Yellow pipe makes utility jobs easier
City Public Services in San Antonio is saving money and making jobs easier for its employees by replacing black steel pipes with yellow polyethylene pipes. The company is the second largest municipally owned gas utility in the United States, serving about 300,000 customers. It has more than 4,000 miles of gas lines installed and does about 5,000 new gas installations a year.
In the 1970s, the utility began replacing steel pipes with black polyethylene pipes, starting with 2- and 4-inch diameter pipe and graduating to 6-inch diameter pipe in 1994. However, the black pipe was difficult for installers and inspectors to see in trenches, and it did not reveal damage as obviously as yellow pipe would. It also soaked up sunlight in the summer, sometimes even blistering the hands of workers, according to Mark Blythe, gas systems planner for the utility.
Following a 1996 pilot program, the utility installed about 8,000 feet of 6-inch diameter Driscopipe Prisma 8100 PE from Phillips Driscopipe, Bartlesville, Okla. “We found the new pipe’s tensile strength was improved,” says Michael Kotara, gas engineering division director. “The yellow coating made visual inspection easier, and it made scratches or gouges in the pipe very obvious. The black undercoat shows through the yellow sheath.”
To replace 1-inch steel pipe services lines with 1-inch polyethylene pipe, as is being done in the older neighborhoods, the new pipe is first attached to the existing pipe near the gas meter at each house or building. Then, a back hoe about 50 feet away pulls the old pipe out of the ground and pulls the new pipe into place. Crews have found they are able to handle the yellow pipe without gloves in 100 degree weather.
The city utility has found that polyethylene pipe up to 6 inches in diameter is less expensive than steel and easier to install. It is evaluating possible use of 8-inch diameter polyethylene pipe to replace the 8-inch steel pipes used as distribution lines underneath the streets.
Lastly, getting the most out of a small inspection staff will be another benefit of the new yellow pipe. Only six inspectors were on staff to check the 237,600 feet of steel and polyethylene gas pipe installed in 1996. The yellow pipe is expected to make their jobs easier. “Our inspectors are stretched pretty thin, and they don’t have a lot of time to spend on each job,” Kotara says.