If a weld is allowed to cool prior to the postweld heat treatment, the rate of uniform cooling must be controlled to prevent a detrimental effect in the piping.Partial heat treatment of a piping assembly that cannot be fitted completely into a furnace is acceptable if there is at least a 300 mm (1 f

At all stages of the heat treatment process, the temperature must be accurately monitored and recorded by a thermocouple or other suitable, approved method, to guarantee that the temperatures specified in the WPS are adhered to during the welding process. When necessary these temperatures must be re