The Engineering World Of Thermoplastic Piping

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Design of Piping Systems Using Thermoplastic Materials

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The Engineering World Of Thermoplastic Piping

  1. 1. <ul><li>Presented By </li></ul><ul><li>Geoffrey D Stone C.Eng FIMechE; CP Eng FIEAust RPEQ </li></ul><ul><li>Design Detail & Development </li></ul><ul><li>http://waterhammer.hopout.com.au/                  Skype address geoffrey.stone@yahoo.co.uk </li></ul>
  2. 2. <ul><li>Thermoplastic Pipe Design </li></ul><ul><li>Material Properties </li></ul><ul><li>Waterhammer Analysis </li></ul><ul><li>Issues arising in design, fabrication, installation & testing </li></ul>
  3. 3. <ul><li>Codes & Standards </li></ul><ul><li>Hydraulic Analysis </li></ul><ul><li>Selection of Pipe Class </li></ul><ul><li>Fittings Class </li></ul><ul><li>Piping Layout </li></ul><ul><li>Thermal: Expansion/Contraction </li></ul><ul><li>Cold Cut & Pull </li></ul><ul><li>Unsustained Loads </li></ul><ul><ul><li>Wind </li></ul></ul><ul><ul><li>Earthquake </li></ul></ul><ul><ul><li>Ship Pitch & Roll </li></ul></ul><ul><ul><li>Vibration </li></ul></ul>
  4. 4. <ul><li>What Customer Expects </li></ul><ul><li>Material Properties </li></ul><ul><li>Design Criteria </li></ul><ul><li>Design Guidance </li></ul><ul><li>Material take off (MTO) </li></ul><ul><li>Applicable Standards </li></ul><ul><li>Final Inspection </li></ul><ul><li>Supplier to take the design risk!!! </li></ul><ul><li>What Supplier avoids </li></ul><ul><li>Taking the design risk </li></ul><ul><li>Taking the MTO risk </li></ul>
  5. 5. <ul><li>International and national standards do not define the design requirements adequately for thermoplastic pipe systems </li></ul><ul><li>Hoop stress is the primary design parameter </li></ul><ul><li>Manufacturers heavily relied upon to provide design assistance </li></ul><ul><li>Material properties vary between manufacturers and resin used but are generally consistent to meet standards </li></ul><ul><li>Properties isotropic </li></ul><ul><li>Thermal strain significant for applications </li></ul><ul><li>NDE technology is not available </li></ul><ul><li>Testing is defined in material standards </li></ul>
  6. 6. <ul><li>Australian standards are material specific for products and cover above ground installation </li></ul><ul><li>ISO 15493 Plastics piping systems for industrial applications — Acrylonitrile-butadienestyrene (ABS), unplasticized poly(vinyl chloride) (PVC-U) and chlorinated poly(vinyl chloride) (PVC-C) — Specifications for components and the system ― Metric series </li></ul><ul><li>AS 4041 Pressure Piping Code </li></ul><ul><li>ASME B31.3 Chemical & Refinery Piping Code </li></ul>
  7. 7. <ul><li>Design Pressure Steady State </li></ul><ul><li>Design Pressure Unsteady State </li></ul><ul><li>Vacuum Conditions </li></ul><ul><li>Industry Application & Environment </li></ul><ul><li>Support distances for deflection </li></ul><ul><li>Wear from abrasive slurries </li></ul><ul><li>Standardization of classes on site </li></ul><ul><li>Risk </li></ul><ul><ul><li>Likelihood </li></ul></ul><ul><ul><li>Consequences </li></ul></ul><ul><ul><li>Responsibility </li></ul></ul>
  8. 8. <ul><li>Fittings do NOT meet all pipe classes </li></ul><ul><li>Injection moulded fittings </li></ul><ul><li>Manufactured fittings </li></ul><ul><ul><li>Tees </li></ul></ul><ul><ul><li>Bends </li></ul></ul><ul><li>Flanges- Composite Metallic and Plastic </li></ul><ul><li>Gaskets </li></ul><ul><li>Expansion Bellows </li></ul><ul><li>Saddles </li></ul>
