B31.8 Age old Fillet Weld Question
B31.8 Age old Fillet Weld Question
(OP)
I have a client that called me last evening with questions about B31.8 and the use of Fillet welds to 36"X1" X52 material. They are wanting to weld a saddle type support in three places along the bottom of the pipe ( Ad Hoc Vessel ) using a circumferential weld down the sides and a longitudinal weld across the tops of the saddle. 31.8 is not my regular construction code but I do know that they only allow fillet welds in certain situations. Any tips would be great as my schedule does not allow myself to research it myself. My first and quickest answer was yes to the circ. welds and no to the long. welds. Any help would be great
Thanks
Thanks





RE: B31.8 Age old Fillet Weld Question
Other than that I can't find a reference which says you can't weld longitudinally, but I do recall some discussion on that, but still can't find anywhere in the code where it says that.
I would be more concerned about the use of the saddle support and noting that 31.8 is a pipeline code and not a pressure vessel code. Yes people do it, but you really shouldn't and it would be interesting to know what design factor they were using. 36" 1" thick X52 sounds like quite a big pressure to me and if you weld on a support then presumably bolt it to something the stress and stress concentration at the "support" could be enormous. Is there any reason he can't just clamp this thing and not weld it?
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: B31.8 Age old Fillet Weld Question
See B31.8 Clarification 15.8 (at the back of the 2010 Edition)
you must get smarter than the software you're using.
RE: B31.8 Age old Fillet Weld Question
This has been included in the 2010 and 2012 version in section 834.5 which a) states that where hoop stress is less than 50% you can weld supports or anchors. Above 50% (b) there should be a full encirclement, with the anchor welded to that.
In your case I hope that the design factor is quite low and hence 834.5 a) will apply , but you will need to check the design....
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: B31.8 Age old Fillet Weld Question
David Simpson, PE
MuleShoe Engineering
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. —Galileo Galilei, Italian Physicist
RE: B31.8 Age old Fillet Weld Question