truss pipe - once upon a time Armco truss pipe company ruled the pipe industry, like all others their day in glory is gone. http://www.contech-cpi.com/corporate/history/255 This was the start of truss pipe. , a double wall ABS with zig zag walls and light weight concrete inbetween. I guess still available by other companies, in PVC.
Air testing problems, more likely, if you don't glue the truss ends. The walls are very thin. I have labored putting in miles and miles.
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Tees - are for waste and supply, made of all sorts of materials, all sizes. A tee is a fitting where a branch connects at a right angle. Saddle tee's are saddles that are strapped onto a line, drilled and then pipe connected to the fixture. Saddle tees are not allowed in Illinois building drains. Tees are good for out side the house clean outs. Clean out tee fittings have the one side threaded (Pete called them box tees). Tees can be leaded, no hub-ed, glued, threaded, soldered.
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trap - see pea trap also - A trap is not a clean out, but a trap might be a access to clean out the drain. The trap in the picture, is a cast iron no-hub trap (connection is by no hub coupling). Cast iron traps are often used under the floor. Basicly the same as the trap under the sink.
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test plug - there are many, many types and sizes. Here is just one type, you need air to inflate.
