Can I weld this in situ?

[ahun]

Hopefully you can view the picture. SS fitting on aluminium mast. It has SS rivets, I don't think I could put it back and make it as strong as it was, if I have to take it off.

Thank you.

[billknny]

If it was me, I’d drill out the rivets, fix (or replace) then reinstall with SS screws tapped into the mast. Liberally slathered in tefgel.

At least as strong as the original. The only reason manufacturers use rivets here is they are fast to install.

[ahun]

Originally Posted by billknny

If it was me, I’d drill out the rivets, fix (or replace) then reinstall with SS screws tapped into the mast. Liberally slathered in tefgel.

At least as strong as the original. The only reason manufacturers use rivets here is they are fast to install.

The wall of the mast is not thick enough to be tapped, unfortunately. I tried it when fitting maststeps. Alu pop rivets are quite strong, but maybe not for this application? Although, they work with the maststeps...

[Uncle Bob]

Originally Posted by ahun

The wall of the mast is not thick enough to be tapped, unfortunately. I tried it when fitting maststeps. Alu pop rivets are quite strong, but maybe not for this application? Although, they work with the maststeps...

Definitely not aluminium rivets, use monel !

[Wotname]

What Uncle Bob said +1.

If you can't get monel, then SS is a distant second best.

[Jd1]

The original question was one of welding. You can not weld steel to aluminum so the answer is 'NO' to welding.

[ahun]

Just want to weld (fix, fill) that crack on the fitting. The q is, can it be done without taking the fitting of the mast? Not welding the steel to alu. Sorry for ambiguity.

[Sailmonkey]

No, the heat required to melt and flow the stainless will destroy the mast.

This type of fitting, once cracked, is better replaced than welded anyway.

[Jim Cate]

IMO, as only an amateur welder, no, not a good idea to try and weld in situ. Possibility of overheating the mast and weakening the extrusion, possibility that the alloy would act as such a heat sink that a good weld is unlikely, possibility of the weld pool being contaminated from behind and making a weak weld... lots to go wrong!

And in fact,I'd be leary of welding it at all... that's an important bit of ironmongery, and your mast could be sacrificed if it failed under load. If it flexed enough from new to crack, further cracking is kinda likely. In your place I'd replace it (but it is always easy to spend someone else's money)!

Jim

[Uncle Bob]

Originally Posted by ahun

Just want to weld (fix, fill) that crack on the fitting. The q is, can it be done without taking the fitting of the mast? Not welding the steel to alu. Sorry for ambiguity.

Sorry, no it can't. The heat required to weld the fitting will affect the alloy mast. Not to mention the strength issue. The fitting for whatever reason has suffered cracking and should be removed from the mast and a new one fitted/fabricated either from the same gauge steel or thicker. Refit with monel rivets and appropriate isolation and you will have no further problems with it. But don't worry, it's a boat so there will plenty more different issues to sort later.

[Jd1]

Originally Posted by ahun

Just want to weld (fix, fill) that crack on the fitting. The q is, can it be done without taking the fitting of the mast? Not welding the steel to alu. Sorry for ambiguity.

Ahh, didn't expand the picture so didn't see the crack .... my bad!


I am sure that somebody could do it but two questions arise:


1) how are you going to be sure the aluminum won't be overheated, changing the temper and thus possibly compromising the mast?
2) Looks like the fitting is by a set of spreaders - how are you going to convince a competent welder to get up there ?


I would suggest that it would make more sense to remove the fitting, weld it and re-attach. It would provide a better/stronger repair without risking damaging the mast.
If you doubt our ability to reattach the fitting, a rigger could do the job in no time flat.


As a bonus, I suspect the overall cost would be cheaper if you drill the rivets out, pull the fitting, have it repaired and have a rigger re-attach the fitting.


If I were faced with this kind of repair I would also reinforce (not just weld the crack shut) both sides of the fitting to strengthen an obviously weak point.


As a side point, that is a very interesting crack and the failure at that point doesn't seem to make any sense to me. One would think the failure point would be the rivet hole if anything.
I would try to understand the cause of the failure before blindly reinforcing things ... just in case.

[Wotname]

Besides, looking closely it appears there is plenty of corrosion underneath the SS tang; now is the right time to remove and clean / repair etc.

[Reefmagnet]

Originally Posted by Jd1

Ahh, didn't expand the picture so didn't see the crack .... my bad!

...

As a side point, that is a very interesting crack and the failure at that point doesn't seem to make any sense to me. One would think the failure point would be the rivet hole if anything.
I would try to understand the cause of the failure before blindly reinforcing things ... just in case.

It's fatigue cracked because that fitting has had a bit of side loading on it, would be my guess.


And that strap cannot be welded in place. Even ignoring possible damage to the mast, unless the finished weld has full penetration and is dressed all round on that strap it will fail again in short order if the same kind of loads are re-applied.

[stainless guy]

Best to replace the bracket.

But contrary to what everyone else has said 20years of fabricating aluminum and stainless steel I would not worry about the mast if you absolutely must weld it aluminum is an excellent heat sink and will likely not become warmer than a cup of tea

That said the backside of the stainless piece will corrode very rapidly unless you full pen weld with a back purge of argon

[Snowpetrel]

No, even welded up it won't be reliable. Looks like a dodgy fitting anyway. What hangs off it? Babystay?