EFM-520 build thread

I get my best parts from demo work!

Nice job on the recycle and piping

Teflon Tape is your friend. You can back up (adjust) a fitting a few degrees - using that other monkey crap if you try to adjust - it leeks.


sometimes - --- sometimes -- if I have a fitting that I want to be sure I will not ever have to touch again - I will apply three rounds of good Teflon tape - not that flimsy thin crap you buy at the big box store - and then I will paint a THIN coat of COMPATIBLE Teflon paste over the taped threads - and then marry the male and female connection.

I think a lot of the issues I've had with thread sealing is the lack of quality in the cutting of the threads themselves.. A lot of the pipe available at the big box stores and even the local hardwares is from questionable sources.. pretty poor threads, with chips, jagged edges and in general rotten quality..

I think a properly cut thread on both the male and female would seal with no sealant,, but you need a lubricant of some sort. I've had mixed results with teflon tape,, again, maybe from the poor threads.. tape can only do so much..

So I experimented with the same RTV sealant I use on all auto/truck/tractor work I do,, Permatex "ultra-black" and it works great.. used sparingly, so as to not make a mess or have excess inside the pipe, it had not yet failed to seal every pipe threaded joint I've used it on.. the first time. And with some of the complicated combination of ells, tees, unions, flanges etc. I really got pissed when the conventional pipe dope failed on 99% of the joints.. and I had to dissassemble the whole setup to reseal every joint... GRRR.

Greg L

I use the high temperature silicone RTV sealant as pipe dope on threads with excellent success. It's much better than the products sold by plumbing suppliers as pipe dope, yes even the premium products. I apply it sparingly to the female threads and liberally to the male threads. I wipe the excess off immediately before the RTV begins to skim over. My theory is after it cures each thread ring of sealant acts like a gasket. A gasket that is pushed by the water pressure to make a tighter seal. Pipe dope can't do this because when cured it looses its resiliency.

Once the joint is as hand tight as I can turn it, how many extra turns do you give it with a wrench and do you use only the RTV and no tape? I know you need at least 3 turns.

One to two turns. Steel to steal it's on the low end. Steel to copper on the high end. I like to pipe so that a male copper fitting mates to a female steel fitting. On temperature rise the copper expands more make a tighter fit.

I dont know if I was clear on my method. I use 3 to 4 wraps teflon and any pipe dope. The tape fills gaps and the dope is the lube. As far as how tight, well for 1'' ,as tight as you can crank w/ 14'' pipe wrench, 1 1/2" as tight as you can w/ 18" pipe wrench, to get an "idea". You should have about 2 threads left showing. As far as a good thread, You take a fitting and thread it on the pipe dry , by hand, as tight as you can (no wrench). Count the threads as you back it off, should have 4 turns + or - 1/2 turn.

Went to the hardware store and the only RTV hi-temp silicone was clear and in tubes, flexible and caulk style. No Permatex ultra black and none available from Orville. There were several types of RTV, all capable of 400 degrees, so which one do you choose?

Also, is the RTV used with or without teflon tape.

As far as thread turns without a wrench, some pipe thread goes 4 turns, some only 2. The quality of store pipe is all over the place.

2 threads are to tight. I would not use any silicone on pipe threads. The cheapest pipe dope used with teflon will hold up to 600 lb. hydro tests every time we do them. Even had a test atover 1000 lbs when the sun came out and heated the lines we were testing at 600. It pinned the gauge that stopped at 1000 lbs, dont know how high it realy was. Another thing to check, take two threads and mesh them together so the threads interlock. you should not see light between the threads. sometimes the dies get out out of alignment and cut out of wack (double cut). I had a hole box of 2"x 6" nipples (50) that were double cut on one side only. You should see a sharp thread peek and vally.

So, Sting, I get the impression that you rarely use pipe dope, just quality teflon. And Greg, it looks like you use RTV and no teflon or dope. Yanche uses RTV as pipe dope, but doesn't say if he uses teflon too. And Kevin passes tests with good teflon tape and any kind of dope.

Can I get a consensus here? I can't always be sweating copper because my steel pipes drip.

I do not use Teflon tape, just RTV. I buy the high temp RTV at an auto parts store. I first clean the threads with alcohol before applying the RTV. I agree with the poor quality of threaded fittings today.

Come on Dave, where is my boiler? I want to get back to the topic of the thread. The only time we (profesional pipefitters) do not use teflon tape on threads is when its not allowed. That would be on gas, propane and oil lines. There is more chance for a leak on these lines without the benifit of the tape. I think what happens with some people is they put too much tape on and it all pushes off when threading the fitting on. 3 to 4 wraps. The sprinkler fitters in my area have been using a great product the last several years, its white, very guey and has teflon in it. Its from long island pipe supply company.

you read me correctly

but I am not a professional at anything

do not follow me - I may find it necessary to trip on myself before reaching safety!

This engine powered wheel chair doesn't move as fast as it used to - the nitrous bottle is loosing pressure

Dave doesn't have your unit yet. I was only able to give him the boiler. The stokers won't be available until at least the first week of August.

Stoker-man,, the Permatex Ultra-black is an automotive product. Available at auto-zone, Napa, just about any autoparts sales department,, maybe even Walmart's auto department.

I've used regular clear silicone caulk too,, not one leak.

Like Yanche said,, clean the threads first to remove oil,, and a thin layer in the female threads, and more on the male threads..

I've used the expensive 'contains teflon' white pipe dope, and teflon tape, and both together,, and have not had 100% success.. and the leaker always seems to be about 6 fittings down from the closest union... GRRR.. so I quit with the pipe dope and tape..I use exclustively RTV,,, and have 100% sealing.

Just my experiences.. maybe if I was a full time pipe fitter I could do better with tape and dope.. but I like to do it once,, not twice or three times.. plumbing boilers that is..

Greg L

I remember installing my oil boiler and I was so careful to do everything right, but I guess I didn't. It always had a drip about 6 pieces away, probably in a T or some other impossible place to deal with, just like you Greg. I learned just to transition to copper as soon as I could, just to avoid steel pipe.