Burst Pressure Test for Stainless Steel Coil Tube (Coiltube)

Product Overview

The Burst Pressure Test (also referred to as Hydrostatic Burst Test or Rupture Pressure Test) is a critical type-test procedure applied to stainless steel coil tubes (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. This destructive testing method involves pressurizing a representative sample of the coil tube to the point of rupture, thereby determining the actual burst pressure and calculating the corresponding safety factor relative to the rated working pressure of the product.

As a type test (型式试验) and research and development verification procedure, the burst pressure test is not performed as a routine factory shipment inspection. Instead, it is conducted during product development, design qualification, material change validation, or periodic verification cycles to ensure that the coil tube design meets or exceeds the required mechanical integrity standards under extreme pressure conditions.

Material & Properties

Stainless steel coil tubes subjected to burst pressure testing are typically fabricated from austenitic, duplex, or precipitation-hardening stainless steel grades. The material properties directly influence the burst pressure outcome and safety factor calculations.

Specifications

Parameter Specification / Description
Test Category Type Test / R&D Verification (Non-routine factory inspection)
Test Method Hydrostatic Pressurization to Rupture
Test Medium Deionized water or hydraulic fluid (non-corrosive)
Pressurization Rate Controlled, typically 0.5–2.0 MPa/s (adjustable per standard)
Pressure Recording Continuous digital recording at ≥10 Hz sampling rate
Burst Pressure Determination Maximum pressure recorded immediately prior to visible rupture or sudden pressure drop
Safety Factor Calculation Safety Factor = Actual Burst Pressure / Rated Working Pressure (MAWP)
Minimum Acceptable Safety Factor ≥ 4.0 for pressure vessel applications; ≥ 3.0 for general industrial use (per applicable codes)
Sample Quantity Minimum 3 samples per lot/design for statistical validity
Test Temperature Ambient temperature (20 ± 5°C) unless specified for elevated/low temperature qualification
Rupture Location Recording Documented (weld zone, body, joint) for failure analysis
Applicable Standards ASTM A269, ASTM A270, EN 10217-7, ISO 1127, ASME B31.3, GB/T 12771
Reporting Detailed test report with burst pressure values, safety factor calculations, failure mode analysis, and compliance assessment

Manufacturing Process

The stainless steel coil tube undergoes a multi-stage manufacturing process prior to burst pressure testing:

  1. Coil Forming: Hot-rolled or cold-rolled stainless steel strip is precision-fed into a coil tube forming machine, which rolls the strip into a tubular shape with controlled wall thickness and outer diameter tolerances.
  2. Seam Welding: A high-frequency (HF) resistance welding or laser welding process joins the longitudinal seam, producing a homogeneous weld with minimal heat-affected zone (HAZ) distortion.
  3. Heat Treatment (if applicable): Solution annealing or stress-relief annealing may be applied to restore corrosion resistance and relieve residual stresses introduced during forming and welding.
  4. Surface Finishing: Electropolishing, pickling, or mechanical polishing ensures a smooth internal and external surface, critical for pressure integrity and fluid compatibility.
  5. Coiling & Packaging: The continuous tube is coiled into manageable lengths for transport and downstream processing.
  6. Pre-Test Preparation: Test specimens are cut to specified lengths, end-capped with pressure-rated fittings, and inspected for surface defects prior to hydrostatic pressurization.

Burst Test Procedure

  1. Test specimens are sealed at both ends with calibrated pressure caps or end plugs rated above the expected burst pressure.
  2. The test assembly is mounted on a hydraulic test rig equipped with a precision pressure transducer (accuracy ±0.25% of reading).
  3. Pressurization is initiated at a controlled rate, with pressure continuously monitored and recorded.
  4. The test continues until the tube ruptures, indicated by a sudden pressure drop or audible/visible failure event.
  5. The maximum recorded pressure is designated as the Actual Burst Pressure (P_burst).
  6. The Safety Factor (SF) is calculated as: SF = P_burst / P_working, where P_working is the maximum allowable working pressure (MAWP).
  7. Failure mode and rupture location are documented for engineering analysis.

Applications

Burst pressure-qualified stainless steel coil tubes find application in demanding environments where pressure integrity is paramount:

Quality Certifications & Compliance

Wenzhou Jixing Metal Materials Co., Ltd. maintains rigorous quality management systems and adheres to international standards for coil tube production and testing:

Unique Selling Points

Technical Notes

Important: The burst pressure test is a destructive test performed as a type test or R&D verification activity. It is not a routine factory shipment inspection. Each test consumes the test specimen and requires dedicated testing infrastructure. Results from burst testing are used to establish design margins, validate manufacturing processes, and support regulatory certifications rather than for lot-by-lot product acceptance.

The combination of advanced manufacturing precision, rigorous material selection, and comprehensive burst pressure validation ensures that Wenzhou Jixing Metal Materials Co., Ltd. stainless steel coil tubes deliver superior pressure integrity and long-term reliability in the most demanding industrial applications worldwide.