Black pipe again..

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JohnCT

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I am going to be working with black iron NPT pipe when installing a boiler (all water connections) next weekend and will have about 10 connections in all, and I just know something will go wrong leak-wise.

I've read the sticky at the top of this forum several times and anything else I can find both here and elsewhere. I've read an engineer report that only pipe dope should be used on NPT and only on the male side, others say to use both teflon tape and pipe dope. Still others mention thread.

I have rarely worked with black pipe and it scares me. I wish I could do this all in copper.. Is pipe dope just a lubricant or is it also a seal? I have a fairly fresh can of Rectorseal 5 ready to go.

If using teflon tape, how many turns and I assume the dope goes over the teflon, yes? Any advice for someone not really experienced with black pipe appreciated. Thanks.

John
 
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Helper Dave

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We use pipe dope only on black pipe. Just don't want bits of tape in systems where black pipe is used, since they can never be removed.

While pipe dope hardens over time, and can act as a sealant to an extent, I wouldn't recommend relying on it to do so. The threads are your true seal, so use them that way. The dope is the lubricant that will allow you to get them significantly tighter than you otherwise could.

Get a pair of good pipe wrenches (a 10" and 16" is a good combo to have). Any connections you can make on the floor, or at a workbench that won't prohibit things going together in place will make it a lot easier. You can lay the longer wrench flat, and use the other to crank a fitting on; that'll give you extra leverage, and make it easy. Holding everything in place so the wrenches don't just fall off can be tricky, so figure out what works best for ya.

And while I've heard it's possible to overtighten, I wouldn't worry about it. Crank em together really good. You'll get a feel for "tight enough" with practice.

The trickiest call is when you're putting things together in their final position. "Can I get another rotation, or am I gonna get myself stuck?" If you find you can't rotate to level, you've over-done it, and, sadly, you'll need to back ALL the way out, and re-dope it. You don't want to back off after tightening if it's going to be any more than a hair or two.

It can be intimidating, but it's doable. At least you're working with water, not gas. Lol. Good luck.
 

Sylvan

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" (a 10" and 16" is a good combo to have) I never heard of a 16" pipe wrench

6, 8, 10, 12, 14, 18 etc

Rule of thumb when making up IPS 3 turns by hand two by wrench

Rector seal , Pro dope (Hercules) leak lock , blue block, Permatex, Grip, Quick wick with pipe joint compound never fails BUT not legal on gas piping

Some people do not trust either the tape (3 -5 wraps depending on quality) others do not trust pipe joint compound so they use both

If you do decide to use Teflon then start 3 threads back from the front and all compound either below or above the tape .. You can also use Teflon joint compound

Or this

https://www.oatey.com/products/hercules-brushon-block-1618445780
 

Fitter30

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Cast not mallable fittings are recommended for the water side. Mallable for gas. Might want to look at a couple of you tube videos on measuring pipe because it can be a bit conf if you don't do it all the time.
 

Jeff H Young

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" (a 10" and 16" is a good combo to have) I never heard of a 16" pipe wrench

6, 8, 10, 12, 14, 18 etc

Rule of thumb when making up IPS 3 turns by hand two by wrench

Rector seal , Pro dope (Hercules) leak lock , blue block, Permatex, Grip, Quick wick with pipe joint compound never fails BUT not legal on gas piping

Some people do not trust either the tape (3 -5 wraps depending on quality) others do not trust pipe joint compound so they use both

If you do decide to use Teflon then start 3 threads back from the front and all compound either below or above the tape .. You can also use Teflon joint compound

Or this

https://www.oatey.com/products/hercules-brushon-block-1618445780

Like the advice! I noticed ref. to a 16 inch wrench but I get my numbers mixed up here and there at times too a plumber my opinion needs a minimum of a 14 and 18 wrench at all times. but Ive got a 10 inch I use like crazy and half the time I use it tightening allthread for hangars and smaller stuff like apliance conections .
 

JohnCT

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WHY NOT USE COPPER ? WHY GO TO ALL THE TROUBLE OF USING B.I. ?

I don't know! The new boiler was shipped with two BI nipples and a couple of other BI couplings and things and the original boiler uses BI to the circs in the input side and to the expansion scoop on the outlet side. I assume this is for rigidity and strength. I've never seen a boiler installed with all copper. Is it doable?

John
 

Sylvan

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Cast not mallable fittings are recommended for the water side. Mallable for gas. Might want to look at a couple of you tube videos on measuring pipe because it can be a bit conf if you don't do it all the time.


The reason a lot of fitters and plumbers use malleable rather then cast is as follows

1- When making up a cast fitting a lot of inexperienced people tend to make it to tight causing a hair line crack that may show months or even years later

2- Malleable is cheaper and less chance of a defect due to a bad a casting

3- On steam fittings (Cast) they can be broken by holding back with a large wrench and hitting the ell and it will split open

4- A lot of new sprinkler systems some contractors are using malleable fittings instead of steam fitting (CAST)

In a closed system sprinkler / hydronics / chilled water Malleable will last just as long

5- Jobbing shops rather then having a large inventory they opt for fittings that can be used in multiple applications

NFPA® 13 Standard for the Installation of Sprinkler Systems

Malleable Iron Malleable iron threaded fittings, Class 150 and 300 ASME B16.3

Only on higher pressure do we need rated fitting
 

JohnCT

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Thanks everyone! My brother and I installed the new boiler over the weekend and experienced no leaks whatsoever. I had a bottle of Rektorseal but my brother always used Hercules with teflon, and since I've seen Hercules get the thumbs up on this forum, we went with that.

Boiler fired right up and ran smoothly for several minutes before some buffeting and damper banging showed up. 99.9% sure I have a flue blockage. Runs better with the inspection door open (seems like pos pressure over the fire). Chimney dude coming at 3PM today.

John
 
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