New York gas piping

Especially when tying in to old fittings...Mad Dog

@ChrisJ

Your experiment has got me too. I have always used dope. Never would have dreamed this. I was always taught to us dope. The reason? To make up imperfections in threads. And now!?

Thanks for sharing bud.

No. I wiped a lead project 1998. Mad Dog

@dko

What pressure do they test at?

100 PSI.
That "8-sided figure" as they call it is the test I took in 1998. I think it was the 2nd or 3rd year that test was the official exam. My brother and father took the lead wiping test years before that. The year I applied, I was one of 2500 applicants. When the test was over, the city gave out 32 licenses that round.
I'm license number 1784, my brother is 1468, my father is 399.

Yeah

And yet all of the npt joints I made aren't leaking. Why? Why isn't there a spiral leak path?

@Mad Dog_2

I was surprised years ago when I read on the Rectorseal True Blue can to "dope the inside threads on pipe 1 1/4" and larger" but that is what they say.

I will just show the can to the inspector and tell him "I put dope on according to the MFG instructions"😎

Never herd of nipples being available in 1/8" increments.

The question that begs regarding any "sealant" or "lubricant" or the lack thereof is as follows:

When a tapered joint is assembled, the contact surfaces are across the face of the thread. No fluid or gas will pass across the faces, along the pitch line, once the joint is made up. Doesn't matter if you use lubricant or sealant, or nothing.

The problem occurs when the major diameter of the male thread fails to contact the major diameter of the female thread and/or the minor diameter of the male thread fails to contact the minor diameter of the female thread. In either event, you have a path for a leak. There is a slight clearance around the edge of the thread for fluid to pass.

Now, the only way you do not have a leak without sealant of some type if IF the pitch diameter, major diameter and minor diameters ALL contact their mating surfaces at the same point. Due to the massive localized forces that cause deformation of the fitting during assembly, this is possible. But, it is certainly not assured.

The above is why folks find the amount of torque necessary to get a seal to be variable. If the fitting is made with very close tolerances, a fairly low torque is necessary (maybe 40 lb-ft on a 1" thread). But, when greater torque is utilized, the potential for full contact between the major and minor diameters is increased while the pitch faces are deformed a bit during the application of this higher torque. It is certainly possible to put 100 ft-lb. into a 1" fitting with a suitable extension on the pipe wrench.

I commend those that can assemble a Chinese fitting without any dope and have a perfect seal!!

One more thought. The nipple is tapered. Turning it too far into cast iron (and other materials) could split the cast iron. That would be an expensive mistake on a new boiler. Less gorilla and some tape and/or dope might be prudent.

There are charts that list the number of turns to make up an NPT joint. If you are going well beyond that, either the threads are cut wrong, or something is going to break.

People who do this for a living develop a feel for what works, what doesn't, and how to avoid callbacks. For the rest of us, don't use a 48" pipe wrench or ridiculous sized cheater on 1" pipe.

I've attempted to use the values for the makeup on various NPT assemblies. Inevitably the claimed makeup value is never achieved. The male is likely too large per the specifications. This results in the wrong length overall (too long) and the calculations became worthless when attempting to get an assembly together in advance. I like to build iron sections in the shop rather than on my knees on the floor!

I am sorry to say that a Vice Grip is no substitute for a proper pipe wrench when you need to get above say 40 lb-ft. The jaws are too narrow to transmit the torque and the shape of the jaws is not tapered like a pipe wrench so that the grip force increases with the torque applied.

Might work for 1/2" and below……….that's about it.

Yes he did!! Well done😁

Every tool kit needs a Visegrip...I have all different configurations..Mad Dog