Corrosion Allowance

CO2 corrosion is a major concern in oil and gas production environment. in boiler, generally treated water is preferred (ie, water is clean).

There would always be some slight amount of carbon dioxide free in the system, as this is a gas with high water solubility. Any air ingress, or water purification shortcoming will "leak by" some carbon dioxide into the water. Carbon dioxide presents a problem in ion exchange equipment due to a "cascading" effect between cation and anion resin, whereby it parasites the capacity of the system. Usually measures are taken to eliminate this upstream, however. I only know of two instances in my years of experience where very low pH condensate was allowed to form in piping. One was a low pressure steam supply that was not treated well at all, and had practically zero condensate return. The lower half of the pipe would eat away such that the pipe was replaced on approximately three year turnaround. Not good practice. The other involved an evaporator system for boiler makeup where the pre-softened water still contained high alkalinity, a high temperature steam extraction was used to drive the evaporator, and the evaporate produced was sent directly into a de-aerating feedwater heater without first being condensed and de-gassed. This evaporate was known to be less than 5 pH, and the boiler feedwater for this entire generating unit ran with a pH value less than 5.6 the entire time this evaporator was in service (over a great number of years). This led to high corrosion of the 90-10 condenser tubes, a great deal of copper deposited in the boiler, and problems deluxe.

In the absence of any local design code, a telephone call to the Engineer/Surveyor from the company providing burst indemnity insurance for the steam generator and the piping is a simple thing to do, and may yield valuable information gleaned from elsewhere over time. So pick up the phone, and get dialling.

"It is good to learn from one's mistakes. It is far cheaper to learn from other people's" - Anon

ASME construction codes have no role in corrosion allowance. What abhout BSEN a.k.a EN construction codes stand on corrosion allowance matter?

voila! ENN codes discuss corrosion issues.

This is ASME about corroshan.

Common Slack, show your EN stuff about corrosion

In order to calculate the minimum wall thickness of any pipe according to any code of record, you must have the allowable stress value.

This value is based on temperature. You have not given us the system temperature.

You have not given us the specific material....

Yet again, we begin this third world process of begging the clueless OP to give us the whole picture.

Is this the first pipe design problem that you have ever encountered ?

GENERAL CORROSION, IE, UNIFORM THINNING OF MATERIAL HAS NO RELATION WITH STRESS OR ANY OTHER FU*KING SUBJECT OTHER THAN HIGH TEMPERATURE IN THIS SCENARIO. IF, STRESS HAS A ROLE, YOU PUT A VALID LINK HERE TO CONVINCE US.