This question has been bothering me for a while now.

What is the best possible way to approach, the bulk material take off at proposal stage?

A] To have a listing of valves and other fittings excluding pipe and elbows and covering the rest using the bulk and spare philosophy.

B] Creating isometric sketches based on piping studies and then calculating the bulk.

C] Using software to create preliminary stage 3D model instead of option B. However, the setup may prove cumbersome.

Kindly advice the best foot forward. I've merely stated what I thought. Any suggestions on information, books and specialized softwares for proposal are most welcome.

Regards,

I have used (and recommend) the following"

Use "A" for all Off-site lines and On-site utility Headers

Use "B" for all On-site (Alloy and other) piping. Note: You must have the time in the schedule and the experienced staff who can average 4 meaningful isometric sketches (8 1/2" x 11") per hour.

"C" is not a viable option for a Proposal Stage MTO

Thanks a lot! In fact, I never thought of the combination of two. I wasn't sure of proposition C.

Meanwhile I decided to work a little on material priority and came up with following things:

Weightage By Bore: Large Bores (Exceeding 24") * (This should be based on size distribution in the project)
The other ones (Remaining)

Weightage By Material: CS, LTCS, Alloy S, Stainless Steel.

A weightage chart based on these can give me the isometrics that go for sketching.

Regarding designers, you hit nail on the head. Both production and quality of isometric varies.

Thank you

Regards,

In recent developments on the software part used on the project PDMS / PDS I think there is always a possibility for using 3D software for bulk MTO as well & now a days it is being done only if you have quality / very experienced staff on board for the project.

It also depends on your budget at FEED stage. I have been on large projects where we built a 3D model to do the MTO for the owners. If there are a lot of dollars involved they want to check their ROI (return on investment) before making a decision on whether to advance into detailed design.

Sometimes simple transpositions and hand drawn Isos are good enough. Tie-ins should be factored in early in preparation for a CWP package as there are valves which may have to be ordered early due to scheduled shut downs. If it is easy to build a 3D model as a tool it is the better method and more accurate than a manual MTO however in complex designs one may not have the budget or hours to do the work. It depends on the DBM and what the client's expectations are. Some owners like to see pre design taken to a 30% model review especially for projects for the Middle East.

One problem with the 3D model is getting the right pipe specs built and approved. If it is an existing client you may have them in house but even then that can change for large clients whose specs change from facility to facility as mergers and aquisitions make for a hodge podge of specs for differing facilities.