316L Sanitary Coil Tube for Dairy CIP (Clean-In-Place) Cleaning Circuits
Product Overview
The 316L sanitary coil tube manufactured by Wenzhou Jixing Metal Materials Co., Ltd is a precision-engineered stainless steel tubing solution purpose-designed for Clean-In-Place (CIP) cleaning circuits within the dairy processing industry. This product is engineered to withstand the rigorous demands of alternating alkaline and acidic chemical cleaning cycles at elevated temperatures, ensuring long-term structural integrity, chemical resistance, and hygienic performance in food-grade environments.
CIP systems represent the backbone of dairy processing sanitation, requiring tubing materials that can endure repeated exposure to caustic and oxidizing cleaning agents without degradation, pitting, or surface contamination. This coil tube product addresses these critical requirements through the use of ultra-low carbon austenitic stainless steel (316L), combined with superior surface finishing and welding practices.
Material & Properties
Base Material: ASTM A213 TP316L / EN 10216-5 X2CrNiMo17-12-2 (316L)
- Ultra-Low Carbon (≤0.03% C): Minimizes intergranular carbide precipitation, ensuring excellent resistance to sensitization during welding and prolonged thermal cycling in CIP service.
- Molybdenum Content (2.0–2.5% Mo): Provides superior resistance to pitting and crevice corrosion in chloride-containing environments, critical for the aggressive alkaline (NaOH) and oxidizing (HNO₃) cleaning agents used in dairy CIP systems.
- Chromium (16.5–18.5% Cr): Forms a robust, self-healing passive oxide layer that protects against general corrosion in alternating acid-alkali conditions.
- Nickel (10.0–14.0% Ni): Stabilizes the austenitic microstructure, ensuring ductility and dimensional stability at operating temperatures up to 80°C and beyond.
- Acid-Alkali Alternating Resistance: The 316L alloy is specifically suited for service in alternating cycles of sodium hydroxide (NaOH, 1–2% concentration) and nitric acid (HNO₃, 0.5–1% concentration) at 70–80°C, a defining characteristic of dairy CIP protocols.
Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Material Grade | 316L (X2CrNiMo17-12-2) | ASTM A213 / EN 10216-5 |
| Form | Coil Tube (continuous coil configuration) | — |
| Surface Finish | Electropolished / Sanitary grade (Ra ≤ 0.4 μm) | ASTM A270 / 3-A Sanitary Standards |
| Weld Quality | Smooth polished welds; internal & external Ra ≤ 0.5 μm | 3-A / EHEDG |
| End Condition | Plain end, beveled end, or welded fittings (as specified) | ASTM A269 / EN 10217-7 |
| Operating Temperature | 70–80°C (CIP cycle); continuous service up to 300°C | — |
| CIP Chemical Exposure | NaOH 1–2% / HNO₃ 0.5–1% | Dairy CIP protocol |
| Corrosion Resistance | Excellent in alternating acid-alkali environments | ASTM G102 (pitting) |
| Hygienic Design | Sanitary-grade; no dead legs; smooth transitions | 3-A / EHEDG / FDA 21 CFR 177 |
| Traceability | Full heat number traceability; mill certificates available | ISO 9001 |
Manufacturing Process
- Material Selection & Incoming Inspection: Virgin 316L stainless steel coil is sourced from certified mills with full chemical composition and mechanical property verification. Each heat is inspected for compliance with ASTM A213 TP316L or EN 10216-5 requirements.
- Precision Coil Forming: The tubing is cold-formed into coil configurations using precision winding equipment, ensuring uniform coil diameter, consistent pitch, and controlled springback to achieve dimensional accuracy throughout the coil length.
- Hygienic Welding (Where Applicable): Orbital TIG (Tungsten Inert Gas) welding is employed for all tubular joints. Inert gas backing (argon) ensures full penetration without oxidation of the inner surface. Weld parameters are controlled to minimize heat-affected zone (HAZ) sensitization.
