5 Things to Know Before Buying Grooved Pipe Fittings

We previously have introduced different types and combinations of threaded fittings - which have been around for more than a century.

Here we're introducing another common way to join pipe; using grooved fittings. 
An attic sprinkler system using a grooved elbow with couplings.  Use of "mechanical" couplings that could allow faster joining of pipe came to life in by Lieutenant Ernest Tribe. Just a few years later the Victory Pipe Joint Company renamed itself to Victaulic (a combination of "victory" and "hydraulic"), and grew to expand the technology worldwide. 

Today, Victaulic and other manufacturing leaders provide grooved fittings that are often used for pipes in fire sprinkler systems. It is not uncommon for both mains and branch lines to be grooved today.

What are common grooved fittings, and how do they work? Let's introduce them.  An in-rack sprinkler with a branch line using (starting with the sprinkler) a groove x thread reducing elbow
​with a grooved coupling, a grooved piece of pipe, and a grooved tee (connection not shown). PIPE
Let's start with the pipe. In order to give grooved fittings an opportunity to "grip" the pipe and remain in place, they need an opportunity to resist the pressure of the water that is trying to "pull away" the pipe from the fittings which join them together. A grooved coupling about to connect two grooved-end pipes. Note the loose nut and bolt on the right-hand side, allowing the coupling to be expanded and "slip" over the pipe on the left. In order to create a groove in the pipe, steel can either be "roll groove" or "cut groove". Roll groove pipe involves pressing an indentation into the pipe near the end of the pipe. This allows a grooved fitting to slip over the end of the pipe and fit into the groove. Roll groove pipe has the advantage of not reducing the pipe thickness, so it can have more tolerance for corrosion than thinner pipe, similar pipe with threads, or pipe with cut grooves.

Pipe which is cut groove involves cutting into the pipe rather than pressing it. This cutting removes a portion of the pipe wall, making a thinner but smooth interior pipe wall. This thinner wall makes it more susceptible to corrosion, however, for pipe systems with a minor slope, the smooth inside of the pipe does not create a ridge where water can sit and corrode the pipe. Roll Grooved Pipe (top) and Cut Grooved Pipe (bottom). Note the ridge on the inside of the pipe wall for roll groove pipe, and the thinner pipe wall along the cut groove pipe. A tape measure with a "go" or "no-go" measurement to determine if the groove is within manufacturer tolerances. ELBOWS & TEES
Let's start with the basics. Elbows allow bends of 90-degrees (most common), 45-degrees, 22-1/2 degrees, and 11-1/4 degrees.

Why not every possible angle? What if I need to have a 60-degree bend because of my building?

First, it wouldn't be economical to make a fitting of every bend. Second, is that using just two 90-degree elbows back-to-back we're able to create a "swing joint" and make any angle we could want, just by changing the elevation of the pipe that's being joined. Victaulic "FireLock" Grooved Fittings; 
90-Degree Elbow #001 (left), 45-Degree Elbow #003 (center), and Standard Tee #002 (right) One notable specialty with the grooved elbow is a "Drain Elbow", which has the elbow except it includes a drain outlet at the bend of the elbow. This is used all the time with fire department connections which come down a wall and need to be capable of being drained (to avoid having water-charged pipe freeze and burst). This is also called a "Drain-El" or is a Victaulic #10-DR. A wall-mounted fire department connection that is away from the riser, here showing the "Drain Elbow" with a ball drip below. The portion upstream of the check valve is intended to be dry unless the FDC is actively being used in order to avoid freezing water inside. COUPLINGS
Nice sketches, Joe, but that's not how things look in the field!

That's because unlike threaded fittings, the actual pipe joining is by a grooved coupling. The coupling has malleable iron bumps that grip the indent of one groove (pipe/fitting) and connect it to the second groove (the other pipe/fitting).  A grooved coupling (here a Victaulic #009N shown). OTHER FITTINGS
There are a host of other fitting types. Grooved Reducing Tees? Yep. Less common. Less common can equate to more expensive, or at least that's what I hear from contractors familiar with all the pricing nuances.

What other grooved fittings do I often see? 

Reducing fittings, which is a concentric, single-cast piece of metal that has a large groove on one end and tapers down to a smaller groove on another end. One note of caution is using these in the vertical orientation; I've heard it is much better, more stable, and stronger to use a reducing-fitting as opposed to a reducing-coupling when in a vertical orientation. One of my clients goes so far to say to not use reducing couplings at all (where the coupling itself has two different groove sizes). I wouldn't have the expertise to gauge that myself. A flange x groove reducer (left) and a grooved cap (right). There are also reducing adapters, than can accept a flange connection and convert it to a reduced groove connection. 

Crosses are also available, as are caps (like the Victaulic #006 shown above on the right) which can terminate the end of a branch line. These caps even have 1-inch threaded opening options for easy auxiliary drains. 
Many manufacturers have equipment and components with grooved ends that can readily attach to pipe and fittings.

Grooved Pipe Couplings and Fittings

Grooved pipe couplings and fittings are used to join pipes in both wet and dry system. They provided some flexibility in terms of movement and deflection to the piping system. The concept of grooved coupling was invented in when Victaulic designed the first mechanical coupling. Though many other companies make mechanical grooved couplings, grooved couplings are still known mostly as Victualic pipe couplings or Victaulic style pipe fittings.

