Tube trailers carry compressed gases, most commonly hydrogen, nitrogen, oxygen, helium, argon, and compressed natural gas. These specialized trailers consist of long, high-pressure steel or composite cylinders bundled together on a flatbed frame, designed to transport gases that need to stay in a compressed gaseous state rather than being liquefied for delivery.
How Tube Trailers Work
A tube trailer is essentially a rolling gas storage system. Multiple large cylinders, sometimes called “tubes,” are mounted horizontally on a semi-trailer chassis. Each cylinder is built to withstand extremely high internal pressure. For hydrogen, those pressures reach 180 bar (roughly 2,600 psi) or higher. The tubes connect to a shared manifold system at one end, which allows the receiving facility to offload the gas through a single connection point.
Unlike tanker trucks that carry liquefied gases at cryogenic temperatures, tube trailers keep their cargo in compressed gas form at ambient temperature. This makes them a practical choice for moderate delivery volumes where building a permanent pipeline would be too expensive, but where the customer still needs a reliable bulk supply.
Gases Commonly Carried
The most frequently transported gases in tube trailers fall into a few broad categories.
Industrial gases: Hydrogen, nitrogen, oxygen, and argon are the workhorses. Hydrogen tube trailers supply fuel cell stations, oil refineries, chemical plants, and electronics manufacturers. Nitrogen gets delivered to food packaging operations, metalworking shops, and laboratories. Oxygen goes to steel mills, wastewater treatment plants, and welding operations. Argon serves welding and metal fabrication shops that need an inert shielding gas.
Energy gases: Compressed natural gas (CNG) is widely delivered by tube trailer in countries where pipeline infrastructure is limited. The U.S. Department of Energy notes that tube trailers designed for hydrogen are also being used internationally for compressed natural gas transport. Hydrogen itself is increasingly delivered this way to support fuel cell vehicle refueling stations.
Specialty and medical gases: Helium for medical imaging equipment and industrial applications, as well as high-purity gases used in semiconductor manufacturing, often travel by tube trailer. Medical-grade oxygen for hospitals is another common payload, particularly for facilities that consume enough volume to justify bulk delivery but not enough to warrant on-site production or a liquid oxygen tank.
Capacity and Pressure Ratings
The amount of gas a tube trailer can carry depends on the operating pressure of its cylinders and the type of gas being transported. Hydrogen tube trailers compressed to 180 bar carry a relatively modest payload by weight, since hydrogen is extremely light. A standard steel-tube hydrogen trailer at that pressure typically holds around 300 to 400 kilograms of usable hydrogen. Newer composite-cylinder trailers operating at higher pressures (250 to 500 bar) can carry significantly more, roughly 500 to 1,000 kilograms per load.
For denser gases like nitrogen or natural gas, the same trailer volume yields a heavier payload. The number of individual tubes on a trailer varies, but configurations of 6 to 12 large-diameter tubes are common, with total water volumes ranging from about 2,500 to 5,000 liters per tube depending on the design.
Safety and Inspection Requirements
Because tube trailers carry gases at thousands of pounds per square inch, they fall under strict federal safety regulations managed by the Pipeline and Hazardous Materials Safety Administration (PHMSA). The cylinders on a tube trailer must comply with requirements under 49 CFR § 173.302a, which governs the filling and marking of compressed gas containers for transport.
Each cylinder must undergo hydrostatic testing, a process where the tube is pressurized with water to verify it can safely handle its rated pressure, at least once every five years. The external threads on each cylinder must be inspected every 10 years. Cylinders that pass testing and meet all requirements under 49 CFR § 180.213(f)(3) receive a plus (+) marking on their retest plate. That marking matters: without it, the filler cannot load the cylinder beyond its marked service pressure. With the plus marking, the cylinder is approved to be filled to 110% of its marked service pressure, allowing slightly more gas per delivery.
Where Tube Trailers Get Used
Tube trailers fill a specific niche in the gas supply chain. They make the most sense when a customer needs a steady supply of compressed gas but is too far from a pipeline and doesn’t use enough volume to justify a dedicated on-site production facility or a large cryogenic liquid storage tank.
In practice, this covers a wide range of settings. Hydrogen tube trailers supply refueling stations for fuel cell vehicles, deliver feedstock hydrogen to small chemical operations, and serve electronics manufacturers that use hydrogen in chip fabrication. CNG tube trailers bring natural gas to industrial sites in areas without pipeline access, or provide temporary fuel supply during pipeline maintenance. Nitrogen and oxygen tube trailers serve metalworking shops, food processors, and smaller hospitals across the country.
One operational advantage is that tube trailers can function as temporary on-site storage. The trailer itself stays parked at the customer’s facility, connected to their piping system, while the gas is drawn off over days or weeks. When the tubes are nearly empty, the supplier swaps in a full trailer and hauls the empty one back for refilling. This swap model eliminates the need for the customer to install and maintain permanent high-pressure storage vessels on their property.