Why inspections are essential

Inspections performed by service stations or state agencies may not include a detailed CNG cylinder visual inspection, as outlined in a standard developed by natural gas vehicle industry engineers. Following this standard, a qualified inspector will note cuts, cracks, gouges, abrasions, discoloration, broken fibers, loose brackets, damaged gaskets or isolators, heat damage or other problems and recommend proper action to assure fuel system safety.

Inspector Qualifications

A qualified inspector must have:

Knowledge of the types of containers used in CNG vehicle systems, and damage allowances for each type, and understanding of inspection requirements, tests, procedures, and the container manufacturer’s current inspection guidelines readily available.

A qualified CNG cylinder inspector also must:

Have a minimum of 2 years’ experience conducting container inspections, or
Be supervised by someone with 2 years’ experience, or
Be approved by the container manufacturer, or
Be certified as an inspector by an organization with NGV training centers, an “authority having jurisdiction” or a nationally recognized certification testing organization

All CNG vehicle fuel containers MUST meet the federal government’s Federal Motor Vehicle Safety Standard (FMVSS) 304 (49 CFR 571.304), Compressed Natural Gas Fuel Container Integrity. All CNG vehicle fuel containers SHOULD meet American National Standards Institute (ANSI)/Canadian Standards Association (CSA) NGV2, Basic Requirements for Compressed Natural Gas Vehicle Fuel Containers. This industry standard is more comprehensive and up-to-date than FMVSS 304.

Periodic In-Service Inspection Requirements (Sec. 4.1.4, NGV2)

Each container shall be visually inspected at least every 36 months, or at the time of any re-installation, for external damage and deterioration … The inspection shall be performed by a qualified container inspector in accordance with (1) the manufacturer’s recommendations and (2) the inspection procedures provided in Compressed Gas Association (CGA) pamphlet C-6.4