removing rivets with minimal damage
removing rivets with minimal damage
(OP)
i'm in the process of retrofitting an old truss with all riveted connections. a couple of the web members (double angles) need to be replaced due to damage, and i was wondering if it's possible to remove the rivets without damaging the gusset plates too much.





RE: removing rivets with minimal damage
Heat the head of the rivet till red. Use a large enough tip that you don't have to spend so much heating and use an oxidizing flame. That reduces the heating of the base metal and keeps it from reaching a temperature that it would melt/oxidize. When the rivet reaches a sutable temperature the excess oxygen in the flame will "cut" the rivet.
Oxygen can be applied with a cutting torch but care must be used.
There are probably tools available that are more efficient and I have NO experience with rivets but I have removed other items in close contact with other materials.
G Austin
RE: removing rivets with minimal damage
RE: removing rivets with minimal damage
RE: removing rivets with minimal damage
RE: removing rivets with minimal damage
I have cut out "about a million" rivets on the last 40 years(also put IN a few). It is NOT rocket science but it does require skill with a oxy/acct torch. On the trusses we reworked at the old South Gate GM assembly plant I used a #2 or larger scarfing tip to cut the tops off the rivets (mostly 7/8 inch and larger) then a straight tip to 'blow' a hole straight through the middle of the rivet(the skill part I was talking about) then take a small rivet gun (80xx will do) a flat nosed punch and drive it out (bull pin and hammer will work, but is 'unfriendly') The hole is necessary because the rivets upset in the hole and need that little hole to 'swuish' into as you drive it out.
Cutting nuts off bolts without damaging the threads is a skill that I have but most don't. It is an easy trick to learn, but most "just don't have the touch".
In referance to Mr. Austins method---It works ok as long as the inspector will let you put that much heat into the truss. Most will not. I have 'washed' rivets and bolts off this way in demo work, but not too often (I REALLY dislike demo work). AND--Yes there are tools to remove revits but they are mostly in MUSEUMS! Besides, you will probably have a difficult time finding anyone who knows how to use them.
Rod
PS---I will note that when a rivet is removed, quite often the hole will still need to be reamed for a replacement bolt one size larger. A red hot rlivet WILL go into a somewhat less than perfect hole. TAKE CARE, INSPECTORS DON'T LIKE TO SEE "NICKS".
RE: removing rivets with minimal damage
As a teacher I often tell my students that if Oxy Actetylene equipment was as portable as a carpenter's saw then it would be carried with the boilermaker at all times. It is certainly an essential piece of equipment to those working in the trade.
RE: removing rivets with minimal damage
Torching is equally effective, but presence of lead based paint could be a very serious problem, as removal of the paint could be required by a local code.
RE: removing rivets with minimal damage
I take it you have never actually used this procedure?
I have. I'll stick to the torch, thank you very much.
The pneumatic tool you speak of (large enough to knock the head of a 1" rivet off without destroying the structure or shaking the operator to death) is called a "helldog" for the uninitiated.
Re lead paint---Here in the L.A. area lead paint removal is pretty much required before starting ANY type of rework, not just torch or welding work. Of course there IS always that one job that cheats a way around lead or asbestos problems. I always turned these RAT outfits in to OSHA whenever I ran into them. The workmen never seem to understand that the job will still get done, just much safer for them and their families.
Rod
RE: removing rivets with minimal damage
What are some of the common errors or problems i should be looking for with the contractor?
RE: removing rivets with minimal damage
Best of luck...hope your contractor is union, it will save you on the "Tums"!
Rod
RE: removing rivets with minimal damage
I will be a learning curve for all.
RE: removing rivets with minimal damage
NYSDOT specs prohibit flame cutting to remove rivet heads. Although once in a while it must be done due to access problems. I've seen plenty of rivets removed by a helldog without any problems to the base metal. The one big concern is making sure someone catches the head when it breaks off.
RE: removing rivets with minimal damage
My company is in the process of retrofitting the south approach span of the Golden Gate Bridge and it's all being done with rivet busters. In my years doing bridge retrofit work in the Bay Area I can't recall anyone every letting us use a torch except as a last resort on an extremely stubborn rivet or you just can't get to it any other way.