A grooved coupling is a two-piece ductile iron housing bolted over a groove at the pipe end, with a rubber gasket inside that seals the joint. A rigid coupling locks the joint with almost no movement; a flexible coupling allows limited angular and axial movement. Where the joint sits in the system decides which one you need.
This article covers the LUYUAN ductile iron grooved range that AZEIDK supplies in Saudi Arabia: rigid and flexible couplings, elbows, tees, reducers, flanges and caps, with the pressures, sizes and approvals stated in the manufacturer’s catalogue and submittal, and what to check before the material approval goes to the consultant.
Key Takeaways
- The LUYUAN XGQT1 rigid coupling covers DN25 to DN300 at a 300 psi (2.07 MPa) working pressure, per AZEIDK’s product page.
- The XGQT2 flexible coupling is rated 300 psi; a heavy-duty version rated 500 psi is offered in DN50 to DN200, rigid or flexible.
- The published submittal shows UL listing for a range of elbows, tees, reducers and caps, and FM approval (Class 1920) for the XGQT3, XGQT3S and XGQT3U mechanical tees and the XGQT8 flange.
- Approval varies by model, size and finish, so check it line by line against the bill of quantities.
- In seismic design, NFPA 13 sets where flexible couplings go; the rest of the system is normally built with rigid couplings.
In this article
- What Is the LUYUAN Ductile Iron Grooved Range?
- Rigid vs Flexible Grooved Couplings: What Is the Difference?
- Elbows, Tees, Reducers and Caps
- UL and FM Approvals: What the Submittal Shows
- When Does a Sprinkler System Need Flexible Couplings?
- Pipe Preparation: Roll Groove or Cut Groove?
- A Note on the XGQT8 and XGQT08 Flanges
- Common Mistakes in Supplying and Installing Grooved Fittings
- What to Send for a Quotation
- Frequently Asked Questions
- Summary
What Is the LUYUAN Ductile Iron Grooved Range?
LUYUAN is the brand of Shandong Luyuan Fire Technology, based in Weifang, Shandong Province, China. Its catalogue states the company was founded in May 2005, specialises in grooved piping products, exports to more than 70 countries and holds ISO 9001:2015, ISO 14001:2015 and ISO 45001:2018. Those certificates cover the factory’s management systems; they do not replace a UL listing or FM approval of the product itself.
AZEIDK presents the full range on the LUYUAN ductile iron grooved fittings and couplings page, together with the catalogue and submittal file. Listed applications include fire-fighting piping, automatic sprinkler systems, fire pump rooms and valve connections, as well as water and mechanical services in commercial buildings, industrial facilities, warehouses and infrastructure projects.
Rigid vs Flexible Grooved Couplings: What Is the Difference?
From the outside the two look alike. The difference is in how the housing engages the groove. A rigid coupling grips the groove tightly, so the pipe run behaves almost like a single length. A flexible coupling leaves controlled clearance that permits axial displacement, rotation and limited angular deflection.
NFPA 13 (2022 edition) defines a flexible coupling as a listed fitting that allows axial displacement, rotation and at least 1 degree of angular movement; for pipe 8 in. and larger, less than 1 degree is accepted but not less than 0.5 degree.
XGQT1 Rigid Coupling
Two ductile iron housings bolted around a gasket. The product page lists sizes from DN25 (33.7 mm OD) to DN300 (323.9 mm OD), a 300 psi working pressure and a red-painted finish. Typical locations are mains, risers, pump rooms and valve connections where the line must stay fixed.
XGQT2 Flexible Coupling
Allows limited angular deflection and absorbs some expansion, contraction and vibration, at 300 psi. It is used next to pumps and where the design calls for seismic protection. The product page gives no numeric deflection angle, so take the value from the datasheet for the size you need.
Other Coupling Models
- XGQT5: reducing flexible coupling for joining two sizes.
- XGQT6: angle pad rigid coupling.
