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Welded Box Girder Bridges
Welded steel box girder bridges for overpasses, viaducts and curved alignments, fabricated in segments to your bridge engineer’s design. The box interior is welded, inspected and coated before the section is closed, and every segment is sized for containers or flat racks with splice plates shop-fitted.
A box girder is closed by its last weld, so everything inside — diaphragms, stiffeners, internal coating — is finished and inspected first. We plan the segment lengths at the drawing stage around the transport route and out-of-gauge limits, then fabricate to that plan.
Flange and web welds are made to qualified procedures and tested by ultrasonic, radiographic or magnetic particle methods as the specification requires, with a report per weld. Splice plates are fitted and match-marked in the shop so site assembly follows the numbered sequence.
Part of Bridge Structures in Steel Bridge Structures . Other components in this sub-system: I/H Beam Simply Supported Bridges · Steel Truss Bridges · Pipe Truss Arch Bridges · Steel-Concrete Composite Bridges · Portal Frame Bridges
Technical Specifications
| Item | Specification |
|---|---|
| Design basis | EN 1993-2 / AASHTO LRFD as the project specifies; design stays with your bridge engineer |
| Material | S355 / S460 to EN 10025 or ASTM A36 / A992, EN 10204 type 3.1 certificates |
| Welding | AWS D1.1 / EN ISO 9606 qualified procedures; full-penetration flange and web welds |
| NDT | Critical full-penetration welds 100% UT or MT tested; RT or MT where the specification names it, report per weld |
| Splices | Shop-fitted, match-marked; HSFG assemblies to EN 14399 / ASTM F3125 |
| Coating | Shot blast to Sa 2.5, ISO 12944 system, DFT recorded |
Section sizes, grades and quantities for this product are issued with the quotation once your design basis and loads are received.
Advantages vs Engineering Considerations
| Advantages | Engineering Considerations |
|---|---|
| Planned around the transport routeSegment lengths and weights are set at detailing for containers, flat racks or breakbulk, not discovered at booking. | Fatigue governs many details; connection categories and weld quality must follow the bridge code. |
| Inside finished before closingDiaphragms, stiffeners and internal coating are completed and inspected before the closing welds. | Transport and launching or crane capacity often dictate segment lengths and splice positions. |
| Welds reportedFull-penetration welds are tested to the method the specification names, with a report per weld. | Corrosion protection for bridges is heavier and needs maintenance access planned from the start. |
| Splices ready for siteSplice plates are shop-fitted with match-marked holes; HSFG assemblies ship with the segments. | Bearings, expansion joints and deck interfaces must be detailed together with the steelwork. |
Certifications & Compliance
Every shipment leaves with the documents an auditor asks for. Scroll the row and open any certificate at full size.
China Steel Structure Manufacturing Grade I
AISC Certification
CE Marking – EN 1090-2 (CPR 01627)
OTC Document of Validity
International Welder Certification
Enterprise Qualifications Portfolio
DG Packaging Certificate
Labor & Scaffolding Contracting
Explosion-Proof Certificate
Industrial Pipeline Installation GC1
Power Facility License
Have drawings or a BOQ ready? Send them through the form and our engineers reply with a preliminary assessment.
Related Projects
Steel structures we fabricated and shipped for the same kind of building.
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Detailed Engineering & Shop Drawing Development
Utilizing advanced BIM platforms such as Tekla Structures, detailed 3D modeling and shop drawings are executed strictly in compliance with AISC 360 or Eurocode 3 (EN 1993). Connection designs are rigorously verified, with manufacturing drawings generated to ISO 2768-m tolerance standards. 100% clash detection with primary architectural and MEP systems is performed to ensure zero structural conflicts during field erection.
Nesting & Material Optimization
Intelligent nesting layouts are performed using advanced software like FastCAM/SigmaNEST in accordance with EN 10029 / ASTM A6 dimensional standards. Accounting for cutting kerf (2mm-5mm depending on plate thickness) and thermal contraction allowances, raw material utilization exceeds 92%. Offcuts are digitally barcode-tracked to ensure 100% mill test report (MTR) traceability.
Raw Material Incoming Inspection
All structural steel (Q355B/C/D, ASTM A572 Gr.50, S355JR/J2) must be accompanied by EN 10204 3.1 Mill Test Reports (MTR). Incoming quality control conducts 100% dimensional and visual inspections under ASTM A6 / EN 10029, verifying thickness tolerances (Class A/B) and internal lamination integrity via Ultrasonic Testing (UT) to ASTM A435. Chemical composition and mechanical properties are spot-verified by accredited 3rd-party labs.
CNC Cutting & Edge Preparation
Plate profiling and component cutting are executed via CNC oxy-fuel, high-definition plasma, and multi-kW fiber laser equipment. Cut surface quality strictly complies with EN ISO 9013 for perpendicularity and surface roughness (Range 3/4 tolerance). Multi-axis CNC beveling machines execute weld prep bevel angles within ±2.5° and root face dimensions within ±1.0 mm.
Primary Structural Welding
Welding is performed exclusively by AWS D1.1 or EN ISO 9606 certified welders using qualified Welding Procedure Specifications (WPS) supported by Procedure Qualification Records (PQR) per AWS D1.1 / ISO 15614. Submerged Arc Welding (SAW) and Flux-Cored Arc Welding (FCAW) dominate Complete Joint Penetration (CJP) and fillet welds. Heat input is strictly controlled, achieving weld quality levels conforming to ISO 5817 Quality Level B or AWS D1.1 standards.
