Grinding Seam Weld

Yes and no. Actually since you are asking this question, it is understood that the drawings/weld design dosn't mention anything about grinding of the weld. I have also not come across any power piping where you need to grind the weld. But if the same is mentioned in approved drawing you have to do the same as the designer has considered it, otherwise grinding is not required at all for power piping. Also if the welding is not done as per the weld design/drawings, you may have to open-up the welds for repair and re-weld. This is the only time you grind the weld (when the drawing is silent of grinding/flushing the weld)

I agree with mahesh....the answer can be yes or no

For piping systems that will require ultrasonic testing of the welds, grinding of the "weld cap" is necessary.

For many other systems, including those subject to other types of testing.....the answer is no

My opinion only