Stainless Steel Internal Heat Extraction Coil Tube (Welded)

Product Code: 1397  |  Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd.  |  Category: Stainless Steel Coil Tube (Coiltube) for Thermal Exchange Systems

Product Overview

The Stainless Steel Internal Heat Extraction Coil Tube is a precision-engineered welded coil tube specifically designed for internal heat recovery and thermal exchange applications. This product represents an advanced solution in the field of process heat management, where high-efficiency heat transfer is critical to system performance and energy conservation. The coil tube is manufactured through specialized welding techniques that ensure structural integrity, dimensional accuracy, and long-term reliability under demanding thermal and pressure conditions.

The product draws upon extensive industry knowledge and engineering expertise in the welding of internal heat extraction coil tubes, incorporating best practices in metallurgical processing, weld design, and quality assurance. It is particularly suited for applications requiring compact heat exchanger configurations with maximum surface area-to-volume ratios, such as those found in chemical processing, petrochemical, power generation, and pharmaceutical industries.

Material & Properties

The coil tubes are fabricated from high-grade austenitic stainless steel, selected for their superior corrosion resistance, thermal conductivity, and mechanical strength across a wide temperature range. The primary material grades utilized include:

• 304 (UNS S30408): General-purpose austenitic stainless steel offering excellent corrosion resistance and formability. Contains approximately 18% Chromium (Cr) and 8% Nickel (Ni).
• 316 (UNS S31608): Enhanced corrosion resistance due to the addition of 2–3% Molybdenum (Mo), making it ideal for aggressive chemical environments and chloride-containing media.
• 321 (UNS S32100): Stabilized with Titanium (Ti) to prevent intergranular corrosion at elevated temperatures, suitable for high-temperature heat exchange applications.
• 316L (UNS S31603): Low-carbon variant (C ≤ 0.03%) offering superior weldability and resistance to sensitization during welding processes.

Key Mechanical Properties (typical values for Grade 316L):

• Tensile Strength (抗拉强度): ≥ 515 MPa
• Yield Strength (屈服强度): ≥ 205 MPa
• Elongation (延伸率): ≥ 40%
• Hardness (硬度): ≤ 217 HB (Brinell)
• Operating Temperature Range: −196°C to +870°C
• Thermal Conductivity (热导率): 16.3 W/(m·K) at 100°C

Specifications

Parameter (参数)	Specification / Range (规格/范围)	Standard Reference (标准参考)
Outer Diameter (OD) (外径)	6.0 mm – 32.0 mm (custom sizes available)	ASTM A269 / ASTM A213
Wall Thickness (壁厚)	0.5 mm – 3.0 mm	ASTM A269 / GB/T 12771
Coil Diameter (盘管直径)	150 mm – 2000 mm (configurable)	Manufacturer Specification
Coil Length (盘管长度)	Up to 500 m per coil (continuous)	Manufacturer Specification
Surface Finish (表面光洁度)	Ra ≤ 0.8 μm (polished); Ra ≤ 1.6 μm (pickled)	ASTM A269 / GB/T 8898
Welding Method (焊接方式)	TIG (GTAW) / Orbital Automatic Welding	ASME Section IX / ISO 15614
Weld Seam Type (焊缝类型)	Single-sided / Double-sided fusion weld	ASME BPVC Section VIII
Heat Treatment (热处理)	Solution Annealing (1050–1150°C), Water Quench	ASTM A269
Pressure Rating (压力等级)	Up to 10 MPa (100 bar) depending on geometry	ASME BPVC / EN 13480
Corrosion Resistance (耐蚀性)	Equivalent to Grade 316L in chloride environments (PIT resistance: PREN ≥ 24)	ASTM G48 / ISO 9650
Dimensional Tolerance (尺寸公差)	OD: ±0.1 mm; Wall Thickness: ±0.05 mm	ASTM A269 / GB/T 12771
End Preparation (端部处理)	Beveled (V-groove) / Flat-cut / Threaded (upon request)	ASME B1.20.1
Packaging (包装)	Wooden crate / Steel frame with moisture-proof wrapping	ISO 4180 / Manufacturer Standard

Manufacturing Process

The production of the Internal Heat Extraction Coil Tube follows a rigorous, multi-stage manufacturing process that integrates precision forming, advanced welding, and comprehensive quality control. Each stage is designed to ensure metallurgical integrity, dimensional accuracy, and long-term performance reliability.

1. Raw Material Selection & Inspection (原材料选择与检验):

   Stainless steel strip or seamless pipe blanks are sourced from certified mills and subjected to incoming inspection, including spectroscopic analysis (PMI), mechanical testing, and visual examination to verify compliance with specified grades and standards.

2. Coil Forming (盘管成型):

   The straight pipe or strip material is fed into a precision coil-forming machine equipped with CNC-controlled tooling. The forming process employs progressive die sets to achieve the desired coil diameter and pitch while minimizing residual stress and geometric distortion. The forming speed and temperature are carefully controlled to prevent work hardening and maintain material ductility.

