DUCTILE IRON COUPLINGS
Ductile iron coupling is a pipe coupling of ductile iron material, mainly used to connect two pipes together, can also be used to repair pipes, change pipe size (step coupling) or material (Connect ductile iron pipe to PVC pipe etc), change pipeline direction（angle coupling）, facilitate maintenance of the pipeline, absorb the movement or vibration of the pipeline, align the pipes（ small gap between two pipes) etc., it can connect pipes of the same material, and can also connect pipes of different materials at both ends. It can connect pipes of the same size, and it can be pipes of different sizes.
Juberd is a ductile iron coupling manufacturer in China with over 30 years of experience.
Judberd couplings family include dedicated pipe coupling, maxi fit coupling(also called universal coupling or wide range coupling) ,dresser coupling ,flange coupling ,flange adaptor coupling ,step coupling ,restrained coupling for HDPE Pipe, multi grip restrained couplings etc as below.
Ductile Iron Coupling Types
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Advantage
We have a professional design team with 30 years of work experience, which ensures that our pipe couplings not only work well but also have advantages such as easy installation, long lifespan, and competitive pricing.
Judberd offers over 20 different designs of pipe couplings to choose from, and we can also design and produce according to customer requirements.
Producing castings using automated production lines results in high quality, low prices, and high efficiency.
Judberd strictly controls the quality of each component, ensuring that every detail maintains good quality.
Coupling Production Process
As a professional coupling Couplings with different designs have different production processes. Take ductile iron coupling as an example
1. Cast test rods and test blocks, and test the chemical composition and mechanical properties of the test rods and test blocks, so as to confirm that the chemical composition, mechanical properties and nodularization rate of the ductile iron meet the requirements
2. Shape
3. Casting
4. Polising and Coarse shot blasting
5,Machining if it is needed and fine shot blasting
6. FBE coating,Nylon11 coating etc
7. Assembling
8,Testing,Please note that after each step is completed, corresponding inspections must be carried out to determine whether the product can enter the next process.
Ductile Iron Coupling Parts
The ductile iron coupling is mainly composed of the following parts:
1，Middle sleeve(Fig No.5 as left diagram): Made of ductile iron or steel, providing good ductility and strength.
2，End rings(Fig No.6 as left diagram): Made of ductile iron, squeeze the gasket during the tightening process of bolts to make a seal.
3，Gasket(Fig No.4 as left diagram): Usually made of EPDM, NBR or other elastic material, used to ensure the sealing of the connection, the sealing function is affected not only by the size matching, but also by the material and hardness of the gasket, so the quality of the gasket directly affects the quality of the ductile iron coupling.
4，Bolt and nut(Fig No.7&2 as left diagram): Used for fastening and connecting, they must have sufficient strength to ensure that they will not be damaged during the tightening process.
5，Restrained ring or wedge, only for the ductile iron coupling that need to be locked, its purpose is to grip the pipe to prevent the pipe from moving. This helps to prevent leaks.
6，Coating/paint: In order to prevent corrosion, protect the parts, and extend the service life, anti-corrosion coating/paint is applied to the internal and external surfaces
7，Protection caps for bolts(Fig No.1 as left diagram), this cap is used to protect the bolts thread to prevent it to be damaged in transportation.
Ductile Iron Coupling Working Principle
The Working Principle of Ductile Iron Coupling is mainly based on the synergy of its various components to ensure the security and sealing of the pipe connection. Here are the basic steps of its working principle:
Align the two sections of the pipe that need to be connected, ensuring clean and undamaged pipe ends.
According to the installation instructions, install the end rings, middle sleeve, and gasket.
Install the bolts. When tightening the bolts and nuts, the gasket will be compressed between the end ring and the middle sleeve to create a reliable seal.
For the restrained coupling, according to the design of the restrained ring or wedge, tighten it correctly according to the instructions to grip the pipe and prevent leaks caused by the movement of the pipe.
Check the connection: After tightening, check the entire connection to ensure that the bolts and nuts are tightened properly, the gasket is not displaced or damaged, and there is no leakage at the entire connection.
Ductile Iron Coupling Advantage
Pipe couplings can be made of many materials, common materials are cast iron (include ductile iron and grey cast iron), steel (include carbon steel and stainless steel), PVC, PP, PE, FRP, Brass and copper.
Compared with couplings of other materials, cast iron couplings (mainly refers to ductile iron couplings, because grey cast iron has low strength and has basically been replaced by ductile iron) have high strength to withstand high pressure, strong and wear-resistant can be used for a long time, corrosion resistance (different coatings / linings on its surface, so that it has different levels of corrosion resistance to apply to different conveyed mediums), heat resistance, stable dimensions (dimensions will not change due to external factors such as thermal expansion and contraction), good sealing performance, low price, fast and simple production, so it is widely used in water supply, sewage, oil and other pipelines, can be used to connect Ductile iron, PVC, HDPE, Steel, AC, GRP etc most pipes.
Please note that the highest working pressure that ductile iron couplings can withstand is PN25. For higher pressures, it is recommended to use steel couplings instead.
