The construction is in general as follows: The inside rubber lining is leak-proof and made of synthetic or natural rubber, depending on the application. This applies also for the outside rubber cover, which has the vital function to protect the canvass, between the cover and the inside lining, from outside damages. Special polymers can be supplied to resist chemicals, oils, sunlight, acid fumes and ozone. The pressure supporting canvass consists of fabric and metal reinforcement, as wire or solid rings.
