What is a Flange?

A flange is a category of gasket made to fix two sections of pipe together, or act as a removable plug at the end of a single pipe. All flanges are round disks with holes for bolts around the rim, but the commonalities end there. There is a variety of flanges to suit every purpose, from blocking high-pressure pipes to attaching two pipes of incompatible material. Also known as pipe flanges or flange gaskets, flanges are most often selected in place of other fittings to make cleaning and repairs more feasible.

flange, heavy duty with large bolts every 2 inches

Blind Flange

The simplest, most straight-forward flange in design, a blind flange is a solid disk used to block the end of a pipe. It’s anomalous in that most flanges are open in the center, allowing the contents of the pipe to move through it. Sometimes, there is a slight indent around the rim, creating a niche for the pipe to fall into. Blind flanges are also known as blank flanges, and referred to as flat face or raised face depending on the presence of an indent.

Weld Neck Flange

Named after the neck shape protruding from the center, a weld neck flange is designed for quick welding. The neck, which extends from the center, is thin and malleable in order to melt quickly. It’s generally butt-welded to the pipe before the disk portion of the flange is affixed to the rim with bolts.

Slip-on Flange

The one-piece version of the lap joint flange, the slip-in flange has a short length of pipe extruding from one end, creating a sleeve for a pipe to nestle into. The pipe is then fillet-welded both along the disk and the inner rim of the flange, adding extra support. 

Lap Joint Flange

The close cousin of the slip-on flange, the lap joint flange comes in two pieces: a disk with a hollow center and a neck piece which fits perfectly inside the hole. This second piece, called the stub-end, is secured to a pipe using a fillet weld.

Threaded Flange

The same shape as a slip-on flange, a threaded flange is a disk with extra material extruding from one end, plus threading to feed the pipe onto the flange. Unlike most flanges, they can be securely attached with or without welding, making them perfect for pipe sections that need regular cleaning. 

Socket Weld Flange

Following the basic design of the slip-on flange, the socket weld flange gets its name from the shoulder, or extended rim at the end of the stub-end. When installed, the pipe is nestled inside the socket of the flange and welded into place. The socket helps steady the pipe during the welding process, and add additional surface area for a successful weld.

Orifice Flange

An orifice flange is a specialized piece designed to house an orifice meter. The basic design is two weld neck flanges back to back, with a gap in the center for the meter. An orifice meter is an excellent tool for tracking the flow speed within a pipe, making this somewhat complex flange a worthy investment. 

Expander Flange

Designed to serve as both a gasket and a reducer, an expander flange is a weld neck flange with a hub that widens at the far end. The neck, working as a funnel, channels the contents into the small opening at the base of the flange, where it’s bolted to the next section of pipe. 
If we don’t have your flange in stock, we will make it to order. We are also glad to consult on the types of flanges and other pipe fittings needed for your project. Please contact us so we can get started building your custom fittings ASAP.


Custom Underground Gutter Drainage Solutions

An underground gutter is designed to prevent soggy soil, keeping lawns and produce healthy….  The basic design of an underground gutter is a PVC underground downspout drain at the bottom of a gravel trench using gravity in its favor to collect and drain water. Where to dig the trench, what quality of gravel to use, and other details depend on the demands of the situation.

Successful Underground Gutter Drainage Guidelines

underground gutter drainage agricultural drain

Soil Moisture Requirements

While the foundation of a building is safest in dry soil, agricultural drainage must facilitate the preferred moisture level for the surrounding produce. While peppers and squash thrive in dry soil, peppermint and rice require muddy conditions to flourish. There are certain tools that can drain excess water while retaining a specified moisture level to the benefit of the produce.

The effectiveness of drainage is determined both grain size and thickness. Clay absorbs water while sand is more hydrophobic. Drainage trenches are generally filled with gravel pieces between 10 and 20 millimeters thick. Larger grains facilitate faster drainage. In some cases, soil is used in order to slow down the drainage and keep the surrounding area moist.

Unlike in agricultural drainage, it is vital that the soil surrounding a building remain dry. The underground downspout must always be pointed away from the foundation of any building, and should not be built less than a meter away.

Water Pooling Prevention

Proper engineering is required in gutter drainage installation in order to avoid problems later on. With 500 pounds of gravel blocking the way, it can be difficult to diagnose issues with the underground PVC pipes, so it is best to prevent them through careful planning.

One common mistake is to place the pipe output where water might pool, such as next to a rain gutter output. If water pushes its way up the pipe, it fills the trench, developing water pockets and causing the soil to grow soggy. In other words, if water flows the wrong way, the drainage trench becomes a water retention pond, and this can be extremely detrimental to the surrounding flora.

Another common mistake is creating gaps that will eventually turn into water pockets. Over time, the smallest water pocket may grow and eventually cause problems. The pipe must be installed at the base of the trench with no room for water to pool beneath it. It must be slotted to allow water to enter from all angles. Only proper installation will prevent problems from occurring.

One water pooling problem that develops over time is pipe blockage. As soil fills gaps in the pipe, the water flow is slowed. To keep the pipe clear of debris, a geofabric filter, or sock, is often installed over the pipe. The same material can be used to create a geofilter over the top of the trench, covered by a thin layer of gravel. The added benefit of this upper geofilter is that it’s easier to replace. It may not catch all the dirt, but it can be swapped out if it becomes ragged over time.

Additional Notes

To prevent damage from trucks, tractors, and heavy equipment, the drainage pipe must be buried beneath 2 feet of gravel or settled soil. If pesticides are used, letting flora grow over the top of the trench will help absorb the chemicals and prevent them from spreading into the local environment.

