Additional information on the PWHT of equipment in Alkaline solutions.
All equipment that handle amine solutions, such as MEA, MDEA, DEA and FLEXSORB amines, with concentrations greater than 2% should be postweld heat treated except the following:
- Atmospheric storage tanks if metal temperature does not exceed 100°F (38°C), and
- The tank does not contain a heating coil, or
- The tank contains a heating coil and is provided with a high temperature alarm set at 100°F (38°C) or less.
Coker and cracker fractionation and light ends equipment handling ammonium carbonate/bicarbonate mixtures (excluding piping) should be postweld heat treated regardless of metal temperature.
All equipment that may be exposed to alkaline solutions as a result of operational upsets should be postweld heat treated as well.