Threaded Fittings

Threaded Pipe Fittings are available in sizes up to 4 inch NPS (nominal pipe size), but are not commonly used in sizes above 2 inch. Piping system requires threaded pipe fittings in order to change direction and connect to all of the equipment and devices required to make them function. These fittings are manufactured in standard dimensions.

Threaded Fitting

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The video below gives and overview of threaded pipe fitting.

 

Video Transcript

Hello. Today we are talking about threaded pipe fittings; these are called pressure fittings. Pressure fittings are of two types, socket weld fittings and threaded fittings. These are a collection of stainless steel threaded fittings and this is a threaded cross. All of these fittings are 3000 pound, and I’ll show you that this is pretty thick.

This is a threaded reducing coupling. This is a threaded pipe cap, threaded from here and capped on the other end. This is a threaded half coupling, this is a threaded full coupling, this is threaded cross, this is threaded 90° elbow, this is threaded union, and this is threaded street elbow.

For comparison, let me show you, this is a socket weld fitting and you can see how it looks in comparison to a threaded fitting. If you look here, in the socket weld, the pipe slides in here whereas, in the threaded fitting, you thread the pipe.

Threaded fittings are available in forged carbon steel, A105, A105 normalized; they are available in stainless steel, 304, 316; and they are also available in nickel alloys, also in duplex stainless steel. Threaded fittings are most commonly used in a 3000 pound and a 6000 pound pressure rating. They are also available in 2000 pound.

To go into the brief detail of each of the components, this is a threaded 90° street elbow, this is how it looks like. Female end here, a male thread here, so this is usually, if you see something like this, it’s a street elbow.

This is a union, threaded union. This is the pipe sample that we have. For the purpose of this video, we are using a carbon steel pipe even though this is a stainless steel fitting. To demonstrate to you, this is how you do it. You thread it on, and that’s how you make a connection on a threaded fitting.

This is a threaded cross, all four sides you can thread the pipe and make a connection. This is a threaded 90° elbow. The difference between a threaded elbow and a butt weld elbow is that you will notice that it’s a much, much tighter turn, it depends on your application. Threaded fittings are usually available from 1/2 inch up to 4 inch. They are more common in about 1 inch, 1 inch and a half, 2 inch. Usually, you will not see a lot of people using a 3 to 4 inch. The most common pressure classification is 3000 pounds. This is a 90° threaded elbow and you can see it’s a much, much tighter turn, more than the short radius butt weld fitting. 90 elbow, it’s a much more sharper turn.

This is a 45 threaded elbow. Again, you thread the pipe right here and that’s how you make a connection. This is a threaded tee, you can also get one, this is a regular tee but you can also get a reducing tee where the branch is smaller than the main run.

This is a threaded cap. Same thing, for a 1 inch pipe, you thread it on and you cap the end of the pipe or nipple or nozzle or whatever you have.

These are different threaded couplings, and we get this question a lot, what is the difference between a full coupling and a half coupling? This is a full coupling and the main difference is that a full coupling has thread on both ends so you can thread a pipe here, you can thread another pipe right here and make a full coupling. This is a 3000 pound threaded full coupling. The same thing in a half coupling only threads from one end. Some people say that the half coupling is half the length, which, in many cases, it is half the length, but the reason they are called half coupling is that you can only couple one half of the pipe. If you thread it right here, there is nothing to thread on the other end. That’s why it’s called half coupling. They are roughly half the length.

This is a reducing coupling, so this one is from 1 inch to 3/4 inch, so if you have a threaded pipe, 1 inch on one side and 3/4 on the other side, then you can use a threaded reducing coupling and put a smaller connection on the other side.

In summary, threaded pipe fitting is part of pressure fitting. Threaded fittings are available in 2000 pound, 3000 pound, 6000 pound pressure rating. Roughly, a 2000 pound is not very common, but it relates to schedule 80, and 3000 pound is roughly schedule 160. The 3000 pound threaded fitting has a pressure rating of 3000 pound maximum pressure rating. This is a little bit more complicated, it’s not very simple, pressure rating is a function of the temperature, so as the temperature goes up, the pressure rating goes down. They are available in forged carbon steel, A105, A105 N; they are available in stainless steel; they are available in nickel alloys.

We’ll show you the difference, in our other video, from a malleable iron fitting. A lot of people ask this question, what is the difference between a forged threaded fitting and a malleable iron fitting? Just to tell you briefly, a malleable iron fitting is used for light industrial application, plumbing application. These threaded fittings have a high pressure rating, they’re made out of a forged steel. One big difference is that malleable iron fitting is not very good with welding whereas, threaded fitting, you can weld. Again, this is a threaded fitting, but depending on your application, if there is a requirement to weld it, then you would be better off using a forged carbon steel. Also, malleable iron fitting come in 150 pound, 300 pound rating which you can make a comparison, much lower, whereas a threaded fitting come in a 3000 and 6000 pound pressure rating. That’s it. Thank you.