Product Description

Produced by cutting or rolling threads onto plain steel pipe ends (for coupling connections), or by cold rolling internal/external helical ribs along the tube length (for enhanced heat transfer). Features reliable mechanical connection (threaded ends), or improved heat exchange efficiency (helical ribs). Available base materials: carbon steel (20#, Q235B, Q355B, ST35.8, ST45.8, J55, K55, N80), stainless steel (304, 316L), and alloy steel. Thread types (end threads): NPT, BSPT, BSPP, API (8-round, buttress), or metric. Nominal diameter: 15mm – 400mm (1/2″–16″). Wall thickness: 1.5mm – 20mm. Length: 3m – 12m (custom). For internal/external helical ribbed tube: base tube OD 16mm – 219mm, rib height 0.5mm – 3mm, rib pitch 5mm – 30mm. Surface finish: black, varnished, or galvanized. End finish: threaded with coupling, plain, or beveled. Meets ASTM A53, API 5CT, EN 10255, GB/T 8163, GB/T 12771 standards. Custom threads, lengths, and protective caps available.

Parameter

Product Name	Threaded Pipe (End-Threaded Pipe / Helically Ribbed Tube)
Base Tube Materials	Carbon steel (20#, Q235B, Q355B, ST35.8, ST45.8, J55, K55, N80), stainless steel (304, 316L), alloy steel
Pipe Type	Seamless or welded (ERW, LSAW)
Nominal Diameter (DN)	15mm – 400mm (1/2″ – 16″)
Outer Diameter (OD)	21.3mm – 426mm (standard; custom up to 610mm)
Wall Thickness	1.5mm – 20mm
Standard Length	3m – 12m (custom up to 18m)
End Thread Types	NPT (60° taper), BSPT (55° taper), BSPP (parallel), API 8-round, API buttress, metric (M)
Thread Direction	Right-hand (standard), left-hand (available)
Thread Gauge	Go / No-go gauges, thread profile inspection
Couplings	Threaded couplings (same standard) supplied loose or hand-tightened
Protection	Plastic end caps on threads, rust preventive oil (optional)
Surface Finish	Black (varnished), hot-dip galvanized, or coated
Helically Ribbed Tube – Base OD	16mm – 219mm
Helically Ribbed Tube – Rib Height	0.5mm – 3.0mm (internal and/or external)
Helically Ribbed Tube – Rib Pitch	5mm – 30mm
Helically Ribbed Tube – Rib Type	Helical, continuous, cold-rolled
Standards Compliance (End-Threaded)	ASTM A53, API 5CT, EN 10255, GB/T 8163, GB/T 12771
Standards Compliance (Ribbed Tube)	GB/T 24591, customer specification
Applications	Fire protection, water/gas/oil pipelines, scaffolding, heat exchangers, boilers, condensers

Application description:

Widely used in high-temperature heat exchangers (boilers, economizers, air preheaters), refinery heaters, furnace tubes, exhaust systems, waste heat recovery units, and flue gas desulfurization systems. Also suitable for carbon black production, chemical processing, and marine exhaust piping where resistance to sulfidation, carburization, and high-temperature oxidation is critical. The aluminized coating significantly extends tube life in aggressive, high-temperature environments.

Production description

Carbon/alloy steel tube is degreased, pickled, and fluxed, then immersed in molten aluminum bath (680–720°C). The aluminum reacts with the steel surface to form an intermetallic Fe-Al layer, topped with a pure aluminum coating. The tube is withdrawn, cooled, and inspected for coating thickness and adhesion.

Shipping Packaging

For export, aluminized tubes are bundled with wooden separators, wrapped with VCI paper and moisture-proof polyethylene, packed on ISPM-15 pallets, secured with steel straps, and fitted with plastic end caps. Labels include base material, coating thickness, dimensions, and heat number for safe sea freight.

Why Choose Us?

1.Factory Strength:Direct manufacturer with continuous or batch hot-dip aluminizing lines, capable of coating carbon/alloy steel tubes (OD 16–219mm, wall 1.5–12mm) with uniform Fe-Al intermetallic + pure aluminum coating (30–120µm).

2.Quality Assurance:Strict control of coating thickness, adhesion (metallurgical bond), high-temperature oxidation resistance (tested up to 800°C), and corrosion resistance in sulfur/carburizing environments; 100% coating integrity inspection (porosity-free); compliant with ASTM A795, EN 10346, GB/T 12415.

3.Certifications & Reports:Mill test certificates (MTC) for base tube and coating with each shipment; third-party inspections (SGS, BV) and salt spray/high-temperature cyclic oxidation test reports available upon request.

4.Customization & Service:Wide range of base tube materials (carbon steel 20#, Q235B, Q355B, ST35.8; alloy steel 15CrMo, 12Cr1MoV), custom diameters (16–219mm), lengths (3–12m), coating thickness (30–120µm), and end preparation (plain, beveled, or threaded) with fast lead times.

5.Export Packaging:Wooden separators + VCI paper + moisture-proof polyethylene + ISPM-15 pallets + steel strapping + plastic end caps + clear labeling for safe sea freight and coating protection.

FAQ

1. How to store aluminized tubes to prevent coating damage and white rust?

Store in dry, clean indoor area on wooden pallets or racks, keep original moisture-proof wrapping intact. Avoid contact with wet ground, acids, or chlorides. For long-term storage, maintain humidity below 60%. Minor scratches on the pure aluminum outer layer do not affect high-temperature oxidation resistance, but deep scratches exposing steel should be repaired with aluminum-rich paint. Do not stack heavy loads that could deform the tube.

2. What is the maximum service temperature of aluminized tubes, and how does it compare to stainless steel?

Aluminized tubes can be used continuously at 700°C (intermittent up to 800°C) in oxidizing and sulfur-containing atmospheres. Above 800°C, the aluminum coating melts and diffuses rapidly. Compared to 304 stainless steel, aluminized carbon steel offers similar oxidation resistance up to 700°C but at much lower cost. For service above 700°C or highly corrosive chloride environments, stainless steel (316L) is recommended. Aluminized tubes excel in sulfidation and carburization resistance, often outperforming stainless steel in refinery and boiler applications.

3. Can aluminized tubes be welded? If so, what precautions are needed?

Yes. Welding removes the aluminum coating in the heat-affected zone, exposing steel. Use TIG or low-hydrogen arc welding with stainless steel or nickel-based filler (e.g., ER309L or ERNiCr-3). Remove coating at least 25mm from the weld area, weld, then apply aluminum-rich paint or thermal spray aluminum to restore corrosion protection on the weld and adjacent zones. For load-bearing welds, consult design codes. Avoid high heat input to minimize coating damage.