Using UT Testing Results 1

[pm66209]

Will soon be UT testing boiler feedwater piping.

The Power Piping Code has an 'A' factor (corrosion/erossion/mechanical strength allowance). Is this just to be used for a new piping installation calculation or should there be some 'A' amount considered to determine minimal thickness for existing piping?

Weld Joint Efficiency 'E'. We have seamless pipe but I don't know how it was previously welded at the fittings and in the pipe runs. What is a good value to use for 'E' in such a case?

With the previous inputs determined would you consider the minimum thickness calculated to be strictly adhered to for pipe that has been in service for quite a while? That is, would you replace pipe and fittings whose thickness was measured to be below the minimum thickness as calculated from the Power Piping Code or would you allow pipe thicknesses some % below the minimum thickness calculation but no thinner? Where do you draw the line?

 

[SJones]

The assessment of the current status of the inspected pipework is known as "fitness for service". It is not possible to go into detail in this forum but you may wish to look at the following:

http://www.fitness4service.com/index.htm

API RP 579

BS 7910

I'm not sure that the latter two documents will be strictly applicable to power piping but they will give you the flavour of what needs to be done to "keep the plant running".

Steve Jones
Materials & Corrosion Engineer

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