High-strength butt-wrap joint for reinforced plastic pipes

A butt-wrap joint for joining fiber reinforced thermosetting resin pipes, comprising:

• a plurality of wraps of material wetted with a thermosetting resin and wrapped circumferentially relative to a first pipe end and a second pipe end, said first and second pipe ends being the respective ends of first and second pipes;
• said pipes being aligned and said first pipe end abutting said second pipe end;
• said first and second pipes being joined at their respective abutting ends by said plurality of wraps disposed generally symmetrically on said abutting pipes;
• a first wrap being disposed relative to the surface of said respective pipes and a second through an n-th wrap of said plurality of wraps being disposed successively outwardly, relative of a respective preceding wrap;
• said first wrap having a width L1 in the pipe longitudinal direction;
• said second wrap having a width L2 in the pipe longitudinal direction;
• said n-th wrap having a width Ln in the pipe longitudinal direction;
• and
• said plurality of wraps being covered by a chopped strand mat wetted with said thermosetting resin and having a width L0 in the pipe longitudinal direction, wherein:
• said first wrap width L1 being greater than the width of any of the subsequent wraps;
• said second wrap width L2 being greater than the width of any of the subsequent wraps;
• the widths L3 to Ln−1 of the intermediate wraps being successively diminishing at a constant rate, said rate being a result of a linear interpolation between she second wrap L2 width and the n-th wrap width Ln;
• the longitudinal stiffness of the wraps is progressively tapered at the edges, in that the longitudinal stiffness of the wraps is increased at a low rate at the edge of the wraps while it is increased at a faster rate away from the edge.