Guide to Pipe Fitting Basics

When something goes wrong with the plumbing, the key is finding the weak link or improper pipe fitting in the construction. Each pipe fitting has a specific job and must be able to handle the demands. Some must be able to withstand intense amounts of heat and pressure. Some must be water-tight while others must be air-tight. Pipe fittings must be compact, flexible, and sturdy enough to handle specific circumstances. The success of a project begins by selecting the right pipe fittings for the job.

Types of Pipe Fittings

pipe fittings elbow and bushings

Adapters and Bushings

steel pipe adapter brass pipe bushing

An adapter creates a direct connection between two pipes of different diameters. Using a pipe fitting of this type cuts out a lengthy and complex process of attaching two dissimilar pipes. While an adapter has two male sides, a bushing has one male and one female side. In some cases, such as when two uncommon pipe varieties must be connected, an adapter or bushing must be custom-made. Adapters and bushings are equipped to handle high pressure, but their cousins, the coupling and the nipple, are not.

Caps and Plugs

brass cap for pipe yellow fire hydrant

To put it simply, a plug has threading and a cap does not. To stop low pressure water, a simple cap will do the trick. When the pressure is exceedingly high, such as inside a fire extinguisher, a sturdy plug must be screwed on tightly. It takes special equipment to remove a high pressure plug. Caps, on the other hand, may be glued or soldered permanently in order to prevent access.


thin copper pipe elbowsthick metal pipe elbows

To avoid putting the pipes under unnecessary pressure, plumbing is built with straight lines of pipe. Any corner or angles are handled with an aptly named pipe fitting called the elbow. The most common elbow angles are 45 and 90 degrees, but they can be custom made to fit any situation. They can be screwed into place or glued to the adjacent pipes.  

Tees and Crosses

tee pipe fitting for watertee pipe fitting with control

A tee or cross is any pipe fitting with more than two openings. A tee has 3 openings while a cross has 4. Both are used to facilitate a great variety of plumbing challenges. For example, water may come into a house in one pipe then split apart when it hits a tee. One pipe heads to the water heater while the other splits off around the house. Some tees and crosses have faucets attached so that water can pass through when the faucet is on but is blocked off when the faucet is off. There is no pump attached to the faucet, so the water pressure must be strong enough to force water up the pipe but not strong enough to break the plumbing.

A healthy pipe system is built with the right pieces. Whether the pipes are carrying hot gasses or high-pressure water, the demands can be very different. Each pipe fitting must be able to handle the challenges. When selecting a pipe fitting, the question is not just what it needs to be shaped like but what it needs to be able to handle.


Domestic Manufactured Plastic Pipe Fittings

In July 2017, Specified Fittings had the privilege of being featured in a Domestic Manufacturing series of Global Business North America Magazine, examining the perks of purchasing domestically manufactured plastic pipe fittings rather than having equivalent parts shipped overseas. We typically rely on word-of-mouth in the plastic pipe fittings world, so this amplification of our services and offerings to the plastic pipe manufacturing industry was a real treat. See the Domestic Manufacturing article below.

Written by Lisa Barry, Senior Editor of Global Business Magazine

Specified Fittings is about to get “crazy.” That’s according to Executive Vice President, Kevin Hawkins. The “crazy” Hawkins is referring to is the good kind of crazy that every company longs for: a success-driven crazy that results in growth and expansion.

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Swedge Reducers

Also known as a “swage” reducer, these fittings have become “regulars” here at Specified Fittings. They offer many advantages for a myriad of situations.

When a pipe fails, it’s rarely due to the main body of the pipe run. The flaw usually lies in the details: individual pipe fittings that must facilitate complex changes without causing pressure to impact any one point. A swedge reducer is one of these crucial pipe fittings, which is why we have devoted so much care and attention to designing reliable versions of this product.

A well made and implemented swedge reducer adjusts the diameter of the main pipe run without inhibiting flow. The smooth, rounded structure causes liquids to bounce rather than hit pressure points and create leaks. Our swedge reducers are built with two top priorities: eliminate failure points and maximize flow.

