A hydraulic ram presses and shapes a solid aluminum billet into a hollow shell, the open top of which is closed and threaded. The newly formed cylinder then undergoes a precisely controlled heat-treatment regimen that adds strength and durability.
After being thoroughly tested to standards established by regulatory agencies, the cylinder is painted or receives a brushed or shot-blasted exterior finish. The result is a seamless, lightweight aluminum cylinder with a consistent wall thickness and naturally corrosion-resistant oxide finish that make it ideal for high-pressure gas containment.
These cylinders consist of an all-aluminum inner cylinder or “liner” capable of holding the same pressure as a comparably-sized all-aluminum cylinder. The “barrel” or middle cylindrical portion of this liner is wrapped with resin-impregnated fiber (typically fiberglass or aerospace-grade carbon) that reinforces the cylinder walls and enables the finished cylinder to hold higher pressure. The crown and base of the liner are not wrapped.