DIRECT ANSWERWhole-vessel postweld heat treatment heats the assembled pressure boundary as one controlled load; local PWHT heats a defined weld zone with a verified temperature gradient. The applicable design and fabrication rules, material, thickness, joint, geometry and access determine whether a local method is permitted.
PWHT route decision
- Code and project rule for each joint
- Material, thickness and qualified heat-treatment cycle
- Furnace envelope or local heating-band geometry
- Thermocouple layout, gradients and records
Relevant manufacturing capability
- Manufacturing-stage quality planning
- Multi-method inspection and test coordination
- Traceable release and manufacturing-dossier records
Key notes
- A portable heater does not automatically make local PWHT equivalent to whole-vessel treatment.