Generally road tankers for compressed gas are medium pressure, self-carrying semitrailers (typically 65 bar Maximum Allowable Working Pressure) for compressed gases, e.g. CNG and helium, transport in an easy and safe way, without requiring high pressure compression.
Notwithstanding their limited payload, when compared with other compressed gases transport units, they find their niche of application over short distances and/or in specific circumstances. The most common example is CNG transport with mother station from a high pressure (≈70 bar) pipeline, allowing tanker loading with just a hose, eliminating compression investment and running costs.
In domestic market they are also, due to their limited working pressure, exploit a specific legislation limiting safely measures (and related costs) for emergency or industrial supplies.
They can be also used for chemically aggressive gas mixtures, for instance raw biogas from small AD plants close to each other for concentration in a unique upgranding facility.