YS STEEL manufactures greenhouse frame fittings for tunnel greenhouses, multi-span commercial greenhouses, shade houses, garden glasshouses, and polytunnels. The products are designed to reduce on-site drilling and welding, allowing faster assembly with standard hand tools. The fittings use a clamp-and-bolt principle that provides strong mechanical grip without damaging the galvanized layer of the pipes.
The base steel grade directly affects the strength and durability of a greenhouse frame fitting. YS STEEL uses three primary steel grades depending on the fitting type and required load capacity.
| Steel Grade | Carbon (max) | Manganese (max) | Silicon (max) | Phosphorus (max) | Sulfur (max) |
|---|---|---|---|---|---|
| Q195 | 0.12% | 0.50% | 0.30% | 0.035% | 0.040% |
| Q235 | 0.22% | 1.40% | 0.35% | 0.045% | 0.050% |
| SPCC | 0.12% | 0.50% | — | 0.040% | 0.045% |
| Steel Grade | Tensile Strength | Yield Strength | Elongation | Hardness |
|---|---|---|---|---|
| Q195 | 315–430 MPa | 195 MPa | ≥33% | ≤HRB 65 |
| Q235 | 370–500 MPa | 235 MPa | ≥26% | ≤HRB 75 |
| SPCC | 270–410 MPa | 140–240 MPa | ≥28% | ≤HRB 60 |
One of the most common installation problems is selecting a fitting that does not match the actual outer diameter of the greenhouse pipe. YS STEEL standard greenhouse frame fittings are compatible with the following pipe outer diameters.
Each fitting model has a defined pipe OD range. For example, a 25–32 mm cross connector can accept both 25 mm and 32 mm pipes, while a fixed 42 mm ridge connector is machined specifically for 42 mm pipe. The internal diameter of the clamp is slightly larger than the pipe OD to allow for galvanizing thickness and easy assembly, but not so large that it reduces contact pressure.
| Parameter | Standard Tolerance | Precision Option |
|---|---|---|
| Pipe OD compatibility | ±0.5 mm | ±0.2 mm |
| Bolt hole diameter | ±0.3 mm | ±0.1 mm |
| Fitting width | ±0.5 mm | ±0.3 mm |
| Fitting height | ±0.5 mm | ±0.3 mm |
| Angle accuracy | ±2° | ±1° |
| Steel thickness | ±0.05 mm | ±0.03 mm |
The greenhouse frame fittings range from YS STEEL is divided into eight main categories. Each category includes multiple models based on pipe size, angle, and finish.
Ridge connectors join the roof pipes at the peak of the greenhouse. They are typically supplied as fixed-angle or adjustable-angle units. Standard angles are 45°, 60°, 90°, and 120°. The connector body is stamped from Q235 steel and hot-dip galvanized after welding. Bolt holes accept M8 or M10 fasteners depending on the model.
Base plates transfer the vertical load of the greenhouse frame to the ground or concrete foundation. They are produced from 2.0–3.0 mm thick Q235 steel plate and can be supplied with pre-punched anchor holes for M10 or M12 ground bolts. Standard base plate sizes are 100×100 mm, 120×120 mm, and 150×150 mm.
Cross connectors join two pipes that intersect at a 90° angle. They are commonly used for purlin connections and roof bracing. The connector uses a two-piece clamp design with four bolts. Standard models cover pipe combinations from 22×22 mm up to 48×48 mm.
Pipe clamps secure pipes to flat surfaces or to other pipes. Saddle clamps are used for attaching purlins to rafters. The clamp width varies from 20 mm to 50 mm depending on the load. Material thickness ranges from 0.8 mm for light-duty saddle clamps to 1.5 mm for structural pipe clamps.
Purlin clips connect horizontal purlins to the main arch pipes. They allow quick installation without drilling through the pipe. The clip wraps around the arch pipe and provides a flat seat for the purlin. Standard purlin clips support pipe OD from 25 mm to 50 mm.
