Stainless Steel Square Tube - Precision Welded, ASTM A554, 304/316 Grade

Kuaima Steel Co., Ltd.

Verified Custom manufacturer 7yrs

Stainless steel square tube image thumbnail

Technical Specifications of Stainless Steel Square Tube

Property	Parameter	Description
Product Name	Stainless Steel Square Tube	Hollow structural section with square cross-section
Material Grade	304 / 316L / 201 / EN 1.4301 / 1.4404	Common austenitic stainless steel grades
Standard Compliance	ASTM A554, EN 10219, JIS G3466	Meets international tube standards
Carbon Content (C)	≤0.08% (304) / ≤0.03% (316L)	Low carbon for improved weldability
Chromium (Cr)	18.0-20.0% (304) / 16.0-18.0% (316L)	Provides corrosion resistance
Nickel (Ni)	8.0-10.5% (304) / 10.0-14.0% (316L)	Enhances ductility and corrosion resistance
Molybdenum (Mo)	- (304) / 2.0-3.0% (316L)	Improves pitting and crevice corrosion resistance
Tensile Strength	≥515 MPa	Minimum tensile strength per ASTM A554
Yield Strength	≥205 MPa	Minimum yield strength for structural applications
Elongation	≥40%	Ductility in 50mm gauge length
Size Range	10×10mm - 300×300mm	Available square tube dimensions
Wall Thickness	0.5mm - 20mm	Standard and custom thickness options
Length	6m or custom cut lengths	Standard length with customization available
Surface Finish	2B, BA, Mirror, Brushed (No.4), Satin	Multiple surface treatment options
Manufacturing Process	Welded (TIG/Laser) or Seamless	High-precision welding or seamless extrusion
Application	Architecture, Furniture, Railing, Machinery	Structural and decorative applications
Certification	EN 10204 3.1, ISO 9001, CE	Quality certifications provided
Packaging	Bundled with steel straps, plastic caps, wooden crates	Standard export packaging for protection
MOQ	500 kg	Minimum order quantity

Stainless Steel Square Tube - Precision Welded, ASTM A554, 304/316 Grade

Stainless steel square tube represents a cornerstone structural component in modern industrial and architectural applications, combining superior corrosion resistance with exceptional mechanical strength. Manufactured through precision welding processes and conforming to ASTM A554 specifications, these hollow sections serve critical roles in construction frameworks, decorative installations, and mechanical systems. Available in premium 304 and 316 grades, our mill-direct square tubes deliver cost-effective solutions for engineers, fabricators, and contractors seeking reliable performance in both corrosive and high-stress environments.

stainless steel square tube supplier

What is Stainless Steel Square Tube?

Stainless steel square tube is a hollow structural section with equal-sided square geometry, produced through continuous forming and welding of flat-rolled stainless steel coils. The manufacturing process employs high-frequency induction welding or TIG welding techniques to create seamless longitudinal joints, resulting in uniform wall thickness and precise dimensional tolerances. Defined by ASTM A554 standards, these tubes maintain consistent mechanical properties throughout their length, with wall thicknesses ranging from 0.5mm to 12mm and outer dimensions from 10mm to 400mm per side.

Stainless Steel Square Tube Technical Specifications

Our precision-welded square tubes comply with ASTM A554-17 Section 5 for dimensional tolerances, maintaining ±0.5mm accuracy on outer dimensions and ±10% variance on wall thickness. Grade 304 tubes exhibit tensile strength of 515 MPa minimum per ASTM A240, while 316 variants achieve 515-690 MPa with enhanced molybdenum content of 2.0-3.0% for superior pitting resistance. Surface finishes range from 2B mill finish (Ra 0.5μm) to 180 grit polished (Ra 0.2μm), with optional electropolishing available to achieve Ra 0.1μm for pharmaceutical applications. Standard lengths span 6 meters with custom cutting services accommodating project-specific requirements.