- XGQT12: heavy-duty flexible coupling; AZEIDK lists a heavy-duty rigid or flexible version rated 500 psi in DN50 to DN200.
- A shouldered flexible coupling, with no model code given on the page.
Elbows, Tees, Reducers and Caps
Beyond the couplings, the range covers the parts that change direction or size or close off a line. The table groups the models as given on the product page and in the catalogue.
| Category | Model | Description |
|---|---|---|
| Couplings | XGQT1 / XGQT2 / XGQT5 / XGQT6 / XGQT12 | Rigid, flexible, reducing flexible, angle pad rigid, heavy-duty flexible |
| Elbows | XGQT01 / XGQT02 / XGQT16 / XGQT10 | 90°, 45°, 22.5°, 11.25° |
| Tees and crosses | XGQT03 / XGQT13 / XGQT13S / XGQT14 / XGQT15 | Tee, grooved reducing tee, threaded reducing tee, cross, grooved reducing cross |
| Mechanical tees | XGQT3 / XGQT3S / XGQT3U | Grooved outlet, threaded outlet, U-bolt |
| Reducers | XGQT07 / XGQT07S / XGQT17 | Grooved concentric, threaded concentric, grooved eccentric |
| Flanges | XGQT8 / XGQT08 | Grooved flange, adaptor flange |
| Caps | XGQT09 / XGQT06S / XGQT05S | Cap, cap with concentric hole, cap with eccentric hole |
AZEIDK’s page states 300 psi for the elbow range. Dimensions, weights and ratings for each size are in the catalogue.
UL and FM Approvals: What the Submittal Shows
The catalogue says most LUYUAN products are listed or approved by UL, FM, CE, KC and LR, and AZEIDK’s page notes that approval differs by model, size and finish. The published submittal file shows:
- UL: listing under “Fittings, Grooved and Plain End”, file EX26538, covering models including XGQT01, XGQT02, XGQT03, XGQT07, XGQT08, XGQT09, XGQT10, XGQT13, XGQT14, XGQT15, XGQT16, XGQT17 and XGQT6S.
- FM: approval to FM Class 1920 (pipe couplings and fittings for aboveground fire protection systems) for the XGQT3, XGQT3S and XGQT3U mechanical tees and the XGQT8 flange, at 300 psi (2065 kPa), with an EPDM gasket, red painted or galvanized.
- The XGQT1 and XGQT2 couplings do not appear in the UL and FM tables included in this file, so ask for evidence of approval for the specific coupling size before it goes into a submittal.
The practical rule: check model and size together in UL Product iQ or the FM Approvals guide, not a logo on the catalogue. For a wider view of brands on the Saudi market, see Sprinkler, Valve and Grooved Fitting Brands in Saudi Arabia.
When Does a Sprinkler System Need Flexible Couplings?
Where seismic protection is part of the design, Chapter 18 of NFPA 13 (2022 edition) sets flexible coupling locations for grooved pipe 2½ in. and larger, including the following, as summarised by QRFS:
- Within 2 ft of the top and bottom of each riser, with exceptions for short risers.
- Within 1 ft above and 2 ft below each floor in multistory buildings.
- Within 1 ft of concrete or masonry walls, unless adequate clearance is provided.
- Within 2 ft of building expansion joints.
A point often missed, noted in the same source: if more flexible couplings are installed than the standard requires, additional sway bracing is needed, because each flexible joint reduces the line’s stiffness. Using flexible couplings everywhere is not the safer option. On the project, SBC 801, the consultant’s specification and Civil Defense requirements govern; NFPA 13 is the technical reference where the design adopts it.
Pipe Preparation: Roll Groove or Cut Groove?