Gutter brackets are used in multi-span greenhouses to support the gutter profile and connect adjacent roof arches. These fittings are made from 2.0–3.0 mm hot-dip galvanized steel and are designed for high vertical load. Standard models fit 32 mm, 42 mm, 48 mm, and 60 mm arch pipes.
Swivel joints allow angular adjustment between two pipes. They are commonly used for knee braces and diagonal wind bracing. The joint can rotate from 0° to 180° and locks in position with a central bolt. Standard models accommodate 22 mm, 25 mm, 32 mm, 42 mm, and 48 mm pipes.
Angle brace fittings reinforce corner connections and resist lateral movement. They are supplied as 45° or 90° fixed brackets or as adjustable angle plates. The fitting thickness is typically 1.5–2.5 mm, with hot-dip galvanized or powder-coated finish.
| Fitting Type | Pipe OD Range | Steel Thickness | Standard Angle | Bolt Size | Finish Options |
|---|---|---|---|---|---|
| Ridge Connector | 25–60 mm | 1.5–2.5 mm | 45°, 60°, 90°, 120° | M8, M10 | HDG, Pre-galv, Powder |
| Base Plate | 25–76 mm | 2.0–3.0 mm | 90° | M10, M12 | HDG, Powder |
| Cross Connector | 22–48 mm | 1.2–2.0 mm | 90° | M6, M8 | Pre-galv, Zinc plated |
| Pipe Clamp / Saddle | 19–60 mm | 0.8–1.5 mm | Adjustable | M6 | Pre-galv, Zinc plated |
| Purlin Clip | 25–50 mm | 1.5–2.0 mm | 90° | M8 | HDG |
| Gutter Bracket | 32–76 mm | 2.0–3.0 mm | Variable | M10 | HDG |
| Swivel Joint | 22–48 mm | 1.2–2.0 mm | 0°–180° | M8 | Pre-galv, HDG |
| Angle Brace Fitting | 25–50 mm | 1.5–2.5 mm | 45°, 90° | M8 | HDG, Powder |
Greenhouse environments are warm and humid, which accelerates metal corrosion. The surface treatment of greenhouse frame fittings determines how many years the structure will remain safe and visually acceptable. YS STEEL offers three main surface finishes.
Pre-galvanized fittings are made from steel sheet that is galvanized before stamping and forming. The zinc layer is thin but uniform, typically 10–20 μm. This finish is cost-effective and works well for small hobby greenhouses, temporary structures, and dry inland climates. Cut edges may show light corrosion over time, which can be touched up with zinc-rich paint.
Hot-dip galvanized fittings are formed first and then immersed in molten zinc. The resulting zinc layer is 40–85 μm thick and covers all surfaces, including edges and weld points. This is the recommended finish for commercial greenhouses, coastal areas, high-humidity regions, and any structure expected to last more than 10 years. The matte gray surface also provides excellent abrasion resistance during transport and installation.
Powder coating is applied over a pre-galvanized or zinc-plated base. The polyester powder layer is 80–120 μm thick and is available in green, black, gray, and custom RAL colors. Powder-coated greenhouse frame fittings are used in retail garden centers, display greenhouses, and residential projects where appearance is as important as function.
| Finish Type | Coating Thickness | Salt Spray Resistance | Edge Protection | Color Options | Recommended Environment |
|---|---|---|---|---|---|
| Pre-galvanized | 10–20 μm | 120–200 hours | Poor | Silver only | Dry inland, hobby greenhouse |
| Hot-dip galvanized | 40–85 μm | 500–1,000 hours | Excellent | Matte gray | Coastal, commercial, high humidity |
| Powder coated | 80–120 μm | 300–600 hours | Moderate | Green, black, gray, custom RAL | Retail, residential, aesthetic projects |
Load capacity of greenhouse frame fittings is not a single fixed value. It depends on the fitting type, steel thickness, bolt grade, pipe diameter, and frame geometry. YS STEEL provides engineering recommendations based on common greenhouse designs.