Our Swedge Reducers

swedge reducer

One Piece Swedge Reducers

Each of our swedge reducers is built in one piece and composed of the same material throughout. We use pipe to reduce diameter instead of sheet material, as pipe is smoother and maximizes flow, protecting the rest of the pipeline from becoming damaged. Our swedge reducers are fully rated, adding no additional restrictions to your design. In addition to the practical perks, our single piece swedge reducers are also faster to manufacture, meaning they will be in your hands faster than multi-material fittings of the same variety.

Concentric and Eccentric Swedge Reducers

Our basic concentric design is available up to 63 inches in diameter. Concentric swedge reducers form a straight line in which the center of each section lines up exactly. For a fully optimized flow rate, we recommend an eccentric swedge reducer, which guides the movement of the contents by varying the center of each section. We custom-engineer eccentric swedge reducers to ensure a maximum flow rate for your project. In addition, we keep a stock of 48″x42″, 42″x36″, and 36″x30″ eccentric swedge reducers, designed for optimal flow characteristics.

All our swedge reducers are compliant with the American Water Works Association in all DR’s. A Factory Mutual certification will be included with your purchase upon request. Please contact us to order your custom swedge reducers.

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PVC Vents vs. Steel Ducts

Some of those in the mining business are comfortable with traditional corrugated steel ducts, but PVC is a safer, more cost-effective alternative that deserves a second look. Next time you repair your underground mining duct, consider the newer, more efficient alternative.

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One-Piece Gasketed Elbows and other Custom Fittings

If a pipe system you oversaw ever had a major leak, the cause was likely a poorly constructed or installed pipe fitting. With greater complexity than a length of pipe, pipe fittings must still bear the weight, friction, temperature fluctuations, and other forms of wear and tear that the rest of the pipeline is exposed to. Universally, the first parts to lose integrity are the seams, so we have done away with seams. Here are the results.

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Custom Backing Rings Pair Perfectly with O-Rings and Flange Adapters

back up rings epoxy coated galvanized steel and stainless steel

A pipe is only as strong as its weakest link. However, an effective backing ring can support and enhance the o-ring, flange adapter, or other fitting it’s paired with. Our pipe fitting design is focused on the big picture: how each piece aligns, how they rely on and support each other to create a reliable, resilient infrastructure. That’s how we got into the custom fittings business. No matter what the ring is backing up, we can custom select the size, shape, and material to get the job done.

Backing Ring Materials

Ductile Iron

This hearty alloy is rich in graphite, making it more resistant to pressure and impact than other grades of cast iron. In the casting process, the graphite forms into spherical nodules, creating a crack-resistant structure.

Ductile iron is the most affordable and most machinable material we suggest for backing rings. We coat each iron fitting in either epoxy or primer to shield against corrosion, though it’s still more vulnerable to moisture than steel. 

It is generally more friction-resistance than steel due to the high graphite content, though this varies depending on the quality of the friction. Consult an expert to determine which material is best for your situation. 

Galvanized Steel

The second-most affordable backing ring option is steel protected from corrosion with a thick zinc coating. If the coating wears away, it still rusts slower than iron. However, galvanized steel doesn’t offer the same level of corrosion resistance as stainless steel. In low-moisture, low-pressure settings, galvanized steel is the best fit. 

Stainless Steel

The most corrosion-resistant iron alloy is formed by introducing chromium to molten steel. It’s well suited for transporting liquids, even salt water and certain acid contents. However, chlorinated water is the enemy of stainless steel and leads to rust.

This in-demand material requires the greatest cost investment but lasts longer in humid conditions.

Pro tip: If two stainless steel fittings are held together under friction, they will eventually weld into one piece. This is something to bear in mind in the long term, as it can complicate repairs.

Don’t see your material on the list? We fabricate and mold new fittings every day. We would love to accept your custom order. Get a quote on your pipe fittings order.