- Weld Polishing & Finishing: All weld seams undergo mechanical polishing followed by electropolishing to achieve a mirror-like sanitary surface finish. Internal weld profiles are smoothed to eliminate crevices and dead zones that could harbor bacterial contamination. The final surface roughness (Ra) is maintained at ≤ 0.4 μm on both internal and external surfaces.
- Pickling & Passivation: Post-weld pickling (using citric acid or dilute HNO₃/HF blend) removes heat-tint and metal oxides. Subsequent passivation treatment re-establishes the chromium-rich passive oxide layer, ensuring maximum corrosion resistance in the CIP operating environment.
- Final Cleaning & Packaging: Tubes are ultrasonically cleaned, rinsed with deionized water, and packaged in protective hygienic packaging to prevent contamination prior to installation.
Applications
Primary Application: Dairy CIP Cleaning Circuits
- Alkaline Cleaning Cycles: Circulation of NaOH (1–2% concentration) at 70–80°C to dissolve protein, fat, and carbohydrate residues deposited on dairy processing equipment surfaces.
- Acidic Cleaning Cycles: Circulation of HNO₃ (0.5–1% concentration) at 70–80°C to dissolve mineral scale (calcium, phosphates) and provide final sanitization.
- Hot Water Rinse & Final Sanitization: The tubing maintains dimensional and surface integrity through repeated hot water rinse cycles and final potable water or sanitizer flushes.
Extended Applications in Dairy Processing
- Milk storage tank circulation loops and transfer piping
- Cheese-making equipment (vats, presses, curd tanks) internal piping
- Yogurt and cultured dairy product processing lines
- UHT (Ultra-High Temperature) and HTST (High Temperature Short Time) pasteurization systems
- Whey processing and concentration circuits
- Ice cream and frozen dairy product manufacturing lines
Quality Certifications & Compliance
- ISO 9001:2015 — Quality Management System certification ensuring consistent manufacturing quality
- 3-A Sanitary Standards — Compliance with the International Association of Milk, Food, and Egg Sanitarians (A3A) requirements for food-grade equipment
- EHEDG (European Hygienic Engineering & Design Group) — Design compliance for hygienic fluid processing systems
- FDA 21 CFR 177.1550 — Compliance with U.S. Food and Drug Administration requirements for stainless steel food contact materials
- EU Regulation (EC) No 1935/2004 & (EC) No 1936/2008 — European food contact material compliance
- NSF/ANSI 61 — Drinking water system components certification (where applicable)
- Mill Test Certificates (MTC) — Full chemical and mechanical property documentation per EN 10204 Type 3.1 for each heat
- Material Traceability — Complete heat number traceability from raw material through final product delivery
Unique Selling Points
1. Superior Acid-Alkali Alternating Durability: The 316L alloy with its molybdenum enhancement provides exceptional resistance to the aggressive alternating cycles of NaOH and HNO₃ at elevated temperatures (70–80°C) that characterize dairy CIP protocols — a condition that challenges lower-grade stainless steels such as 304L.
2. Mirror-Finish Weld Quality: Internally and externally polished welds eliminate crevices, dead zones, and surface irregularities that could harbor biofilm formation, ensuring true hygienic integrity throughout the tubing system.
3. Coil Configuration for Flexible Installation: The continuous coil form enables custom field fabrication, reducing on-site welding requirements and minimizing potential contamination points during installation.
4. Comprehensive Hygienic Certification: Full compliance with 3-A, EHEDG, and FDA standards ensures acceptance across global dairy processing markets.
5. Extended Service Life: The ultra-low carbon content prevents sensitization-induced corrosion, and the robust passive layer ensures decades of reliable service in the demanding CIP environment.
Technical Summary
Wenzhou Jixing Metal Materials Co., Ltd's 316L sanitary coil tube for dairy CIP cleaning circuits represents a purpose-built solution for the most demanding chemical cycling environments in the food processing industry. By combining the corrosion resistance of 316L austenitic stainless steel with precision manufacturing, hygienic welding, and electropolished surface finishes, this product ensures the sanitary reliability, chemical durability, and regulatory compliance required for modern dairy processing operations worldwide.