CNG manufactures grooved couplings for fire sprinkler systems, fire pump rooms, risers and fixed fire protection piping networks. Our product range includes rigid, flexible and reducing grooved couplings for joining grooved-end pipes without welding.
Fire protection contractors, EPC companies, distributors and project procurement teams can select couplings according to pipe outside diameter, joint movement, working pressure, surface finish, gasket material and required product approval.
For complete fire protection piping products, including couplings, elbows, tees, reducers, mechanical outlets and flange adapters, explore our fire protection grooved pipe fittings.
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Grooved couplings connect two grooved-end pipes using coupling housings, a gasket, bolts and nuts. The mechanical connection allows fire sprinkler piping to be installed and maintained without field welding.
CNG supplies different grooved coupling configurations for sprinkler mains, risers, branch piping and equipment connections. The correct product should be selected according to the required joint restraint, allowable movement, pipe dimensions, pressure rating and applicable listing.
Rigid couplings are designed to create restrained pipe joints where angular or axial movement needs to be limited. They are commonly considered for straight pipe runs, vertical risers, valve connections and other locations requiring stable pipe alignment.
View the CNG rigid grooved coupling for fire sprinkler systems for fire protection applications and project purchasing.
For dimension tables and available configurations, review the main rigid coupling product page.
Flexible couplings allow controlled angular and axial movement within the limits of the selected coupling design. They may be considered around pumps, equipment connections, changes in direction or other locations where vibration and limited piping movement must be evaluated.
Explore CNG flexible grooved couplings for fire protection systems.
Detailed dimensions and product configurations are available on the flexible grooved coupling page.
Reducing couplings connect grooved-end pipes with different outside diameters without requiring a separate reducer and two additional couplings. They can simplify selected transitions in sprinkler mains, risers and equipment piping.
Review the available reducing flexible grooved couplings and confirm the inlet and outlet pipe OD before ordering.
Buyers frequently search and purchase grooved couplings by nominal pipe size. CNG provides dimension tables for different pipe outside diameters, but the nominal size alone is not sufficient for final product selection.
Available size-specific pages include:
When submitting an inquiry, specify both the nominal pipe size and actual pipe OD to prevent selection errors.
Rigid and flexible couplings perform different functions in a fire sprinkler piping system. They should not be treated as interchangeable products without reviewing the piping design.
| Selection Factor | Rigid Grooved Coupling | Flexible Grooved Coupling |
|---|---|---|
| Joint behavior | Restrains pipe movement | Allows controlled movement within product limits |
| Typical design objective | Maintain alignment and joint rigidity | Accommodate limited deflection, movement or vibration |
| Common locations | Straight runs, risers and restrained equipment connections | Pumps, equipment areas and locations requiring controlled flexibility |
| Pipe support | Must follow the approved piping design | Must follow the approved piping design |
| Product verification | Confirm model, size, pressure and approval | Confirm movement capability, model, size, pressure and approval |
The project engineer, sprinkler designer or responsible contractor should determine where rigid or flexible joints are required. Coupling selection must also comply with the applicable installation instructions and fire protection system specifications.
Rigid and flexible couplings can be selected for grooved sprinkler mains and vertical risers according to the required pipe restraint, support arrangement and system design.
Fire pump rooms contain pumps, valves, manifolds and other equipment that require reliable pipe connections. The selection between rigid and flexible couplings should consider vibration, pipe movement, equipment connection and engineering requirements.
Grooved couplings can connect branch piping where the pipe size and installation method make grooved joining appropriate. Mechanical tees and grooved tees may be used to create branch outlets elsewhere in the system.
Selected grooved couplings can be used in fixed fire hydrant mains and risers when the product model and approval meet the project requirements. These products are pipe-joining couplings and should not be confused with fire hose couplings, Storz couplings or hydrant outlet adapters.
CNG grooved fire sprinkler couplings can be selected for commercial buildings, warehouses, manufacturing facilities, logistics centers and infrastructure projects. Final suitability depends on the required size, pressure, coating, gasket and certification.
