Q. Corrosion - Erosion Allowance?
The required design life shall be based on written agreement between the user and the Engineering Contractor. Allowance specified shall be based on need, and can best be determined by past experience in similar operating environments. If no past experience is available, such as a new process, a Materials Engineer should examine the process and make judgment on the expected corrosion rate. Corrosion allowance should not be arbitrary; rather it should be compatible with design life requirements. However, it is customary to include a 1/8 in (3.2 mm.) corrosion allowance on most carbon steel process vessels.