Removing Tang Bolts

[Russ L]

Hi Greg,
Are the "ears" welded to the compression tube? BTW, we call those ears "doublers" in the tank & pressure vessel world, as in doubler plates. So it's the term I use around masts as well.
Before proceeding with heat, make a dam around the damn bolt and try a vinegar soak. It will take some time but vinegar can dissolve the products of corrosion without hurting the aluminum.
If the comp tube is not welded in you will have an easier time of it and heating will work. In heating you are trying to rapidly warm and expand the surrounding area without heating the part intended for removal. So use very high heat on the doublers away from the hole (1/2" ) for a short period of time. Keep the flame moving. Keep the flame away from the comp tube as much as possible. The aluminum will absorb heat very quickly. Remember, you are attempting to set up expansion in the doulblers without expanding the diameter of the comp tube.
It is best to do heat both sides at the same time, try thirty seconds then strike two hard blows. If you see any movement keep striking ('though usually not as hard). If it siezes again... stop & cool, then repeat (but try heating a bit longer).
If the comp tube is welded to the doubler it will be much much more difficult. You need to heat longer since the goal is to expand the comp tube all the way through without heating the bolt much (I know, it's pratically impossible.) In this case I suggest long vinegar soaks and 3 heat & cool cycles, as above, before striking.

Good luck, Russ

[Greg Rodgers]

Greetings,

I don't think the compression tubes are welded to the doublers. I was able to remove the bolt holding the tangs for the running backs without much trouble. Some banging on a wrench attached to the bolt head started some movement. I then kept working the penetrant and tapping and the compression tube and bolt came out intact. The bolt was so jammed in the compression tube due to corrosion that I would have had to cut the tube off. I understand that aluminum oxide expands to something like 13 times the volume of the original aluminum so it swells up pretty tight.

Like I said, I had little problem with the bolt for the running backs, but I've had no luck with the bolts for the intermediates or uppers. I haven't even attempted the bolt for the lowers yet.

Thanks,

Greg