Typical CNG grooved coupling configurations include the following options. Actual specifications vary by model and size.
| Component | Available Product Direction |
|---|---|
| Coupling housing | Ductile iron conforming to ASTM A536 Grade 65-45-12 on applicable models |
| Bolts and nuts | Carbon steel options |
| Gasket | EPDM, nitrile or silicone rubber, depending on service requirements |
| Pressure rating | Selected products are shown within the 300–500 PSI range; confirm by model and size |
| Surface finish | Epoxy powder coating, electrophoretic coating or hot-dip galvanizing |
| Color | Red and other available colors |
| Coupling types | Rigid, flexible and reducing configurations |
| Pipe selection | Confirm nominal size, actual OD and groove dimensions |
The available pressure rating and certification may change across different sizes within the same product family. Buyers should request confirmation for every size listed in the BOQ.
Selected CNG grooved coupling series are available with cULus listings and FM approvals. Approval coverage is product-, model-, size- and pressure-specific.
Do not assume that every coupling or every size carries the same certification. For approval-sensitive fire sprinkler projects, provide:
Required UL listing or FM approval;
Rigid, flexible or reducing coupling requirement;
Nominal pipe size;
Actual pipe outside diameter;
Required working pressure;
Pipe and groove standard;
Surface finish;
Gasket requirement;
Project country or applicable specification.
CNG can review these requirements and identify the relevant product direction and available documentation.
View our UL/FM flexible grooved couplings for certification-focused purchasing information.
Wet, dry and pre-action sprinkler systems can have different operating conditions and material requirements. Coupling selection should consider more than the housing and nominal size.
Before ordering, confirm:
Whether the system normally contains water, pressurized air or nitrogen;
Required gasket material;
Minimum and maximum operating temperature;
Working and test pressure;
Pipe material and outside diameter;
Required coupling movement or rigidity;
Applicable product listing;
Indoor, outdoor or corrosive installation environment.
Product compatibility should be verified against the selected coupling model, gasket and approval documentation.
CNG, Hebei Dikai Piping Products Co., Ltd., was founded in 2002 and specializes in grooved couplings, fittings, mechanical tees and grooved flanges.
The product range includes rigid, flexible, reducing and other grooved coupling configurations, allowing buyers to source different joint types for the same fire protection project.
CNG reports an annual casting production capacity of more than 50,000 tons and a production base covering more than 110,000 square meters.
CNG operates metal, rubber, hydraulic and piping-system testing facilities. Available inspection capabilities include material analysis, hardness testing, pressure testing and leakage testing.
Couplings can be selected with different surface treatments and gasket materials according to the project environment, system medium and technical requirements.
CNG works with distributors, fire protection contractors, EPC companies and project procurement teams requiring multiple coupling types and sizes in one order.
Rigid and flexible couplings are the most common categories. Reducing couplings may be used where two different pipe sizes need to be connected. The appropriate type depends on joint restraint, movement, pressure and project requirements.
No. Grooved sprinkler couplings join fixed grooved-end piping. Fire hose couplings and hydrant outlet adapters use different connection structures and standards.
The decision depends on the system design, pipe support, movement requirements and applicable installation rules. Rigid couplings restrain the joint, while flexible couplings permit controlled movement within their design limits.
Selected couplings and gasket configurations may be suitable, but compatibility must be confirmed by model, gasket, operating condition and listing. Do not select a coupling for dry service based only on nominal size.
Selected CNG coupling pages show rated pressure options within the 300–500 PSI range. The applicable rating varies by coupling model and size and must be confirmed before ordering.
No blanket assumption should be made. cULus listing and FM approval coverage can vary by model, size, pressure and configuration. Request documentation for the exact coupling included in the project BOQ.
Selected products are available with epoxy powder coating, electrophoretic coating or hot-dip galvanizing. Confirm the required finish, model, size and quantity when requesting a quote.
Send CNG your required coupling types, pipe sizes, working pressure, approval requirements, coating preference, quantities and delivery destination. Our team will review the specification and provide product and quotation information.
For elbows, tees, reducers, mechanical outlets, end caps and flange adapters, visit our complete fire protection grooved pipe fittings range.
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