All you need to know about Dresser Style 90 Compression Coupling

Written by Asif Ehtesham
December 18, 2016
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All you need to know about Dresser Style 90 Compression Coupling

Dresser Style 90 compression couplings are widely used in industrial piping systems for their strong build and dependable sealing performance. They are designed for applications that involve higher pressure and tougher operating conditions than standard light-duty compression fittings. If you work with steel pipe, gas lines, repair joints or maintenance operations, understanding how Style 90 couplings function can help you choose the right product for your project.

This article explains the different types of Style 90 couplings, how they are built, how they compare with lighter models, common field uses and what to keep in mind during installation.

What Is a Dresser Style 90 Compression Coupling?

A Dresser Style 90 is a heavy-duty compression coupling designed for industrial service. These fittings connect two pieces of pipe without welding, threading or grooving. Instead, they use a mechanical design consisting of a retainer cup, a large gasket and a nut that tightens around the pipe to create a secure seal.

Style 90 couplings are known for:

  • A stronger body compared to light-duty compression fittings

  • A 300-pound service rating

  • A tighter seal suitable for demanding environments

  • Use in gas, oil, industrial water and maintenance work

When you hold a Style 90 in hand, the first thing you notice is its weight. Compared with a Style 65 (which is rated at 150 pounds), the Style 90 is heavier, more solid and built for tougher jobs.

Types of Dresser Style 90 Fittings

Style 90 compression fittings come in several configurations. Each type supports a specific pipe layout or connection requirement.

Style 90 Regular Compression Coupling

This is the standard version used for straight pipe-to-pipe connections. It includes:

  • A retainer cup

  • An armored gasket

  • A nut on each side

The armored gasket offers better rigidity and helps create metal-to-metal contact between the pipe and the coupling. This feature is one reason Style 90 couplings are widely used in gas service.

Style 90 Universal Compression Coupling (with Lock Ring)

This version includes a lock ring that grips the pipe and limits axial pullout. The lock ring has jaws designed to bite into the pipe wall when tightened. Its main benefits include:

  • Extra pipe restraint

  • Better support in systems with pipe movement

  • Use in gas lines, industrial repairs and situations where the pipe must not slip

The gasket used in the Style 90 Universal is the same size as the gasket used in the Dresser Style 38, giving users a larger sealing surface.

Style 90 Compression Elbow

The Style 90 elbow allows a 90-degree change in direction without welding or threading. It is often used in tight spaces or repair areas where cutting and reworking the system is difficult. It includes:

  • Armored gasket

  • Retainer cup

  • Heavy nut similar to the straight version

The installation procedure is the same as the regular coupling, except it changes the direction of the run.

Style 90 Male Adapter

This fitting converts a threaded connection into a compression connection. One end has male pipe threads; the other end functions like a standard Style 90 compression joint.

It is commonly used when you need to connect compression fittings to:

  • Valves

  • Threaded tees

  • Threaded manifolds

  • Other threaded pipeline components

The male adapter offers a simple way to use compression joints in sections of pipe that already have threaded ends.

How Style 90 Differs From Style 65

Both Style 65 and Style 90 are compression couplings, but they are built for different pressure levels and field conditions. For a clear comparison:

Feature

Style 65

Style 90

Service Rating

150 lb

300 lb

Weight

Lighter

Heavier / stronger

Gasket

Smaller

Larger armored gasket

Uses

General water service

Gas, industrial work, high-demand repairs

When the job requires a more rugged connection, most technicians and installers choose Style 90.

Components of a Style 90 Universal Coupling

Although the body style may vary, the basic components of a Style 90 Universal coupling include:

  • Retainer cup

  • Armored gasket

  • Lock ring

  • Heavy nut

  • Matching components on both sides

The lock ring is the key difference. When tightened, it clamps the pipe and helps prevent pullout. This feature makes universal couplings useful in areas where strong axial resistance is important.

Installing a Style 90 Compression Coupling

The installation process is simple, but accuracy matters. Below is the typical assembly method for a universal coupling (the regular version is the same without the lock ring):

  1. Measure the Coupling Length
     Mark the pipe so the coupling does not bottom out in the middle. Leave about one inch of space between the pipe ends.

  2. Slide the Components On
     Start with the nut, followed by the lock ring (tapered edge facing the right direction), then the retainer cup and gasket.

  3. Assemble the Gasket and Retainer Cup First
    It is easier to install these two pieces together before sliding them onto the pipe.

  4. Tighten Using Proper Tools
    Use a pipe vise to hold the pipe. Tighten the nuts using a torque wrench to reach the correct torque.

  5. Repeat the Steps on the Other Side
    Apply the same process to complete the full coupling.

The design creates a reliable seal without welding, threading, heat or special equipment.

Using Style 90 Couplings on PVC or PE Pipe

Style 90 couplings can also be used on PVC or PE pipe if the size matches properly. The key point to remember is that these couplings are strong enough to clamp tightly around the pipe. For softer pipes, this may cause deforming unless you use a stiffener.

A stiffener supports the inside of the pipe and prevents crushing during tightening. When using a Style 90 with PVC or PE:

  • Confirm sizing carefully

  • Use stiffeners to avoid pipe damage

This setup can work well for certain utility and repair jobs that involve non-metallic pipe.

Common Industrial Applications

Style 90 compression fittings are used across many industries, including:

  • Gas distribution lines

  • Industrial water systems

  • Oil and fuel lines

  • Plant maintenance and repair operations

  • Utility and service connections

  • Emergency repairs where welding is not possible

The armored gasket and strong body make the Style 90 a common choice for gas applications, where a stable seal and firm contact with the pipe are important.

