How Are High Pressure Vessels for Compressed Gas Made?

If you are a buyer of pressurized gas for your business, you may be curious about how a commercial metal forming company produces high pressure vessels suitable for containing compressed gas. There are several steps involved in making pressure vessels that can withstand up to 1000 times more pressure than other more basic containers that may be used for storing dry goods under normal pressure.

Heat Treated Metal and Chemical Baths

Metals such as the steel alloy chromoly are often used for high-pressure vessels. These metals are initially treated at a temperature near 1300 degrees Fahrenheit for 36 hours before being immersed in the first of a series of chemical baths intended to allow the metal to flex and be capable of safely storing compressed gas. Once dried, the metal is moved over a hydroforming press to be formed into the shape outlined by the designer. Often there is a deep draw die that is made based upon the specifications provided by the client.

A Series of Presses

Several different types of powerful presses are used to shape compressed gas vessels. A mandrel pressor hydroforming sheet metal press applies up to 800 tons of force before another type of press may be used to continue refining the vessel shape with up to 150 tons of force while using a coolant to prevent overheating. Several presses may be employed to stretch the metal until the closed bottom end of the vessel is shaped and reinforced.

Finishing the Top and Exterior

In order for a commercial metal forming company to complete a pressure vessel, it is necessary to create a leak-proof neck and valve connection. First, a band saw is used to slice off the top of the container following pressing. A torch then heats the edge to more than 1500 degrees Fahrenheit for 90 minutes before the vessel is returned to yet another chemical bath for several minutes. The vessel is finally reheated to a slightly lower temperature around 1200 degrees Fahrenheit for 90 minutes before being left to cool for several hours. The surface is smoothed by shot blasting and the finished container is tested by being filled with and submerged in water.

All of the transitions between extreme heat and cooling involved in the production of a high-pressure vessel temper the metal and allow it to flex enough to safely contain pressurized gases. There are several major types of pressured vessels that that can be created by shaping deep drawn aluminum, specialty alloys and carbon steel. There are only a handful of hydroforming companies in USA that specialize in making pressure vessels for the compressed gas market.