Corrosion allowance 2

[liberoSimulation]

I have a question with respect to corrosion allowance for piping and vessels.
What is the criteria that determines CA of for any process piping or equipment?
I know the more corrosive service a high CA to be considered but do no know a reference or standard giving the recommended CA for various services.
Can anyone give references or standard explaining the appropriate CA for some services?

Regards

 

[zcp]

Your corrosion allowance is most often based on your inspection interval in addition to the service. For standards, API510 for vessels and API570 for piping are excellent places to start for inspection intervals. There are several API publications that offer help with corrosive service and corrosion allowances for the petroleum industry.

http://www.api.org

ZCP

http://www.phoenix-engineer.com

 

[ijzer]

The corrosion allawance is based on the required design life time. Could be 20 years or more for vessels and piping . Using corrosion curves showing corrosion rates for different media compositions / temperatures and material , the most suitable material is selected together with the corrosion allawnce.

 

[EdStainless]

The big trick is making sure that you have a system that will undergo uniform corrosion. If the system will possibly suffer localized corrosion (pitting or crevice) then a CA has no benifit.


= = = = = = = = = = = = = = = = = = = =
Corrosion, every where, all the time.
Manage it or it will manage you.

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[SJones]

You will not find a standard because the magnitude of corrosion allowance is driven by many factors, not least economics. The first thing you need is information on the corrosivity of the medium within the system with respect to carbon steel. Then you will need to have a detailed prediction on the required minimum wall thickness for the system over its lifetime. This could be deterministic or probabilistic. Knowing the wastage rate, the desired lifetime, the thickness below which the system cannot be used, and the likelihood of reaching that thickness will give you some idea of the corrosion allowance required. Going this route will also incur the operating expenditure of inspection, maintenance, repair, and possibly corrosion inhibition, and maybe replacement. The whole can then be compared against using a material not subject to corrosion in the given fluid on a life cycle cost basis - see ISO 15663.

http://www.iso.org/iso/en/Standards...ALL&isoDocType=ALL&title=true&keyword=costing

As you may have gathered, it is not a simple subject to readily answer in a forum such as this.

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdo/