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.
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Dresser Pipeline products have many coupling options to choose from. While one coupling type may work in place of other, it may not be the best use of money and space while repairing a pipe or working on a new construction. Dresser also offers several clamps that can achieve somewhat similar results but we will keep that discussion for another blog to keep this topic focused on couplings. Let’s assume a coupling is a best option and we need to make sure we select the right one.
Dresser coupling offers a fast and convenient way of joining two sections of pipe when you are able to slide the coupling onto the pipe. If the space does not warrant a cutout and repair with a coupling, a clamp may be a better option. However we will not discuss clamps in this blog.
Dresser couplings can be divided into two main categories;
Dresser couplings should be selected based on the intended applications. Factors that can affect coupling performance includes;
Other factors that can affect the selection includes;
Location (at a plant, on a vessel etc.)
Application (pipe, pump, compressor, process line etc.)
Dresser couplings are widely used in water, waste water, gas and many other downstream fluid applications.
All dresser couplings are made of carbon steel middle ring and follower. Bolts are also made of carbon steel. All stainless steel Dresser couplings are available on request. Gasket is either Buna S, Buna N, Viton, EPDM or Graphite Fiber hybrid. 27 Buna S is the most common gasket used. All gaskets are available in the armored version also that adds addition rigidity to the seal and also provide means of electrical contact to the pipe. Click here to learn more about Dresser Gaskets. You can buy these gaskets online here.
Other consideration is pressure rating. Dresser couplings are rated from 150 psi to 2250 psi maximum working pressure. Dresser light pattern couplings are rated up to 150 psi. Dresser style 65 and style 90 couplings are considered 150# and 300# couplings respectively. Refer the size and dimension table to look up the pressure rating of a bolted coupling. Generally, as the size goes up, the pressure rating goes down. Any coupling with 150 psi working pressure is a light pattern coupling.
Temperature mainly affects the gasket and pressure rating of the coupling. Higher the temperature, lower the pressure rating. Different gaskets are rated for different temperatures. Dresser makes lifetime® gaskets but factors that can affect the performance of gasket are temperature “cycle” that can result in compression set, abrasive line content that can damage the lip of seal and combination of chemical compatibility, temperature and pressure. Generally speaking, anytime the temperature is above 200 deg F, you should pay close attention to your selection of gasket, gasket chemical compatibility and pressure.
Location can affect your selection criteria if you have specific restrictions such as ABS approved coupling for vessels, stainless steel body due to corrosive environment, maintenance concerns and any other area-specific requirements. Generally the hot work permit is not an issue for Dresser Coupling as there is no welding needed. In hazardous locations, non-sparking hand tools can be used to tighten the bolts or the nut of the coupling, which is the only assembly step required on the coupling.
This is the most important factor of all. What are you trying to achieve? Some of the reasons customers use Dresser couplings are;
Repair a pipeline
Connect a pump or compressor with Dresser style 128 flange adapter for ease of access to the equipment in future
Repair a pipe that will be buried
Allow for thermal expansion and contraction and avoid pipe bends & cracks
Minimize vibration damage. The seal in the coupling acts as a cushion
Straddle two couplings and repair a longer than normal section of pipe
Repair pin hole leak that cannot be repaired with a clamp
This is also very important. If you are repairing a pipe that is under 2 inch nominal dimension and you do not need more than 300 psi pressure, style 65 or style 90 may be your best choice. If you are repairing a gas line, style 90 universal coupling is very popular to repair gas lines. If you are repairing a PVC or PE pipe or any combination of steel and PVC/PE pipe, style 90 universal coupling has a lock ring to prevent from pipe pull out.
If space is not an issue, light pattern should be your next choice as along as pressure requirement is no more than 150 psi. You will save money and space as long as light pattern can work in your application. Your next choice could be style 38, style 40, style 39, style 138 or style 62, all depends on the specific application.
How important is the application of coupling? Have you done any risk assessment if anything goes wrong? How difficult it will be to access the equipment or the pipeline. Can you afford downtime while an equipment is being repaired? In most situations, Dresser Coupling offers fast and convenient way to join pipe connections & equipment. If selected correctly, Dresser coupling provides years of service without needing any maintenance.
So which coupling I should use?
Below is a rough guideline of where each coupling should be used;
Style 38 Dresser Coupling
We sell more style 38 couplings that any other coupling combined. Style 38 coupling is available in a wide range of size, wall thickness and lengths. While choosing style 38, you should consider following;
Would light pattern work for me?
If under 2 inch nominal pipe, can I use style 65 or style 90
Is pipe pull out a concern?
Also make sure you always select the right combination of middle ring wall thickness, number of bolts and length.
Fig 1 - Dresser Style 38 & 40 Coupling
Style 40 Dresser Coupling
Style 40 is a TALLER brother of style 38. The only reason you will NOT use style 38 is if you need 12 inch or longer coupling. Style 40 couplings are available up to 24 inch length.
REMEMBER: You can always straddle a piece of pipe with two style 38 or style 40 couplings to repair a much longer section.
