Description
ASTM Welded SHS/RHS Direct from Mill — Every Q235, Q345, and S355JR tube is verified against mill heat numbers before dispatch, eliminating tolerance surprises on structural frames.
Technical Specifications
| Parameter | Value |
|---|---|
| Designation | Q235/Q345/S355JR Welded Square and Rectangular Steel Tube |
| Product Type | Welded Square and Rectangular Steel Tube (SHS/RHS) |
| Steel Grade | Q195, Q235, Q235B, Q345, Q345B, S235JR, S275JR, S355JR, St37, St37-2, St42, St35, St35.4, St52.4 |
| Standard | ASTM |
| Section Shape | Square / Rectangular |
| Size Range | 40×80 mm, 40×60 mm |
| Wall Thickness | Per ASTM tolerance |
| Length | 6 m, 6.4 m, 12 m |
| Technique | ERW (Electric Resistance Welded) |
| Surface Treatment | Hot Rolled, Non-oiled (Black finish) |
| Tolerance | ±1% |
| Application | Fluid Pipe, Boiler Pipe, Drill Pipe, Hydraulic Pipe, Gas Pipe, Oil Pipe, Chemical Fertilizer Pipe, Structure Pipe |
| MOQ | 1 Ton |
| Origin | Shandong, China |
Application Suitability
| Industry | Typical Applications |
|---|---|
| Industrial Construction | Warehouse frames, factory building columns, mezzanine platforms |
| Oil & Gas | Gas transmission lines, chemical fertilizer transport pipes |
| Power Generation | Boiler tubes, hydraulic system supports |
| Machinery Manufacturing | Conveyor structures, equipment frames, drill pipe casings |
What Negative Tolerance Costs on a Warehouse Frame Order
Dimensional drift beyond ±1% forces on-site rework or outright rejection.
Overseas buyers sourcing Carbon Steel Square and Rectangular Tube Supplier products from fragmented traders frequently encounter wall thickness variations that exceed acceptable limits. A 40×80 SHS quoted at 3.0mm arriving at 2.7mm means the entire batch fails structural calculations — replacement costs and air freight eat margins before the warehouse frame even goes up. Material traceability gaps compound the problem: when fabricators source from third-party mills, heat number certification chains break, leaving engineers unable to verify compliance with ASTM requirements. [NEED_CITE: steel grade equivalence between EN and ASTM standards]
Matching ERW Welded Tubes to Structural Frame Requirements
ERW welded SHS/RHS in Q235 and Q345 grades deliver the dimensional consistency that warehouse frames and industrial buildings demand. The ±1% tolerance ensures connection plates fit without forcing, while hot rolled black finish provides clean weldability for on-site modifications. Our vertically integrated mill-to-fabrication model means every 40×60 and 40×80 tube traces back to a single heat number — no third-party sourcing gaps that leave structural engineers guessing about material provenance.
Engineering Compliance for ASTM-Certified Projects
ASTM-standard welded square and rectangular tubes must meet dimensional tolerances and chemical composition requirements before customs clearance in North American markets. Q345 and S355JR grades serve load-bearing columns and beams where yield strength consistency matters, while Q195 and S235JR suit secondary structures and bracing. The 6m and 12m standard lengths align with typical container loading plans, though custom cutting to 6.4m or site-specific dimensions reduces field welding. Third-party inspection reports from SGS or BV confirm compliance when project specifications demand independent verification. [NEED_CITE: ASTM A500 Grade B and Grade C dimensional requirements]
Understanding ERW Process and Grade Selection
Electric Resistance Welding creates a longitudinal seam by passing current through the tube edges under pressure — no filler metal, no weld beads to grind. This process suits Carbon Steel Square and Rectangular Tube Supplier applications where internal surface smoothness matters for fluid transport or where external appearance affects architectural visibility. Q235 and Q345 represent the Chinese grade system, directly equivalent to S235JR and S355JR in European standards, while St37 and St42 follow older DIN designations still specified in legacy projects. Hot rolled black finish means the tube receives no oil coating after rolling — the scale layer provides temporary corrosion protection during storage and transit, but requires shot blasting before painting for long-term outdoor exposure. Negative tolerance within ±1% affects theoretical weight calculations: buyers ordering by weight must confirm whether mills calculate using nominal or actual thickness. [NEED_CITE: ERW versus seamless tube manufacturing differences]
Hidden Costs of Unverified Material Certification
Purchasing Carbon Steel Square and Rectangular Tube Supplier products without mill test certificates risks structural rejection during inspection. ASTM standards require chemical composition and mechanical property documentation — missing heat numbers mean customs holds or site engineers refusing installation. Negative tolerance exceeding ±1% doesn’t just reduce load capacity; it triggers redesign costs when calculated deflections exceed limits. Third-party re-inspection after arrival costs more than upfront verification, and replacement shipments delay project schedules by weeks. [NEED_CITE: EN 10219 cold-formed hollow section certification requirements]
Why Source Welded SHS/RHS from XJY Structure
Our own steel mill produces the raw material for every welded square and rectangular tube we fabricate — no broker markups, no third-party quality gaps. The 2,800+ specification range covers Q195 through S355JR in sizes from 40×60 to large structural sections, meaning one purchase order consolidates your entire project bill of materials. Each heat number receives in-house testing for chemical composition and mechanical properties before the tube leaves the production line. Certified welding procedures per AWS and EN standards ensure ERW seams meet international requirements, while complete documentation packages include WPS, PQR, weld maps, and dimensional inspection reports. Professional loading teams understand oversized cargo requirements — 12m tubes need specialized lashing to prevent transit damage, and we handle the stowage planning.
Documentation & Compliance
- Mill test certificate documenting Q235/Q345/S355JR chemical composition and mechanical properties per ASTM requirements
- Material traceability report linking each tube bundle to specific heat numbers from our integrated steel mill
- Third-party inspection certificates from SGS or BV confirming dimensional tolerance and surface quality
- Welding procedure specifications (WPS) and procedure qualification records (PQR) for ERW seam integrity
- Export documentation package including packing list, bill of lading, and certificate of origin for customs clearance
- Dimensional inspection reports verifying ±1% tolerance compliance on 40×80 and 40×60 sections
Packaging, Loading & Delivery
- Hot rolled black finish tubes bundled with steel straps and edge protectors to prevent surface damage during ocean transit
- 6m and 12m lengths loaded in dedicated containers with wooden chocks preventing longitudinal movement
- Custom cut lengths (6.4m or site-specific) packaged separately with heat number stenciling for easy identification
- Non-oiled black finish requires moisture barriers in container — desiccant packets and plastic wrapping prevent scale rust
- FOB, CIF, and DDP terms available with door-to-door logistics coordination for project sites
- Bundle tags display steel grade (Q235/Q345/S355JR), size, length, and heat number for receiving verification
Requesting Quotation for Your Project Specifications
Submit your project drawings, steel grade requirements, and quantity needs to receive detailed pricing including material, fabrication, coating, and shipping costs. We provide shop drawing reviews and material optimization recommendations before contract signing, ensuring your Carbon Steel Square and Rectangular Tube Supplier order matches engineering specifications. Confirm ASTM certification requirements and third-party inspection needs upfront so documentation packages align with your project’s compliance framework.
Get Your Welded SHS/RHS Quote with Mill Test Certificates
Share your project specifications, required steel grades, and destination port to receive pricing and material certification details within 24 hours.
Contact: Shandong Xin Jiyuan Special Steel Tube Co., Ltd
Email: admin@xjystructure.com
Mobile/WhatsApp/WeChat: +86 188 5315 7756