To have your underground gutter drain installed or modified, please reach out to Specified Fittings.


Stormwater Management: Beat the Rain at its Own Game

Left to its own devices, rainfall can be a costly and destructive force on a property. By flagging problems and fixing them early, a property owner can save thousands on property damage. Stormwater management is summarized into three easy steps:

1. Identify the problem.

2. Install the solution.

3. Move on.

With the right parts in place, you will never have to think about the problem again.

catch basins with multiple inputs and outputs

1. Identify the Problem

The cause of a problem is never too far from the evidence. Just ask yourself, “Where is the water going?”

Broken-Down Materials

Oftentimes, a drainage system will work for years or decades before falling into decay. This is often due to outdated materials. Metal may appear hardy but will give in to corrosion and rust after years of use. Cheap and light plastics break down under the weight of heavy rainfall, especially when the drains become cluttered with debris. These parts must be swapped out with PVC or HDPE: reliable, water-tight materials that last longer than the alternatives

Water Pooling

Large land spaces require occasional maintenance over the years as water begins to pool in different areas. Golf courses, parking lots, highways, ball fields, and business fronts are common places for water-pooling issues to come up. New drainage devices must be installed to help with the target areas.

Debris Buildup

If not properly installed, stormwater drains become stuffed with dirt, pine needles, and trash. These systems can be modified or replaced to include snouts, clean-outs, and valves to manage the debris and prevent clogging.

2. Install the Solution.

Once the problem is identified, all that’s left is to replace what’s broken. The replacement parts must fit the exact parameters of the existing system, form a water-tight connection, and withstand the environmental factors of the area. In some cases, the parts can be purchased at local department stores, but when a unique part is needed, it must be built-to-spec. This is Specified Fittings’ forte.

Catch Basins

Our catch basins can be built to any parameters between 6″ and 48″ (12″ wider than most competitors offer). We recommend either SDR35 or Sch40: sturdy, high-quality materials that most piping companies don’t have access to. Our catch basins are designed with internal snouts to expel debris.

Downspout Adaptors

When two pipes of different dimensions must interconnect, this is where an adapter comes in. No matter the shape or material, so long as the diameters fall between 3″ and 12″, Specified Fittings can build it.

Custom Structures

custom pipe fitting

The Specified Fittings CAD team will design and build what you need, making use of the latest technology to make your drainage clean, efficient, and reliable. We may make use of notches, weirs, gates, valves, clean-outs, shear gates, and snouts to create the piece that meets your needs.

3. Move on

A lot of factors go into installing a stormwater management system, but the best solution is a final solution. Once installed, the drainage system will keep doing what it does best.
If you require special parts, go to the experts with access to the highest quality materials and manufacturing tools. See more info on our stormwater management solutions.


HDPE: Best Uses

On the microscopic level, high-density polyethylene has a clean, linear structure that makes the plastic light and strong. It can be manufactured and shipped at low costs, saving companies millions in materials. The simple material is waterproof, UV-resistant, and flexible under pressure, making it the perfect material for numerous uses.

Cost-Effective Uses of HDPE Sheets


HDPE is commonly recognized as the most cost-effective piping material. Pipe-grade HDPE retains its flexibility at temperatures down to -220˚ Fahrenheit, making it a great candidate to distribute cold liquids underground.


What the plastic is infamous for is being tricky to bond. Luckily, bonding techniques have been perfected since HDPE’s invention in the 1930’s. The most cost-effective technique is called electrofusion. Two pipe components are fitted together with a specially designed electrofusion fitting, which is then slowly heated to the melting point. The two pipes then weld into one.

Food Containers

Where HDPE shines brightest is in the consumable goods industry. It’s flexible, strong, and non-leaching. That makes it the perfect container for everything from cereal to ice cream. Best of all, consumers can drop HDPE containers right into the recycling bin when they’re done.

Unlike PVC and polystyrene, HDPE does not leach into water, making it a safe and healthy food container. Not surprisingly, HDPE is the preferred material for baby bottles and disposable cups.

Chemical Bottles

HDPE does not interact with most chemicals. It can safely contain laundry detergent, household cleaner, motor oil, or antifreeze. Adding a pigment to the plastic increases its strength and lengthens the shelf life of the product.


Being both durable and flexible, HDPE toys usually bounce instead of breaking. The material is safe for infants and toddlers as it does not leech in liquids. Being UV-resistant, HDPE also retains its color for longer than most plastics.

When Not to Use HDPE

This plastic is immune to most chemicals, but will oxidate in acids. For containing acids, we recommend PCTFE. PCTFE is a durable, waterproof plastic with a variety of uses, but is not as cost-effective as HDPE.

Like most plastics, HDPE melts quickly when exposed to open flame. When working with fire, there are two options. One is to treat the plastic with a flame-retardant layer. The other is to use metal instead of plastic.

HDPE is the best budget plastic. That is why it is the material of choice for consumable goods containers everywhere. To see where your company can save, consult Specified Fittings for free.


Why Use HDPE

When selecting a type of plastic, you have to consider s strength, flexibility, heat resistance, and solubility. No single plastic is perfect for every use, but there is one plastic out there that can take on almost any job: HDPE.

HDPE, or high-density polyethylene, is the most widely used type of plastic in the world. This versatile material is in hard hats and shampoo bottles. It’s the lining of your cereal box and the jug of milk in your fridge. It can last for decades underground exposed to mold, mildew, insects, and rushing water. It’s not a question what HDPE can do. It’s a question what it can’t do.

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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.


Ready to Get “Crazy”

In July 2017, Specified Fittings had the privilege of being featured in a Domestic Manufacturing series of Global Business North America Magazine. 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 industry was a real treat.

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.