| Hot-Dip Galvanized Steel Pipe | Carbon steel with a zinc coating applied after fabrication; commonly supplied to structural or tube standards. | Outside diameter: approximately 19–76 mm Wall thickness: approximately 1.0–3.0 mm | Main frames, columns, arches, sidewalls, purlins, doors, and crop-support structures. | High strength, widely available, suitable for bolted or welded structures, and economical for medium- to large-scale greenhouses. | Heavier than aluminum or polymer pipe; cut or welded areas require corrosion protection; zinc coating can be affected by acidic or salty environments. | High in normal outdoor conditions; higher protection is available with thicker zinc coatings or duplex coating systems. | Approximately 15–30 years, depending on coating thickness, humidity, salt exposure, and maintenance. | Most climates, including commercial greenhouses exposed to wind, snow, or repeated seasonal loading. |
| Pre-Galvanized Steel Tube | Cold-formed steel tube coated with zinc before forming; coating quality varies by product specification. | Outside diameter: approximately 19–60 mm Wall thickness: approximately 0.8–2.5 mm | Light greenhouse frames, cross-bracing, benches, shelving, trellis supports, and secondary members. | Lower initial cost, good dimensional consistency, easy cutting and assembly, and adequate strength for light-duty structures. | Exposed cut edges and weld zones may rust sooner; generally less suitable than hot-dip galvanized pipe for highly humid or saline conditions. | Moderate to high, depending on zinc coating mass and environmental exposure. | Approximately 8–20 years in typical greenhouse conditions. | Dry or moderately humid regions and economical small- to medium-sized structures. |
| Aluminum Pipe or Tube | Common structural aluminum alloys such as heat-treatable 6000-series alloys. | Outside diameter: approximately 20–80 mm Wall thickness: approximately 1.0–3.0 mm | Frames, glazing bars, roof members, doors, vents, benches, and lightweight modular structures. | Low density, naturally protective oxide layer, easy handling, good appearance, and strong resistance to atmospheric corrosion. | Lower stiffness and strength than many steel sections; thermal expansion is relatively high; galvanic corrosion can occur when directly joined to some dissimilar metals. | High in most atmospheric environments; additional care is needed in coastal or chemically aggressive conditions. | Approximately 25–40 years or more with suitable design and maintenance. | Regions where lightweight construction, fast installation, and corrosion resistance are priorities. |
| Stainless Steel Pipe | Usually austenitic stainless steel, such as corrosion-resistant 300-series grades, selected according to exposure. | Outside diameter: approximately 20–76 mm Wall thickness: approximately 1.0–3.0 mm | High-value greenhouse frames, hygienic crop-support systems, food-production areas, fittings, and components exposed to aggressive moisture. | Excellent corrosion resistance, high cleanliness, long service life, and strong resistance to many fertilizers and cleaning chemicals. | High material cost; fabrication and joining require suitable tools and compatible fasteners; not always economical for the entire frame. | Very high, although chloride-rich environments can still cause localized corrosion if the grade or maintenance is unsuitable. | Approximately 30–50 years or more, subject to grade selection and exposure. | Coastal areas, high-humidity sites, hygienic production, and facilities using frequent chemical cleaning. |
| PVC or uPVC Pipe | Rigid polyvinyl chloride used mainly for water distribution, drainage, and low-load services. | Outside diameter: approximately 16–110 mm Pressure class and wall thickness vary by pipe standard. | Irrigation lines, nutrient-solution distribution, drainage, condensate removal, and non-structural service piping. | Lightweight, electrically non-conductive, resistant to many fertilizers and salts, smooth internal surface, and easy solvent or mechanical joining. | Not normally suitable for primary structural frames; can become brittle under prolonged ultraviolet exposure or low temperatures; softens at elevated temperatures. | High against many common agricultural chemicals, but compatibility should be checked for concentrated chemicals and solvents. | Approximately 10–25 years outdoors, depending on UV stabilization, pressure, temperature, and installation quality. | Irrigation and drainage systems where low weight and chemical resistance matter more than structural strength. |
| HDPE Pipe | High-density polyethylene, commonly specified for water, irrigation, and fertigation systems. | Outside diameter: approximately 16–160 mm Wall thickness depends on pressure rating and pipe series. | Buried or exposed irrigation mains, fertigation lines, drainage, and flexible water distribution. | Good impact resistance, flexibility, resistance to many agricultural chemicals, and reliable leak-resistant fusion joining. | Not a primary structural material; thermal expansion is significant; direct sunlight requires UV-stabilized material; pressure capacity decreases as temperature rises. | Very high against many salts, acids, and alkalis used at controlled agricultural concentrations. | Approximately 25–50 years for properly selected and installed water systems. | Large irrigation networks, uneven terrain, buried services, and systems requiring flexible pipe runs. |
| Fiberglass-Reinforced Plastic Pipe | Glass-fiber reinforcement embedded in a resin matrix, with resin selected for the chemical and temperature environment. | Outside diameter: approximately 25–150 mm Wall thickness varies according to pressure and structural design. | Specialized irrigation, chemical-resistant service lines, drainage, and selected lightweight structural or support components. | Low weight, high corrosion resistance, good dimensional stability, and useful performance in chemically aggressive environments. | Higher purchase and fabrication cost than common plastic pipe; can be damaged by impact; joints and supports require careful engineering. | High to very high when the resin system is correctly matched to the chemicals and temperature. | Approximately 20–40 years, depending on resin type, UV exposure, pressure, and maintenance. | Industrial-scale or chemically aggressive greenhouse operations where conventional metals may corrode quickly. |