INJURED, FUSING HDPE PIPE, SUSTAINED A BRUISE TO THE RIGHT KNEE. INJURY OCCURRED WHEN THE 24 INCH PIPE BEING FUSED WAS LIFTED ALONG SIDE A 12 INCH LINE AND SPRUNG BACK TO THE STRAIGHT POSITION WHEN IT CLEARED THE 12 INCH LINE. AS IT SPRUNG BACK, IT STRUCK THE INJURED'S KNEE. LIGHT DUTY WAS PRESCRIBED.