There are various Ductile iron pipe (DI pipe) joints on the market. These different types of joint designs can now allow for additional benefits for various applications. Joining pipe together is just as important as the pipe itself. It sounds like a simple procedure, but the environment in which the pipe is assembled is critical.
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Whatever you can imagine, a DI pipe joint is most likely available to be used in the application. Let us look at the different types of DI pipe joints and find the right one for your application.
Centuries ago, the first type of joint was a flanged joint. They used leather between the flanges, which equals the rubber gasket of today. The next type of joint was bell and spigot. It was assembled with jute packing with lead poured behind the packing. With manufacturers always looking for better designs, various joints have been developed over the decades.
How the joints are assembled is another feature that has evolved over the years, especially since Ductile iron pipe became the norm back in the s. You may experience different joints of pipe when repairing or replacing. Therefore, manufacturers will continue to publish information about their joints even though they no longer manufacture them because those joints are still in service.
The most common joint is the Push-On Joint. This joint is the simplest to install and is used in underground applications. Push-on pipe is a non-restraint joint. The full-circumference radial compression of the gasket between the bell and spigot forms the watertight seal.
You may take the necessary deflection if your line requires horizontal or vertical deflection once the joint is assembled. The size and the manufacturer of the pipe determine the allowable amount of deflection. The majority of push-on pipe allows for five degrees of deflection.
A five-degree deflection equals 19 inches in any direction – AFTER THE JOINT IS PROPERLY MADE.
PRO TIP: Using the 1-INCH PER FOOT RULE in the field is a safe and effective method to avoid over-deflecting joints. For example, 18-foot pipe = 18-inch / 10-foot field cut = 10-inches deflection, and so on.
Mechanical Joint Pipe (MJ) is primarily used in fittings and valves. The mechanical joint may be configured as a non-restrained or retrained joint using a wedge action retained gland. These joints use the gland’s compression against the bell to wedge the gasket, forming a watertight seal.
The evolution of the MJ restraint gland provides the design engineer the option to eliminate the use of thrust blocks reducing cost and improving the efficiency of the project.
Mechanical joints may be deflected to achieve the desired alignment after the joint has been tightened. A common error in assembling a mechanical joint is not using lubricant on the gasket. Not using lubricant on the gasket forces the gasket into the gasket recess. Once the gasket relaxes, the bolts become loose and require tightening again.
Proprietary Restraint Push-On Joints are unique to each manufacturer. These joints use the basic design of the push-on pipe to make the watertight seal. Each manufacturer has its own design that uses a deeper push-on bell and either specially designed wedges or rings to restrain the pipe against a welded bead on the pipe's spigot.
Restraint joints again provide the design engineer with excellent options to eliminate the use of thrust blocks. This reduces the cost and improves the efficiency of the project. Restraint joints are often required for high-pressure applications such as Pen Stocks or where operating pressures exceed typical conditions.
These joints also allow for different degrees of deflection depending on the design and size of the pipe. The deflection may be obtained after the joint assembly. These joints require minimal labor and time to assemble. These joints may be used in various installations including:
You cannot go wrong with the use of this type of restraint joint.
Locking Gaskets are used on push-on pipe to restrain the pipe. Locking gaskets are also unique to each manufacturer. There are currently other manufacturers developing locking gaskets. Before using locking gaskets from a supplier other than a DI pipe manufacturer, ensure they are approved for use with their pipe. Some locking gaskets are developed without the pipe manufacturers' written consent and may not work correctly on the pipe.
The restraint is engaged after the joint has been properly assembled, including deflection. Pulling back on the joint will “lock” the teeth in place. Restraint gaskets are an excellent option and are primarily used in smaller diameters (24 inches and down). Primarily used for buried applications, restraint gaskets are not recommended for above-ground applications, bridges, or vertical applications.
One thing to remember when using a locking gasket is that you only get one shot on assembly, and they are extremely difficult to disassemble once assembled, even when using a shim kit to deactivate the wedges within the gasket.
