Stainless Steel Coil Tube for Steam Dryer Applications

Product Overview

The Stainless Steel Coil Tube (Coiltube) is a precision-engineered tubular product designed specifically for use in industrial steam drying systems. Manufactured by Wenzhou Jixing Metal Materials Co., Ltd, this coil tube is formed from high-grade stainless steel wire or seamless tubing into a continuous helical or spiral configuration, optimized for maximum heat transfer efficiency and prolonged service life under high-temperature, high-pressure steam environments.

Extensive research into Steam Dryer Coil Tube Life Extension has led to significant advancements in material selection, manufacturing tolerances, and surface treatments, resulting in a product that addresses the critical failure modes—corrosion, thermal fatigue, and mechanical degradation—commonly observed in conventional coil tube assemblies.

Material & Properties

The coil tube is fabricated from premium austenitic and duplex stainless steel grades, selected for their exceptional resistance to oxidation, pitting corrosion, and thermal cycling fatigue. Key material characteristics include:

• Stainless Steel Grade 304 (UNS S30400) — General-purpose grade offering excellent formability and resistance to atmospheric and mild chemical corrosion.
• Stainless Steel Grade 316L (UNS S31603) — Enhanced molybdenum content (2.0–3.0%) providing superior resistance to pitting and crevice corrosion in aggressive environments.
• Stainless Steel Grade 321 (UNS S32100) — Titanium-stabilized grade offering outstanding resistance to intergranular corrosion at elevated temperatures (up to 870 °C).
• Duplex Stainless Steel 2205 (UNS S31803) — High-strength, high-corrosion-resistance grade with a yield strength approximately twice that of standard austenitic grades.

Mechanical Properties (Typical for Grade 316L):

• Tensile Strength (UTS): ≥ 515 MPa
• Yield Strength (0.2% offset): ≥ 205 MPa
• Elongation (at break): ≥ 40%
• Hardness (HBW): ≤ 230
• Thermal Conductivity (at 100 °C): ~16.3 W/(m·K)
• Maximum Service Temperature: 870 °C (continuous); 1100 °C (intermittent)

Specifications

Parameter	Specification / Range	Standard / Method
Outer Diameter (OD)	6 mm – 50.8 mm (¼" – 2")	ASME B36.19M
Wall Thickness (WT)	0.5 mm – 3.0 mm	ASTM A213 / A269
Coil Pitch	15 mm – 100 mm (customizable)	Customer Specification
Coil Diameter	100 mm – 1000 mm	Customer Specification
Tube Length per Coil	1 m – 50 m (continuous)	—
Surface Finish	Mirror Polish (Ra ≤ 0.1 μm) / Brushed / Pickled & Passivated	ASTM A967
End Forming	Plain, Flanged, Grooved, or Custom	Customer Specification
Pressure Rating	Up to 4.0 MPa (at 200 °C, Grade 316L, OD 25 mm, WT 2.0 mm)	ASME B31.3
Material Certification	Mill Test Certificate (MTC) per EN 10204 Type 3.1	EN 10204

Manufacturing Process

The production of high-performance coil tubes follows a rigorous, multi-stage manufacturing workflow designed to ensure dimensional accuracy, metallurgical integrity, and surface quality:

1. Raw Material Selection & Inspection — Certified stainless steel seamless tubes or precision-drawn wire are sourced from accredited mills. Incoming material undergoes 100% visual inspection, dimensional verification, and spectrographic analysis (PMI) to confirm chemical composition compliance.
2. Cutting & Deburring — Tubes are cut to the required length using precision sawing or laser cutting. End faces are deburred and chamfered to eliminate stress concentration points.
3. Heat Treatment & Annealing — Where required, tubes undergo solution annealing (1050–1150 °C) followed by controlled cooling to relieve residual stresses and restore full austenitic microstructure.
4. Coil Forming — Tubes are formed into the specified helical coil geometry using CNC-controlled coiling equipment. Forming parameters (bend radius, pitch, tension) are precisely controlled to prevent wall thinning, ovality, or micro-cracking at the inner bend radius. Minimum bend radius is maintained at ≥ 3× OD to preserve structural integrity.
5. Post-Form Annealing — Coils are re-annealed to eliminate work-hardening effects introduced during forming, ensuring uniform mechanical properties throughout the coil.
6. Pickling & Passivation — Coils are subjected to acid pickling (nitric/hydrofluoric acid blend) to remove surface oxides, followed by passivation treatment per ASTM A967 to establish a protective chromium oxide layer.
7. Surface Finishing — Mirror polishing (electrolytic or mechanical) or brushing is applied as specified, achieving the target surface roughness for optimal heat transfer and corrosion resistance.
8. Final Inspection & Testing — Each coil undergoes hydrostatic pressure testing, dimensional inspection, surface finish measurement, and visual examination. Radiographic testing (RT) is performed on critical applications to detect internal defects.
9. Packaging & Marking — Coils are wrapped in protective packaging, clearly marked with material grade, heat number, dimensions, and traceability information.