  9. 9. <ul><li>Piping connecting equipment </li></ul><ul><li>Flexibility </li></ul><ul><li>Physical damage </li></ul><ul><li>Number and type Fittings </li></ul><ul><li>Loads on nozzles </li></ul><ul><li>Horizontal or vertical </li></ul><ul><li>Straight lengths </li></ul><ul><ul><li>Flow metering </li></ul></ul><ul><ul><li>Pump suctions </li></ul></ul><ul><li>Supports </li></ul><ul><ul><li>Use existing steelwork </li></ul></ul><ul><ul><li>Saddles-Local Stresses </li></ul></ul><ul><ul><li>Springs </li></ul></ul><ul><ul><li>Hangars </li></ul></ul><ul><ul><li>Concentrated weights </li></ul></ul><ul><li>Maintenance </li></ul><ul><ul><li>Pipework </li></ul></ul><ul><ul><li>Equipment </li></ul></ul><ul><li>Erection </li></ul><ul><li>Access </li></ul><ul><li>Cost </li></ul>
  10. 10. <ul><li>Coefficient of thermal expansion </li></ul><ul><li>Modulus affects loading </li></ul><ul><li>Friction </li></ul><ul><li>Use of elbows and bends </li></ul><ul><li>Stress intensification factors </li></ul><ul><li>Elastic follow up/strain concentration </li></ul><ul><li>Ratcheting </li></ul>
  11. 11. <ul><li>To reduce loads </li></ul><ul><li>Impact on stress cannot be included </li></ul><ul><li>Installed versus Service Temperature </li></ul><ul><li>Supports </li></ul><ul><li>Signage </li></ul>
  12. 12. <ul><li>Specialist engineering required </li></ul><ul><li>National codes apply </li></ul><ul><li>Local conditions </li></ul><ul><li>Risk </li></ul><ul><ul><li>- Likelihood </li></ul></ul><ul><ul><li>- Consequences </li></ul></ul><ul><ul><li>- Responsibility </li></ul></ul><ul><ul><li>- Safeguarding </li></ul></ul><ul><li>Earthquake </li></ul><ul><ul><li>Building Influence </li></ul></ul><ul><li>Wind </li></ul><ul><ul><li>Height of external piping </li></ul></ul><ul><ul><li>Shading from buildings </li></ul></ul><ul><ul><li>Supports </li></ul></ul><ul><li>Vibration </li></ul><ul><li>Shock </li></ul><ul><li>Ship pitch & roll </li></ul><ul><ul><li>Ship’s data </li></ul></ul>
  13. 13. <ul><li>Benefits of Thermoplastic Pipe </li></ul><ul><li>Low modulus hence low wave speed (celerity) and hence low increased pressure </li></ul><ul><li>Instantaneous stress property values </li></ul><ul><li>Vacuum Resistance </li></ul><ul><li>Fatigue Resistance </li></ul><ul><li>Disadvantages of Thermoplastic Pipe </li></ul><ul><li>Low pressure rating </li></ul><ul><li>Low surface roughness delays pressure decay </li></ul><ul><li>Longer valve closure times because reflection times increased </li></ul>
  14. 14. <ul><li>Modulus </li></ul><ul><li>Hoop stress </li></ul><ul><li>Ring bending strain </li></ul><ul><li>Creep </li></ul><ul><li>Stiffness </li></ul><ul><li>Temperature variation </li></ul><ul><li>Design life </li></ul><ul><li>Toxicity & taint </li></ul><ul><li>Abrasion resistance </li></ul><ul><li>Chemical resistance </li></ul><ul><li>Ultraviolet resistance </li></ul><ul><li>Comparison with other materials </li></ul>
  15. 15. <ul><li>Data is published at 20 ºC only </li></ul><ul><li>Values determined by ASTM test </li></ul><ul><ul><li>Standard dog bone test specimen </li></ul></ul><ul><ul><li>Fixed strain rate </li></ul></ul><ul><li>Values at other temperatures required for design </li></ul><ul><li>Strain rate changes modulus value </li></ul><ul><li>Resin properties changes values </li></ul><ul><li>Short term property needed to determine maximum loads and transient pressures </li></ul><ul><li>Long term property used to determine maximum deflection </li></ul>
  16. 16. <ul><li>Importance of Strain </li></ul><ul><li>Comparison thermoplastic materials </li></ul><ul><ul><li>ABS 1% </li></ul></ul><ul><ul><li>FRP 0.2 to 0.6 % </li></ul></ul><ul><ul><li>PE 4.0% </li></ul></ul><ul><ul><li>PVC-U 1% </li></ul></ul><ul><ul><li>PVC-O & PVC-M1.3% </li></ul></ul>
  17. 17. <ul><li>Variation of properties in time </li></ul><ul><li>Long term loading/stress relaxation </li></ul><ul><li>Reverse loading/stress magnitude </li></ul><ul><li>Repetitive loading/fatigue </li></ul>
  18. 18. <ul><li>The design temperature may vary due to:- </li></ul><ul><ul><li>Ambient diurnal temperature </li></ul></ul><ul><ul><li>Flow rate </li></ul></ul><ul><ul><li>Fluid temperature range </li></ul></ul><ul><ul><li>Installation ambient temperature </li></ul></ul><ul><ul><li>Exothermic chemical reaction </li></ul></ul>
