Square & Rectangular Tubes

Structural steel fabricators in Poland build frames, halls, canopies, carports and solar mounting systems with square and rectangular steel tube. Sino East Steel is a structural tube manufacturer and factory producing EN 10219, ASTM A500 and JIS G3466 square, rectangular and special-section tube from 20×20 mm to 400×400 mm, in black, pre-galvanized and hot-dip galvanized finishes. As the factory, we control weld quality, corner radii and straightness, and we supply mill certificates so your structural calculations and EU documentation are straightforward.
Square & Rectangular Steel Tubes for Structural FramingSquare and rectangular hollow sections (SHS/RHS) are cold-formed or hot-formed steel tubes whose flat faces simplify welding, bolting and connection design — which is why they dominate steel framing, railings, machinery frames and architectural structures across Europe. Sino East Steel supplies SHS and RHS in sizes from 20×20 mm to 400×400 mm, with wall thicknesses from 1.2 mm to 16 mm, in EN 10219 S235JR to S355J2H, ASTM A500 and GB/T 6728 grades, in black, galvanized and pre-galvanized finishes. Tubes can be delivered in standard 6 m and 12 m lengths or cut to drawing.
Forming and Sizing of Hollow SectionsStrip or coil is roll-formed into a closed section on a continuous mill, welded by high-frequency ERW, and then passed through sizing rolls that form the exact square or rectangular profile. Galvanized versions receive a hot-dip zinc coating after forming, which protects the corners and internal surfaces uniformly. Every batch is straightened, cut and checked for corner radius, flatness and weld quality before packing.
ApplicationsSquare and rectangular tubes are used in steel frame construction, mezzanines and platforms, handrails and balustrades, gates and fences, solar panel mounting frames, carports, greenhouses, agricultural buildings, vehicle and trailer frames, conveyor supports, exhibition stands and architectural detailing. Galvanized RHS is especially popular with Polish fabricators because it eliminates painting on outdoor structures.
Selecting the Right SectionFor load-bearing columns and beams, calculate the section modulus and choose EN 10219 S355J2H for efficient strength-to-weight. For railings and lightweight frames, S235JR is the economical standard. Consider the corner radius for welding fit-up, and choose galvanized sections for outdoor or humid environments. We can also provide structural design data (section properties) for the sizes you order.
Standards, Grades & Equivalents

StandardGradeTypical Use
EN 10219-1/-2S235JR – S355J2HCold-formed welded hollow sectionsEN 10210S235JRH – S355J2HHot-formed hollow sectionsASTM A500A, B, CCold-formed welded carbon steelGB/T 6728Q235B – Q355BStructural hollow sections
Available Sizes & Range

ItemRangeNotes
Square20x20 – 400×400 mmWT 1.2 – 16 mmRectangular40x20 – 400×200 mmWT 1.2 – 16 mmLength6 / 12 mor cut to size
Specification Deep-Dive for Square & Rectangular TubesStructural square and rectangular tube is produced to EN 10219 (cold formed, welded) or ASTM A500 (Grades B and C), with dimensions from 20×20×1.5 mm up to 400×400×16 mm (square) and 500×300 mm (rectangular). Corner radius, straightness and twist tolerance are the three dimensions Polish fabricators check when welding frames — we hold corner radius to 2-3 times wall thickness per EN 10219 and straightness within 0.1% of length. Yield strength for EN 10219 S235 is 235 MPa and S355 is 355 MPa; ASTM A500 Grade C offers 345 MPa minimum yield with high weldability. Wall thickness tolerance is typically ±10%. Tubes are supplied in 6 m or 12 m lengths, or cut to custom lengths, with plain ends (deburred) or bevelled ends for welding. Finishes: black (mill finish), pre-galvanized (Z180-Z275) and hot-dip galvanized (Z400+) for external structures. Each batch ships with mill certificates documenting chemistry and mechanical properties, and we can supply load tables for standard sections so your engineer can size members without waiting for material tests. Solar mounting, carports, canopies, mezzanine floors and agricultural frames are the fastest-growing tube applications in Poland — we supply the consistent sections those industries need.
