Initially, people used animal hides sewn together to form tubular structures to meet the needs of production and combat. After a considerable period, by the late 17th century, the Vandel Geigen brothers of the Netherlands created longitudinally sewn canvas hoses, which were widely used in firefighting at the time. Later, with the emergence of rubber on the international market and the development of vulcanization technology, rubber hoses and rubber hoses armored with metal wire or hemp rope were introduced. However, for engineering applications involving high-temperature media such as steam and hot air, low-temperature media such as liquid hydrogen, liquid oxygen, and liquid helium, as well as corrosive media such as gasoline, kerosene, acids, and alkalis, rubber hoses were clearly unsuitable. Especially under high-temperature conditions, their safety and reliability were even more difficult to guarantee.
Therefore, people gradually focused their attention on metal pipes, modifying their geometry to create corresponding corrugations on their inner and outer surfaces. This gave them the flexibility of rubber hoses while also providing resistance to high and low temperatures, aging, and corrosion. Thus, the metal corrugated hose, as the body of the metal flexible hose, was born.
In 1855, Germany first published a patent for manufacturing bellows. It utilized existing principles of jewelry making to create the bellows. Thirty years later, E. Levavasseur of France and H. Witzenmann of Germany collaborated to develop a new type of metal bellows, obtaining patents in France and Germany in August 1885.
This was a spiral bellows made by winding S-shaped metal strips on specialized equipment. Rubber strips, cotton fabric, or asbestos rope were used to fill the seams between adjacent turns to facilitate a seal within the bellows cavity.
In 1894, the structure of this type of bellows was improved: two metal strips of different diameters were wound in opposite directions. This allowed the metal strips to achieve mutual balance under stress, overcoming the problem of self-unwinding.
In 1929, another technological revolution occurred in the structure of bellows, completely solving the problem of loss of sealing performance caused by uneven changes in the grooves of the rubber strips or asbestos ropes used for filling during bending. This opened up broad prospects for the development of bellows. Integral bellows were made from steel and copper-zinc alloys, using seamless or welded pipe materials. These bellows rely on the elastic deformation of the corrugated sidewalls to maintain a certain degree of compressibility or stretchability while ensuring a reliable seal.
From the 1950s onwards, double-layer, triple-layer, and multi-layer bellows, especially ultra-thin-walled stainless steel bellows, developed rapidly. To meet application requirements, various processes such as welding, electroforming, machining, hydraulics, and mechanical spinning were used to manufacture bellows. The minimum nominal diameter is 2 mm, and the maximum nominal diameter can reach 400-500 mm, with even giant bellows reaching 10 meters in diameter. The number of corrugations ranges from a minimum of 1-2 to hundreds, thousands, or even tens of thousands.
From the perspective of the corrugated pipe's significance as the body of a flexible metal hose, the development of corrugated metal pipes signifies the development of flexible metal hoses.
Subsequently, materials such as rubber, plastic, or nylon were coated onto the corrugated pipe's exterior, and a braided sheath composed of metal wires or strips was added, resulting in various joint types. This led to the creation of numerous forms of flexible metal hoses to meet the diverse requirements of various usage conditions.