Module 13 plant piping design

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Module 13 plant piping design

  1. 1.  Manual Drafting Method  Piping Design Model Method  CADD Method  CADD Model Combined with Physical Scale Model
  2. 2.  Involves determination of detailed piping with the use of drawings  Process scheme transposed from flow diagrams onto Equipment Location Plan  Designer then produces detailed drawings in form of Piping Plans and Piping Sections called Piping Arrangement Drawings  Drawn to a scale of 3/8” = 1’0” (imperial) or 1:30 (metric)  Isometrics are then developed from the Arrangement Drawings
  3. 3.  Plastic Scale Models  Lay out piping and valves directly on model  Arrangement and isometric drawings developed from model  scale of 3/8” = 1’0” (imperial) or 1:30 (metric)  Advantages  Accurate and reliable  Points out costly interferences & construction problems  Produces better plant layout  Improves communication between design disciplines
  4. 4.  Better indication of progress to management  Reduces construction costs by eliminating “ignorance contingencies” used by bidders  Assists in the writing of better operation manuals  Reduces amount of time spent training plant operators
  5. 5.  Speed up drawing function and enhance design function  Allows production of “intelligent” flow diagram  Reports line & instrumentation list and prelim M.T.O.  Reports inconsistencies in pipe sizing and specs  Major strength: data storage and retrieval capability which allows massive amounts of design information to be available for checking and reporting
  6. 6.  Designer produces plant design using following steps:  Set up section of plant as computer model in isometric  Insert foundations and structures  Construct vessels and equipment  Route piping between nozzles  Add fittings, vales and instruments  Report interferences  Report inconsistencies re: size, specs or space  Produce double line plan or section views  Automatically produce isos incl. M.T.O.  Link all sections of plant together
  7. 7.  Combined to produce faster, more efficient and effective design with cleaner construction  Early design – plastic model  Plastic model data fed into CADD database which:  Allows for interference checks to be made  Allows Structural load verification to indicate supports and hangars and interface with stress analysis programs  Provides easy access to drawings of each area  Aids with MTOs and spec compatibility checking  CADD designs related back to physical model  CADD develops Isos, arrangement drawings, MTOs and inventory lists for use during construction  Physical model available during approvals, construction, operator training and as basis for revision
  8. 8.  Positive Pressure Head must be present at piping outlet  Produced by pump, gravity, displacement or static head, suction  Friction loss  Keep piping runs short as possible with few fittings  Viscosity (internal friction of fluid)  Design piping and valving for minimum liquid hold-up during shut-down  Vents and drains  Properly placed to allow filling and draining of vessels during testing and purging  Turbulence is required  Avoid dead spots in piping and use bends of 5 pipe diameter  Control valves  Commonly one pipe size smaller than line size  Points of sudden pressure drop causing “flashing”  Provide sufficient N.P.S.H.  Vapour lock  Slope the line or vent high point  Condensable vapours like steam piped to avoid liquid pocketing  Special pipe materials  may be needed when transporting hazardous liquids
  9. 9.  Economics  Minimize length of lines and number of fittings  Carefully consider design changes due to increasing operation costs in facilities  Maintenance  Adequate space must be provided for assembly, disassembly, adjustment and lubrication of equipment  Utility stations should be readily available  Special lifting or rigging devices may be required  Breakout flanges may be required to aid equipment removal  Vibration  Air chambers may be required for quick valve opening & closing  Reciprocating equipment requires surge tanks or pulsation bottles plus sufficient piping support

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