Dresser Coupling, Dresser Expansion Joint, Dresser Dismantling Joint and Dresser Style 65 and Style 90 Couplings are most popular forms of joining two pieces of pipes. Dresser Flange Adapter allows standard flange connection on one end and slip on type coupling connection on the other end. Dresser Expansion Joint is common on big pipes to allow for axial movement.
Dresser Coupling - Style 38 - Style 40 - Video Overview
Video Transcript - Style 38 - Style 40 Coupling
Dresser couplings come as small as 1/2 inch, and go just about as large as you want them. We actually have some 108 inch that we have sold. Components of a Dresser coupling, it has two middle rings, it has two gaskets, it has however many bolts are necessary depending on the size, we have a 2 inch that’s a 3 bolt coupling over here, we have two bolt couplings. As the couplings get larger, there are more bolts and nuts. The bolt itself has an oval head that fits in the oval head of the follower. The bolt fits in, it doesn’t turn as you're tightening on the nut.
A common misconception people see on the Dresser couplings, they’ll see those bolts and they’ll want to bolt it up to a flange. The bolt pattern of a Dresser coupling does not match a flange. They do make what’s called a flanged adapter, it’s a Dresser coupling on one end, and it’s a flange on the other. Just match your standard 150 pound flange bolt pattern. it can be done with heavier flange, with a 300 or 600 pound flange, it’s made per spec that way.
You have the middle ring, this is the part that holds the pressure, holds the pipe in the middle ring, and the gasket and follower on the other end. The normal Dresser coupling is made out of steel, they can also be made out of stainless steel, they can be made out of different types, different grades of pipe depending on your application, different coatings. the standard coating is an epoxy coating that comes on the Dresser coupling, you can get it galvanized, they have plastic coatings on certain of their couplings. The standard gasket in a Dresser coupling is a BUNA S gasket, what Dresser calls a plain grade 27. They also make that in an armored gasket that has a small brass helix embedded into the tip of the gasket. That allows metal to metal contact all the way through because, as that gasket is squeezed into the coupling, it touches the middle ring, it touches the pipe, so you have metal to metal contact all the way through.
The next most popular grade is their grade 42, which is a BUNA N gasket. If you get higher temperatures, and different applications you can have Butyl, you can have EPDM. For good, high temperatures, you can go to Viton, up to 350°. They even have a carded glass, a graphite impregnated carded glass gasket that can go up to 1200°. That does require a different coating because the epoxy coating will not go that hot, it does require a different coating.
As far as pressure, the Dresser couplings, the smaller ones, they can handle up to 1500 pounds of pressure if properly anchored. They do make a light pattern coupling that only goes up to 150 pounds; that’s only made in 2 inch through 8 inch. The bigger the coupling goes, the lower the pressure rating. That’s how it is. If you need a higher pressure than what is normal, generally they can make something out of a thicker, heavier material to do the higher pressure. They can also make restraints, if is needed, where a pipe pullout may occur because the Dresser coupling is not made to keep pipe from pulling apart. It must be within the system or it must be properly anchored with some external factor to keep the pipe from pulling apart.
The light pattern comes in 2 inch through 8 inch, a 2, 3, 4, 6, and 8 inch. It’s very good for low pressure water applications, it is a lighter weight steel, a little bit shorter, a little bit thinner material, a little easier to handle. Especially if you’re looking at the 6 and 8 inch, where a regular 6 or 8 inch coupling may weigh 25 or 30 pounds or more, the light pattern may weigh 15, 16 pounds or something like that. A little easier to handle for low-pressure applications.
They also make a style 40 coupling. It looks just like the style 38, does the exact same thing as the style 38, only longer. The size is up through 5 inch, they come 12 inches long and 24 inches long. In larger sizes, they come 16 and 24 inches long. You may have a larger gap between the pipe, so you need something a little bit longer. On your style 38, the middle rings, normally 12 inch and smaller, come with either a 5 inch middle ring or a 7 inch middle ring from 2 inch through 12 inch. The light patterns that I mentioned, those come with a 4 inch middle ring, hence they are much lighter weight. Once you get larger than 12 inch, 7 inch is the normal middle ring until you get to the really large sizes like 42 inch, 48 inch, then suddenly you’re looking at a 10 inch long middle ring.
The wall thickness for 6 inch and larger is normally a 1/4 inch thick. Again, until you get to larger than 24 inch, then they generally become 3/8 of an inch thick, possibly even 1/2 inch thick as you get a larger coupling.
On the gaskets, the thickness and length, or the cross-section of the gasket, the light pattern coupling has a thinner cross-section, 3/8 of an inch thick. 2 inch and larger couplings generally have a 1/2 inch thick gasket. Once you get on up to 12 inch, larger than that, they start getting to about a 5/8 inch thick gasket section.