3. Welding of Internal Heat Extraction Coil Tube (内取热盘管的焊接):

   This is the critical process step that defines the product's quality and performance. The welding of internal heat extraction coil tubes requires specialized techniques to address the unique challenges of confined-space welding, thermal management, and joint integrity:

   • Welding Process: Gas Tungsten Arc Welding (GTAW/TIG) is employed as the primary welding method, utilizing a tungsten electrode and inert shielding gas (Argon, Ar; or Helium, He, for enhanced penetration). For production-scale operations, orbital automatic welding (自动环形焊接) is utilized to ensure consistent weld quality and high productivity.
   • Shielding Gas Configuration: Back-purging with high-purity Argon (≥ 99.99%) is applied to the internal surface of the coil tube to prevent oxidation and ensure a clean, corrosion-resistant internal weld seam. The purge gas flow rate is maintained at 15–25 L/min to ensure complete displacement of atmospheric oxygen.
   • Weld Parameters: Typical parameters include a welding current of 80–200 A (DC), arc voltage of 10–18 V, travel speed of 30–80 mm/min, and tungsten electrode diameter of 2.0–3.2 mm. Parameters are adjusted based on wall thickness, material grade, and joint configuration.
   • Interpass Temperature Control: For multi-pass welds, the interpass temperature is maintained below 150°C to prevent sensitization and maintain the austenitic microstructure. Temperature monitoring is performed using infrared thermometers or thermocouples.
   • Weld Joint Design: Butt joints (对接接头) with V-groove preparation (V型坡口) are the standard configuration, with groove angles of 60°–70° and root gap of 0.5–1.5 mm. Fillet welds (角焊缝) are used for branch connections and tie-in joints.
4. Post-Weld Heat Treatment (焊后热处理):

   Following welding, the coil tube assembly undergoes solution annealing (固溶处理) at 1050–1150°C followed by rapid water quenching. This process dissolves carbide precipitates, restores full corrosion resistance, and relieves residual welding stresses. The annealing cycle is carefully controlled to avoid grain growth and maintain mechanical properties.

5. Surface Treatment & Cleaning (表面处理与清洗):

   The coil tube surface is subjected to acid pickling (酸洗) and passivation (钝化) using a blend of nitric acid (HNO₃) and hydrofluoric acid (HF) to remove oxide scale and restore the passive chromium oxide layer. Internal surfaces are cleaned using chemical cleaning solutions or mechanical brushing to ensure cleanliness for fluid service.

6. Quality Inspection & Testing (质量检验与测试):

   A comprehensive inspection program is conducted, including:

   • Visual Inspection (VT): 100% examination of all welds for surface defects, undercut, porosity, and geometric irregularities per ASME BPVC Section V, Article 1.
   • Penetrant Testing (PT): Applied to all weld seams to detect surface-breaking defects per ASTM E165 / EN ISO 3452.
   • Ultrasonic Testing (UT): Performed on critical welds to detect volumetric and internal defects per ASTM E2473 / EN ISO 17637.
   • Radiographic Testing (RT): Applied to a defined percentage of welds (typically 10–100%) to verify weld penetration and internal quality per ASME BPVC Section V, Article 2.
   • Hydrostatic Pressure Testing (水压试验): Each coil tube assembly is pressure-tested at 1.5 times the design pressure for a minimum hold time of 30 minutes to verify leak-tightness per ASTM A269.
   • Dimensional Inspection: Verification of coil diameter, pitch, OD, wall thickness, and overall geometry using calibrated measuring instruments.
7. Packaging & Dispatch (包装与发货):

   Finished coil tubes are carefully packaged in moisture-proof wrapping and secured within wooden crates or steel frames to prevent mechanical damage and corrosion during transit. Each shipment is accompanied by a full documentation package including material test certificates (MTC), welding procedure qualifications (WPQ), welder performance qualifications (WPQ), and non-destructive examination (NDE) reports.

Applications

The Stainless Steel Internal Heat Extraction Coil Tube is engineered for a wide range of industrial applications where efficient heat transfer, corrosion resistance, and mechanical durability are paramount:

• Chemical Processing (化学加工): Heat exchangers in chemical reactors, distillation columns, and process cooling systems handling corrosive media such as acids, alkalis, and organic solvents.
• Petrochemical Industry (石油化工): Crude oil distillation, catalytic cracking, and hydrotreating units where coil tubes serve as internal heat recovery elements.
• Power Generation (发电): Supercritical and ultra-supercritical boiler systems, waste heat recovery units (WHRU), and cogeneration plants.
• Pharmaceutical Industry (制药): Clean-in-place (CIP) heat exchangers and process cooling systems requiring sanitary-grade surfaces and high purity.
• Food & Beverage Processing (食品饮料加工): Pasteurization, sterilization, and evaporator systems where food-grade stainless steel coil tubes ensure product safety and regulatory compliance.
• Marine & Offshore (海洋与海上): Heat exchange systems in marine engines, offshore platforms, and desalination plants exposed to seawater and high-temperature environments.
• Energy Storage & Thermal Management (储能与热管理): Thermal energy storage systems, geothermal heat exchangers, and industrial waste heat recovery systems.
• Cryogenic Applications (低温应用): Liquefied natural gas (LNG) processing, cryogenic distillation, and superconducting magnet cooling systems requiring materials that maintain ductility at extremely low temperatures.

Quality Certifications & Standards Compliance

Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system and holds the following certifications and complies with the following international and national standards:

Management System Certifications:

• ISO 9001:2015 — Quality Management System (质量管理体系)
• ISO 14001:2015 — Environmental Management System (环境管理体系)
• ISO 45001:2018 — Occupational Health and Safety Management System (职业健康安全管理体系)
• EN 1090 — Execution of Steel and Aluminium Structures (钢结构与铝结构执行标准)

Product Standards & Codes:

• ASTM A269 — Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubes for General Service
• ASTM A213 — Standard Specification for Stainless Steel Tubing for Heat-Exchanger and Heat-Trapper Service
• ASME BPVC Section VIII, Division 1 — Rules for Construction of Pressure Vessels
• ASME BPVC Section IX — Qualification Rules for Welding, Brazing, and Fusing Procedures and Personnel
• GB/T 12771 — Stainless Steel Seamless Tubes for General Purposes (中国国家标准)
• EN 10216-5 — Seamless and Welded Stainless Steel Tubes for Mechanical and