Cast Iron Coupling Use
Ductile Iron couplings are mainly used for 5 pipelines as below
1, Widely used in water supply , because of its high strength and corrosion resistance, can transport high pressure and different water quality.
2, Used in urban underground drainage , because of its durability and low maintenance costs.
3, Sewage pipeline , because ductile iron has good corrosion resistance and wear resistance, it can transport abrasive wastewater. However, pay attention to the selection of surface treatment, gasket material and bolt material suitable for conveying sewage.
4, Agricultural irrigation , because the pressure of irrigation systems is generally low, sometimes grey cast iron couplings are used instead of ductile iron couplings, because cast iron couplings are more cost-effective than ductile iron couplings.
5, Petroleum transportation, ductile iron couplings can withstand high pressure and complex working environments. However, because the pressure of petroleum pipelines is generally high, if the working pressure is greater than PN25, carbon steel couplings should be used instead.
How to select the right ductile iron coupling?
When we need to connect two pipes, do we have a headache about which kind of ductile iron coupling to choose? You should know that choosing the correct ductile iron coupling is the most important step to ensure the correct installation of the pipe.
How do you choose the correct ductile iron coupling? We need to consider the following key factors:
1, The type of ductile iron coupling, select the type of ductile iron coupling according to the characteristics of the pipe and the actual use conditions. For example, because HDPE pipes are easily deformed, you must choose the restrained type of ductile iron coupling. For pipes with high strength and not easy to deform, such as ductile iron pipes, steel pipes, GRP pipes, PVC pipes, etc. You can choose non-restrained type ductile iron coupling. However, if the working conditions are likely to cause pipe movement, such as ground settlement, severe thermal expansion and contraction, you must choose the restrained type of ductile iron coupling even for pipes with high strength. If it is used underground, you can choose ductile iron couplings without a locating plug, but if it is used above ground and the pipes are easy to move, you should choose ductile iron couplings with a locating plug according to the actual situation to limit the movement of the pipes.
2, The size of the ductile iron coupling, make sure that the size of the coupling matches the outer diameter of the pipe. Different pipe sizes require different specifications of the coupling. If you are connecting pipes with the same outer diameter, you need to choose a straight coupling, but if you are connecting pipes with different outer diameters (different size pipes of the same material or pipes of different materials, such as connecting a ductile iron pipe to a PVC pipe, a ductile iron pipe to a steel pipe, etc.) you need to choose a step coupling.
3, The pressure that the ductile iron coupling can withstand ,choose the corresponding ductile iron coupling according to the working pressure of the pipeline system. The coupling needs to be able to withstand the highest working pressure of the system.
4, Coating ,Choose suitable coating materials and coating processes according to the medium transported by the pipeline. For example, for corrosive media, you need to choose a coupling with an anti-corrosion coating.
5, Gasket material ,The gasket material needs to adapt to the nature of the medium being transported and the working temperature. For example, if you are transporting drinking water, you need to use EPDM gaskets certified for drinking water, but if you are transporting highly corrosive media, you need to use fluororubber with good corrosion resistance.
6, Connection method ,Choose the appropriate connection method according to the installation space and requirements, such as bolt connection, clamp connection etc.
7, Brand and quality,Choose a well-known brand and reliable product to ensure its stability and durability during use.
8, Standards and certifications Ensure that the selected ductile iron coupling complies with relevant industry standards and certifications, such as WRAS certification for use with drinking water.
By considering the above factors comprehensively, you can select the appropriate ductile iron coupling to ensure the safety and reliability of the pipeline system.
RFQ
Pipe coupling length
Pipe coupling length is up to client requirements ,shorter or longer is ok
How to install pipe coupling?
- Inspect all components of the pipe coupling to ensure the quality of each part is intact.
- Insert the two pipes to be connected into the pipe coupling from both ends. Although each end of the pipe can have a maximum deflection of 6 degrees, during connection, strive to make the two pipes concentric and parallel.
- Pay attention to the gaps required inside the pipe coupling for the two pipes, as specified in judberd’s datasheet. It is prohibited for the two pipes to touch each other to prevent damage when the pipes move.
- Following the sequence shown in the left diagram 1, tighten each nut 1-2 turns diagonally, ensuring that each bolt is tightened to the specified torque with even force.
- The sealing ring should undergo sufficient deformation to fill all gaps between the pipe coupling and the pipes, and it should withstand the outward pressure generated by the internal fluid.
- During the pressure test in the pipeline trial run, if there is any leakage, follow the steps above to further tighten the bolts until no water leaks out.
What is max. angular deflection of pipe couplings?
When we use pipe coupling to connect pipes, the maximum allowable deflection angle of the pipe is determined by the distance “L” between the pipe coupling central sleeve and the outer diameter of the pipe, as shown in the diagram on the right. The larger the value of “L,” the greater the permissible deflection angle of the pipe. Additionally, the thickness of the sealing gasket should be larger. If it’s a restrained type coupling, then the maximum deflection angle of the pipe is also influenced by the locking ring or block. You can tighten or loosen the locking ring or block to adjust the maximum deflection angle of the pipe. If customers have specific requirements for the maximum deflection angle of the pipe, they can contact Judberd for special design to meet the needs of the engineering project.