Grooved joints rely on a groove formed at the pipe end, either rolled (displacing the wall without removing metal) or cut (removing part of the wall thickness). That is why groove type is tied to wall thickness. The FM remarks in the LUYUAN submittal give these minimums:
| Groove type | 6 in. and smaller | 8 in. and larger |
|---|---|---|
| Cut groove | Schedule 40 | Schedule 30 |
| Roll groove | Schedule 10 | 0.188 in. (5 mm) wall for 8 and 10 in.; 0.250 in. (6.35 mm) wall for 12 in. |
These remarks apply to the FM-approved models in the file. For pipe types, schedules and delivery inspection, see Fire Pipes: Types, Schedules, Grooved Joints and Delivery Inspection.
A Note on the XGQT8 and XGQT08 Flanges
Flanges connect a grooved line to flanged equipment such as a valve or pump. The catalogue lists both flanges as Class 150 and PN16, while the FM table for the XGQT8 states an ANSI 125 bolt pattern for the approved sizes. Match the mating flange on the valve or pump before ordering and state the bolt pattern on the purchase order. Where grooved-end valves such as the AFC grooved butterfly valve are used, no flange is needed at that point.
Common Mistakes in Supplying and Installing Grooved Fittings
- Submitting a general brand approval instead of proof for the specific model and size.
- Using flexible couplings at every joint without adding the extra sway bracing.
- Cut-grooving pipe thinner than the approval table allows.
- Mixing galvanized and painted finishes in one line item without confirming the approval covers the supplied finish.
- Not matching the flange bolt pattern to the valve or pump.
- Ignoring gasket type and fluid temperature when grooved fittings are used outside ordinary water service.
After installation, the hydrostatic pressure test before handover exposes any joint that was not made up correctly.
What to Send for a Quotation
AZEIDK’s product page asks for: fitting type and model code, pipe size, connection type, working pressure, gasket type, system fluid, operating temperature, finish, required approval, quantity, project and consultant specifications, and authority requirements. Preparing this list upfront cuts review rounds with the consultant. Our technical supply service checks these items against the datasheets before ordering.
To compare with another brand AZEIDK carries, see the Shurjoint rigid and flexible grooved couplings page.
Frequently Asked Questions
What is the difference between a rigid and a flexible grooved coupling?
A rigid coupling holds the pipe ends with almost no movement. A flexible coupling allows axial displacement, rotation and at least 1 degree of angular movement under the NFPA 13 definition (0.5 degree for 8 in. and larger).
What is the working pressure of LUYUAN couplings?
The XGQT1 rigid and XGQT2 flexible couplings are rated 300 psi (2.07 MPa); the heavy-duty version is rated 500 psi for DN50 to DN200, per AZEIDK’s product pages.
What sizes does the XGQT1 rigid coupling cover?
DN25 (1 in.) to DN300 (12 in.). Bolt sizes and weights per size are in the catalogue.
Are LUYUAN grooved fittings UL listed and FM approved?
The submittal shows UL listing for a range of elbows, tees, reducers and caps, and FM approval for the XGQT3, XGQT3S and XGQT3U mechanical tees and the XGQT8 flange. Check each model and size separately, especially couplings.
Should every joint use a flexible coupling?
No. Flexible couplings go where the design requires them, such as the top and bottom of risers in seismic design. Extra flexible couplings require additional sway bracing under NFPA 13.
What gasket do FM-approved LUYUAN fittings use?
The FM table in the submittal lists an EPDM gasket for the approved models. State fluid and temperature when ordering so the right gasket is confirmed.
Summary
Choosing a grooved coupling starts with its location: rigid for fixed runs, flexible where the design needs movement or seismic protection. Then come working pressure, size, groove method and finish, followed by checking each model and size against the submittal before it reaches the consultant. The LUYUAN range covers couplings, elbows, tees, reducers, flanges and caps from one source, with an approvals file that shows what UL covers and what FM covers.
Preparing a grooved fittings BOQ for your project? Send us sizes, working pressure and required approvals, and we will return suitable LUYUAN models with the catalogue and submittal file. Contact the AZEIDK team
