Corrugated drainage pipe

Claim 1

A corrugated resilient plastic drainage pipe having spaced apart successive annular ribs with annular valley portions therebetween, the majority of said annular ribs being uninterrupted and successively arranged in spaced groups, the remaining ribs being interrupTed and each comprising a set of three circularly arranged spaced apart arcuate rib segments, the rib segments forming each of the interrupted ribs being correspondingly arranged throughout the pipe with one of the interrupted ribs being positioned between each adjacent pair of said groups of uninterrupted ribs, one rib segment of each set being substantially longer than the other two rib segments and having an arcuate extent of about 200* to 220*, said other two rib segments each having an arcuate extent of about 40* to 45*, a series of three drainage holes being provided between said rib segments of each set with the diameter of the holes being at least one half inch and greater than the width of the ribs, two of said drainage holes being positioned between the opposite terminal ends of said long rib segment and the respective shorter rib segments, the third drainage hole being positioned between the shorter rib segments and being substantially centrally disposed between said two holes, and sight means extending longitudinally of said pipe on and along the outer surface of said annular ribs thereof, directly opposite said third drainage holes, for visually aiding in installing the pipe in the ground with all of the drainage holes located below the horizontal center line of the pipe and with the third drainage holes occupying lowermost position.