ISO 12614-11:2021

Overview

ISO 12614-11:2021 specifies tests and requirements for fittings used in liquefied natural gas (LNG) fuel systems for road vehicles as defined in ISO 3833. The part focuses on ensuring mechanical integrity, leak-tightness and operational reliability of fittings installed on vehicle fuel lines. The standard excludes fuel containers, stationary gas engines, container mounting hardware, electronic fuel management and refuelling receptacles.

Key practical points:

• Base working pressure: 1.6 MPa (16 bar). Other pressures are accommodated by multiplying pressures by the appropriate ratio (for example, 2.0 MPa requires a factor of 1.25).
• All pressures are gauge pressures unless otherwise stated.

Key Topics

Marking and traceability

• Fittings must be marked so that the manufacturer, model/part number, working pressure or range, and serial number/date code can be traced.
• Recommended markings include flow direction, fuel type, electrical ratings (if applicable), certification symbol, type approval number, and reference to ISO 12614-11.

Construction and compatibility

• Fittings shall meet applicable provisions in ISO 12614-1 and ISO 12614-2 and be compatible with rigid fuel line systems.

Tests and performance requirements ISO 12614-11 references test procedures from ISO 12614-2. Applicable test categories include:

• Hydrostatic strength - fitting hydostatic testing uses a test pressure equal to four times the working pressure.
• Leakage - to verify seal integrity after applicable test sequences.
• Continued operation - fittings are subjected to operational cycling (100 cycles) while connected to rigid fuel lines; connection/disconnection cycles (typically 25) apply unless declared single-use by the manufacturer.
• Vibration resistance - pressurized fittings are vibrated along three orthogonal axes for 30 minutes each at the most severe resonant frequencies using 1.5 g, over 10 Hz–500 Hz, with a 10 min sweep; fittings must show no fatigue and pass leakage and hydrostatic tests afterwards.
• Pull-off - tensile pull-off testing of a fitted rigid fuel line: the required minimum pull-off force is calculated per the document's formula, based on internal diameter (mm) and pressure (bar); the formula already incorporates a safety factor of four.
• Additional tests in scope: excess torque resistance, bending moment, corrosion resistance, oxygen ageing, brass compatibility, electrical overvoltage and non-metallic material immersion where applicable.

Applications

ISO 12614-11 is intended for manufacturers, suppliers, test laboratories and vehicle integrators working with LNG fuel system fittings. Use cases include:

• Component design validation and type approval
• Supplier quality control and incoming inspection
• Integration checks for rigid LNG fuel lines on road vehicles
• Regulatory compliance and certification preparation

Related Standards

• ISO 12614-1 - General requirements and definitions for LNG fuel system components
• ISO 12614-2 - Performance and general test methods referenced throughout Part 11
• ISO 3833 - Road vehicle types, terms and definitions

Compliance with ISO 12614-11:2021 supports safer, more reliable LNG fuel systems through standardized testing and traceability for fittings used in road vehicles.