Style 39 Insulating Coupling: Style 39 Insulating Dresser Coupling follow the same basic design as the Style 38, but have insulating properties. Style 39 is ideal for industrial applications for water lines where electrical isolation is needed. Besides being used for tank hook-ups, intake or discharge lines and pumping stations, Style 39 Dresser Coupling are also widely used on gas service lines.
Style 39 also comes in insulating and reducing style. Regardless if you need insulating feature, the reducing feature can be used to connect steel pipe to cast iron pipe.
Fig 2 – Dresser Style 39 Coupling
Style 138 Coupling
Style 138 Dresser Coupling for Cast & Ductile Iron Pipe provide flexible, leak-proof connections whether the cast iron pipe was made in 1890 or from your latest shipment. The unique feature of this product is one middle ring can be used with up to six different gaskets and three followers to cover a wide range of pipes.
Fig 3 – Dresser Style 138 coupling
Dresser Style 128 Flange Adapter
Style 128 Flange adapter should be used where you have a regular flange connection (150#, 300#) on one end and want Dresser Coupling-Style connection on the other end. This type of connection is very popular on pumps and compressors, with flanged ends. This provides an easy access for maintenance in future.
One common misconception people have is that the coupling follower ring bolt pattern will match a flange bolt pattern. The follower ring (2 ea. end plates) has bellowed shape. It used to be flat face and looked very similar to flange fitting. Since Dresser Coupling is available in many configurations with multiple bolts, many customer tried to connect it to a flange with no success. Dresser style 128 is the ONLY way you can connect to a flange on one end.
Fig 4 – Style 128 Flange Adapter
Style 62 Coupling
Style 62 coupling should be used where you want to connect two pipes of different sizes or steel pipe to a cast iron pipe. Choices are limited to what reduction you can have so it is important that you check the diameter range of reducing end while selecting the coupling.
Fig 5 – Style 62 reducing coupling
Style 65 Compression Coupling
Style 65 is a 150# galvanized compression fitting intended for plumbing and light industrial use. It is available in sizes from ½” to 2” nominal. Style 65 is very popular in industrial installations and repair, especially for tight spaces where threading, bolting or welding is not a good option. Style 65 is also maintenance friendly and can be easily disassembled to access the pipe, change gasket in the coupling or perform line repairs. Dresser style 65 is available as;
90 degree elbow
Style 65 should NOT be used where pressures are greater than 150 psi. Refer to our video on style 65 to learn more.
Fig 6 – Dresser style 65 fittings
Dresser Style 90 Coupling
Style 90 is also a compression-type fitting available in sizes from ½” to 2” nominal. Style 90 is a 300# coupling and provides an alternative to style 65 for heavier use. Style 90 also comes in a “universal” style with lock ring that prevents pipe pull out. Style 90 coupling is very popular on gas service lines due to armored gasket, ability to prevent pipe pull out and heaver grade. Refer to our video on style 90 to learn more about this style of dresser coupling.
Fig 7 – Dresser Style 90 couplings
Dresser Style 88 Coupling
Style 88 is made exclusively for copper tubing. Since copper tubing dimensions are different from steel pipe, the coupling has different IDs to match that of copper tubing. Style 88 coupling can also be used in tandem with style 65 coupling by using insulating adapter. Insulating adapter is a gasket adapter that fits over the copper tubing which in turn fits inside the style 65 compression coupling.
Fig 8 – Style 88 Dresser Fitting
Style 440 Joint Harness
Remember that with the exception of Style 90 universal coupling, Dresser Couplings will not prevent excessive axial forces. If pipe pull out a major concern, one should use Dresser Style 440 Joint Harnesses are steel tie-bolts, diametrically opposite, which extend across a coupled joint from lugs welded to the pipe on either side of the joint. Joint harnesses are particularly effective on unanchored bends subject to pulsating pressures of sharp intensity.
Fig 9 – Style 440 Joint Harness
As you can see, Dresser offers a broad line of choices for couplings. Each of these couplings are made for specific application and offer unique advantages. Coupling should be selected based on the intended application, pressure & temperate requirement, space available and any regulatory requirement. When used properly, Dresser Couplings offers a long life that often exceed the life of equipment/pipe. Dresser couplings can be used on steel pipe, cast iron pipe, ductile iron pipe, PVC pipe & HDPE pipe.
Dresser couplings are being used for more than 100 years and are proudly Made in USA. Trupply is an authorized Dresser Coupling Distributor and we stock pretty much all the styles and sizes for immediate shipment. Call us at 281.516.8100 or email firstname.lastname@example.org
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.
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Those syle of Dressor's are not easy to find out there. We used to use this style for the 2" x 1-1/2" swage pipe reducer assemblies for the reverse air-pulse system years ago with our production. We cut those Dressor Couplings in half, and weld those cut ends to the side of the steel filter housing. Of course, with the rubber ring gasket removed. Thank you Trupply for having those in stock, and also reasonably priced, too.