New Zealand’s pressure equipment regulations require modifications to existing pressure pipes and vessels to go through the same process that applies to new pressure equipment :

• Design to a recognised code
• Design verification by a certified engineer
• Fabrication quality control (material certificates, weld procedures)
• Inspection and testing by a certified inspector
• Regular in-service inspections
  
  

Two issues arise :

• What types of modifications require the approval process noted above?
• How are the latest codes applied to existing vessels, in particular the required seismic loads?

Practice Note 19 issued by the Institution of Professional Engineers NZ in 2013 (see article in our 2013 newsletter on our website) is the accepted document for the seismic design of pressure equipment. Appendix D of Practice Note 19 addresses existing pressure equipment.

Carter Holt Harvey (now Oji Fibre Solutions), Fonterra, Refining NZ, Bluescope (NZ Steel) and Dobbie Engineers have presented joint submissions to IPENZ and WorkSafe on suggested changes to Appendix D. That document has now been revised and clarifies the steps required for modifications and repairs. It also explains the seismic requirements.