Stainless Steel Coil Tube (Coil Tube) — Product Technical Specification
Product Code: 885 | Product Category: Literature Study & Technical Reference | Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd.
This technical specification document provides a comprehensive overview of the Stainless Steel Coil Tube (盘管, Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. The specification is informed by the technical study titled "Creeper Data Measurement and Analysis of Coil-Type Preheater Furnace Tubes" (《盘管式预热炉炉管蠕变数据测量及分析》), which documents the long-term performance evaluation, mechanical behavior under sustained thermal-mechanical loading, and analytical methodologies applied to coil-type furnace tubes in industrial metallurgical applications.
1. Product Overview
The Stainless Steel Coil Tube is a continuous-length tubular product formed into a coiled configuration, designed for use in high-temperature industrial environments such as preheater furnaces, reheating systems, heat exchangers, and process heating applications in the metallurgical and petrochemical industries. Unlike straight-length seamless tubes, coil tubes are wound into large-diameter coils during or after manufacturing, offering significant advantages in terms of material utilization efficiency, transportation logistics, and on-site installation convenience.
Coil tubes are particularly critical in applications involving preheater furnaces (预热炉), where they serve as heating elements or structural components exposed to sustained elevated temperatures over extended operating cycles. The performance of these tubes under creep loading (蠕变, sustained deformation under constant stress at elevated temperature) is a primary concern for long-term structural integrity and operational safety.
Wenzhou Jixing Metal Materials Co., Ltd. specializes in the supply of high-quality stainless steel coil tubes that meet stringent international standards, ensuring reliable performance in demanding industrial environments.
2. Material & Properties
2.1 Base Material Grades
Stainless steel coil tubes are typically manufactured from austenitic and austenitic-ferritic stainless steel grades, selected based on the specific service conditions including temperature, pressure, corrosive media, and mechanical load requirements. Commonly used grades include:
- SAE 304 / 304L (UNS S30400 / S30403) — General-purpose austenitic stainless steel with excellent corrosion resistance and formability.
- SAE 316 / 316L (UNS S31600 / S31603) — Molybdenum-enhanced austenitic stainless steel offering superior resistance to pitting and crevice corrosion.
- SAE 321 / 321H (UNS S32100 / S32109) — Stabilized austenitic stainless steel with titanium addition for enhanced resistance to sensitization and intergranular corrosion at elevated temperatures.
- SAE 310 / 310S (UNS S31000 / S31008) — High-temperature austenitic stainless steel suitable for sustained service temperatures up to approximately 1100°C.
- SAE 347 / 347H (UNS S34700 / S34709) — Niobium-stabilized austenitic stainless steel providing excellent high-temperature strength and resistance to intergranular corrosion.
- SAE 310S (Super 310H) — Enhanced composition variants for ultra-high-temperature furnace applications.
2.2 Mechanical Properties (Typical Values at Room Temperature)
| Property | SAE 304 / 304L | SAE 316 / 316L | SAE 310 / 310S | SAE 321 / 321H |
|---|---|---|---|---|
| Tensile Strength (MPa) | ≥ 515 | ≥ 515 | ≥ 515 | ≥ 515 |
| Yield Strength (0.2% Proof Stress, MPa) | ≥ 205 | ≥ 205 | ≥ 205 | ≥ 205 |
| Elongation (% min.) | ≥ 40 | ≥ 40 | ≥ 40 | ≥ 40 |
| Density (g/cm³) | 8.00 | 8.00 | 8.03 | 8.00 |
| Modulus of Elasticity (GPa) | 193 | 193 | 193 | 193 |
| Thermal Conductivity (W/m·K at 100°C) | 16.3 | 14.6 | 33.5 | 26.2 |
2.3 Creep Behavior and High-Temperature Performance
A critical aspect of coil tube performance in furnace applications is its creep resistance (蠕变抗性). Creep refers to the time-dependent, permanent deformation of a material under sustained stress at elevated temperatures, typically occurring at temperatures above approximately 0.4 times the absolute melting temperature (Tm). For austenitic stainless steels used in preheater furnace applications, creep becomes a significant design consideration at temperatures exceeding 600°C.
The study referenced in this specification — "Creeper Data Measurement and Analysis of Coil-Type Preheater Furnace Tubes" — documents systematic measurement and analytical approaches for evaluating creep behavior in coil-type furnace tubes. Key findings and considerations include:
- Creep Rate Characterization: Creep strain rate (ds/dt) is measured under controlled temperature and stress conditions to determine the primary, secondary (steady-state), and tertiary creep stages.
