JB Weld to fill corrosion pitting.

Unless you got the surface down to clean metal, it won't stay put in any kind of long run.

@JMC3

I never used it on an internal boiler surface. But we serviced a ton of HB Smit CI boiler the "Mills Style" boiler. Thes boilers had sections that were connected to a CI header external to the boiler. The connections to the header were an 1 1/2" or 2" nipple (depending on the model boiler) with a locknut and an elastomer gasket. When the gasket leaked the surface on the CI header would get corroded and pitted. We used to grind them down and this worked as you could tighten the locknut to make up for the metal ground off.

But some of them were too pitted to take off that much metal so we ground it as much as possible then used JB weld.

It worked well.

How long it lasted I can't really say but we had no problem getting the gaskets to seal. At the very least it will buy you a few years.

Not sure Permatex will get along with the gasket material

do you have any pics?

filling it with something like this might help too by removing the chlorides from the water which is what the synthetic rubber compounds tend to not be compatible with so removing the chlorides may slow the hardening of the o-rings.

https://www.supplyhouse.com/Axiom-PUROPAL-1W-Puropal-1W-H2O-Demineralizer

For some reason I think their seals are EPDM, but, I have no idea why I think that and honestly wouldn't trust it without getting confirmation on it.

But I'm not sure of many things that aren't compatible with silicone RTV. I suspect silicone rtv will not want to stick to it, but I don't think it would hurt it.

@JMC3 is this an EG series you're fixing? I'd love to see pictures of the before / during / after.

Many of you are too young to remember this and no I am not trying to be snarky. As best I can recall when I started in 73 most boilers had CI push nipples.

I have been trying to recall when the rubber gaskets started coming out. I know HB Smith started the #28 series boiler about 1977 and that was the first rubber gasket boiler I remember.

Certainly, Weil McLain could have been earlier but at that time Weil McLain was not big in my area.

I did install a bunch of the P68 series boilers, but they always came fully assembled.

At the beginning especially with Smith boilers, you would place the gaskets in the nipple port and slide the next section into place only to find that the gaskets had fallen out of the nipple port. A lot of people for that reason put some pipe dope or something in the nipple port to attempt to hold the gasket in place, both Smith and Weil McLain then came out and said use nothing on the gaskets because it will deteriorate the gaskets. Smith said to stretch the gasket to enlarge it so it would stay in the nipple port

So, the boiler would leak after a while and the installers complained because "the instructions didn't say not to use a sealant on the gaskets". After all push nipple boilers always had a lubricant used

Same thing happened with torquing the draw rods. Push nipples took a lot of torque, and we were told to pull the sections together until you have iron to iron contact.

But Smith (originally) had no torque spec with rubber gaskets so once again many were over torqued. The results were cracked sections from overtightening until Smith changed their spec.

Anyhow

Good luck with the Permatex hopefully it will hold up until you eventually replace the boiler

weatherstrip adhesive is a really old way of doing it, before rtv was common. it is a sort of duro or speaker cement sort of product so it has a very short shelf life.

many years ago I was helping a friend wire up his deck and hot tub. One run was 60 ft from the house and it all was in plastic conduit 4 ft deep - digging that trench by hand was work, luckily we had his 14 year old son helping. At the house we had some LB's at the house and a length of conduit going down into the trench.

We found one run was 5 ft short and we didn't have that much wire left (back then stores were not open on Sundays). We decided to splice the run down in the hole so I put a 4" box and made the splice in that, I soldered the splice so I knew it would hold. back then we both worked for a manufacturing company so we has access to a range of Castall epoxies so we selected one we knew would work and borrowed some epoxy and hardener. i used this epoxy a lot at work ( i was a senior technician back then working on HV power supplies that we sold to the navy) if it was ok for the US Navy it was good enough for this patch job

This stuff cures quick on a warm day so after cleaning everything with tricho, mixing and pouring it in it was ready to go in 30 minutes. I checked the line with a 500v meggohmeter and closed the box. We threw the breakers on and everything worked. That was back in 1985 and as of July 4th is was still holding (41 years later). It was not the right thing to do but it was outside four feet worn so there was no danger if anything went sideways. As we used to sat in the army ya gots to do what ya gots to do - just don't tell the old man.