Can I caulk this sewer end cap gaps?

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Billbill84

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IMG_0851.JPG Hi guys. I noticed in my sump room that my sewer main end cap, just before it leaves house to sewer, the end cap has some old cement looking yellowish stuff on it but I see a small gap on the last most threads. Nothing is leaking but wanted to make sure the cement stuff isn't breaking down already (house built in 2001). I really do not want to mess with this sewer main cap for obvious reasons but I don't want it to eventually start dripping either. Is it safe to just put a bead of 100% silicon caulk over the small gap in thread and the gap where the adapter meets the pipe and be done with it??? Here's a pic
 
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It looks like they put an orange lubricant on the threads of the clean-out plug. PVC cement melts the two pipes together so it’s unlikely it’s breaking down. If it was structurally unsound then a bead of calling isn’t going to do anything to help it. To my knowledge the fittings are supposed to have a gap between them when properly set.

I would suggest not putting any silicone on the pipes. It may make it harder to service when it comes time to do so, and it’s only going to provide you with a false sense of security. It looks like the glue they used is a clear type, and they either did a very clean job with the purple primer or they didn’t use any at all.
 
I think I see some purple primer on the pipe in the background. They probably just did a clean job of the insulation.
 
I think I see some purple primer on the pipe in the background. They probably just did a clean job of the insulation.
Actually that purple primer you see is my backup sump pump that was recently installed. There is no evidence of purple primer on my of my pipes that go to the sewer main. The actual clean out is literally 3ft away from that plug in the picture but outside on other side of the foundation wall. That very small gap u see on the plug is what Im mainly concerned about.
 
When the drain system is assembled it is tested by being capped off and then filled with a column of water and let stand, filled, for a specific length of time, and then inspected for leaks, so the probability of that fitting leaking, is negligible.
 
Everything looks fine there, except no obvious primer.
But I have seen big fittings do fine even though primer AND glue were not used.
Someone was dry fitting, forgot to glue, and by tight fit and good luck all stayed dry.

Besides, that big plug is screwed in there pretty good.
If the joint on the left was iffy, screwing in the plug should have made it fail.
 
Everything looks fine there, except no obvious primer.
But I have seen big fittings do fine even though primer AND glue were not used.
Someone was dry fitting, forgot to glue, and by tight fit and good luck all stayed dry.

Besides, that big plug is screwed in there pretty good.
If the joint on the left was iffy, screwing in the plug should have made it fail.
10-4! That's reassuring to hear at least. So many issues and bad luck with this "monster house" I'm paranoid and everything is suspect at this point
 
Not all state or municipalities require purple primer. Illinois if an inspector sees the purple primer it does not have to be pressured tested,but a lot of states you can use clear primer.
For the threads I use silicone grease. It helps seal but does not seize the threads.
 
Clean outs are not tapered like other pipe fittings so some one just used a little glue to stop it from leaking.
If it is not leaking just leave it be.
 

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