Corrosion Rate 1

powerguy,

I can make some qualitative suggestions and offer some experience. Rather than give you a "rate" I can offer some guidelines and specific systems in power plants to keep an eye on

In most power plants, all carbon steel piping systems use 0.0625" (1/16&quot for a corrosion allowance in the calculation of piping wall thicknesses. Stainless steels and heat exchanger tubing typically use 0.0" as a corrosion allowance.

There is no formal "code" or "standard" requirement that addresses this issue.........the piping codes (B31.1 and B31.3) as well as the Vessel code (ASME VIII) leave this up to the component specifier.

Based on my experience, watch out for condensate return piping and systems. They commonly start out with extra wall thickness and erode/corrode away to nil. Any system where air can ingress is subject to doubt. Never, in my opinion, re-use condensate piping.

Another area in a power plant subject to erosion/corrosion is "wet-steam" service. Periodically review and UT test the vent piping on closed feedwater heaters and piping downstream of emergency condensate "dump valves" (anywhere there may be water flashing to steam) Continuous blowdown systems and tanks (on watertube boilers) are another location where there is a problem

Hope that this helps.......

Can you be more specific about your needs ???


MJC

Standard publications such as API-653 (for tanks), API 570 (Piping) and API-510 (Pressure Vessels) address issues of calculating corrosion rates based on inspection data if you are looking for those. They also address methods of inspection and evaluation of the inpsection data.

There are also industry specific documents which categorize the corrosion behavior in different environments. Please note though that corrosion rates are extremely dependent on the material, process, and fabrication methods and as such are very much site specific.

- RKC

You can get this information in a corrosion lab using a sample of steel in its environnement (water), this potentiometric test will give the corrosion rate in mm/year
This is a usefull site
you can found what you need in corrosion section