ASME B31.3 Process Piping - psig.sg

1 asme Process Piping Course7. Layout and SupportBECHTENGINEERING COMPANY, and Support -1 asme Process PipingCharles Becht IV, PhD, PE Don Frikken, PEInstructorsBECHTENGINEERING COMPANY, and Support -21. Establish applicable system standard(s)2. Establish design conditions3. Make overall Piping material decisions Pressure Class Reliability Materials of construction4. Fine tune Piping material decisions Materials Determine wall thicknesses Valves5. Establish preliminary Piping system layout & support configuration6. Perform flexibility analysis7. Finalize layout and bill of materials8. Fabricate and install9. Examine and testPiping Development ProcessASME Process Piping Course7. Layout and SupportBECHTENGINEERING COMPANY, and Support -37. Layout and Support General Considerations Support Spacing Support Locations Support ElementsBECHTENGINEERING COMPANY, and Support -4 The Material in This Section is Addressed by in:Chapter II - DesignASME Process Piping Course7.

2 Layout and SupportBECHTENGINEERING COMPANY, and Support -5 General Considerations Access for operation (valves) Access for maintenance of in-line devices instrumentation Traps strainers, etc. Avoiding interference with other activities Removing heat exchanger bundles Clearance for pump maintenance, etc. AppearanceBECHTENGINEERING COMPANY, and Support -6 General Considerations Drainage (slope) requirements Pressure drop Cost of Piping , including maximizing use of existing supports Avoiding interference with other Piping Clearance for application of insulation Clearance for Piping displacement, etc. Provisions for future additionsASME Process Piping Course7. Layout and SupportBECHTENGINEERING COMPANY, and Support -7 Support SpacingLoads to consider Dead Weight Pipe Insulation Valves, specialty items and instruments Live loads Pipe contents Ice, snow PeopleBECHTENGINEERING COMPANY, and Support -8 Support SpacingTwo principal sources:1. Recognized codes & standards asme MSS SP-69: Pipe Hangers and Supports Selection and Application2.

3 Owner or designer calculated valuesASME Process Piping Course7. Layout and SupportBECHTENGINEERING COMPANY, and Support -9 Support CalculatedMSS SP-69 NPSBECHTENGINEERING COMPANY, and Support -10 Support SpacingUsually based on simplifying assumptions Combination of pipe material and wall thickness used in the facility that gives the shortest spans Contents specific gravity, usually Typical insulation thickness and density Person walking on pipe for larger sizesASME Process Piping Course7. Layout and SupportBECHTENGINEERING COMPANY, and Support -11 Support SpacingLwLwTwo Models Frequently UsedBECHTENGINEERING COMPANY, and Support -12 Support SpacingSL= stresses caused by bending moment and pressure= M/Z + PD/4t =(wL2+ 2HL) / (8Z) + PD/4tHLwASME Process Piping Course7. Layout and SupportBECHTENGINEERING COMPANY, and Support -13 Support SpacingSL= (wL2+ 2HL) / (8Z) + PD/4tWhereD = pipe outside diameterH = concentrated load (people)L = trial length for support spacingM = bending momentP = design pressuret = pipe wall thickness nominal wall thickness less mechanical, corrosion and erosion allowancesw = uniform load due to pipe, contents & insulationZ = pipe section modulusBECHTENGINEERING COMPANY, and Support -14 Support SpacingSome designers limit support spacing using an arbitrary deflection criterion.

4 In. (12 mm) is frequently max= (5wL4 / 384EI) + (HL3/ 48EI)WhereE = pipe material elastic modulusI = pipe moment of inertiaASME Process Piping Course7. Layout and SupportBECHTENGINEERING COMPANY, and Support -15 Support Spacing This calculation method is only applicable to straight pipe with more-or-less uniformly spaced supports. Using the simply supported beam model versus the fixed beam supported model adds some conservatism to the calculation. Other models that can be used are shown on succeeding COMPANY, and Support -16M = wL2/8 max= 5wL4/384 EIUniform loadM = HL/4 max= HL3/48 EIConcentrated loadSupport SpacingAssuming simply supported endsHLLwASME Process Piping Course7. Layout and SupportBECHTENGINEERING COMPANY, and Support -17 Support SpacingAssuming Fixed endsM = wL2/12 max= wL4/384 EIUniform loadM = HL/8 max= HL3/192 EIConcentrated loadHLLwBECHTENGINEERING COMPANY, and Support -18 Support LocationsSupports must be located such that SL Sh. Following these rules of thumb will help: Piping running up the side of vessels should be supported from the vessel, generally near the top of the run.

5 Locate concentrated loads ( valves) near supports. Use rigid supports ( not spring supports) at safety Process Piping Course7. Layout and SupportBECHTENGINEERING COMPANY, and Support -19 Support LocationsFollowing these rules of thumb will help when doing the flexibility analysis: As much as possible, attach supports to straight pipe rather than elbows or other fittings. Provide space for adding loops to Piping near load sensitive equipment, in pump suction lines. Consider the need to add friction reducing slides between the Piping and support COMPANY, and Support -20 Support LocationsFollowing these rules of thumb will help operation and maintenance: Attach supports to pipe, not valves, flanges or instruments. Provide supports near instruments, and other devices that are likely to be removed for maintenance. Support Piping such that spools to be removed for equipment maintenance can be removed without adding temporary supports. Minimize the use of spring Process Piping Course7.

6 Layout and SupportBECHTENGINEERING COMPANY, and Support -21 Support ElementsSupport elements are classified by the degree of restraint provided to the pipingRestrains movement in all directions (welded to support steel)AnchorRestrains axial movement (and sometimes vertical movement as well)Longitudinal Pipe RestraintRestrains lateral movement (and sometimes vertical movement as well)GuideOnly provides vertical restraintSimple SupportBECHTENGINEERING COMPANY, and Support -22 Simple Support(from Anvil International)(from Piping Technology & Products) asme Process Piping Course7. Layout and SupportBECHTENGINEERING COMPANY, and Support -23 Simple Support(from Anvil International)(from Piping Technology & Products)BECHTENGINEERING COMPANY, and Support -24 Guide(from Anvil International) asme Process Piping Course7. Layout and SupportBECHTENGINEERING COMPANY, and Support -25 Spring Hangers(from Anvil International)Variable TypeConstant TypeBECHTENGINEERING COMPANY, and Support -26(from Anvil International)Special Purpose SupportsSway strut used toprevent horizontal snubber used to prevent sudden horizontal movement but allow slowly applied Process Piping Course7.

7 Layout and SupportBECHTENGINEERING COMPANY, and Support -27 Support Element SelectionResting pipe directly on structural steel should be avoided when: Carbon steel pipe is in a wet environment and failure by corrosion is not tolerable Stainless steel pipe would be in contact with galvanized steel and failure by liquid metal embrittlement during a fire is not tolerableBECHTENGINEERING COMPANY, and Support -28 Support Element SelectionSupport elements on outdoor insulated Piping should penetrate the insulation on the bottom of the pipe. (from Anvil International) asme Process Piping Course7. Layout and SupportBECHTENGINEERING COMPANY, and Support -29 Support Element SelectionSome solutions:Use pipe shoesSupport outside the insulationBECHTENGINEERING COMPANY, and Support -30 Support Element SelectionIn aggressive external corrosion environments, support should be via structural steel under the pipe rather than hanger rods with multiple threaded connections that may fail in a few years.

8 (from Anvil International)