Seamless Stainless Steel Coil Tube — Theoretical Weight Pricing (Wenzhou Jixing)
Product Overview
Wenzhou Jixing Metal Materials Co., Ltd. offers a comprehensive range of seamless stainless steel coil tubes engineered for demanding industrial and commercial applications. These coil tubes are supplied in continuous, coiled lengths that eliminate the need for butt-welding at joints, resulting in superior structural integrity, reduced leak risk, and streamlined installation. The product line is categorized under commercial procurement with weight-based pricing, ensuring transparent and predictable cost structures for buyers.
Material & Properties
- Material Grades: 304, 304L, 316, 316L, 321, 310S, and custom alloy compositions available upon request
- Tube Form: Seamless, cold-rolled and cold-drawn coil configuration
- Surface Finishes: 2B, No. 1, BA (Bright Annealed), Pickled, and custom polished finishes
- Key Properties: Excellent corrosion resistance, high strength-to-weight ratio, non-magnetic (austenitic grades), and full weldability
- Temperature Range: Suitable for cryogenic to high-temperature service up to 870°C depending on grade
Specifications & Weight Pricing
A defining feature of Wenzhou Jixing's coil tube offering is the theoretical weight settlement model, which provides buyers with a clear, standardized method for calculating material weight and cost. The theoretical weight formula is as follows:
W = (OD − WT) × WT × 0.02491 kg/m
Where:
- W = Theoretical weight in kilograms per meter (kg/m)
- OD = Outer diameter in millimeters (mm)
- WT = Wall thickness in millimeters (mm)
- 0.02491 = Density conversion constant for stainless steel
| Parameter | Specification |
|---|---|
| Outer Diameter (OD) | 6.0 mm – 219.1 mm (custom sizes available) |
| Wall Thickness (WT) | 0.5 mm – 12.0 mm |
| Coil Length | Continuous coil; typically 30 m – 500 m per coil |
| OD Tolerance | ±0.15 mm (standard); custom tolerances negotiable |
| WT Tolerance | ±10% (standard); ±5% available on request |
| Pricing Basis | Theoretical weight (kg/m) × unit price per kg |
| Weight Formula | W = (OD − WT) × WT × 0.02491 kg/m |
| Packing | Steel band wrapped coil on wooden or steel pallet; export-grade packaging |
Manufacturing Process
The seamless coil tubes are produced through a rigorous multi-stage manufacturing process designed to ensure dimensional accuracy and metallurgical excellence:
- Billet Preparation: High-purity stainless steel billets are selected and inspected for chemical composition and inclusion content.
- Piercing & Extrusion: Billets are heated to forging temperature and pierced to form seamless hollow tubes, avoiding any welded seams.
- Cold Rolling & Cold Drawing: Tubes are cold-worked to achieve precise OD and wall thickness dimensions with enhanced mechanical properties.
- Heat Treatment: Solution annealing is performed to restore full austenitic structure, relieve residual stresses, and optimize corrosion resistance.
- Coiling: Finished tubes are precisely coiled onto mandrels to maintain shape, prevent deformation, and facilitate transport and downstream processing.
- Quality Inspection: Each coil undergoes ultrasonic testing, eddy current inspection, dimensional verification, and chemical analysis prior to shipment.
Applications
- Heat Exchangers & Boilers: Ideal for coil-wound heat exchanger tubes where seamless construction eliminates weld-induced failure points.
- Food & Beverage Processing: Hygienic-grade 316L coil tubes for dairy, brewing, and pharmaceutical equipment.
- Chemical & Petrochemical Industry: Corrosion-resistant tubing for reactors, condensers, and process piping systems.
- Automotive & Aerospace: Fuel lines, exhaust components, and hydraulic systems requiring high-temperature and pressure resistance.
- Medical Equipment: Instrument tubing for MRI machines, surgical instruments, and diagnostic apparatus.
- Oil & Gas Exploration: Downhole tubing, casing, and subsea production systems.
Quality Certifications & Compliance
- ISO 9001:2015 Quality Management System Certification
- ISO 3834 Welding Quality Certification (for associated fabrication services)
- CE Marking compliance for European market requirements
- EN 10216-5 (seamless steel tubes for pressure purposes)
- ASTM A312 / A269 / A213 standards compliance
- GB/T 14976 (Chinese national standard for seamless stainless steel tubes)
- Mill Test Reports (MTR) provided with every shipment
- Third-party inspection available (SGS, Bureau Veritas, Lloyd's Register)
Unique Selling Points
- Transparent Theoretical Weight Pricing: The standardized formula W = (OD − WT) × WT × 0.02491 kg/m enables buyers to calculate exact costs independently, ensuring full pricing transparency and eliminating ambiguity in commercial negotiations.
- Seamless Construction: Absence of longitudinal weld seams provides superior pressure containment, eliminates weld decay risk, and ensures uniform material properties around the entire tube circumference.
- Coil Format Advantage: Continuous coil delivery reduces material waste from cutting, minimizes butt-weld joints during fabrication, and accelerates manufacturing throughput for downstream users.
- Buyer-Protective Tolerance Awareness: Wenzhou Jixing maintains clear communication regarding tolerance implications. Buyers are advised that when positive tolerance delivery is specified, the actual weight may exceed theoretical weight — a critical consideration for cost management in weight-based pricing models. Wenzhou Jixing recommends negotiating tolerance bands that align with project specifications to optimize value.
- Comprehensive Grade Availability: Full range of austenitic, duplex, and specialty alloy grades stocked or available on short lead times.
- Export-Ready Logistics: Professional coil packaging with rust-preventive treatment, wooden pallets, and documentation compliant with international trade standards.
Procurement Guidance
When procuring seamless stainless steel coil tubes from Wenzhou Jixing under the theoretical weight pricing model, buyers should note the following:
- The theoretical weight formula assumes standard stainless steel density and does not account for manufacturing tolerances. Actual weight may vary based on OD and WT tolerance ranges.
- For positive tolerance deliveries (where actual dimensions exceed nominal specifications), the buyer may incur additional cost since weight-based pricing directly correlates to actual delivered weight.
- It is recommended to specify tolerance requirements clearly in purchase orders and request dimensional inspection reports to ensure alignment between theoretical and actual weights.
- Wenzhou Jixing supports custom coil lengths, special surface treatments, and end-finishing operations (beveling, threading, cutting to length) to meet specific project requirements.