Q235 Q345 ERW Welded Square Rectangular Steel Tube 10-600mm

Description

Factory-Direct ERW Tubes — 2,800+ specs in stock from a single mill

Technical Specifications

Application Suitability

Where Sharp-Corner Tolerance Decides Facade Acceptance on an ERW Welded Square and Rectangular Steel Tube Order

Rounded corners on a standard rectangular tube create visible gaps at welded joints — our patented sharp-corner process eliminates this at the forming stage.

When facade contractors receive rectangular tubes with R≥2t corners, the mismatch between tube profile and curtain wall bracket forces on-site grinding or custom filler plates. On a recent Southeast Asia high-rise project, an entire curtain wall bay had to be re-fabricated because the specified right-angle profile was substituted with a standard rounded-corner tube from a different supplier. Dimensional drift beyond ±1% tolerance compounds the problem: even a 1 mm deviation on a 200×100 mm section throws off bolt-hole alignment across a 6-meter span. [NEED_CITE: EN 10219 dimensional tolerance requirements for cold-formed structural hollow sections]

How ERW Welded Square and Rectangular Steel Tube Profiles Match Structural Frame Demands

An ERW welded square and rectangular steel tube in Q345 or S355 grade delivers the section modulus needed for moment-resisting frames while maintaining flat bearing surfaces at connection nodes. The sharp-corner rectangular profile — produced through our patented forming process — sits flush against gusset plates and bracket flanges without shimming, which matters when a glass curtain wall system requires zero-gap tolerance across hundreds of connection points. For machinery builders, the ±1% wall thickness consistency ensures predictable deflection under cyclic loading on hydraulic press frames.

Engineering Compliance and Certification Pathways

Structural hollow sections used in load-bearing frames must conform to EN 10219 for cold-formed welded profiles or ASTM A500 for North American projects — the steel grade equivalence between Q345 and S355JR requires documented chemical and mechanical mapping, not just a label swap. [NEED_CITE: steel grade equivalence mapping between GB Q-series and EN S-series standards] CE certification under EN 10210/10219 is mandatory for EU customs clearance, while Singapore FPC approval governs public infrastructure supply in Southeast Asia. Surface treatment selection — bare for indoor structural use, pre-galvanized for moderate corrosion environments, hot-dip galvanized for coastal or industrial exposure — must align with the project’s corrosion category classification before fabrication begins.

Steel Grade Selection and ERW Welding Metallurgy

The Q-series (Q195–Q345) follows Chinese GB standards where the number denotes minimum yield strength in MPa; S235 and S355 follow EN 10219 with equivalent yield designations; GR.A and GR.B map to ASTM A500 for North American structural applications. ERW welding produces a longitudinal seam through resistance heating without filler metal — the heat-affected zone remains narrow, preserving base metal ductility for subsequent cold-bending operations. Wall thickness from 0.8 mm to 30 mm covers everything from light-gauge purlin systems to heavy-duty column sections, but negative tolerance beyond the ±1% threshold reduces actual load capacity below design calculations. Our patented sharp-corner forming process maintains consistent corner radius — true 90-degree angles — without cracking the outer fiber, which is critical when the tube serves as both structural member and architectural finish.

The Hidden Cost of Unverified Wall Thickness on Structural Orders

A 5% negative tolerance deviation on a 10 mm wall tube means the actual section carries roughly 10% less load than the engineer calculated — and no amount of Mill Test Certificate paperwork fixes a column that fails inspection under ultrasonic thickness testing. [NEED_CITE: structural hollow section tolerance impact on load-bearing capacity] Material substitution without grade equivalence documentation triggers customs holds in EU markets; missing CE marks on EN 10219-profiled tubes result in outright rejection at port. The real cost is not the per-ton price difference — it is the six-week project delay when 40 tons of non-conforming tubes sit in a bonded warehouse waiting for re-certification or return shipment.

Why Project Procurement Teams Source from SD XJY Pipe

We invented China’s first sharp-corner rectangular tube and hold 41 patents on the forming process — this is not a marketing claim but a verifiable technical distinction that eliminates the rounded-corner gap problem at the source. Our in-house physical and chemical laboratory tests every heat number for dimensional accuracy, yield strength, and chemical composition before release; the Mill Test Certificate you receive reflects actual batch data, not template values. With 3 production lines covering 2,800+ specifications and wall thickness up to 40 mm, we consolidate structural tubes, section steel, and specialty profiles into a single shipment — reducing your forwarding costs and customs documentation burden. Full CE certification under Lloyd’s registry, ISO 9001:2015, and Singapore FPC approval means your procurement team spends time on engineering decisions, not certification chasing.

Documentation & Compliance

• Mill Test Certificate documenting Q345 or S355JR chemical composition and yield strength per EN 10219 or ASTM A500, traceable by heat number
• CE certificate issued under EN 10210/EN 10219 for structural hollow sections exported to EU member states
• ISO 9001:2015 quality management certificate covering ERW welding process control and dimensional inspection
• SGS or BV third-party inspection report verifying wall thickness, corner geometry, and surface treatment compliance before shipment
• Material traceability report linking each bundle to heat number, production date, and test specimen results
• Customs documentation including packing list, bill of lading, and certificate of origin formatted for destination-port clearance

Packaging, Loading & Delivery

• ERW welded square and rectangular steel tubes bundled with high-tensile steel strips; sharp-corner profiles separated by edge protectors to prevent zinc coating abrasion on galvanized finishes
• Hot-dip galvanized tubes wrapped in waterproof membrane at bundle ends to prevent white rust formation during ocean transit
• Container loading optimized by nesting smaller-section tubes inside larger rectangular profiles — a 200×100 mm section fits inside a 300×200 mm, maximizing payload per 40ft container
• Custom cut-to-length service available for 6 m standard lengths; cut ends deburred and re-oiled to prevent edge corrosion
• Heat number and steel grade stenciled on each tube end for site identification; bundle tags include PO number, specification, and gross weight
• FOB Jinan/Qingdao port with CIF and DDP options; professional lashing and anti-roll bracing for 6 m+ lengths to prevent transit damage

How to Initiate Your ERW Welded Square and Rectangular Steel Tube Inquiry

Submit your specification sheet — section dimensions, wall thickness, steel grade, surface treatment, quantity, and destination port — and receive a detailed quotation within 12 hours including unit pricing, production lead time, and applicable certification documentation. For non-standard sizes or sharp-corner rectangular profiles outside catalog ranges, our engineering team provides custom feasibility assessment and tooling timeline.

Request Your Quotation and Mill Test Certificate Today

Send your technical specifications and quantity requirements to receive pricing, certification documentation, and container loading plan.

Shandong Xin Jiyuan Special Steel Tube Co., Ltd

Tel: +86 531 8573 6315

Mobile/WhatsApp/WeChat: +86 188 5315 7756

Email: admin@sdxjypipe.com