We are having considerable drop in yield strength once we have steel coil formed into pipe. We are seeing average drop of 15-18 ksi, where normally only 2-5 ksi is expected. Without having seen steel mill test data, what could be causing such drop in yield???
I have looked in our company specs and API 1104 but can't find any requirements on wait time before a production weld on pipeline should be x-rayed. Are there any guidelines for this?