Weld Distortion Straightening
Post-weld angular distortion, camber, and sweep are rectified using automated hydraulic flange straighteners and controlled thermal flame straightening. Heating temperatures for High-Strength Low-Alloy (HSLA) steels are strictly maintained between 600-650 Celsius (air-cooled, zero water quenching) to prevent microstructural degradation. Post-straightening straightness tolerances meet ±3 mm, conforming to EN 1090-2 Execution Class 2 (EXC2) and AISC COSP standards.
Non-Destructive Testing (NDT)
NDT protocols are operated by ISO 9712 / ASNT Level II certified NDT personnel. 100% of critical Complete Joint Penetration (CJP) welds undergo Ultrasonic Testing (UT per ISO 17640 / ASTM E164) or Magnetic Particle Testing (MT per ISO 17638 / ASTM E709). Radiographic Testing (RT) is applied as requested for heavy sections. Weld acceptance conforms strictly to ISO 11666 Acceptance Level 1 or AWS D1.1 criteria.
Trial Assembly & Shop Alignment
Complex geometries, long-span trusses, and heavy framing undergo 1:1 physical trial assembly or high-precision 3D laser scanning virtual assembly per EN 1090-2 / AISC requirements. Bolt hole alignment is verified (≥95% free-pass rate for high-strength bolts), and critical dimensions (span, camber, 3D spatial alignment) are verified within tight tolerance limits (±2.0 mm) to eliminate site fitting risks.
Surface Preparation & Protective Coating
Structural members undergo automated shot blasting to achieve SSPC-SP10 / NACE No. 2 / ISO 8501-1 Sa 2.5 cleanliness, with a surface profile (anchor depth) of 45-75 microns. High-performance protective coatings are applied using airless spray technology in compliance with ISO 12944 (C3 to CX corrosive environments), featuring Zinc-Rich Epoxy Primers, Epoxy Micaceous Iron Oxide Intermediate coats, and Polyurethane/Fluorocarbon Topcoats. Dry Film Thickness (DFT) is verified adhering strictly to the 90/10 rule.
Final Quality Inspection & Certification
Final Quality Control (FQC) performs a comprehensive audit, inspecting paint aesthetics (zero runs, pinholes, sagging), critical geometry, bolt hole pitches, and component mark traceability. A complete Manufacturing Data Report (MDR) comprising MTRs, NDT records, coating inspection logs, and Certificates of Conformance is compiled to support CE Marking (DoP under EN 1090) and AISC final acceptance.
Export Packaging & Logistics Protection
Protective packaging is engineered for containerized (40HQ/OT/FR) and breakbulk ocean freight under heavy maritime transit conditions. Structural members are bundled on heavy-duty steel skids with high-tensile steel strapping. Machined connections are wrapped with VCI anti-corrosion film, EPE foam padding, and heavy rubber cushions. All timber packing complies fully with ISPM 15 phytosanitary standards and IMO Cargo Stowage and Securing (CSS) rules.
Global Field Erection & Site Management
We deliver international site erection supervision and turnkey EPCM construction services adhering to OSHA 1926 safety protocols, AISC COSP, and EN 1090-2 erection standards. Field teams, led by multilingual HSE and QA/QC engineers, utilize high-precision total stations to maintain structural plumbness within H/1000 (25mm max). High-Strength Structural Bolting is executed via calibrated Wrench or Turn-of-Nut methods with 100% torque audit documentation.
Frequently Asked Questions
How are steel box girders shipped?
In segments sized for standard containers or flat racks, with internal welding and coating completed in the shop and splice plates fitted for site bolting or welding as designed.
Can you fabricate curved box girders?
Yes, to the alignment on your engineer’s drawings. Curved segments are set out from the 3D model and checked dimensionally before the box is closed.
Do you fabricate to EN 1993-2 or AASHTO for bridge work?
Either, whichever the project specifies. The difference matters most in fatigue detail classification and weld acceptance criteria, so we ask which code governs before quoting rather than after.
What happens if a segment exceeds out-of-gauge limits?
Girders that exceed OOG limits are spliced at a low-stress location agreed with your engineer, with the lifting and lashing plan produced during detailing.
Do you supply the shear studs for a composite deck on the box?
Yes. Headed shear studs are supplied to the diameter, length and layout on the bridge drawings, with material certificates.
Can you supply this sub-system on its own, without the full frame?
Yes. We quote sub-systems separately where the scope makes sense — for example secondary framing or bracing against an existing structure. Send the BOQ and connection details of the receiving structure so the interfaces are engineered rather than assumed.
Which design code do you fabricate to?
Whichever your design specifies. Design intent to AISC 360 or Eurocode 3 (EN 1993), execution to EN 1090-2 EXC2 under certificate 2787-CPR-01627.
Do you substitute section sizes or grades?
Never without written approval. If a specified section has a long lead time we propose the alternative with the calculation showing equivalence, and you decide.
What documentation ships with these components?
Mill test certificates per heat, WPS/PQR, welder qualification certificates, NDT reports with technician level, and coating thickness records against the specified ISO 12944 system.
What is a realistic lead time?
The standard cycle for a single-building scope is 40 to 50 days: 1–2 weeks to shop drawings for your approval, then 4–5 weeks for procurement, fabrication, coating and loading.
Send Us Your Drawings or BOQ
Tell us the footprint, span, crane capacity and local loads — our engineering team reviews every request and replies with a preliminary assessment.
- Reviewed by our engineering team
- AISC certified · CE marked EN 1090-2 (EXC2)
- Mutual NDA available on request
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