Material Grade Comparison and Selection

Grade 304 Square Tube Characteristics

The 304 austenitic grade finds extensive application in general-purpose structural and decorative installations, offering excellent forming characteristics and weldability at value-driven pricing. With chromium content of 18-20% and nickel at 8-10.5%, this grade demonstrates adequate corrosion resistance in atmospheric conditions and mildly corrosive industrial environments. The carbon content limited to 0.08% maximum ensures optimal welding performance without carbide precipitation during heat exposure.

Grade 316 Enhanced Corrosion Protection

For applications requiring superior resistance to chloride-induced corrosion, 316 grade square tubes incorporate 2-3% molybdenum alongside 16-18% chromium and 10-14% nickel composition. This alloying strategy provides exceptional durability in marine environments, chemical processing facilities, and food production equipment. The material maintains structural integrity in temperatures up to 870°C, making it the preferred choice for thermal cycling applications.

stainless steel square tube manufacturer

Manufacturing Process and Quality Control

Precision Forming and Welding Technology

Our production facility employs computer-controlled roll forming equipment that progressively shapes flat coils into square profiles through multiple forming stations. High-frequency induction welding operates at 400 kHz frequency, generating localized heating to 1400°C within a 3mm fusion zone, ensuring complete metallurgical bonding without filler material. Post-weld heat treatment at 1050°C followed by rapid cooling eliminates residual stresses and restores corrosion resistance in the weld zone.

Dimensional Accuracy and Surface Treatment

Inline laser measurement systems monitor outer dimensions with ±0.1mm precision during production, automatically adjusting roll gaps to maintain ASTM A554 tolerances. Wall thickness verification employs ultrasonic testing at 5MHz frequency, detecting variations exceeding ±8% for rejection. Surface conditioning through mechanical polishing or passivation treatment per ASTM A967 removes free iron contamination and establishes protective chromium oxide layers.

stainless steel square tube wholesale

Applications Across Industries

Architectural and Structural Applications

Stainless steel square tubes serve as primary structural members in curtain wall framing systems, balustrade posts, and canopy supports where aesthetic appeal combines with load-bearing requirements. The material's inherent corrosion resistance eliminates maintenance painting cycles, reducing lifecycle costs by 40-60% compared to carbon steel alternatives in coastal or industrial atmospheres.

Industrial Equipment and Fabrication

Manufacturing sectors employ square tubes extensively in conveyor frames, machine guards, and process equipment construction. The square geometry facilitates simplified connection detailing through bolted or welded joints, while the hollow section provides efficient strength-to-weight ratios. Food processing and pharmaceutical industries specify 316L grade tubes with electropolished finishes to meet FDA 21 CFR 177.2600 contact surface requirements.

Transportation and Infrastructure

Railway platform canopies, pedestrian bridge railings, and highway noise barriers utilize stainless square tubes for their exceptional durability in outdoor exposure. The material withstands thermal expansion cycles from -40°C to +80°C without structural degradation, maintaining dimensional stability throughout seasonal temperature variations.

Frequently Asked Questions

What is the minimum order quantity (MOQ)?

Our standard MOQ is 500 kilograms per specification, equivalent to approximately 15-20 pieces of 6-meter length 50x50x2mm tubes. For commonly stocked sizes in 304 grade, we accommodate smaller quantities of 100kg minimum. Custom sizes or 316 grade materials require 1000kg minimum due to mill production constraints.

Do you provide material test certificates?

Yes, we supply EN 10204 Type 3.1 mill test certificates with every shipment, documenting chemical composition analysis per ASTM E1019 and mechanical properties per ASTM E8. Certificates include heat number traceability, dimensional inspection reports, and surface finish verification. Third-party inspection by SGS, TUV, or equivalent agencies can be arranged at customer request.

What is the typical delivery time?