Wedge Action Retainers are used with a mechanical joint to achieve a restrained joint that has deflection. The wedge action retainer takes the place of the MJ gland. Once you have assembled the joint, you may take the required deflection before tightening the bolts on the wedge. The wedges' bolts are designed to break or snap off once they reach the proper torque.
Wedge action retainers may be re-used if necessary. The key factor is to review the manufacturer’s instructions for re-use provided with the gland to obtain the proper torque for the restraint.
A Bell Harness Restraint is an external restraint on push-on joint. The bell harness restraint utilizes a split gland behind the bell and a wedge action retainer on the spigot in front of the bell with a threaded rod secured by two nuts to hold the joint from disassembling when pressure is applied. This type of restraint is labor-intensive and requires additional excavation depth to properly allow the harness to be assembled around the push-on bell.
The Flanged Joint was one of the first joints ever used. This joint should be used for an above-ground application. It is a rigid joint and does not allow deflection or expansion. Therefore, it is not recommended for underground use because of ground shift. Ground shift could damage the integration of the joint. The watertight seal is formed by tightening the bolts and compression of the gasket between the two flanges.
Grooved and Shoulder Joints use u-shaped coupling that goes around the plain end of a pipe that either has a groove cut into it or a shoulder threaded onto it. The u-shaped coupling fits into the groove to join/restrain the pipe.
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Inside the u-shaped coupling is a gasket that compresses between the coupling and the pipe to form the watertight seal. This type of joint is used in above-ground applications. Grooved/shoulder joints should never be used in underground applications.
Grooved joints are available in flex or rigid configurations depending on the need for deflection.
Ball and Socket Pipe has the greatest degree of deflection of any joint, for up to as much as 4.5 feet of offset for an 18-foot length of pipe. It ranges from twelve to fifteen degrees per joint. This joint describes itself.
Components of the River Crossing joint are machined to precise dimensions providing optimal deflection capabilities. Pipe class options are also available, providing installation options to either “float” or “sink” the pipe into place. Like the wing of an airplane, the structure and strength of this specialized joint serve to split any water or current it passes through harmlessly while it settles to the bottom of the waterway on its own.
This joint deflection may be horizontal or vertical. This deflection capability allows the pipe to be assembled on the bank or the back of a barge. The joints deflect as needed to adapt to the bottom of any waterway.
Pipe fittings are a perfect solution for providing connections for pipelines. Additionally, they can modify pipeline systems by extending the run or altering the pipe flow direction. Various pipe fittings exist for different applications and industries, including water supply, pharmaceuticals, power generation, petrochemicals, pulp & paper, and others. Pipe fittings for water supply come in multiple materials, types, shapes, and sizes. Hawle offers a wide range of mechanical pipe fittings for the most common types of pipes used in the water supply. Prior to selecting the ideal pipe fitting for your application, you should base your decision on certain criteria to assure its compatibility.
Flanged pipe fittings are a prevalent type of pipe fittings. They connect piping system equipment such as pipes, valves, and pumps by being screwed together. When two flanges are bolted together, and a gasket forms a seal between them, the result is a flanged junction.
The selection of the type of flanged fitting depends on the system and application, where temperature and pressure are important factors. Flanged pipe fittings are often employed in water supply networks and are compatible with most common pipe types. They are simple to use, universal, and great for rigid pipelines, given they fit in tight spaces. Moreover, their maintenance is simple as it is easy to disconnect and reconnect them. However, note that flanged pipe fittings require bolts and are prone to leakage. Hawle offers a vast range of flanged pipe fittings to fit your need.
System connections are unique mechanical pipe fittings designed to attach water pipes made of plastic, such as HDPE/PE/PEX and OPVC/PVC.
There are still many pipes older than a century in several European cities that need to be replaced because of significant leakage rates. When these pipes fail, they are frequently replaced by PE and PVC pipes, as they offer lower failure rates than other materials. To meet this need, Hawle offers System pipe connections that are perfect for plastic pipes. System pipe connections are attached to the pipes using a brass grip ring with teeth elements, providing a restraint connection for plastic pipes.
Compared to other pipe laying technologies like PE-welding, for the System installation, no special tools or machinery or specially trained personnel are needed. Cold, rainy weather or groundwater in the pit also do not affect the fast and safe System assembly. In addition to that, Hawle has a certificate from an external independent institution ”100 Years Expected Lifetime”.
