Stainless Steel Coil Tube — Standards, Tolerance Grades & Technical Specification

Product Designation: Stainless Steel Coil Tube (Coiltube) | Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd | Product No.: 206

Category Classification: Commercial Procurement → Contract Terms → Tolerance Agreements → Standards and Grade Clarification

1. Product Overview

Stainless Steel Coil Tube (Coiltube) refers to continuously produced tubular products formed into coils, offering superior flexibility in downstream processing, storage efficiency, and material utilization compared to straight-length pipe sections. These coiled tubular products are supplied in accordance with internationally recognized standards governing dimensions, mechanical properties, chemical composition, and tolerance classifications.

The critical procurement consideration for Coil Tube lies in the explicit specification of applicable standard numbers and tolerance grades within contractual documentation. Failure to clearly designate these parameters results in default application of the widest permissible tolerance class, which is identified as a high-risk area for delivery disputes and non-conformance claims.

Key Procurement Principle: When tolerance grades are not explicitly stated in the purchase order or contract, the supplier defaults to the loosest (widest) tolerance classification permitted under the referenced standard. This significantly increases the probability of dimensional non-conformance upon receipt, leading to disputes, rejections, and production delays on the buyer's part.

2. Applicable Standards and Grade Designations

The following international and national standards govern the production, dimensional tolerances, and performance requirements for Stainless Steel Coil Tube:

3. Material Grades and Properties

Stainless Steel Coil Tube is available in a comprehensive range of alloy grades, each selected based on specific corrosion resistance, mechanical strength, and temperature performance requirements:

Typical mechanical properties for Grade 304 Coil Tube (cold-worked condition):

4. Dimensional Specifications and Tolerance Classes

The following table summarizes key dimensional parameters and their associated tolerance classes. It is imperative that the buyer explicitly specifies the tolerance grade in all contractual documentation:

Parameter Unit Typical Range Tolerance Class A (Precision) Tolerance Class B (Standard) Tolerance Class C (Wide / Default)
Outer Diameter (OD) mm 6.0 – 219.0 ±0.10 mm ±0.25 mm ±0.50 mm (default if unspecified)
Wall Thickness (WT) mm 0.5 – 6.0 ±0.05 mm ±0.10 mm ±0.15 mm (default if unspecified)
Length per Coil m Variable (coiled) ±0.5% of stated ±1.0% of stated ±3.0% of stated
Coil Weight kg 200 – 500 ±1.0% ±2.0% ±5.0% (default if unspecified)
Coil Inner Diameter (ID) mm 200 – 600 ±5 mm ±10 mm ±20 mm
End Form — Sheared / Beveled / Notch As specified Sheared (±1°) Sheared (±3°)
CRITICAL NOTE: Per standard industry practice, if the buyer does not explicitly state the tolerance class in the purchase order, quotation, or contract, the supplier is entitled to deliver product conforming to the widest (Class C) tolerance. This is the single most common cause of dimensional disputes upon delivery. It is strongly recommended that all procurement documents clearly reference the specific standard number AND the required tolerance grade.

5. Manufacturing Process

The production of Stainless Steel Coil Tube involves a multi-stage precision manufacturing sequence:

  1. Hot Rolling (热轧): Stainless steel slabs are hot-rolled into hollow rounds (blank tubes) at temperatures above 1,100°C, establishing initial dimensional geometry.
  2. Piercing and Rolling (穿孔轧制): The solid billet is pierced to create a hollow tube blank, which is subsequently rolled to approximate final dimensions.
  3. Heat Treatment (热处理): Annealing and pickling processes (酸洗退火) restore full austenitic structure, dissolve carbides, and provide a clean, oxide-free surface.
  4. Cold Drawing / Cold Rolling (冷拔/冷轧): The tube is drawn through precision dies or cold-rolled on mill rolls to achieve final dimensions within specified tolerance classes. This stage is critical for dimensional accuracy.
  5. Precision Sizing (精整): Final calibration passes ensure conformance to the specified OD and wall thickness tolerances.
  6. Coiling (盘卷): The finished tube is wound into coils of specified inner diameter and weight, typically with protective wrapping and moisture barriers.
  7. Quality Inspection (质量检测): 100% visual inspection, dimensional measurement, ultrasonic testing (UT), hydrostatic testing, and chemical analysis are performed prior to dispatch.

6. Applications

Stainless Steel Coil Tube finds extensive application across multiple industries:

7. Quality Certifications and Compliance

Wenzhou Jixing Metal Materials Co., Ltd maintains the following quality management and product certifications:

8. Unique Selling Points

9. Procurement Recommendations

To ensure seamless delivery and avoid dimensional disputes, buyers are advised to:

  1. Always specify the applicable standard number (e.g., "per ASTM A554, Table 3") in the purchase order.
  2. Explicitly state the required tolerance class (e.g., "OD tolerance: ±0.10 mm, per Precision Class A").
  3. Define acceptable coil weight range and inner diameter specifications.
  4. Request pre-shipment dimensional verification reports for critical dimensions.
  5. Clarify surface finish requirements (e.g., 2B, BA, No. 4, Mirror) in writing.
Disclaimer: All specifications, tolerances, and dimensional data provided herein are subject to the applicable standard version in force at the time of order placement. In the absence of explicit buyer specification, the supplier reserves the right to manufacture to the widest permissible tolerance class as defined by the referenced standard. Any deviation from stated specifications must be agreed upon in writing prior to production commencement.