Eric Green wrote:
am full of bolt questions this week:
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