Stocked items in standard sizes ship within 3-5 business days after order confirmation. Custom dimensions or special surface finishes require 15-20 days production lead time, including material procurement, forming, and quality inspection. International ocean freight typically adds 20-35 days depending on destination port, while express air shipment delivers within 5-7 days for urgent requirements.

Can you cut to custom sizes?

Our fabrication facility offers precision cutting services using automated band saws with ±1mm length tolerance. Miter cutting at angles from 15° to 90° accommodates frame assembly requirements. We also provide end finishing operations including deburring, chamfering, and end cap welding. Custom cutting incurs additional charges of $0.50-$2.00 per cut depending on wall thickness and complexity.

Get a Competitive Quote for Stainless Steel Square Tube

Partner with our experienced team to source premium-grade stainless steel square tubes at factory-competitive pricing. We maintain extensive inventory across 304 and 316 grades in standard architectural sizes, ensuring rapid fulfillment for your project timelines. Our technical consultation services assist with material selection, structural calculations, and fabrication recommendations to optimize performance and cost-efficiency.

24/7 customer support available via phone, email, and online chat
Free samples for quality evaluation - up to 3 pieces per specification
Competitive pricing for bulk orders with volume discounts up to 15%
Professional technical consultation by certified welding engineers
Flexible payment terms including LC, TT, and credit arrangements for qualified buyers

Contact us today to get your free quote within 24 hours!

Ratings & Reviews

5.0

Very satisfied

Based on 9 reviews for verified purchases

Supplier service

5.0

On-time shipment

5.0

Supplier service

5.0

Robert Brown

United Kingdom

verified purchases

2025-08-26

Acceptable Quality with Minor Issues Resolved
Decent product, some issues resolved. We received 2 tons of 304 tubes (50x50x2.5mm) for architectural balustrade posts. About 8% of tubes had surface scratches from handling, not meeting our 180-grit polished specification. Contacted supplier with photos, and they offered two options: 10% price reduction or replacement of affected pieces. We accepted the discount given our project timeline. The supplier's willingness to negotiate showed good faith. Material properties were correct per certificates, and undamaged tubes performed well in our installations. Suggestion: improve quality control inspection before shipping and use better protective wrapping for polished finishes. Would consider ordering again for mill-finish products where surface perfection is less critical, but hesitant for polished material until packaging improvements are confirmed.

Chris Martin

Canada

verified purchases

2025-09-13

Perfect 304 Tubes for Machine Guard Fabrication
We ordered 1.2 tons of 304 square tubes (40x40x2mm) for manufacturing safety guards and equipment enclosures. Every piece arrived cut to precise 6-meter lengths with clean, deburred ends ready for welding. The high-frequency weld seams are barely visible and grind smoothly when needed. Material hardness tested at 187 HB, consistent with annealed 304 specifications. Supplier accommodated our request for split shipment (600kg immediate, 600kg after 3 weeks) without additional charges. Their flexible approach to order management suits our just-in-time manufacturing process. Documentation included batch traceability codes matching certificates. This level of quality control and customer service is exactly what we need for repeat business.

William Taylor

Australia

verified purchases

2025-10-01

Good Value 316L Tubes for Offshore Platform
Ordered 4.5 tons of 316L square tubes (various sizes: 50x50x3mm, 75x75x4mm) for offshore platform modifications. Carbon content verified at 0.024%, well within 316L specification for superior weld corrosion resistance. Wall thickness uniformity was excellent at ±0.15mm variation. Delivered to Perth in 26 days including sea freight. Technical team provided helpful calculations for our structural load requirements. Pricing was 18% below local Australian suppliers for equivalent certified material. Minor concern: two bundles had slightly loose packaging straps upon arrival, though no product damage occurred. Would recommend for projects where budget matters but quality cannot be compromised. Planning to reorder for upcoming maintenance work.

