Stainless Steel Coil Tube — Cleanliness Verification via Liquid Particle Counter (LPC) Testing
Product Overview
Wenzhou Jixing Metal Materials Co., Ltd. manufactures high-purity stainless steel coil tubes (Coiltube) engineered for ultra-clean industrial applications. The product quality assurance framework incorporates rigorous cleanliness verification protocols, with Liquid Particle Counter (LPC) testing serving as the definitive batch release criterion. This inspection methodology ensures that every coil tube batch meets cleanroom-grade contamination control standards, providing traceable, quantifiable evidence of surface and internal cleanliness prior to shipment.
The LPC testing protocol employed by Wenzhou Jixing conforms to international cleanliness classification standards, enabling customers in pharmaceutical, semiconductor, and bioprocessing industries to maintain validated process integrity throughout their supply chains.
Material & Properties
- Base Material: Austenitic stainless steel (e.g., Type 304, Type 316L) — selected for superior corrosion resistance and biocompatibility
- Surface Finish: Electro-polished or mechanical-polished internal surface achieving Ra ≤ 0.4 μm roughness
- Wall Thickness: Engineered to specification for pressure containment and flow dynamics
- Form: Coiled (spooled) configuration enabling continuous-form processing and reduced weld joints in downstream assembly
- Purity Grade: Ultra-low carbon (LC) variants available to prevent chromium carbide precipitation during welding
Specifications — LPC Cleanliness Testing Protocol
| Parameter | Specification / Requirement |
|---|---|
| Testing Method | Liquid Particle Counter (LPC) — Laser Diffraction / Light Scattering |
| Particle Size Channels | ≥ 0.1 μm / ≥ 0.2 μm / ≥ 0.5 μm (three-tier graded counting) |
| Sampling Medium | Ultrapure water (UPW) or application-specific solvent rinse |
| Acceptance Criteria | Defined particle count thresholds per channel — batch release gate |
| Classification Reference | ISO 14644-1 (Cleanroom Air) / ASTM F2189 (Liquid Particulate Contamination) |
| Equipment Calibration | Annually calibrated particle counters with certified polystyrene latex (PSL) spheres |
| Reporting | Per-batch CoA (Certificate of Analysis) with particle count data and trend documentation |
| Batch Release Authority | Quality Assurance (QA) sign-off contingent upon LPC pass/fail determination |
Manufacturing Process — Cleanliness Control Integration
- Raw Material Inbound: Incoming stainless steel coil undergoes visual and spectroscopic verification (PMI — Positive Material Identification) to confirm alloy grade and purity.
- Forming & Sizing: Precision cold-forming to achieve dimensional tolerance while maintaining surface integrity; all tooling contacts are cleanroom-managed.
- Pickling & Descaling: Controlled acid bath treatment removes mill scale and surface oxides, restoring passive chromium oxide layer.
- Passivation: Nitric or citric acid passivation enhances corrosion resistance and removes free iron from the surface.
- Internal Cleaning: Multi-stage rinse using progressively higher-purity water; final rinse conducted with water meeting ≥ 18.2 MΩ·cm resistivity.
- Coiling & Packaging: Tubes are coiled under controlled environmental conditions; sealed in cleanroom-compatible packaging (e.g., HDPE bags, vacuum-sealed) to prevent post-process contamination.
- LPC Verification: Representative samples are extracted from each batch; internal surfaces are flushed with ultrapure water and subjected to LPC analysis at ≥ 0.1 μm, ≥ 0.2 μm, and ≥ 0.5 μm channels. Only batches meeting all three-channel thresholds receive release approval.
Applications
- Pharmaceutical & Bioprocessing: CIP/SIP (Clean-In-Place / Sterilize-In-Place) piping systems, bioreactor connections, and sterile fluid transfer lines requiring ISO Class 5–7 cleanroom compatibility.
- Semiconductor Manufacturing: Ultra-pure water (UPW) distribution systems, chemical delivery lines, and process gas supply networks where sub-micron particle contamination is unacceptable.
- Food & Beverage: Hygienic-grade processing lines, CIP loop piping, and product transfer conduits subject to FDA 21 CFR Part 117 compliance.
- Medical Device Manufacturing: Clean water systems, steam generation lines, and purified process fluid circuits in GMP-regulated facilities.
- Electrochemical & Battery Industries: High-purity electrolyte delivery systems requiring ultra-low particulate contamination control.
Quality Certifications & Compliance
- ISO 9001:2015 — Quality Management System certification ensuring consistent production quality and traceability.
- ISO 14644-1 — Cleanroom cleanliness classification alignment for particle control methodology.
- ASTM F2189 — Standard Practice for Determination of Liquid Particulate Contamination via LPC.
- ASME BPE (Bioprocessing Equipment) — Design and fabrication compliance for pharmaceutical-grade piping systems.
- EU GMP Annex 1 — Alignment with European pharmaceutical manufacturing cleanliness requirements.
- FDA 21 CFR — Compliance with U.S. food and drug equipment material safety standards.
Unique Selling Points
1. Three-Channel LPC Graded Verification: Unlike single-threshold cleanliness checks, Wenzhou Jixing implements a comprehensive three-tier particle counting protocol (≥ 0.1 μm, ≥ 0.2 μm, ≥ 0.5 μm), providing granular contamination profiling that enables early detection of upstream process deviations.
2. Batch-Level Release Gate: LPC results serve as a mandatory, non-negotiable batch release criterion — no coil tube shipment proceeds without documented particle count compliance, ensuring zero-defect delivery.
3. Full Traceability: Each batch is accompanied by a Certificate of Analysis (CoA) detailing LPC channel-specific results, equipment calibration status, and environmental conditions during testing — enabling downstream customer audit readiness.
4. Cleanroom-Grade Assurance: The entire manufacturing and testing workflow is designed to prevent post-cleaning recontamination, making these coil tubes suitable for the most demanding cleanroom integration scenarios.
Technical Note
The Liquid Particle Counter (LPC) methodology utilized by Wenzhou Jixing operates on the principle of laser light scattering (or laser diffraction), wherein particles suspended in the sample fluid scatter or diffract an incident laser beam. The intensity and angular distribution of scattered light are correlated to particle size, enabling simultaneous classification across multiple size thresholds. This non-destructive, quantitative approach provides statistically significant contamination data with a minimum detectable particle size of 0.1 μm — well below the threshold of concern for critical process applications. The three-channel reporting structure (≥ 0.1 μm, ≥ 0.2 μm, ≥ 0.5 μm) follows the convention established by ASTM F2189 and aligns with ISO 14644-1 cleanliness class mapping, facilitating direct cross-referencing with customer facility cleanroom classifications.