What is dresser coupling?
The dresser coupling is the best design for connecting tubes, allowing for slight misalignment, vibrations, expansion and contraction, but not for axial displacement. The length of the tube inserted into the dresser coupling is determined by the length of the middle barrel of the dresser coupling and a gap is left between the two tubes to prevent them from touching each other during slight misalignment or vibration.
The judberd dresser coupling is designed to reach 330 psi. judberd’s dresser coupling consists of a ductile iron middle sleeve, a gland at each end, a rubber ring between the gland and the middle sleeve and a bolt that runs across the entire length of the dresser coupling. The grade of ductile iron can be changed according to the customer’s requirements. ENGJS450-10, ENGJS500-7, EN GJS400-18 according to EN1563, ASTM65-45-12 are the most commonly used. Other materials, such as ductile iron with high elongation for low temperature resistance, can also be produced according to customer requirements. Rings can be made of EPDM, NBR, SBR or special materials according to the customer’s requirements. The bolts can be made of carbon steel grade 4.8, 6.8, 8.8, 10.8 or stainless steel (surface coated with teflon), and can be fitted to the pipe by tightening the diagonal bolts in sequence with a spanner to the required torque. Please note that the coupling does not support the pipe, so make sure the ground is level , for some special pipes such as HDPE pipes that are easily dislodged or where there is a large vibration in the ground, we need to install a restrained type. Do not over-tighten the bolts, as excessive torque can cause extreme stress on the coupling. If required, please contact judberd for installation instructions.
How to choose satisfied manufacturer for flange adapter coupling?
Maybe the products looks very similar,but the products quality details are very different as below
1,The gasket quality,the gasket is most import parts for flange coupling adaptors,the EPDM/NBR/SBR ‘s Chemical composition affects the quality of the gasket.So one certificate for gasket is very important to know the gasket’s material.Good gasket material can assure long warranty period.
2,The material for body,chemical composition and mechanical properties are the very import indicator to measure whether the composition of ductile iron is qualified to standard
3, adhesion and thickness of the powder. Poor adhesion of the powder is a common quality problem for suppliers, so be sure to conduct an impact test before shipping to ensure that the powder does not come off. Another is the thickness of the powder, many suppliers in order to reduce the cost of using the powder, so the thickness does not meet the EN14901-1 standard. Therefore, the thickness of the powder must be tested before delivery to ensure that the average thickness is not less than 250um and the minimum thickness is not less than 200um.
4, the bolt quality inspection, first of all, to see whether the bolt grade has reached ISO898-1 standard, in addition to the strength grade of the bolt, we also want to test the thickness of the bolt’s anti-rust coating, such as Dacromet can be plated a layer can also be plated two layers, the price and the time of anti-rust is very different.
In addition, the bolts also need to be tested for torque and tension.
5,The inner wall of the pipe coupling is smooth, and there are no burrs or dead corners inside. The surface of pipe coupling is bright and clean wout any sand hole or crack,no surface defects such as uneven color and spots.
Pipe coupling types
1,Universal coupling(also called maxifit coupling,wide range coupling,supa coupling )
2,Dedicated coupling
3,Restrained coupling
4,Multigrip restrained coupling
5,Step coupling
Mechanical coupling joint restraint couplings
What is mechanical coupling joint restraint couplings?
There are many benefits to using restrained joint couplings, especially for HDPE pipes. Not only do they provide an additional level of security against leaks, but they also allow for a more secure connection overall. In addition, restrained joint couplings are less likely to come apart than other types of connections, making them ideal for use in areas where there is a high risk of displacement or where the pipes are particularly vulnerable to deformation.
Mechnical joint pipe coupling has an additional mechanical joint (also called restrained joint) compared to a normal pipe coupling to catch the pipe and prevent it from deflecting or coming out and causing leak.This mechnial joint or restrained joint can be designed by manufacturer.Judberd have designed mechnical joint (also called restrained joint) for PE pipe,we added gripper which consists of galvanised cast iron Tightening blocks and carbon steel grade 4.8 bolts.Once we have installed the pipe, we tighten the bolts so that the pipe can be gripped with the tightening block.
Maxifit pipe couplings
Maxifit pipe coupling types ?
The advantage and disavantage of maxifit coupling VS dedicated coupling?
The maxifit coupling is also available in several designs, material can be in ductile iron, carbon steel, or ductile iron gland carbon steel middle sleeve, and the range can be designed according to the customer’s requirements. The advantage of a large range is that as many pipes as possible can be connected by the same coupling. This keeps the number of maxifit coupling in stock to a minimum. However, a maxifit coupling with a large range requires a large deformation of the rubber ring when connecting small pipe outside diameter, which means that more torque and more time is required for installation. Dedicated couplings or couplings with a small range , on the other hand, require a higher stock to meet the requirements of connecting different pipes, but require less torque and time to install. So there are advantages and disadvantages to maxifit coupling and dedicated coupling and the user can choose according to the actual situation.
