Removing Tang Bolts

[Greg Rodgers]

Greetings,

I have a 28 year old Le Fiell aluminum mast on my Peterson 44. The SS tang bolts are frozen into the mast by corrosion. The bolt passes through an aluminum compression tube. There are "ears" welded onto each side of the mast (someone PLEASE correct my terminolgy) to increase the wall thickness. I've tried heat with a propane torch and PB Blaster penetrant with no success. I've also tried to put a deep socket the same diameter as the compression tube over the end of the bolt to pound out the tube and bolt but have only mashed in the end of the tube a bit. I don't want to go with the Big Bang solution any further than that. There is no movement of the tube or bolt whatsoever. Any suggestions?

Thank you,

Greg Rodgers

[Bob Pingel]

It sounds like you are doing the right things, but I have a few ideas to try...

You may want to try Kano Kroil (kanolabs.com) as the penetrant -- I have had good luck with it.

Can you turn the bolt?

Sharp taps with a smaller hammer can sometimes be better than big blows with a big hammer.

I just saw a cold penetrant advertised in the general media -- not sure of the name. It combines an oil with a cold propellant, the idea is the the that cold shrinks the metals and allows the oil to penetrate.

When you put things back together please use TefGel.

Good luck,

Bob

[Greg Rodgers]

The boat and I are in Turkey at the moment so it's tough to procure some of the wonder products you mentioned.

The bolt does not turn, frozen solid.

I've done sharp taps with a smaller hammer to help the penetrant work as well as big bangs with a larger hammer for encouragement and to relieve frustration.

I am definitely using TefGel on any fastener I remove from the mast... in fact anywhere I've got SS fasteners going into aluminum. I don't want to have to go through this again. Once I've overhauled the fasteners on the mast I plan to periodically ensure they can be loosened. I'd much rather do preventive maintnenance than repairs.

The cold propellant sounds interesting. It's difficult to direct the heat to a small area quickly.

Once again, thanks.

Greg

[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