What is Composite overwrapped pressure vessel?

A composite overwrapped pressure vessel is a vessel consisting of a thin, non-structural liner wrapped with a structural fiber composite, designed to hold a fluid under pressure. The liner provides a barrier between the fluid and the composite, preventing leaks and chemical degradation of the structure. In general, a protective shell is applied for protective shielding against impact damage. The most commonly used composites are fiber reinforced polymers , using carbon and kevlar fibers. The primary advantage of a COPV as compared to a similar sized metallic pressure vessel is lower weight; COPVs, however, carry an increased cost of manufacturing and certification.