For high wind and heavy snow regions, the frame design should include diagonal bracing, reduced fitting spacing, and additional anchor points. YS STEEL engineers can review frame drawings and provide specific fitting recommendations for wind speeds up to 160 km/h and snow loads up to 75 kg/m².
Most greenhouse frame fittings from YS STEEL are supplied with matching bolts, nuts, and washers. The fastener grade is matched to the fitting load class.
| Bolt Size | Thread Pitch | Standard Grade | High-Strength Option | Recommended Torque |
|---|---|---|---|---|
| M6 | 1.0 mm | 4.8, 6.8 | 8.8 | 10–15 N·m |
| M8 | 1.25 mm | 4.8, 6.8 | 8.8 | 20–30 N·m |
| M10 | 1.5 mm | 6.8 | 8.8 | 35–50 N·m |
| M12 | 1.75 mm | 6.8 | 8.8 | 55–75 N·m |
Every batch of greenhouse frame fittings passes through a documented quality control process before shipment. The QC flow includes the following inspection points.
Each shipment includes a detailed inspection report and material certificate when requested. YS STEEL maintains ISO 9001 certification for quality management and can provide third-party inspection by SGS, BV, or TUV for large orders.
Correct installation is essential for long-term frame stability. The following professional guidelines help greenhouse builders avoid the most common assembly mistakes.
YS STEEL greenhouse frame fittings are used in a wide range of protected agriculture and garden structures.
Standard greenhouse frame fittings support pipe outer diameters from 19 mm to 76 mm. The most commonly used sizes for greenhouse construction are 25 mm, 32 mm, 42 mm, and 48 mm. Each fitting model has a specific pipe OD range listed in the product specification. For non-standard pipe dimensions, YS STEEL can develop custom tooling and produce compatible fittings within 30–45 days depending on the design complexity.
Pre-galvanized fittings are made from steel sheet that is galvanized before forming. They have a thinner zinc layer of 10–20 μm and are best suited for small hobby greenhouses, temporary structures, and dry inland areas. Hot-dip galvanized fittings are formed first and then dipped in molten zinc, creating a 40–85 μm coating that covers all edges and weld points. For commercial greenhouses, coastal regions, high-humidity environments, or any structure expected to last more than 10 years, hot-dip galvanized fittings are the stronger long-term choice.
Yes, as long as the pipe outer diameter matches the fitting size. The fittings are designed primarily for steel pipe, but they can clamp PVC or aluminum pipe when the wall thickness is sufficient to handle bolt compression. For thin-wall aluminum, use a lower tightening torque or insert a rubber sleeve to prevent pipe deformation. Always confirm the actual pipe OD before ordering, because nominal PVC pipe sizes often differ from steel pipe OD standards.
In most cases, yes. YS STEEL greenhouse frame fittings follow common pipe outer diameter standards used by greenhouse kit manufacturers worldwide. However, fitting shapes, bolt hole spacing, and clamp widths can vary between brands. Before ordering, share your existing pipe diameter, frame drawings, and photos of the original fittings. YS STEEL can confirm compatibility or suggest an equivalent model from the standard range.
For standard greenhouse frame fittings, the minimum order quantity is 500 pieces per model. Mixed model orders in full cartons are accepted. Sample orders of 5–20 pieces are available for testing and dimensional checks. Standard production lead time is 15–25 days after deposit confirmation. Custom sizes, special coatings, or private packaging may extend the lead time to 30–45 days depending on order volume and tooling requirements.
Most YS STEEL greenhouse frame fittings are supplied complete with matching bolts, nuts, and washers unless the customer specifies otherwise. Standard bolt grades are 4.8 and 6.8, with 8.8 available for high-load ridge and gutter connections. Stainless steel fasteners and custom thread types can be quoted separately. If you prefer to source fasteners locally, fittings can also be supplied without hardware.
