ASTM A270 Sanitary Grade Seamless & Welded Stainless Steel Coil Tube

Product Overview

This premium-grade stainless steel coil tube is manufactured in strict compliance with ASTM A270, the internationally recognized standard for welded and seamless austenitic stainless steel tubing intended for sanitary and hygienic service. Designed specifically for demanding applications in the food and beverage, pharmaceutical, biotechnology, and dairy industries, this coil tube delivers exceptional hygiene performance, corrosion resistance, and dimensional accuracy in a continuous coil configuration that facilitates efficient processing, forming, and installation.

Available in both seamless and welded variants, this product line accommodates diverse application requirements — from high-pressure hygienic fluid transfer to precision sanitary piping systems. The coil form factor provides superior handling convenience, reduced material waste, and streamlined downstream fabrication compared to straight-length alternatives.

Material & Properties

The coil tube is fabricated from austenitic stainless steel grades conforming to ASTM A270 specifications, including but not limited to:

• Type 304 (UNS S30400): General-purpose sanitary applications with excellent corrosion resistance and formability
• Type 316 (UNS S31600): Enhanced pitting and crevice corrosion resistance for aggressive chemical environments
• Type 316L (UNS S31603): Low-carbon variant offering superior resistance to intergranular corrosion after welding

Key metallurgical properties include:

• Excellent resistance to oxidation and corrosion in food-grade and pharmaceutical environments
• High-temperature strength and thermal stability
• Non-magnetic in annealed condition
• Outstanding hygienic surface characteristics enabling thorough CIP (Clean-In-Place) and SIP (Sterilize-In-Place) procedures

Specifications

Parameter	Specification
Applicable Standard	ASTM A270 / ASTM A270M
Manufacturing Method	Seamless & Welded (TIG/Orbital)
Stainless Steel Grades	304, 304L, 316, 316L, 321
Outer Diameter	6.35 mm – 168.3 mm (1/4" – 6")
Wall Thickness	0.5 mm – 6.4 mm
Inner Surface Roughness (Ra)	≤ 0.5 µm (standard); ≤ 0.25 µm (electropolished); ≤ 0.1 µm (mirror finish)
Weld Surface Finish	Ground & polished flush; orbital weld with internal & external grinding
Surface Treatment	Pickling & Passivation (HNO₃/HF); optional electropolishing
End Condition	Plain, beveled, or pre-formed for welding
Coil Form	Continuous coil, available in various coil diameters per customer requirement
Quality Grade	Sanitary / Hygienic Grade

Manufacturing Process

Seamless Coil Tube Production

1. Hot Rolling & Annealing: Billet stock is hot-rolled into seamless tube blanks with precise dimensional control.
2. Cold Drawing & Mandrel Drawing: Tubes are cold-worked over precision mandrels to achieve exact wall thickness, roundness, and tight dimensional tolerances.
3. Pickling & Passivation: All tubes undergo chemical pickling (typically nitric acid/hydrofluoric acid blend) followed by passivation to remove scale, decarburized layers, and contaminants, forming a stable chromium oxide passive film.
4. Coil Winding: Finished straight tubes are carefully coiled onto precision mandrels to maintain dimensional integrity and surface finish.

Welded Coil Tube Production

1. Strip Milling & Annealing: Precision-milled stainless steel strip is annealed to achieve optimal formability and mechanical properties.
2. Forming & Welding: Strip is formed into tube shape and welded using orbital TIG welding with inert gas (argon) shielding on both internal and external surfaces.
3. Weld Grinding & Polishing: The internal and external weld seams are ground and polished flush to eliminate any crevice or protrusion, ensuring a smooth, continuous interior surface critical for sanitary applications.
4. Pickling & Passivation: Post-weld pickling and passivation treatment restores full corrosion resistance and achieves the required surface chemistry.
5. Optional Electropolishing: For applications requiring ultra-low surface roughness (Ra ≤ 0.25 µm), electropolishing further refines the interior surface, removing micro-roughness and enhancing the passive chromium oxide layer.

Key Quality Indicators

Inner Surface Roughness (Ra)

The inner surface roughness is the single most critical parameter for sanitary applications. This product meets or exceeds the following requirements:

• Standard sanitary finish: Ra ≤ 0.5 µm — suitable for general food and beverage processing
• Enhanced sanitary finish: Ra ≤ 0.25 µm — recommended for pharmaceutical, bioprocessing, and dairy applications
• Mirror finish: Ra ≤ 0.1 µm — reserved for ultra-clean and aseptic processing environments

Weld Seam Quality

Welded coil tubes undergo rigorous weld seam treatment including:

• Full internal and external grinding to achieve flush continuity with the tube body
• Post-grinding passivation to ensure weld zone corrosion resistance matches base material
• Visual and dimensional inspection of weld geometry
• Optional dye penetrant testing (DPT) or eddy current inspection for weld integrity verification

Passivation Treatment

All tubes receive comprehensive pickling and passivation treatment to:

• Remove all iron contamination, scale, and fabrication residues
• Establish a uniform, stable chromium oxide passive film
• Ensure maximum resistance to corrosion under service conditions
• Facilitate microbiological cleanliness and ease of sterilization

Applications

ASTM A270 sanitary grade coil tubes are engineered for the most demanding hygienic environments across multiple industries:

• Food & Beverage Processing: Milk processing, juice production, brewing, beverage transfer, and hygienic fluid handling systems
• Pharmaceutical & Biotechnology: Bioreactors, fermentation systems, CIP/SIP loops, sterile fluid transfer, and GMP-compliant piping
• Dairy Industry: Milk collection, pasteurization, UHT processing, and distribution systems
• Chemical & Petrochemical: Corrosive chemical transfer, process piping, and heat exchange systems
• Medical Devices: Hydraulic and pneumatic tubing in medical equipment manufacturing
• Heat Exchangers & Coils: Sanitary heat exchangers, jacketed vessels, and process heating/cooling applications
• Water Treatment: Ultrapure water systems, RO feed piping, and hygienic water distribution

Quality Certifications & Compliance

• ASTM A270 / A270M — Full compliance with chemical composition, mechanical properties, and dimensional requirements
• 3-A Sanitary Standards — Designed to meet International Sanitary Construction Association requirements
• EHEDG Compliance — European Hygienic Engineering Design Group standards for hygienic design
• ISO 22000 / HACCP — Suitable for food safety management systems
• ASME BPE — Bioprocessing Equipment guidelines compatibility for pharmaceutical applications
• MILL TEST CERTIFICATES — Full chemical analysis and mechanical property test reports available with every shipment

Why Choose Wenzhou Jixing Metal Materials

Wenzhou Jixing Metal Materials Co., Ltd. is a leading manufacturer of sanitary grade stainless steel coil tubes, delivering:

• Precision Engineering: Tight dimensional tolerances and consistent quality across every coil
• Superior Surface Finish: Advanced electropolishing capabilities achieving Ra values as low as 0.1 µm
• Flexible Configuration: Seamless and welded options in multiple grades, sizes, and coil diameters to match your specific project requirements
• Rigorous Quality Control: Multi-stage inspection including visual, dimensional, surface roughness, and material verification
• Custom Solutions: Tailored specifications, special end treatments, and bespoke coil configurations available upon request
• Comprehensive Documentation: Full traceability with mill certificates, test reports, and material origin documentation