I need to use a seamless hot rolled pipe of material E235+N (1.0308) because that is what I found at the shop with the required dimensions. Here is a reference:
http://www.steelnumber.com/en/steel_composition_eu.php?name_id=566
It is in the list of material of the standard EN 10305-4:2016...
According to API 7.1.6.2.5 "Stay-bolts shall not be used."
While it seems there is no problem using a "stud bolt", from other parts of the standard.
I am not able to figure it out what should be the difference for API 661 of a stud bolt versus a stay bolt. I used to think they were synonyms for...