Patent ID: 7627992

Claim:
An access riser section comprising a single sidewall having a first end, a second end, and an inner surface; said second end defining a channel end; a plurality of vertical bosses extending along the inner surface of said sidewall; said bosses connected to said sidewall by offsetting portions that are narrower than said bosses; said channel end including wall portions defining a channel to receive bosses of another riser section; one of said channel defining wall portions defining a plurality of slots open at an edge of said slot defining wall portion; at least two of said slots including at least a portion defined by parallel edges formed by said slotted wall portion, the spacing of said parallel edges of said at least two slots being wider than the width of said offsetting portions and narrower than the width of said bosses; said at least two slots adapted to receive offsetting portions of another riser section; and wherein said at least two slots further include diverging edges defined by said slotted wall portion extending from said parallel edges and forming a portion of each said slot that is progressively wider than the distance between said parallel edges from the juncture with said parallel edges to said open end of each said at least two slots at said edge of said slotted wall portion.