Radiography & PWHT Requirements as per ASME Sec.I

[ukmet]

Dear All,

I had started working on a coal fired water tube boiler for power plant. There is a confusion in contract that main boiler is designed on ASME and rest of the parts on GB standard. Following are my queries:

1. What are the boundaries of boiler? Do economizer, super heaters and headers come under boilers?

2. Which joints usually come under PWHT criteria for boiler?

3. As per PW-11 tubes and pipes below 4" RT is not required. So usually boilers have tubes of 2" to 2.5" so we will do zero RT? Also for economizer and super heater piping we will not go for RT?

4. In my area I had observed lot of leakage of boilers in operations especially boiler tubes leakage. Can poor workmanship be a reason or zero RT criteria as per ASME Sec.I? (I know its generic wide scope question if someone could answer)

5. When we are not doing RT for pressure parts what other means are there to ensure joint quality on which we could convince contractor?

 

[metengr]

Please review Section I and come back with questions AFTER you reviewed the applicable sections. It is self explanatory.

 

[weldstan]

3. While Code does not require RT, it is often mandated by clients or Engineers in the Contract on a percentage basis to keep welders on their toes - to get some assurance of acceptable welding quality.
4. Poor welding workmanship is often but by no means always a causal agent in boiler tube leakage.
5. Beside the mandatory hydrostatic test, you can require further inspections and qualification of tube welders on mock assemblies in the initial contract.