Among other valve manufacturers of comparable mechanical connections for PE pipes, Hawle offers one of the broadest product pallets with System : Pipe connections, bends, couplings, end caps, combi- and gate valves, suited for all types of installations are all part of the Hawle System offering. System diameters might be as little as d63 or as large as d630, depending on the product.
Most old water pipelines are built using cast iron, concrete, or asbestos cement. Retrofitting these old pipes with lighter and more flexible plastic components is common. However, properly connecting more recent plastic pipes to older concrete and metal ones might be difficult due to size and coupling incompatibilities. Synoflex range facilities this operation easily thanks to its high tolerance and multirange restraint couplings which were exclusively designed to join incompatible pipes. Hawle Synoflex multirange restraint joints can join a wide range of unique pipe combinations, such as:
Hawle Synoflex multirange restraint joints also enable metal – metal or plastic – plastic combinations. Some of the advantages of Synoflex connections include:
Synoflex provides various pipe connections to meet a vast range of needs. These include the Synoflex couplings, Synfolex flange adapter, Syno connector, and SynoZAK adapters. However, it is worth noting that Synoflex is only available up to DN 400.
Hawle has a broad palette of pipe fittings for house connections up to 2", offering a versatile range of fittings to suit your needs. These include non-threaded pipe fittings, including push-fit fittings, Hawle ZAK connections and and conventional threaded pipe fittings. Pipe push fittings are becoming increasingly popular compared to conventional fittings as they are much faster to install without needing specialized equipment, saving time and money.
Hawle ISO pipe fittings made of ductile iron (with an epoxy powder coating) or polyoxymethylene (POM) are suitable for PE pipes according to EN -2 and DIN , up to PN 16. The Hawle ISO pipe fitting is the ideal push connection for PE pipes that have been tried and tested for decades. The joint is flexible, making the installation of the fitting quick and straightforward. Similar to the Hawle-FIT series, ISO fittings are available in various types: with external and internal thread, connector, elbow 45°- 90°, T-piece, end stop, wall inlet fitting, etc. By using the new 2-K gripring the ISO fittings can be used for PVC pipes acc. to EN ISO -2.
ZAK connections are threadless, restraint-joining systems for service connections. The bayonet-style connection of the ZAK-system is simple and fast, meaning service line connections can be made or removed in seconds. The ZAK-system saves time and does not require separate sealing products to make 100% leak-proof connections. Made from high-quality castings in Europe, ZAK-system fittings are made of GJS-400-15 ductile iron and coated inside and out with a durable epoxy powder coating.
To ensure its safety for distribution, fittings used in the water supply must meet the standards set by European Authorities. These include the drinking water certification, for example, from the Austrian and German Associations for Gas and Water (ÖVGW and DVGW, respectively. Protecting human health and the environment is a top priority at Hawle. Most fittings on the Hawle portfolio are designed for municipal water supply. This means that parts in contact with drinking water are certified and lead-free to ensure their safety for human health and the environment.
T-fittings, or pipe tee fittings are fittings that are used to connect two or more pipes. These fittings, characterized by their T-shaped form, attach the two pipes at a 90-degree angle. Among all pipe fittings and connectors, the T-fitting is one of the most adaptable and is frequently used in domestic, industrial, and commercial settings. Hawle offers various T-fittings made of different materials, also available in the Hawle-FIT and ISO-fittings series.
Similarly, a cross fitting is a pipe fitting with four openings in four directions used to connect four pipes. The pipe cross may have one inlet and three outlets or vice versa. In addition, the inlet and outlet diameters may be the same or different.
In water systems involving the underground piping of water to domestic or to industrial areas, there is the need to bring a water supply to the surface at various strategic locations. Duck foot bends are often employed to connect fire hydrants away from or at the end of a pipeline. A duck foot bend fitting consists of two ends, where one end is vertical and the other is curved. In a fire hydrant application, the vertical end is connected to the bottom of the hydrant while the other end is often connected to a pipeline at a recommended depth below the ground.
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