Ordering Square and Rectangular TubeSpecify the tube dimensions (width × height × wall), length, standard (EN 10219, ASTM A500) and finish (black, pre-galvanized, hot-dip). Fabricators ordering standard sizes in volume benefit from mill pricing and fixed monthly production slots. We also cut to length and pack for direct delivery to your fabrication hall.
Quality Control & CertificationEvery batch of material delivered from our Tianjin plant passes through a documented inspection routine: chemical composition analysis, tensile and yield testing, dimensional checks and, where applicable, hydrostatic or flattening tests. Each consignment ships with an EN 10204 3.1 mill test certificate (MTC) and batch traceability records, so your incoming inspection at Gdansk, Gdynia, Szczecin or any other EU port is straightforward. The factory operates under an ISO 9001:2015 quality management system and is independently audited by SGS and TUV Rheinland for production capacity and export reliability.
Export Documentation IncludedEvery order is shipped with a complete documentation set: commercial invoice, packing list, bill of lading, certificate of origin, and the EN 10204 3.1 mill test certificate with heat numbers and test results. Where your project requires third-party inspection, we can arrange SGS, TUV or Bureau Veritas inspection before loading, with the inspection report issued in English for easy clearance in the EU.
Why European Buyers Source This Product from Sino East SteelImporting steel from China to Poland is a routine, well-understood process when you work with a manufacturer that has done it hundreds of times. Sino East Steel combines factory-direct pricing with export experience across the EU, so you avoid the margin stack of trading companies and the documentation delays that slow down first-time imports. Our export team prepares commercial invoices, packing lists, certificates of origin, and the EN 10204 3.1 mill certificates your quality department and customs broker expect. We also coordinate vessel booking from Tianjin/Xingang to Baltic ports, and for regular customers we can hold production slots so repeat orders keep your warehouse stocked without interruption.Because we are the manufacturer, specification changes, coating requirements, packing instructions and delivery dates are agreed directly with the people who control the production line. This transparency is what distributors and contractors in Poland value most: one accountable partner, one set of documents, and material that matches the sample on every shipment.
Packaging & Delivery to Poland and the EUProducts are packed in seaworthy export condition: steel strapping, waterproof wrapping, and wooden or steel pallets where required, with clear marking for safe handling. For pipe and tube orders we use the standard export bundle format with plastic end caps on request. Sea freight to Polish and Baltic ports (Gdansk, Gdynia, Szczecin, Klaipeda) is arranged from Tianjin or Xingang port, with typical lead times of 15–25 days after production. FCL and LCL options are both available, and mixed-container consolidation is offered for regular customers who combine several product lines in one delivery.
Customization & Value-Added ServicesBeyond standard supply, our finishing lines can prepare material for your exact production step: cutting to length, drilling, bevelling, threading, coating, marking and custom bundling per your drawings. Packaging can be adapted to your handling equipment — pallets, frames, slings or individual protective wrapping — and private labeling is available for distributors who resell under their own brand. For customers with regular monthly programs, we schedule production slots so that reorder quantities arrive on time, allowing you to run leaner stock without risking supply gaps on your own production line.
Technical Support & After-Sales ServiceOur export engineers support you from specification to installation: confirming grade and size selections, advising on coatings and packing for your climate and handling equipment, and answering technical questions from your quality department. After delivery, we keep the batch records on file and can issue additional documentation, arrange replacement paperwork, or support you in the rare case of a claim. For Polish customers this means a single point of contact who knows your orders, your specifications and your delivery history — service that trading intermediaries rarely match.
Inspection & Testing Before ShipmentBefore any material leaves the plant it passes through a defined inspection gate. Dimensional checks are performed against the ordered specification, surface quality is inspected visually and with instruments where required, and the relevant mechanical and chemical tests are verified against the mill certificate. For pipe and tube products, hydrostatic and non-destructive testing results are reviewed against the standard’s acceptance criteria. Customers who request it can witness the inspection or receive photographs and video of the loaded goods before the vessel sails — a practical way to build confidence without travelling to China.
