Rigid tubes - have inner and outer walls enclosing fibrous mat material

摘要

The inner and outer walls are of a chemically resistant, pref. inert, material and the fibrous material may be resin impregnated cardboard, or resin impregnated glass fibre mat. A tape is helically wound onto a former to produce the inner wall; one or more helically wound layers of a tape of the fibrous material are wound onto the inner wall; and the outer wall is wound onto the fibrous material.