When Rudy Camarillo of TD Industries first encountered plans for the Davis Building (Dallas, TX) renovation project, he might well have thought it was a job for the gravity-defying talents of Spider-Man. The specifications called for an iron-pipe gas line to run inside the structure for the first four floors. The line would then be redirected to the building's exterior, where it would climb the building's façade the final 16 levels, all the way to the roof.
Gas pressure coming into the building was set at five pounds per square inch (psi) to accommodate the Davis' gas load, consisting of three boilers, two swimming pool heaters and a backup gas generator. As a result, two-inch piping was required with welded - not threaded -connections. But how would TD installers make the 10 to 12 welds needed to run the pipe up the side of the building?
"We probably would've had to shimmy it with a window-washer's boom crane on the outside, carefully lowering the piping down the side of the building,"
Keep it CleanThe TD project team concluded that keeping the gas lines inside would be more practical as well as less disruptive to the building's appearance. Erected a half-century ago in the heart of downtown Dallas, the Davis Building has genuine historic value.
Not that black pipe was all that installer-friendly inside the Davis Building. Because of the incoming 5-psi pressure, the City of Dallas required that all the gas piping be sleeved in some other piping material. This stipulation effectively doubled the number of connections TD's installers would have to make - again, all of them welded if black iron was the pipe of choice.
The solution soon became obvious: Switch to Gastite corrugated stainless steel tubing (CSST), whose superior flexibility translated into far fewer connections, none of them welded. Gastite was also easier to thread through the lengths of four-inch cast-iron pipe that TD's mechanics used to encase the gas lines in certain areas.
Pipe PathThe Davis installation involves no manifold, just two 400-foot gas lines running from the meter on the first level to six pieces of equipment at the top of the structure. The first major section of piping is a 100-foot horizontal run through an open ceiling in the first-floor lobby. Since this pipe is exposed, it must be encased in cast iron.
From the lobby, the Gastite moves to a vertical chase located behind the walls in the northwest corner of the structure, one of five channels that were saw-cut into the Davis to route the various mechanical lines. TD persuaded the city that the Gastite inside the enclosed chase up to the 20th floor did not need to be sleeved.
"The chase itself is fire-rated for two hours,"
Two Days vs. Two WeeksInstallation of the Gastite flexible piping took four installers two days: one day to run the CSST and a second to set 200 feet of cast-iron sleeving. Precise labor calculations for the original, up-the-side-of-the building strategy were never made. But even discounting the need for a special boom or other equipment, Camarillo estimates that the metal pipe would have required 75 welds.
"That probably would have taken six guys running, cutting and welding pipe for seven to 10 days. So the labor-savings with flexible gas piping were substantial."