How to Order & Request a QuotationTo receive a firm quotation, please send your required specification: grade and standard, dimensions, quantities (in tons or pieces), end use, and the destination port in Poland or the EU. Our export team replies within 24 hours with pricing, availability and a proposed shipping schedule. We work with T/T and L/C payment terms, and for established EU customers longer payment arrangements can be discussed on a project basis.Request a quote: use the contact form, WhatsApp +86-186-2208-8833, or email [email protected].
Frequently Asked Questions
Can you supply square and rectangular tubes galvanized?Yes. Hot-dip galvanizing after forming is available for all sizes, with coating weights up to 600 g/m² per EN ISO 1461. The galvanized tube can be supplied in standard or cut lengths.
What lengths do you produce?Standard lengths are 6 m and 12 m; we also cut to exact lengths for railing posts, frame members and prefabricated components.
What is the maximum tube size you manufacture?Square tube up to 400×400 mm and rectangular tube up to 500×300 mm, with wall thicknesses from 1.5 mm to 16 mm, in EN 10219, ASTM A500 and JIS G3466 specifications.
Do you supply galvanized structural tube?Yes, both pre-galvanized (zinc-coated strip) and hot-dip galvanized after forming. HDG is recommended for external structures such as solar frames and outdoor canopies in Poland.
What documents do you provide with each shipment?Each shipment includes the EN 10204 3.1 mill test certificate, packing list, commercial invoice and bill of lading. Inspection reports and third-party certificates (SGS, TUV, Bureau Veritas) can be arranged before loading if your project requires them.
Can you supply to Polish and European standards?Yes. We regularly export to EN and DIN specifications used across the EU, including EN 10219, EN 39, EN 10210, EN 10305 and DIN 2440, in addition to ASTM and API standards. Tell us the standard your project specifies and we will quote accordingly.
What are your MOQ and lead times?MOQ depends on the product and size — typically from 1 to 10 tons for standard lines. Production and shipping to Polish ports normally takes 15–25 days from order confirmation.
Do you ship to Polish ports and handle customs paperwork?Yes. We ship FOB Tianjin/Xingang, CIF or CFR to Gdansk, Gdynia, Szczecin and other Baltic ports, and we prepare the export documentation (commercial invoice, packing list, bill of lading, certificate of origin, mill certificates) needed for import clearance in Poland.
Can we arrange a pre-shipment inspection?Yes. Third-party inspection by SGS, TUV, Bureau Veritas or your own representative can be arranged before loading, and the inspection report is provided before the vessel departs.
Do you offer samples before a full order?For most products we can provide small samples or cut pieces so your quality department can verify the material. Sample cost is credited against the first order for regular customers.
About Sino East Steel — Sino East Steel is a factory-direct manufacturer and exporter of carbon steel, galvanized steel and structural steel products, operating from a 65,000 m² production base in Tianjin, China. Since 2005 the company has built a steady export record across Europe, the Middle East and the Americas, supplying distributors, contractors and engineering companies that require consistent quality, complete documentation and dependable delivery. For Polish buyers, this means a single certified source for pipes, coils, sheets, bars and structures, with every shipment supported by mill test certificates and traceable batch records.
Sourcing This Product from China to Poland — What to ExpectImporting steel from China to Poland is a standard, well-documented process when the manufacturer manages it end to end. After you confirm the specification, we issue a proforma invoice with price, production time and shipping terms (FOB Tianjin/Xingang, CIF or CFR to Gdansk, Gdynia, Szczecin or Klaipeda), produce and inspect the material, prepare the full export documentation set, and book the vessel. Total lead time from order confirmation to arrival at a Polish port is typically 15–25 days for standard products. Polish importers pay import VAT and customs duties at the EU border using the commercial invoice, packing list and certificate of origin we provide; the EN 10204 3.1 mill certificates satisfy your quality department and any project documentation requirements. For first orders we recommend a trial container with the most popular sizes, so you can verify material, documents and delivery performance before committing to a larger supply program.