  19. 19. <ul><li>Design life criteria is 50 years </li></ul><ul><li>50 year does not mean the pipe has a 50 year life span </li></ul><ul><li>50 Years is an arbitrary period to provide comparative data </li></ul><ul><li>No matter how old it is, the pipe will still exhibit instantaneous properties similar to when it was made when subjected to high rates of strain </li></ul>
  20. 20. <ul><li>Size distribution of particles </li></ul><ul><li>Concentration of solids by volume </li></ul><ul><li>Relative density of solids </li></ul><ul><li>Shape of particles </li></ul><ul><li>Sharpness of particles </li></ul><ul><li>Flow regime affecting angle of impingement, sliding bed etc </li></ul><ul><li>Temperature of fluid </li></ul><ul><li>Velocity of slurry </li></ul><ul><li>Chemical resistance </li></ul><ul><li>Some relationships predicting wear in pipelines: </li></ul><ul><li>Wear  Velocity (2.5-4.5) </li></ul><ul><li>E = 6.1 dm 2.15 . U 3.7 </li></ul><ul><li>Where :- </li></ul><ul><li>E = wear rate (at bottom of pipe, mm/year </li></ul><ul><li>dm = mean particle size, </li></ul><ul><li>U = mean slurry velocity, m/s </li></ul>
  21. 21. <ul><li>Offer high chemical resistance </li></ul><ul><li>Preferred materials for particular processes </li></ul><ul><li>Chemical resistance charts are a guide only </li></ul><ul><li>Contaminated fluids can be highly corrosive </li></ul><ul><li>Stress test recommended </li></ul><ul><li>No pickle & passivation as in stainless steel </li></ul><ul><li>No cathodic protection needed </li></ul><ul><li>No corrosion inhibitors </li></ul>
  22. 22. <ul><li>Coefficient of Thermal Expansion </li></ul>
  23. 23. <ul><li>Design </li></ul><ul><li>Fabrication </li></ul><ul><li>Installation </li></ul><ul><li>Testing </li></ul><ul><li>Product quality </li></ul>
  24. 24. <ul><li>Design pressure does not include surge </li></ul><ul><li>Temperature profile not defined </li></ul><ul><li>Design layout not adequately drawn </li></ul><ul><li>Supplier has to provide more than guidance in design </li></ul><ul><li>Consultant expects sub contractor to do detail design </li></ul><ul><li>Lower pipe class than necessary specified to save costs </li></ul>
  25. 25. <ul><li>Inadequate detail drawings </li></ul><ul><li>Insufficient joints for erection </li></ul><ul><li>Incomplete insertion in solvent welded or electro fusion joints </li></ul><ul><li>Inadequate time for butt fusion welds </li></ul><ul><li>Contaminated electro-fusion welds </li></ul><ul><li>Belief that all pipe can be site run rather than designed </li></ul><ul><li>Lack of training or supervision </li></ul>
  26. 26. <ul><li>Spools forced to fit </li></ul><ul><li>Designed supports missing or modified </li></ul><ul><li>Insufficient clearance in clamps & guides </li></ul><ul><li>Variations from design not engineered </li></ul><ul><li>Surfaces contaminated </li></ul><ul><li>Physical damage </li></ul><ul><li>Other services supported from pipes </li></ul><ul><li>Incorrect slings </li></ul><ul><li>Insufficient weld time </li></ul><ul><li>Lack of training or supervision </li></ul>
  27. 27. <ul><li>Excessive hydrotest pressures </li></ul><ul><li>Lack of planning & procedure </li></ul><ul><li>Standard provisions not understood </li></ul><ul><li>Inexperienced testers </li></ul><ul><li>Test pressure unknown </li></ul><ul><li>Equipment not isolated </li></ul><ul><li>Premature testing </li></ul><ul><li>Records of test not prepared </li></ul><ul><li>Person to witness test not available </li></ul><ul><li>Equipment not available </li></ul><ul><ul><li>Water supply </li></ul></ul><ul><ul><li>Pump </li></ul></ul><ul><ul><li>Gauges </li></ul></ul><ul><ul><li>Data logger </li></ul></ul><ul><ul><li>Temperature instrument </li></ul></ul>
  28. 28. <ul><li>Virgin material or % regrind </li></ul><ul><li>Standard compliance </li></ul><ul><li>QA documents </li></ul><ul><li>Inspection at works or on site </li></ul><ul><li>If the price is low then you may not get what you expect </li></ul>

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