Specification for post weld heat treatment of pressure equipment
1 Scope
This standard specifies the general basic technical requirements for post weld heat treatment of pressure equipment.
This standard is applicable to the post weld heat treatment of boilers and pressure containers (excluding gas cylinders).
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced documents (including any amendment) applies.
GB/T 3375 Welding terminology
GB/T 9452 Testing method for working zone of heat treatment furnace
NB/T 47014 Welding procedure qualification for pressure equipment
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 3375 and GB/T 9452 and the following apply.
3.1
weldment
pressure equipment or its parts that have been welded
3.2
post weld heat treatment
process that the weldment is uniformly heated to a high enough temperature below the phase transition point of metal for a certain time, and then uniformly cooled in order to eliminate welding residual stress and improve the structures and properties of welded joints
3.3
soak band
surface area where the weldment reaches the volume range of specified temperature during local post weld heat treatment. It includes weld zone, fusion zone, heat affected zone and its adjacent base metal
3.4
heated band
area to be heated for ensuring that the weldment can reach the specified soak volume during local post weld heat treatment
3.5
gradient control band
area coved with thermal insulation materials to prevent heat dissipation of soak range and heating range of the weldment during local post weld heat treatment
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Basic process
5 Equipment, instruments, temperature measuring articles and thermal insulation materials
6 Technical preparation
7 Heating and temperature control
8 Temperature measurement
9 Thermal insulation
10 Post weld heat treatment report
Annex A (Informative) Post weld heat treatment thickness (δPWHT) diagram
Annex B (Informative) Recommended width of heated band and gradient control band for local post weld heat treatment of cylinder
Annex C (Normative) Method for determination of effective heating zone of furnace for post weld heat treatment
Annex D (Informative) Record of integral post weld heat treatment outside the furnace of pressure equipment (example)
