99 Questions to Ask during a Design Review Session (Part II of III)

The design review acts as a forum where questions can be answered, assumptions clarified, and advice sought. It is a useful mechanism whereby the project design can be optimised through a systematic review and feedback on design process outputs. The design review process shall not be confused with process safety studies, like HAZID, HAZOP and LOPA. Typically, a number of formal and informal reviews are conducted during the project. These reviews may last a few hours or a few days depending on the scope and the phase of the project.

The design review process can be based on a checklist review, where questions are asked to Technology Licensor or EPCM to ensure deliverable documents contain necessary information for the design to continue. As many ammonia plant designs are similar, this is a good check on making sure the project specific requirements are covered, and any unusual, new, or otherwise note-worthy information is passed along to the downstream disciplines.

Below is a second list of 33 questions recommended to asked during a design review session:

  1. Have considerations been given to steam out, process upset conditions and possible vacuum conditions in selecting materials of construction and ratings of equipment and piping?
  2. Are specialty items, such as strainers and traps, compatible with piping classes?
  3. Is any material substitution made during the design stage been discussed and approved with the metallurgist and corrosion specialist?
  4. Have piping classes been selected based on materials of construction and corrosion allowances given by the metallurgist and corrosion specialist?
  5. Have lines requiring alloy verification been identified?
  6. Has the potential of stress corrosion cracking been taken into account?
  7. Has the selection of materials of construction accounted for the effects of depressurization?
  8. Any components used in a Piping specification which have lower design pressure/temperature limits than the subject spec (Check notes) are qualified for their individual rating?
  9. Has the selection of materials of construction considered the chemical composition of waters?
  10. For the total power failure case, has the effect of the following been considered:
    1. All motor driven pumps shut down
    2. Air cooled exchanger fans are lost
    3. Motor driven compressors shut down
    4. Instrumentation is affected (unless a back-up is available)
    5. Motor operated valves fail in place (unless a back-up is available)
  11. Has the effect of cooling water failure, which could cause the loss of overhead condensers and shut down condensing turbines, been taken into consideration?
  12. Has the effect of additional flow as a result of upstream control valve/valve failure been taken into consideration in establishing the relieving load? Has maloperation of the bypass been checked and discussed during Design Review or HAZOP study?
  13. Has the actual CV of the valve purchased been used?
  14. Have the potential hazards, including ignition of vents, associated with static electrical discharge been considered?
  15. Have the critical lines been identified and their routing approved?
  16. Have the number and location of eyewashes, showers, utility stations and steam hoses been reviewed?
  17. For underground manholes:
    1. Is there a requirement to vent underground manholes to a safe location?
    2. If so are they piped together and routed accordingly?
  18. Have correct test medium and pressure been specified on the Line List, and is the test pressure specified in accordance with code requirements?
  19. When equipment is planned to be included in the piping system during testing, is it ensured that piping test pressure is compatible with equipment design pressure?
  20. For pneumatic testing, has maximum stored energy been evaluated?
  21. Has the procedure for pressure testing existing lines been agreed with EPC Contractor (this should be part of tie-in coordination meeting)?
  22. Has the procedure for pressure testing been determined for systems containing high pressure, high temperature piping welded to vessels (e.g. high-pressure steam systems)?
  23. Are there any national or local regulations prohibiting/limiting pneumatic testing?
  24. Have Material Safety Data Sheets (MSDS) for hazardous substances, chemicals, and catalysts been reviewed with regard to auto-ignition temperature, flash point, explosive limits, toxicity handling and corrosivity? Have these substances been reviewed with regard to their potential locations in the plant?
  25. Have all process design parameters and design cases been taken into consideration?
  26. If appropriate, have notes been added to the P&ID’s to indicate any special measures required to reduce the risks at time of installation or use of the pressure assemblies?
  27. Where the potential for misuse is known or can be clearly be foreseen, has the pressure equipment been designed to prevent danger from such misuse? If this is not possible, have notes been added to the P&ID’s to provide adequate warning that the pressure equipment should not be used in such a way?
  28. Have pressure assemblies that are subject to high reaction forces and require increased support been identified on the P&ID’s?
  29. Have pressure assemblies that are subject to acoustic fatigue been identified and adequate measures taken to alleviate this?
  30. Have pressure assemblies that are subject to reaction forces due to decomposition of unstable fluids been noted on the line lists/equipment data sheets?
  31. Where materials are subject to creep at high temperature, have the design hours of operation at the specified temperature been noted on the line list/equipment data sheet?
  32. Where materials are subject to cyclic fatigue, have the design number of cycles at specified stress levels been noted on the line list/equipment data sheet?
  33. Where systems are subject to decomposition of unstable fluids during operation/maintenance, has this been noted on the P&ID’s?
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