Crack in cap to an old steam pipe concern

Alexnyu10

dear group, 

this year we had one of the radiators removed from our upstairs because the room was always hot even with the radiator turned fully off (enough heat easily rose from main level to heat it (this is a single pipe steam system in a residential home) and we had the old radiator pipe capped on the main level where the pipe used to go up to second floor. 

I noticed this morning that the cap has a crack forming on it, and I’m trying to figure out if this is normal or am “oh ****” moment that requires a plumber sooner than later. 

Thanks so much for your guidance as always, I plan to message my plumber a pic tomorrow as well but figured I would ask here today to see if it’s urgent enough for a weekend call. 

Mad Dog_2

Thats extremely odd.  Malleable black Iron will rarely split like that unless it's on a seam. Cast Iron will do that. I wouldn't be super concerned. Just throw a bucket over it until he comes.  Mad Dog 🐕 

EdTheHeaterMan

Is that a crack or a casting seam?
I don't think you have a problem

Alexnyu10

EdTheHeaterMan said:

Is that a crack or a casting seam?

Ed you may be right. My spouse is also convinced it’s a casting seam and was always like that; so maybe I am jumping the gun and it’s actually always looked this way. Either way I’m going to work on getting mad dog 2 out here to assess my system. 

Intplm.

It's not a crack. That is a seem from when the thing was cast.
So, I guess you could say its not a crack until it leaks.

EBEBRATT-Ed

Just the casting seam not a crack

Alexnyu10

Very much appreciate everyone’s help here, incredible peace of mind, I love this forum!

Jamie Hall

That's what I was going to say. Beat me to it.

Neild5

Looks like the casting seam, but a way to test it, while the heat is running hold a spoon or a mirror over it, any steam leak will condense on the surface.

Alexnyu10

Neild5 said:

Looks like the casting seam, but a way to test it, while the heat is running hold a spoon or a mirror over it, any steam leak will condense on the surface.

This is a great idea, will test this out for extra peace of mind 

Mad Dog_2

I'm going with a crack. Look at the side of the cap..Little hunk out of it. Mad Dog 🐕 

WMno57

Hmm, hard to tell from here. Drag a fingernail over it. Run a file over it. Is it an innie or an outie?

EdTheHeaterMan

WMno57 said:

Hmm, hard to tell from here. Drag a fingernail over it. Run a file over it. Is it an innie or an outie?

Don't you think that is getting a little personal

I prefer the innies personally, Just saying, since you mentioned it

realliveplumber

Casting seam.