Wei Chen

Singapore

verified purchases

2025-10-20

Solid Quality 304 Tubes for Boat Railings
Purchased 850kg of 304 square tubes (38x38x2mm, polished finish) for yacht railing fabrication. Material quality is good - passivation treatment was properly done, salt spray test in our facility showed no rust after 48 hours. Polished surface at 180 grit matched our samples. Price point was competitive for marine-grade material. One tube had a minor dent (likely shipping damage), but supplier quickly offered 5% discount on that piece without hassle. Overall, decent product that meets marine fabrication standards. 4 stars because packaging could be more robust for international shipping, but the material itself performs well in saltwater exposure testing.

Ahmed Al-Hassan

UAE

verified purchases

2025-11-06

Premium 316 Tubes for Architectural Canopy Structure
We specified 3.2 tons of 316 grade square tubes (100x100x4mm and 80x80x3mm mixed) for an exterior canopy framework in high-humidity coastal environment. Material arrived with full EN 10204 3.1 certificates showing chromium at 17.2% and nickel at 12.1%, perfect for our corrosion resistance needs. The tubes were remarkably straight - less than 1mm deviation over 6-meter lengths, which simplified our welding assembly. Supplier provided free samples before bulk order, allowing us to verify compatibility with our existing structural components. Compared quotes from 5 suppliers, their combination of quality certification and competitive pricing won the contract. Highly recommended for demanding architectural projects.

Carlos Silva

Brazil

verified purchases

2025-11-24

Reliable 304 Square Tubes for Food Processing Equipment
Long-term partner for stainless steel hollow sections. This is our 4th order over 14 months. Consistent quality across all shipments - dimensional tolerances always within ±0.4mm, surface finish uniformly 2B grade with Ra values between 0.45-0.52μm verified by our lab. We use their 304 tubes (various sizes from 25x25mm to 80x80mm) for food processing conveyor frames and equipment stands. Material certificates always include complete chemical composition and mechanical properties per ASTM standards. Their understanding of food industry requirements (low carbon content for welding, smooth surfaces) demonstrates real expertise. Looking forward to continued partnership.

Hans Mueller

Germany

verified purchases

2025-12-08

Good Value 304 Tubes for Machinery Frames
Ordered 1.5 tons of 304 square tubes (60x60x2.5mm) for conveyor frame construction. Quality meets ASTM A554 standards, tensile test results at 535 MPa as certified. Weld seams are clean with minimal grinding needed. Price was 12% lower than our German supplier for comparable material. Minor issue: delivery took 22 days instead of promised 15 days due to customs documentation delay, but supplier proactively communicated throughout. Overall, solid product quality and competitive pricing make this a viable alternative to European mills. 4 stars because of the delivery delay, but would order again for non-urgent projects.

Michael Johnson

United States

verified purchases

2025-12-23

Outstanding Service from Quote to Delivery
Excellent service experience from inquiry to delivery. Communication: Sales engineer responded within 3 hours with detailed specifications and provided CAD drawings for our custom 40x40x2mm tubes. Delivery: Shipped 4 days ahead of the promised 20-day timeline, tracking updates were accurate throughout. Packaging: Each bundle of 15 pieces was individually wrapped with corner protectors, zero damage upon inspection. They accommodated our request for custom 2.4-meter cutting at reasonable cost. Professional team that understands B2B requirements. Already planning our next order for 304 grade material.

James Wilson

United Kingdom

verified purchases

2026-01-07

Excellent 316 Square Tubes for Marine Handrail Project
We ordered 2.8 tons of 316 grade square tubes (50x50x3mm, 6-meter lengths) for our seaside boardwalk handrail installation. Material certificates confirmed molybdenum content at 2.4%, exceeding our corrosion resistance requirements for coastal exposure. Wall thickness measured consistently at 2.95-3.05mm across all pieces. The 180-grit polished finish arrived without scratches, well-protected in wooden crates with plastic wrapping. Delivered to Southampton port in 18 days. Technical support helped us calculate load-bearing capacity for wind loads. This is our second order this year - reliable quality for marine applications.