Welded Stainless Steel Heat Exchanger Coil Tube — GB/T 24592

Product Overview

The Welded Stainless Steel Heat Exchanger Coil Tube, manufactured by Wenzhou Jixing Metal Materials Co., Ltd., is a precision-engineered coil tube product designed specifically for thermal exchange applications. Conforming to the Chinese National Standard GB/T 24592 — the definitive specification for welded heat exchanger tubing — this product delivers exceptional thermal conductivity, mechanical integrity, and corrosion resistance in demanding industrial environments.

Unlike standard fluid transfer tubing, this coil tube is engineered with enhanced weld quality verification protocols, ensuring superior joint integrity under continuous thermal cycling and pressure conditions. The coiled configuration facilitates compact heat exchanger assemblies with maximized surface-area-to-volume ratios, making it ideal for shell-and-tube, plate-fin, and air-cooled heat exchanger systems.

Material & Properties

Welded stainless steel heat exchanger coil tubes are fabricated from austenitic and austenitic-ferritic stainless steel grades selected for their combination of thermal performance, weldability, and long-term corrosion resistance. Common grades include:

Key material properties include:

Specifications

Parameter Specification
Applicable Standard GB/T 24592 — Welded heat exchanger tubes
Tube Type Welded coil tube (continuous coiled configuration)
Outer Diameter (OD) 6.00 mm – 48.00 mm (custom sizes available upon request)
Wall Thickness 0.50 mm – 3.00 mm (tolerance ±10%)
Coil Inner Diameter 150 mm – 800 mm (configurable per customer requirement)
Length per Coil Continuous coil; typical lengths 100 m – 500 m per coil
Surface Finish Pickled & passivated (2B finish); Ra ≤ 0.4 μm available
Weld Joint Continuous longitudinal butt weld with full heat-affected zone control
Weld Inspection RT (Radiographic Testing) / UT (Ultrasonic Testing) — sampling rate significantly higher than standard fluid tubes per GB/T 24592
Material Grades 304, 304L, 316, 316L, 321, 310S, 2205, 316Ti, 904L, and custom alloys
Forming Tolerance OD tolerance: ±0.15 mm; Wall thickness tolerance: ±10%
Packaging Steel frame with moisture-proof wrapping; coil secured with steel strapping

Manufacturing Process

The production of welded stainless steel heat exchanger coil tubes follows a rigorously controlled multi-stage process to ensure dimensional accuracy, metallurgical homogeneity, and weld integrity:

  1. Raw Material Selection & Inspection: Cold-rolled stainless steel strip is sourced from certified mills with full material traceability. Incoming material undergoes 100% visual inspection, dimensional verification, and spectrographic composition analysis (PMI) to confirm grade compliance.
  2. Coil Winding & Forming: Precision CNC coil forming equipment winds the strip into the target outer diameter with controlled springback compensation, ensuring uniform OD and wall thickness throughout the coil length.
  3. Continuous Longitudinal Welding: A high-frequency induction or TIG (Tungsten Inert Gas) welding process creates the continuous longitudinal weld seam. Weld parameters (voltage, current, travel speed, shielding gas flow) are tightly controlled and monitored to minimize heat input and ensure a tight, penetration-free weld joint.
  4. Weld Seam Finishing: The weld seam is dressed to be flush or slightly below the tube surface through mechanical grinding or laser peening, followed by pickling and passivation to restore the full chromium oxide protective layer.
  5. Heat Treatment (if required): Solution annealing and quenching may be performed to relieve residual stresses and ensure optimal metallurgical properties, particularly for duplex and precipitation-hardening grades.
  6. Dimensional & Geometric Inspection: 100% optical and mechanical measurement of OD, wall thickness, and coil diameter at defined intervals.
  7. Non-Destructive Testing (NDT) — Enhanced Protocol: In accordance with GB/T 24592, weld seams undergo RT (Radiographic Testing) and/or UT (Ultrasonic Testing) at a sampling rate significantly higher than that required for standard fluid transfer tubes. This elevated inspection frequency is the defining quality differentiator of heat exchanger tubing, ensuring that even minor weld defects — which could lead to thermal leakage or catastrophic failure under thermal cycling — are detected and rejected.
  8. Hydrostatic / Pneumatic Pressure Testing: Each coil is subjected to pressure testing at 1.5× the maximum design pressure to verify weld integrity and tube body soundness.
  9. Final Surface Treatment: Acid pickling and passivation to remove any heat-tint, scale, or contamination, restoring the full passive film integrity.
  10. Final Inspection & Documentation: Comprehensive quality documentation including material certificates (EN 10204 3.1), NDT reports, dimensional inspection records, and pressure test certificates.

Applications

Welded stainless steel heat exchanger coil tubes conforming to GB/T 24592 are deployed across a broad spectrum of thermal management applications:

Quality Certifications & Compliance

Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework to ensure full compliance with applicable standards and customer requirements:

Key Differentiators

Elevated Weld Integrity Assurance: The defining advantage of GB/T 24592-compliant heat exchanger coil tubing is the significantly higher RT/UT sampling rate applied to weld seams compared to standard fluid transfer tubes. This enhanced non-destructive testing protocol provides quantifiable assurance that weld joints — the most critical failure point in heat exchanger service — are free from porosity, lack of fusion, cracks, and other discontinuities that could compromise thermal performance or lead to in-service failure.