Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

Re: Flamecut Holes for Bolting

[Subject Prev][Subject Next][Thread Prev][Thread Next]
 

Eric Green wrote:

I am full of bolt questions this week:

The Specification for Structural Joints Using ASTM A325 or A490 Bolts allows flame cut holes for bolts. It further states that thermally cut surfaces do not have to be ground for static loads (Section 3.3). How do I convince an erector that this is referring to the surface of the cylindrical hole he has cut, and does not mean that he can leave slag on the faying surface? I have pointing out section 3.2 that states these surfaces must be clear of foreign material but he says this is in contradiction to 3.3 and he chooses 3.3. I would like a written reference if you know of one, otherwise it is simply my opinion and since he is older, he is obvious correct in matters of opinion (in his opinion). Ouch, my head is hurting.


Having been through this previously, Section 3.2 and Section 3.3 deal with two different but related physical areas. Tell the erector that in Section 3.3, the thermally cut surface is the metal thickness the torch cut on and doesn't need to be ground,  provided that the hole surface doesn't have a jagged appearance. However, I would follow the recommendations of the Structural Bolting Handbook, and cut the holes undersize and then ream them to the appropriate size. In Section 3.2, "Faying surfaces and surfaces adjacent to the bolt head and nut shall be free of dirt and other foreign material." In a snug-tightened condition, anything beyond mill scale is foreign material. Finally, in  Section 3.4 of the June 23, 2000 Specification for Structural Joints states that "Burrs that extend 1/16 in.or less above the surface are permitted to remain on the faying surfaces of snug-tightened joints .... and pretensioned joints...  . Burrs that extend over 1/16 in. above the surface shall be removed from all joints."  A small amouint of splatter from a torch wonm't hurt a snug-tight bolt since it is bearing. However, anything larger than 1/16 in should be removed.
 
--
Davis G. Parsons II, PE AEI
a practical architectural engineer
in Fort Worth, Texas