- Steady-State Creep Rate: The minimum creep rate (ε̇min) during the secondary stage is used as the primary design parameter for predicting long-term tube life.
- Ramberg-Odger Power Law: The relationship ε̇ = A·σn·exp(-Q/RT) is employed to correlate creep rate with applied stress (σ), temperature (T), and material constants (A, n, Q).
- Creep Life Prediction: Time-to-rupture (TTR) data obtained from accelerated creep testing are extrapolated using Larson-Miller (L-M) and Monkman-Grant (M-G) parametric methods for service life estimation.
- Microstructural Evolution: Long-term exposure at elevated temperatures can lead to grain boundary precipitation, phase transformation, and microstructural coarsening, all of which affect creep resistance and must be monitored.
2.4 Corrosion Resistance
- Excellent resistance to atmospheric corrosion, dilute acids, and alkaline solutions
- Resistance to intergranular corrosion (IGC) in stabilized grades (321, 347)
- Superior resistance to pitting and crevice corrosion in molybdenum-bearing grades (316, 316L)
- Resistance to oxidation at elevated temperatures up to grade-dependent limits
- Resistance to stress corrosion cracking (SCC) in chloride-containing environments (low-carbon grades preferred)
3. Specifications
3.1 Dimensional Specifications
| Parameter | Specification Range | Standard Reference |
|---|---|---|
| Outer Diameter (OD) | 6.0 mm – 219.0 mm (¼" – 8½") | ASTM A269 / A313, GB/T 12771 |
| Wall Thickness | 0.5 mm – 6.0 mm (0.020" – 0.236") | ASTM A269 / A313, GB/T 12771 |
| Coil Length (Continuous) | Up to 120 m (custom lengths available) | Manufacturer specification |
| Coil Outer Diameter | 1.0 m – 2.5 m (adjustable per logistics requirements) | Manufacturer specification |
| OD Tolerance | ±1.0% or ±0.25 mm (whichever is greater) | ASTM A269, GB/T 12771 |
| Wall Thickness Tolerance | ±10% (or ±0.05 mm, whichever is greater) | ASTM A269, GB/T 12771 |
| End Condition | Plain end, beveled end, or thread-protected end | Per customer requirement |
3.2 Chemical Composition Requirements (Typical, wt%)
| Grade | C (max) | Mn (max) | P (max) | S (max) | Si (max) | Cr | Ni | Mo | Other |
|---|---|---|---|---|---|---|---|---|---|
| 304 / 304L | 0.08 / 0.03 | 2.0 | 0.045 | 0.03 | 1.0 | 18.0–20.0 | 8.0–10.5 | — | — |
| 316 / 316L | 0.08 / 0.03 | 2.0 | 0.045 | 0.03 | 1.0 | 16.0–18.0 | 10.0–14.0 | 2.0–3.0 | — |
| 310 / 310S | 0.20 / 0.08 | 2.0 | 0.045 | 0.03 | 1.5 | 24.0–26.0 | 19.0–22.0 | — | — |
| 321 / 321H | 0.08 / 0.08 | 2.0 | 0.045 | 0.03 | 1.0 | 17.0–19.0 | 9.0–12.0 | — | Ti ≥ 5×C |
| 347 / 347H | 0.08 / 0.08 | 2.0 | 0.045 | 0.03 | 1.0 | 17.0–19.0 | 9.0–13.0 | — | Nb ≥ 10×C |
3.3 Applicable Standards
- ASTM A269 — Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubing
- ASTM A313 — Standard Specification for Seamless Austenitic Chromium-Chromium-Nickel Alloy Steel Tubing for High-Temperature Service
- ASTM A213 — Standard Specification for Seamless Austenitic Chromium-Chromium-Nickel Alloy Steel Tubing for Heat-Transfer Equipment
- ASME SA-213 / SA-269 / SA-313 — Boilers and Pressure Vessel Code, Section II, Part D
- GB/T 12771 — Non-alloy and Alloy Steel Tubes for General Purposes (Chinese National Standard)
- GB/T 14976 — Seamless Steel Tubes for Fluid Service (Chinese National Standard)
- EN 10216-5 — Seamless and Welded Stainless Steel Tubes for Pressure Purposes
- ISO 3506-3 — Stainless Steel Tubing for General Purpose
4. Manufacturing Process
The manufacturing of stainless steel coil tubes involves a series of precisely controlled metallurgical and