Hot-Dip Galvanized I-Beam is a hot-rolled I-section steel beam finished with a zinc coating through hot-dip galvanizing. The I-shaped section provides structural resistance through its web and flanges, while the galvanized surface provides corrosion protection for exposed steelwork.
Rongheng supplies galvanized I beams in Q235B and Q355B, with common sizes from 10# to 63#, standard lengths of 6 m, 9 m and 12 m, and customized lengths from approximately 2–19 m. Cutting, drilling, beveling, straightening, grinding and deburring can be arranged before galvanizing according to project drawings.
| Item | Specification |
|---|---|
| Product | Hot-Dip Galvanized I-Beam |
| Base section | Hot-rolled I beam |
| Steel grade | Q235B, Q355B |
| Chinese standard | GB/T 706-2016 currently applicable |
| New standard | GB/T 706-2026, effective December 1, 2026 |
| Galvanizing standard | GB/T 13912-2020 |
| International reference | ASTM A123/A123M-24 where applicable |
| Common size | 10#–63# |
| Standard length | 6 m, 9 m, 12 m |
| Custom length | Approximately 2–19 m |
| Common zinc coating | 85–120 μm |
| Increased zinc coating | Approximately 100–140 μm by project requirement |
| Processing | Cutting, drilling, beveling, straightening, grinding, deburring |
For export orders, the structural steel standard, galvanizing standard, section size, steel grade, zinc coating and processing requirements should be confirmed against the project drawings and contract before production.
I beams and H beams are different structural sections and should not be treated as interchangeable. A conventional I beam has a narrower flange arrangement and inclined inner flange surfaces, while H beams generally have wider flanges and different section geometry.
When ordering, identify the beam by its section designation, dimensions and applicable standard rather than using only the general term "steel beam." The supplier should match the supplied section with the approved drawing before cutting and galvanizing.
The preferred sequence is to complete the required cutting and machining before galvanizing so that the processed steel receives zinc protection after fabrication.
Hot-rolled I beam → material inspection → straightening → cutting and machining → degreasing → pickling → fluxing → drying → hot-dip galvanizing → cooling → finishing → zinc coating inspection → dimensional inspection → packing.
The steel member is immersed in molten zinc at approximately 450°C. The zinc coating covers the exposed web, flanges, edges and other accessible surfaces.
For larger or heavier sections, straightness and dimensions should be checked after galvanizing because heating and cooling can affect the final geometry.
Rongheng commonly supplies a zinc coating of 85–120 μm, with approximately 100–140 μm available when a higher coating requirement is specified.
| Application Environment | Coating Consideration |
|---|---|
| Normal outdoor exposure | 85–120 μm |
| Humid industrial environment | Higher coating requirement may be specified |
| Coastal or salt-laden environment | Increased coating and corrosion assessment |
| Severe chemical exposure | Confirm coating compatibility with the project environment |
| Continuous seawater immersion | Do not rely on standard atmospheric galvanizing alone |
A thicker zinc coating provides more zinc mass for atmospheric exposure, but coating thickness should be selected according to the actual environment and project corrosion requirements rather than used as a substitute for a complete corrosion-control system.
Q235B is used for conventional structural applications where the required section meets the calculated load and service requirements. Q355B provides higher yield strength and can be specified for applications requiring higher structural capacity.
The steel grade should be selected together with the beam size, span, loading and connection design. A higher-strength grade does not automatically compensate for an undersized section or unsuitable structural design.
A clear purchasing specification can be written as:
Q355B / 25# I Beam / 12 m / hot-dip galvanized / specified zinc coating / cut to drawing.
Where possible, fabrication should be completed before hot-dip galvanizing. Available processing includes:
Completing these operations before galvanizing helps provide zinc protection over the processed member. If cutting, drilling or welding is carried out after galvanizing, the exposed or heat-affected areas require suitable repair.
For galvanized I beam orders, inspection should cover both the base steel and the finished galvanized member.
Material certificates, galvanizing inspection records, dimensional inspection data and third-party inspection documentation can be arranged according to project requirements.
A coastal industrial project used 10# and 12# Q235B hot-dip galvanized I sections for outdoor structural support members. Because of the high humidity and salt-laden air, the project specified an increased zinc coating.
The galvanized members were supplied after dimensional checking and required processing. According to the supplied project record, the structure remained free from widespread rusting or coating peeling for seven years and passed repeated supervision inspections.
A large ground-mounted photovoltaic project required Q235B I beams for equipment bases and supporting structures exposed to sun, wind and rain. The beams were supplied with fixed-length processing and hot-dip galvanizing according to the project requirements.
The galvanized members arrived ready for structural installation, avoiding a separate large-scale site painting operation. The galvanized specification was selected for the project's 25-year design-life requirement.
For export orders, the following information should be confirmed before production:
Rongheng's supply chain is based in Tianjin Daqiuzhuang, providing access to hot-rolled steel, galvanizing and downstream steel processing resources.
For standard I beam sizes, stock-based supply can be coordinated where available. For project orders, fixed-length cutting, drawing-based processing, galvanizing, inspection and export preparation can be coordinated before shipment.
I beams generally have narrower flanges and inclined inner flange surfaces, while H beams generally have wider flanges and different section geometry. They should be specified by the exact section designation and dimensions rather than substituted based only on appearance.
Common grades include Q235B and Q355B. The appropriate grade should follow the structural design and project specification.
The common zinc coating range is 85–120 μm. Approximately 100–140 μm can be discussed for projects requiring an increased coating, subject to the applicable specification.
Yes. Fixed-length cutting, drilling, beveling, straightening, grinding and deburring can be completed before galvanizing according to the drawings.
Yes, but the zinc coating should be selected according to the actual exposure. Coastal and salt-laden environments require more corrosion assessment than ordinary inland outdoor conditions. Continuous seawater immersion requires a separate corrosion-control approach.
Not automatically. Changing the steel grade requires confirmation that the lower-strength material still meets the required structural load and service conditions.
Heating and cooling during galvanizing can affect the dimensions and straightness of steel members, particularly larger sections. Finished beams should therefore be inspected after galvanizing.
Yes, but welding removes the zinc around the heated area. The affected zone should be cleaned and repaired with a suitable zinc-rich coating after welding. Where possible, connection details should be completed before galvanizing.
Standard lengths include 6 m, 9 m and 12 m. Fixed lengths from approximately 2–19 m can be discussed according to production and transportation requirements.
Depending on the project, material certificates, galvanizing inspection records, dimensional inspection data, packing information and third-party inspection documentation can be provided.
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Secondary Arterial Road No. 2-1, Expansion Area of Daqiuzhuang Industrial Zone, Jinghai District, Tianjin, China
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