vessel nozzles. If you effectively have greater wall thickness, or if you have "composite" construction ("pipe-within-a-pipe") I think the pipe streses would be lessened.

As Rich says, you will have to "account" for the total weight of the piping material (and all the support hardware, etc.) in the analyses.

I have asked Rich to put an ExCel spreadsheet template on the COADE site for the use of anyone who would find it useful. The spreadsheet is offered with NO IMPLIED GUARANTEES OF ITS ACCURACY. Like all such tools the user is cautioned to check out the resulting calculated values - it is your responsibility as an engineer to check your answers. The spreadsheet may prove useful for those who would like to quickly check the stiffnesses ("Z") of piping of standard and non-standard wall thickness.

Best regards, John.