Product Overview & Core Specifications
High-pressure Type I all-steel CNG cylinders are forged from premium chromium-molybdenum alloy steel billets. Built for heavy-duty commercial transport and industrial gas cascading, these cylinders provide mechanical robustness and predictable fatigue resistance under cyclic pressure loads up to 250 bar.
Standard Technical Parameters
Use the matrix below for exact technical matching and engineering layout planning.
|
Model Code |
Water Capacity (L) |
Outer Diameter (mm) |
Nominal Length (mm) |
Wall Thickness (mm) |
Working Pressure (bar) |
Test Pressure (bar) |
Tare Weight (kg) |
Thread Standard |
|
CNG-320-50L |
50 |
320 |
950 |
5.2 |
200 |
300 |
48.5 |
PZ27.8 / W28.8 |
|
CNG-356-80L |
80 |
356 |
1080 |
5.8 |
200 |
300 |
74.0 |
PZ27.8 / W28.8 |
|
CNG-406-120L |
120 |
406 |
1230 |
6.4 |
200 |
300 |
105.0 |
PZ27.8 / W28.8 |
|
CNG-406-140L |
140 |
406 |
1420 |
6.4 |
200 |
300 |
121.0 |
PZ27.8 / W28.8 |
|
CNG-457-180L |
180 |
457 |
1510 |
7.1 |
200 |
300 |
168.0 |
PZ27.8 / W28.8 |
Material & Manufacturing Process
Mechanical safety in high-pressure containment relies on absolute metallurgical control and automated thermal processing.
Raw Material: Sourced exclusively from premium 34CrMo4 seamless steel tube billets. Each batch includes a verifiable Mill Test Certificate (MTC) detailing chemical composition limits (C: 0.30-0.37%, Cr: 0.90-1.20%, Mo: 0.15-0.30%).
Hot Spinning Formation: Billet ends undergo controlled induction heating followed by computerized hot-spinning to form uniform, stress-free dome profiles without structural welding seams.
Quenching & Tempering (Q&T): Full-body thermal treatment via automated vertical quench lines ensures uniform martensitic transformation, followed by precise high-temperature tempering to achieve optimal yield-to-tensile strength ratios (Yield Strength >= 750 MPa, Tensile Strength >= 850 MPa).
Internal Surface Shot Blasting: Mechanical descaling and cleaning eliminate internal oxidation layers, preventing particulate contamination in downstream fuel injectors or regulators.
Mandatory Quality Control & Testing
Every production lot undergoes destructive and non-destructive testing (NDT) witnessed by authorized independent inspection bodies (TUV, BV, or SGS).
Ultrasonic Testing (UT): 100% volumetric inspection of cylindrical walls and neck sections to detect internal laminations or inclusions.
Hydrostatic Pressure Test: Each cylinder is pressurized to 1.5 times the working pressure (300 bar or 375 bar) held for a minimum of 30 seconds to verify elastic deformation limits.
Burst Test: Conducted at a ratio of 1 cylinder per batch of 200 units, measuring volumetric expansion and verifying that burst pressure exceeds 2.25 times working pressure without fragmentation.
Flattening & Tensile Tests: Transverse and longitudinal coupons pulled from finished shells to confirm elongation and tensile thresholds meet ISO 11439 criteria.
Internal Corrosion & Hydrogen Embrittlement Resistance: Monitored via microstructural grain size analysis (ASTM E112 compliant).
Typical Applications
Engineered for integration into high-vibration automotive chassis and high-flow industrial gas distribution setups.
Commercial Fleets: Fuel storage for CNG-powered transit buses, municipal waste collection trucks, and long-haul logistics tractors.
Stationary Cascade Systems: Modular storage banks for CNG fueling stations, providing buffer storage for fast-fill dispenser operations.
Mobile Transport Skids: Containerized gas transport modules moving compressed natural gas from wellheads or primary grid injection points to remote industrial consumers.
Procurement & Supply Chain Parameters
Minimum Order Quantity (MOQ): 1 x 20-foot container (quantities vary by diameter and length matrix).
Packaging Specifications: Cylinders ship bare or with heavy-duty nylon protective mesh nets, secured in wooden cradle pallets to prevent exterior impact or thread damage during ocean transit.
Documentation Provided:
Full Mill Test Certificates (MTC) per heat number.
Third-Party Inspection Certificate (TUV / BV / SGS) bearing official agency accreditation marks and traceable QR verification codes.
Dimensional Inspection Report per serial number.
User and Maintenance Manual (Multilingual options available).
Lead Time: Standard production runs complete within 35 to 45 calendar days from order confirmation and drawing sign-off.
Frequently Asked Questions
Q: What is the official design life (service life) of these steel CNG cylinders?
A: Built in accordance with ISO 11439 regulations, the standard operational life is 20 years (or specific cycles as defined by local national transport authorities), provided periodic requalification intervals are maintained.
Q: Can you customize the water capacity or outer diameter for restricted chassis spaces?
A: Yes. OEM/ODM customization is available for bulk volume orders. Engineering layout drawings are supplied within 48 hours for customer integration sign-off prior to tooling setup.
Q: What thread specifications are available for the cylinder neck?
A: Standard production configurations utilize PZ27.8 or W28.8 internal threads. Parallel or alternative tapered threads can be machined upon engineering request to match specific valve manifolds.
Q: How do you handle third-party inspection requirements?
A: Routine production batches are inspected by recognized agencies such as TUV, Bureau Veritas, or SGS. Buyers can also designate their own third-party inspection representatives to witness hydrostatic and burst testing onsite prior to shipment.
Q: What corrosion protection is applied to the exterior surface?
A: External surfaces undergo abrasive grit blasting (Sa 2.5 grade), followed by electrostatic powder coating (epoxy-polyester formulation) cured at 200°C, providing mechanical impact resistance and salt-spray corrosion protection exceeding 500 hours.
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