- 1. What Is a Circular Structural Steel Tube?
- 2. Standards Commonly Used for Round Structural Steel Tubes
- 3. Selecting the Steel Grade
- 4. How to Evaluate a Manufacturer in China
- 5. Supplier Qualification Checklist
- 6. LONGMA Circular Structural Steel Pipe Manufacturing
- 7. FAQ
- 8. Request a Round Structural Steel Pipe Quotation
China has a broad steel pipe manufacturing base, but a competitive quotation does not by itself establish that a supplier is suitable for a structural project. Buyers should verify the actual manufacturing facility, round-pipe production range, steel grade, product standard, inspection capability, traceability, surface protection, documentation, and delivery plan before placing an order.
This guide focuses on circular hollow sections (CHS) and other round structural steel pipes. Square and rectangular hollow sections are outside the LONGMA manufacturing scope and are not included in the quotation guidance below.
What Is a Circular Structural Steel Tube?
A circular structural steel tube is a hollow round steel section selected primarily for load-bearing or structural use. Its suitability depends on the complete engineering design, including member loads, section properties, buckling resistance, connections, wall thickness, steel grade, fabrication, corrosion protection, and service environment.
The product standard defines manufacturing and delivery requirements for the tube, while the structural design code governs how the member is used in the completed structure. Supplying a recognized steel grade does not, by itself, demonstrate that a finished building, tower, bridge, or support structure satisfies its design code.
Standards Commonly Used for Round Structural Steel Tubes
EN 10219
EN 10219 covers cold-formed welded structural hollow sections. EN 10219-1 specifies technical delivery conditions, and EN 10219-2 covers tolerances, dimensions, and sectional properties. The applicable edition and any project amendments should be stated in the purchase specification.
ASTM A500/A500M
ASTM A500/A500M covers cold-formed welded and seamless carbon steel structural tubing in round and other shapes. For a LONGMA inquiry, buyers should specify the round product, manufacturing route, grade, dimensions, and inspection requirements rather than assuming that every shape covered by the standard is available from the same factory.
AS/NZS 1163 and Project Specifications
Projects may also specify AS/NZS 1163 or owner-specific requirements. Product availability must be confirmed against the requested grade, diameter, wall thickness, length, inspection plan, and destination market.
Selecting the Steel Grade
Grade selection should come from the structural design and project specification. Yield strength is important, but it is not the only criterion. Design temperature, impact requirements, section thickness, welding procedure, forming route, connection design, availability, and corrosion conditions can all affect the final choice.
| Grade example | Typical procurement consideration | What the buyer should verify |
| S235JRH | General structural use where the specified strength and toughness are adequate | Design demand, thickness range, delivery condition, and product standard |
| S275J0H | Higher nominal strength and a defined impact designation | Required test temperature, section thickness, and project acceptance criteria |
| S355J2H | Higher-strength structural use with specified impact properties | Design temperature, welding requirements, impact testing, and documentation |
These grades are not automatic substitutes for one another. The project engineer should approve any proposed material change, including its effect on member resistance, connections, fabrication, and inspection.
How to Evaluate a Manufacturer in China
Confirm the Actual Production Scope
Ask the supplier to confirm whether the required round pipe is manufactured at its own facility and whether the proposed diameter, wall thickness, length, grade, and standard fall within the normal production range. A large overall capacity is less useful than proven capability for the specific product being purchased.
Review Manufacturing and Weld Control
For welded circular structural tubes, review the forming route, welding process, weld inspection, dimensional control, and repair procedure applicable to the ordered standard. The inspection plan should reflect the product standard and project risk rather than applying the same NDT scope to every order.
Verify Traceability and Documentation
The supplier should maintain identification from incoming material through pipe production and final shipment. If EN 10204 Type 3.1 documentation is required, it should be specified in the purchase order. Independent third-party inspection is a separate requirement and should be defined through an agreed inspection and test plan.
Check Surface Protection and Logistics
Mill finish, shop primer, paint, galvanizing, or another protection system should be selected according to the exposure environment and project specification. Buyers should also review packing, lifting points, loading plans, end protection, transport route, destination, and delivery sequence for large-diameter round pipe.
Supplier Qualification Checklist
| Evaluation item | Evidence or information to request |
| Manufacturer identity | Legal company name, factory address, and confirmation of the production facility |
| Round-pipe capability | Outside diameter, wall thickness, length, grade, standard, and ERW or LSAW route |
| Quality control | Dimensional inspection, chemical and mechanical testing, weld inspection, and applicable NDT |
| Traceability | Heat number, production records, inspection records, and marking procedure |
| Documentation | Required MTC, coating records, inspection reports, and release documents |
| Project experience | Comparable round-pipe sizes, grades, quantities, applications, and destination markets |
| Commercial delivery | Quantity, production schedule, packing, Incoterm, port, and shipment plan |
LONGMA Circular Structural Steel Pipe Manufacturing
LONGMA manufactures round ERW and LSAW steel pipe. According to the company’s ASTM A671 product page, LONGMA operates two factories with a combined plant area of 200,000 square meters and reports an annual steel pipe output of 300,000 tons. These company-level figures should not replace project-specific confirmation of the required diameter, wall thickness, grade, standard, and schedule.
For structural inquiries, LONGMA can review round-pipe dimensions, steel grade, product standard, inspection, documentation, end preparation, surface protection, packing, and delivery requirements. Square and rectangular hollow sections are not part of the stated manufacturing scope.
FAQ
What should I check before buying round structural steel tube from China?
Start with the approved product specification. Confirm outside diameter, wall thickness, grade, length, standard, quantity, surface protection, inspection, documentation, and destination. Then verify that the proposed factory can manufacture and document that exact configuration.
What is the difference between EN 10219-1 and EN 10219-2?
EN 10219-1 addresses technical delivery conditions. EN 10219-2 addresses tolerances, dimensions, and sectional properties. Both may be relevant to an EN 10219 order.
Can EN 10204 Type 3.1 documentation be requested?
Yes, when agreed in the purchase specification. It documents product-specific inspection results through the manufacturer’s authorized inspection representative. Third-party inspection should be specified separately.
Does LONGMA manufacture square or rectangular structural tubes?
No. This article and the associated quotation guidance apply to round ERW and LSAW steel pipe only.
Request a Round Structural Steel Pipe Quotation
Send the outside diameter, wall thickness, length, steel grade, product standard, quantity, surface treatment, inspection and documentation requirements, destination, and required schedule to info@ilongma.com. LONGMA will review the requested round-pipe configuration before confirming the technical and commercial offer.
