ASK NDE’s TECHNICAL EXPERTS - CREVICE CORROSION

NDE’s technical team receives enquiries on a daily basis that require input from a stainless steel specialist.ASK MARCH2

Below is one of the questions, with the response from our technical experts.

QUESTION

A stainless steel pump for pumping fresh water on a smallholding has sprung a leak after only two years of use. Opening the pump revealed metal loss and a crack on a fitting in the pump, especially around the thread.  What is the cause and the solution?

ANSWER

This wasting of material in the thread is almost certainly crevice corrosion.

Lack of oxygen in the thread is the problem.

There are a few things which you could consider:

  • Use of a higher grade stainless steel material
  • Putting some kind of sealant into the threads before tightening
  • Welding around the fitting to prevent access to the thread by water