Product Description
Manufactured within our specialized high-alloy casting and machining workshops in Jingjiang, our Gas Fired Radiant Tubes are indirect-heating combustion tube assemblies engineered for controlled-atmosphere continuous annealing lines (CAL), continuous galvanizing lines (CGL), and industrial heat-treatment furnaces. Drawing upon 26 years of high-temperature metallurgical manufacturing experience and certified under ASME "U" and "S" standards, we manufacture each Gas Fired Radiant Tubes assembly using centrifugally cast heat-resistant alloy outer sleeves (such as ZG4Cr25Ni20Si2 and ZG3Cr30Ni10N) paired with internal recuperators or ceramic flame nozzles. By containing the combustion process entirely within the tube assembly, these radiant tubes isolate combustion products from the furnace chamber, preventing strip surface oxidation while delivering uniform radiant heat across the pass line, providing heat-treaters and strip producers with a durable indirect-heating platform built for long campaign lives.
Applications
Continuous Galvanizing Lines (CGL): Supplying indirect radiant heat inside protective-atmosphere (N2/H2) heating and soaking furnace zones.
Continuous Annealing Lines (CAL): Heating cold-rolled steel strip without flue gas contact to preserve bright, oxide-free surfaces.
Roller Hearth Heat Treatment Furnaces: Providing controlled radiant heating for automotive forgings, bearings, and precision tubing.
Bell & Pit Annealing Furnaces: Operating as gas-fired radiant heating elements in batch annealing furnaces.
Technical Specifications
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Design Standards |
Industrial Furnace Heating Equipment Standards, ASTM A608, DIN 17465, API 530 |
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Tube Geometries |
W-type, U-type, I-type (straight through), P-type, or O-type radiant tubes |
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Outer Tube Metallurgy |
Centrifugally cast heat-resistant alloys: ZG4Cr25Ni20Si2, ZG3Cr30Ni10N, GX40CrNiSi25-20, Incoloy 800H |
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Outer Tube Diameter |
Ø120 mm to Ø320 mm; Wall thickness: 6 mm to 14 mm |
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Design Operating Temperature |
Up to 1,150°C tube wall design temperature |
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Burner Compatibility |
Matched for recuperative gas burners, self-recuperative burners, or electric radiant heating cores |
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Thermal Efficiency |
80% to 88% (Equipped with internal plug-in or metallic recuperators recovering exhaust air heat) |
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Heat Release Uniformity |
Tube surface temperature profile variation ≤ ±10°C along active heating legs |
Customization Capabilities
Geometry Tailoring: Manufacturing W-tubes for wide horizontal strip furnaces, U-tubes for vertical furnace cabins, or compact single-ended P-tubes.
Integrated Heat Recuperators: Fitting internal metallic or ceramic recuperators in the exhaust leg to preheat combustion air to 450°C–600°C, significantly cutting fuel gas use.
Flexible Furnace Wall Seals: Providing spring-loaded or bellow-sealed wall mounting flanges that allow axial thermal expansion while maintaining positive furnace atmosphere seals.
Electric Conversion Options: Supplying identical outer cast sleeves fitted with high-resistance Cr20Ni80 or Fe-Cr-Al spiral electric elements and ceramic spacers.
Zero MOQ Restriction: Custom engineered for individual tube replacements during plant turnarounds or delivered in volume for complete furnace builds.
Quality Control
Manufacturing Accreditations: ISO 9001:2015, ISO 14001:2015, and ISO 3834-2 welding quality management.
Full Process QR Code Traceability: Every centrifugally cast tube leg, cast return bend, and mounting flange carries an individual QR code linked to certified chemical analyses and inspection records.
Non-Destructive Testing: 100% Radiographic Testing (RT) on circumferential return bend welds; Liquid Penetrant Testing (PT) across all outer tube surfaces.
Pressure & Leak Testing: 100% pneumatic pressure leak tests on assembled radiant tubes to ensure zero gas leakage into controlled furnace atmospheres.
Heavy Ocean Packaging: Contoured wooden transport cradles, end-face protective caps, moisture barrier wrapping, and rigid timber crates.
FAQ
Q: Why are W-type and U-type radiant tubes widely used in continuous galvanizing lines?
A: W-type and U-type configurations provide long effective heating lengths within a compact envelope, allow free thermal expansion back toward the burner mounting wall, and facilitate the installation of recuperators on the exhaust leg to recover waste heat.
Q: What is the typical fabrication lead time for a set of radiant tubes?
A: Casting, machining, assembly, and pressure testing typically require 3 to 4 months from drawing approval to dispatch.
Q: What warranty coverage do you provide?
A: We provide an 18-month warranty from site arrival or 12 months from commercial operation (whichever comes first).
Q: What payment terms are accepted?
A: Standard commercial terms are 30% advance deposit, 40% manufacturing milestone payment, and 30% balance prior to export shipment, payable in USD, EUR, or RMB.
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