Filament winding is an automated process in which continuous filament or tape is treated with resin and wound on a mandrel in a pattern that provides maximum strength in one direction. By varying relative amounts of resin and reinforcement along with the winding pattern, the strength of the filament-wound structures may be controlled to resist stresses in specific directions. After sufficient layers are wound, a structure is cured. Filament winding is used to make hollow tubular structures such as pressure vessels, pipes and storage tanks. PPG's HYBON sing-end fiber glass roving is well suited to filament winding, with maximum wet-out and excellent fatigue performance.