Conical wall riser with interleaved tab connectors

An assembly comprising a first riser and an identical second riser,

• the first riser having:
• a first end which is circular and has an associated first diameter;
• a second end which is circular and has an associated second diameter;
• said first end and said second end spaced apart along a first central lengthwise axis;
• a first wall, running from the first end to the second end, having the shape of a truncated hollow cone centered on said first central lengthwise axis;
• a plurality of first tabs spaced apart around the circumference of the first end, each first tab comprising angled circumferential direction-facing opposing ends and a radially extending lip comprising a first notch shaped to accommodate a first boss and a first screw;
• a plurality of first rim segments spaced apart around the circumference of the first end, wherein each first rim segment comprises the first boss configured to receive the first screw;
• a plurality of second tabs spaced apart around the circumference of the second end, each second tab having angled circumferential direction-facing opposing ends and a radially extending lip comprising a second notch shaped to accommodate a second boss and a second screw;
• a plurality of second rim segments spaced apart around the circumference of the second end wherein each second rim segment is positioned in a space between a pair of second tabs and wherein each second rim segment comprises the second boss configured to receive the second screw;
• the second riser having:
• a third end which is circular and has an associated third diameter;
• a fourth end which is circular and has an associated fourth diameter;
• said third end and said fourth end spaced apart along a second central lengthwise axis;
• a second wall, running from the third end to the fourth end, having the shape of a truncated hollow cone centered on said second central lengthwise axis;
• a plurality of third tabs spaced apart around the circumference of the third end, each third tab having angled circumferential direction-facing opposing ends and a radially extending lip comprising a third notch shaped to accommodate a third boss and a third screw;
• a plurality of third rim segments spaced apart around the circumference of the third end, wherein each third rim segment comprises the third boss configured to receive the third screw;
• a plurality of fourth tabs spaced apart around the circumference of the fourth end, each fourth tab having angled circumferential direction-facing opposing ends and a radially extending lip comprising a fourth notch shaped to accommodate a fourth boss and a fourth screw;
• and,
• a plurality of fourth rim segments spaced apart around the circumference of the fourth end, wherein each fourth rim segment is positioned in a space between a pair of fourth tabs, wherein each fourth rim segment comprises the fourth boss configured to receive the fourth screw;
• wherein, the first riser and the second riser are configured to mate with each other to form a circumferential joint between either the first end of the first riser and the third end of the second riser, or between the second end of the first riser and the fourth end of the second riser;
• wherein, when said circumferential joint is between the first end of the first riser and the third end of the second riser, each first tab is engaged with a third rim segment and each third tab is engaged with a first rim segment;
• wherein, when said circumferential joint is between the second end of the first riser and the fourth end of the second riser, each second tab is engaged with a fourth rim segment and each fourth tab is engaged with a second rim segment;
• wherein each of the engagements between the first, second, third, and fourth tabs and the respective rim segments includes a radially deflecting engagement between the radially extending lip of the tabs and the rim segments.