The San Francisco Fire Department has provided information on the design of tubes used by demonstrators and how to cut them. These tubes are used to link a number of demonstrators together to create a circle that blocks intersections. Demonstrators also secure themselves around fixed objects. A 30 to 40 inches long tube with thin walls is used. Tubes range from 4 to 6 inches in diameter. Electrical conduit appears to be the most used product. They are using light weight materials otherwise the pipe would be too heavy on their arms. They weld a rod of rebar into the center of the tube and reinforce the area. A carabineer or other spring clip is clipped to the rod. A dog choke chain is them slipped round the wrist and they reach into the tube and clip the free end of the chain to the carabineer. Another person does the same from the other end. You can’t pull the arms out or reach in to release the chain. The demonstrator can release themselves by unclipping the chain or relaxing the choke chain and slipping their hand out. There are some reports of the tubes being wrapped with tape that might hid wire to make cutting with a saw harder.
One method for removal is to cut the tube in sections all the way around the tube and then separate them enough to access the chains for cutting. This is hard and time consuming. Berkeley Fire Department is looking at using a 6 inch pipe cutter if there is room to rotate one. If the demonstrators really jam their arms into the tube and the wrist chain is tight the tube may not separate enough to access the chains for cutting. The method used most yesterday was to cut a trap door into the tube near the rod in the center. Don’t cut to close because the rod is reinforced. Using a metal cutting blade on a rescue saw or grinder make three cuts 4 to 5 inches long, three sides of a square and then pry it open. Fish out the chain and cut it or unclip it from the carabineer. This takes about four minutes. The San Francisco Fire Department used water extinguishers to cool the area and they provided protection from sparks. The tube gets hot and there is danger in doing this cutting. The SFFD removed 40 of these during the first days of the protest. They had seven taskforces running around the city handling these incidents. The task force was made up of a brush patrol with 2 firefighters, a truck with 5 firefighters and a rescue ambulance) for EMS support.
Some ABS plastic is being used also. You can download a copy of the device and removal method here.
Courtesy of the California Fire Chiefs Association