Applications

The stainless steel coil tube is engineered for demanding thermal and chemical service environments. Primary applications include:

• Industrial Steam Dryers — Heat exchange coils in continuous and batch steam drying systems for pharmaceutical, food processing, and chemical industries. The research on coil tube life extension has demonstrated service life improvements of 40–60% over conventional designs through optimized material selection and surface engineering.
• Heat Exchangers & Condensers — Spiral wound and helical coil heat exchangers for process heating and cooling applications.
• Refrigeration & HVAC Systems — Evaporator and condenser coils requiring high thermal conductivity and corrosion resistance.
• Pharmaceutical & Bioprocessing — Sanitary-grade coils for CIP (Clean-In-Place) compatible drying and sterilization systems (GMP compliant).
• Food Processing — Drying chambers for freeze-drying, spray drying, and thermal processing of food products (FDA/3-A compliant).
• Chemical Processing — Reaction vessel heating coils and distillation column internals exposed to aggressive chemical media.
• Petrochemical & Marine — High-temperature steam tracing coils and heat transfer components in offshore and onshore installations.

Quality Certifications

Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management system and holds the following certifications, ensuring product reliability and regulatory compliance:

• ISO 9001:2015 — Quality Management System certification for consistent product quality and continuous improvement.
• ISO 14001:2015 — Environmental Management System certification for sustainable manufacturing practices.
• ISO 45001:2018 — Occupational Health and Safety Management System certification.
• EN 10204 Type 3.1 — Mill Test Certificates with independent third-party inspection for material traceability.
• ASME / PED 2014/68/EU — Pressure Equipment Directive compliance for pressure-containing coil assemblies.
• CE Marking — Conformity with European health, safety, and environmental protection standards.
• RoHS & REACH — Compliance with Restriction of Hazardous Substances and Registration, Evaluation, Authorization and Restriction of Chemicals regulations.
• Food-Grade Certification — FDA 21 CFR compliant materials and 3-A Sanitary Standards for food and pharmaceutical applications.

Unique Selling Points

Extended Service Life Through Advanced Material Engineering

Building upon the findings of the Steam Dryer Coil Tube Life Extension Research, Wenzhou Jixing Metal Materials Co., Ltd has developed proprietary material and process solutions that address the root causes of coil tube degradation. Key differentiators include:

• Optimized Grade Selection — Data-driven material selection matching the specific thermal, chemical, and mechanical demands of each application, reducing premature failure by up to 60%.
• Enhanced Surface Integrity — Multi-stage pickling, passivation, and polishing processes produce a surface finish with Ra values as low as 0.05 μm, minimizing corrosion initiation sites and improving heat transfer efficiency by up to 15%.
• Controlled Forming Technology — CNC coiling with real-time tension monitoring ensures uniform wall thickness variation (±5%) and eliminates micro-cracking at bend zones, significantly improving fatigue life.
• Full Traceability — Every coil is traceable to its mill heat number, chemical analysis, mechanical test results, and forming parameters, supporting regulatory audits and quality investigations.
• Custom Engineering Support — Dedicated technical team provides application-specific design optimization, thermal simulation, and failure analysis to maximize system performance and coil longevity.
• Comprehensive Testing Protocol — Hydrostatic testing, radiographic inspection, surface roughness measurement, and corrosion testing (salt spray, pitting) performed on every production batch.

Summary

The Stainless Steel Coil Tube from Wenzhou Jixing Metal Materials Co., Ltd represents the culmination of advanced metallurgical research and precision manufacturing expertise. By integrating findings from steam dryer coil life extension studies into every stage of the production process—from raw material selection through final surface finishing—this product delivers superior thermal performance, exceptional corrosion resistance, and significantly extended service life compared to industry-standard alternatives. Suitable for the most demanding industrial applications, this coil tube is the definitive solution for reliable, long-duration heat transfer in steam drying and thermal processing systems.