Link to CNG

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Grooved Coupling Video Overview

Grooved pipe fittings consist of grooved couplings, grooved fittings, grooved outlets, grooved valves and grooved replacement parts. Typical application of grooved fittings are in sprinkler risers, pipe feeds passing from one building area to another, locations prone to earthquakes, in discharge line above pump suction, in air or water fire services lines, piping systems subject to excessive vibration, and installation in tight spaces or where pipe alignment is difficult.

Grooved pipe fittings are limited to use with rolled or cut groove pipe, valve and fittings. These fittings are rated to 175 psi ( kPa) as a minimum. Pipe grooves are made according to ANSI/AWWA C606 specification "Grooved and Shouldered Joints".

These couplings are FM approved and can be used in underground services. The maximum ambient temperature for these couplings are 225 deg F (107 deg C)

These couplings are sold by nominal pipe sizes and will fit the corresponding nominal pipes ,valves and fittings.

4 Components of Grooved Pipe Fitting

A grooved coupling or a Victualic style groove coupling has four main components:

1. A grooved pipe (grooved or cut)
2. Coupling Housing
3. Sealing Element (Gasket)
4. Fastener (Nut and Bolt)

Five Benefits of Grooved Piping System

A grooved piping system is the most versatile, reliable and economical piping system. It is more reliable than a threaded or flanged connection and often results in 2x-4x faster installation. The system is designed to work with rolled or grooved pipes. Flexible grooved pipe couplings offer the flexiblity needed for vibration dampening or installation in earthquake prone areas.

1) Cost Saving

Grooved piping systems offer up to 30% cost savings. It offers fast assembly in tight systems, cleaner systems with no welding slag, contamination or hot work permit. More predictable cost estimates for contractors, resulting in faster and cheaper installation.

Additional resources:
Pixellated Arrays - Shalom EO
What Are The Types of Atomic Clocks? - Science | HowStuffWorks
Madhura Patwardhan's Post - LinkedIn

For more Heavy Duty Flexible Couplinginformation, please contact us. We will provide professional answers.

A simple system with 3 components only Each pipe joint is a union Rolled or cut pipe groove

2) Each Joint is a Union

Each pipe joint is a flexible joint and removing the couplings allows removal of pipe for easy cleaning, servicing and maintenance. It also allows the flexibility to change the piping system and add / remove equipment.

3) Easy Installation with Rolled or Cut Grooved Pipe

Grooved pipe couplings require creating either a rolled groove or a machine cut groove. A rolled groove creates an indentation in the ID of the pipe whereas the machine cut groove is smooth on the ID. A rolled grooved is mostly done on thinner wall pipe whereas the machine cut groove is more common on thicker wall pipes. Grooved couplings are commonly installed on pipe schedules 5 to schedule 40.

A grooved pipe is much easier than a welded pipe joint, requiring no X Ray, hot work permit and associated hazards of welding a pipe.

4) Minimize Noise and Vibration

Use of grooved pipe coupling isolates the noise and vibration. Resilient gasket absorbs noise and vibration resulting in a quieter system. Provides superior vibration attenuation and eliminates the need of noise suppression devices.

5) Provide Expansion and Contraction

A grooved pipe joint allows for expansion and contraction of the pipe joint without compromising the integrity of the connection. It eliminates the need for costly expansion joints. Grooved pipe joints also eliminate pipe stresses for buried and underground pipes.

Five Types of Grooved Pipe Fittings

1) Grooved Coupling

A groove is made in the pipe by cold forming and machine cutting a groove into the end of pipe. See figure below for difference between rolled and cut groove. A gasket is housed in the coupling housing and is wrapped around the pipe ends. The groove in the pipe mates with tongue in the pipe and creates a restraint that prevents pipe pull out. Gasket / sealing element creates the pressure barrier. The entire assembly is tightened with bolts and nuts.

Flexible grooved pipe coupling

There are two types of basic grooved couplings:

• Flexible grooved coupling that allows a limited amount of angular movement
• Rigid grooved coupling that does not allow movement and is similar to a fanged or a welded pipe joint

2) Grooved Pipe Fittings

Grooved Concentric Reducer Grooved 90 Deg Elbow Grooved Tee Grooved Eccentric Reducer Grooved and Threaded Adapter

3) Grooved Pipe Outlets

Grooved Strap Tee Grooved Mechanical Tee

4) Grooved Valves

Grooved Butterfly Valve Grooved Check Valve

5) Grooved Replacement Parts and Accessories

150# Grooved Weldolet Grooved X Threaded Nipple

Grooved Pipe Fitting Manufacturers

Grooved pipe fittings were introduced in by Victaulic. Since then several manufacturers have entered the market. Notable among them are:

• Victualic
• Cooplok (by Smith Cooper)
• Gruvlok
• Shurjoint
• Grinnell / TYCO
• AnvilStar

The link below has part numbers cross referenced between different manufacturers. If you are used to other brands, the table below will help you choose an equivalent fitting from the other manufacturer.