Style 90 Elbows and Male Adapters in Real-World Work

Although straight couplings are the most common, elbows and male adapters fill practical needs:

Elbows

Used when the line must change direction without adding welded or threaded fittings. Helpful in repair jobs where space is limited.

Male Adapters

Useful for connecting compression ends to valves, threaded couplings or existing threaded outlets. The male adapter creates a reliable transition point.

These options make Style 90 a flexible system for both new installs and system repairs.

Video Reference

Below is the detailed demonstration video showing Style 90 couplings, components, installation points and differences with other Dresser models.

Buy Dresser Style 90 Fitting Online 

Video Transcript (see video below)

Hello. We are talking about Dresser style 90 fitting, it’s also called style 90 compression coupling or compression fitting. This is a style 90 universal coupling, this is a style 90 regular coupling, this is a style 90 compression elbow, and this is a style 90 male adapter. I just want to give you a quick comparison. This is a style 65 coupling that you can see in our other videos, and if you compare it with a style 90, they are both for a 1 inch pipe, and you can see that a style 90 is much heavier than the style 65. They are both are compression coupling, compression fitting, style 65 is 150 pound coupling whereas style 90 is a 300 pound. For a much more rugged application, you will use a style 90.

Style 90 couplings are also very popular in gas applications, and that’s where you use style 90 universal coupling. The main difference between a style 90 universal coupling and a regular coupling is that a universal coupling has a lock ring so it prevents from the pipe pulling out. You can see right here, again, this one is even beefier than this, a slightly different nut to accommodate the lock ring, and I’ll show you that.

Let’s talk about the style 90 universal coupling first that has the ability to restrain the axial movement of the pipe. You can see, this is the lock ring that goes like this. Once you tighten it up, the sealing closes and there are jaws right here that would grip on the pipe and prevent it from pulling out. The other end is pretty much similar, it has a gasket. In fact, this gasket is interchangeable with the style 38 coupling gasket, so it’s a much bigger gasket. In fact, I’ll show you for comparison purpose. If you take the style 65 out, you can see the difference. They both are for 1 inch pipe, but this is, for style 90, a much beefier gasket and a retainer cup, style 65, for much lighter application.

These are the components of a style 90 universal coupling, retainer cup, gasket, lock ring, and the same thing on the other side, like this. The way you put this together is, remember, you just measure the coupling, make a line right here. You don’t want your coupling to be touching in the middle; it’s always good to leave about an inch of room. Subtract an inch from here, make a line here, so start from the very outer, this is the nut, slide this on, this is the lock ring that goes like this, and the way to remember is that the tapered edge goes like this, then the retainer cup. In fact, it’s better to assemble the retainer cup and the gasket. On the gasket and retainer cup, the wedge end is always pointing inside. Put it like this, and like this, slide it on, and once you... Of course, you will use a pipe vise or something to grab onto it, and once you make it tight, the lock ring will grab onto the pipe and prevent any axial pullout. Then you repeat the same thing on the other side and you have a compression coupling.

These can also be used on HDPE pipe, we get that question a lot. You have to remember, if you are using it on a PVC pipe or a PE pipe, then the rigidity of the pipe is also important because this thing will really clamp onto it. We usually recommend that, if you’re using it on a PVC pipe or a PE pipe, then use stiffeners that will prevent the pipe from crushing. But it can be used as long as the size matches, you can use it on a PVC pipe also.

This is a style 90 regular coupling. This does not have a lock ring; that’s the only difference between this one and the universal coupling. You can see. This one has a lip, this is an armored gasket. Again, as I said, the style 90 coupling is very popular in gas applications where sometimes you want to maintain electrical contact and this armored gasket, this lip here, gives a little bit more rigidity, it also creates a contact with the pipe, a metal to metal contact, so this is how an armored gasket looks like on a style 90 coupling. As I mentioned, this is the exact same gasket that is usually style 38 coupling also. But remember, that’s not the case with a style 65.

This is a style 90 compression coupling elbow. Again, it looks exactly like a regular coupling; instead, it’s just in a 90° elbow shape. The same thing, armored gasket, a retainer cup goes like this, and I’ve shown you how to assemble it. Take it out, slide your pipe in, measure how far it has to go, leave about an inch room, put the gasket, and it’s better you put it on a vise, and then you use a torque wrench and tighten it to that required torque and that’s how you get a compression coupling.

Remember, other than the universal coupling, which has a lock ring, the elbow, the regular coupling, the male adapter does not prevent axial pullout. This one will create a seal and will hold the pipe to some extent but if there’s a lot of axial force, then it can pullout.

This is a style 90 compression male adapter. As I showed you for the style 65, it allows you to take a threaded connection and make a compression coupling out of it. This has a cap on it, but this is a male thread and you can thread it onto any coupling, any 3000 pound, any 2000 pound, or threaded coupling and then the other end now becomes a compression coupling, which is exactly like the other ones. This also has a retainer cup and a gasket, and the installation is exactly the same. The male adapter allows you to convert any regular threaded connection into a compression fitting.

In summary, Dresser offers a line of compression couplings. These are available in sizes of up to 2 inch nominal pipe. This is a style 90 compression coupling; this is a style 90 universal compression coupling. The only difference between a universal and a regular coupling is that the universal coupling has lock rings and it prevents from the pipe pulling out. This is the style 90 compression elbow, and this is a style 90 male adapter. Once again, if you compare it with the style 65, you can see it’s much more heavier, much more beefier connection. Style 90 coupling are rated for 300 pound service, it’s also very popular in gas service because of the armored gasket. A style 90 coupling, universal coupling, can be used on a PVC pipe or a PE pipe as long as the size matches. You may have to use a stiffener.