ISO 15500-20:2015 provides specific requirements and tests applicable to the rigid fuel line in carbon steel, intended for use on the types of motor vehicles, as defined in ISO 3833, with a service pressure for natural gas as a fuel of 20 MPa (200 bar) settled at 15 °C.

ISO 15500 is intended to be applied to vehicles using natural gas which comply with requirements established in ISO 15403‑1 (mono-fuel, bi-fuel, or dual-fuel applications). This part of ISO 15500 does not apply to the following:

a) liquefied natural gas (LNG) fuel system components located upstream of, and including, the vaporizer;

b) fuel containers;

c) stationary gas engines;

d) container mounting hardware;

e) electronic fuel management;

f) refuelling receptacles.

NOTE All references to pressure in this part of ISO 15500 are considered gauge pressures unless otherwise specified.[1]

[1] 1 bar = 100 kPa = 0,1 MPa.