FURNACE POSTWELD HEAT TREATMENT OF CARBON STEEL PIPING 1. 2. 3. 4. 5. 6. 7. Install thermocouples on the piping component. The rate of rise from 600°F to 1150°F not to exceed 400°F/hour. Hold at a soak temperature of 1125°F to 1175°F for a minimum of one hour per inch of thickness, but not less than one hour. Lower temperature from soak at a rate not greater than 500°F/hour until the weldment is at or below 600°F. Allow to cool in still air from 600°F to ambient. After the completion of the heat treatment process, visually inspect the weld and piping for adverse conditions such as cracks, warpage, overheating, etc. Perform a Brinell hardness test on the weld. The hardness after postweld heat treatment shall not exceed 200 BHN.