As a first step, check all of the information in the title block for conformance with the P&ID and the plot plan. Double check the line number, area number and piping material spec. Step two, yellow off the flowsheet as the isometric is traced on the flowsheet from start to finish. All inline components should appear on the iso. Check flow dierction. Check all continuations on the iso (against vessel drawings, including nozzle number, nozzle orientation, coordinates and flange type, gasket and rating.
Using a 3-D system and computer spec ? Check the Bill of Materials. Getting carbon steel materials in stainless stell lines is easy, especially if the final spec was not available when modelling started. Are all of the components in the line from the spec the line was modelled in? Check for fabrication category (shop - field) against the requirements for your projects. Many designers field run every thing below 40mm, some field run everything below 50mm.
Valves can be a pain, especially generic ones. Small bore valve dimensions change. Every manufacturer and valve type uses different overall dimensions. Here it is important to specify the make and model of every valve. The use of generic face to face dimensions will produce spool drawings with cut lengths that will be incorrect. The overall length of control valves, speciality items, instrumentation and anything else that is inline needs to be checked against the certified vendor data published for the project.
Always consider manufacturing restrictions when selecting field weld locations. Prefabricated spools will be shipped by tractor-trailor. Make spools fit on trailers and where appropriate into the average stress relieving oven. Allways allow for adjustment with appropriately selected field welds.
Colour is an extremely usefull tool. Yellowing off checked items on the P&ID, linelist, iso and GA takes away the need to recheck already checked areas.
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