Abstract: The present invention involves a low permeation pinchoff connection at a pinchoff region having a pinchoff end between first and second formed sheets of a fluid tank. The low permeation pinchoff connection comprises a continuous inner polymeric layer at a pinchoff region having a pinchoff end between the first and second formed sheets. The connection further comprises an outer polymeric layer in side-by-side relationship with the continuous inner polymeric layer. The outer polymeric layer tapers at the pinchoff region to first and second outer polymeric ends at the pinchoff end separating the first and second outer polymeric ends. The connection further comprises a low permeation barrier layer disposed between the continuous inner polymeric layer and the outer polymeric layer. The low permeation barrier layer tapers with the outer polymeric layer at the pinchoff region to first and second barrier ends separated at the pinchoff end to determine a pinchoff gap.

Abstract: The present invention involves a low permeation pinchoff connection at a pinchoff region having a pinchoff end between first and second formed sheets of a fluid tank. The low permeation pinchoff connection comprises a continuous inner polymeric layer at a pinchoff region having a pinchoff end between the first and second formed sheets. The connection further comprises an outer polymeric layer in side-by-side relationship with the continuous inner polymeric layer. The outer polymeric layer tapers at the pinchoff region to first and second outer polymeric ends at the pinchoff end separating the first and second outer polymeric ends. The connection further comprises a low permeation barrier layer disposed between the continuous inner polymeric layer and the outer polymeric layer. The low permeation barrier layer tapers with the outer polymeric layer at the pinchoff region to first and second barrier ends separated at the pinchoff end to determine a pinchoff gap.

Abstract: A method of thermoforming a thin flexible film comprising a series of steps. A thin flexible film capable of being thermoformed is heated until it is pliable. A mold having first and second surfaces on different planes forms a thermoformed article having a contoured surface. A first portion of the pliable film is contacted with the first surface. A first vacuum is applied through the first surface to draw the first portion against the first surface. After the first portion of the film is drawn against the first surface, a second portion of the film contacts the second surface. A second vacuum is applied through the second surface to draw the second portion of the film against the second surface. Air trapped between the mold and the film is first removed between the first surface and the first portion of the film and then removed from between the second surface and the second portion of said film so that the thermoformed article is substantially defect-free.