L51473 Investigation of Wrinkling at Low Bend Angles During Field Bending of Line Pipe

Severe problems with wrinkling when making field bends in ERW pipe coated with a fusion-bonded thin-film coating have been reported by several PRCI member companies in recent years. When these problems were encountered, wrinkling was controlled by careful alignment of the bending equipment, by procuring another lot of pipe for bending, or by increasing the bend radius. The occurrence of wrinkling results in considerable inconvenience, such as increased cost and construction delays, particularly when it cannot be controlled solely by realignment of the bending equipment.

An investigation was conducted to determine the factors responsible for the development of wrinkles at low bend angles during the field bending of certain lots of line pipe. The investigation included both a survey of users to obtain information on field bending problems and laboratory studies at Battelle designed to identify factors responsible for wrinkling at low bend angles.