Contractor Switiches to Pneumatic Impact Tools for Casing Installations

Almost a year ago Keith Murt, President of Murtco Mechanical Contractors, Inc. of Paducah, Kentucky, was introduced to pipe ramming using large-scale pneumatic impact tools. Since then, the auger boring machines he traditionally used have have been replaced to use pipe ram steel casings in the western Kentucky clay soil conditions he normally encounters.

To install a 20-inch casing for a gravity sewer run under an access road near Paducah, Murt brought in a 12-inch HammerHead Mole to push the 240 feet of casing 20 feet below the road’s surface.

To ensure success in the clay soil conditions, the crew welded a half-inch diameter schedule 80 steel pipe to the casing. This line carried a biodegradable polymer to lubricate the inside and outside wall of the leading edge of the pipe, making the push easier, and aiding in the eventual spoil blow out. The pneumatic tool was set into collets placed inside the casing and started. Forty-eight hours later the pipe exited on the other side.

Murt now uses pipe ramming in many other casing installations. “The HammerHead pneumatic hammers push pipe cheaper than it would take to auger bore the jobs I’ve used them on,” explained Murt. “It doesn’t take as long to set up, there is less labor involved, and we’ve been able to push longer lengths of pipe — cutting down on welding time.”

Murtco Mechanical Contractors installs 240 ft of 20-in. diameter casing under a roadway during a recent project near Paducah, KY.

Crews blow spoil out of the casing
with the assistance of polymer that is
pumped to the front of the ram.

Murt’s 16-inch diameter HammerHead was first used at Fort Campbell for the Army Corps of Engineers. Pushing under a road for new line, they drove a single-welded piece of 80-foot, 18-inch diameter casing through in 45 minutes, and 30-inch diameter casing in just over two hours.

Two-inch wide cutting edge soil shoes were fabricated out of 1/4-inch steel and welded inside and outside of the leading edge of the first casing. With the diameter of the outside cutting edge slightly larger than the diameter of the pipe, friction between the soil and pipe was lessened as the casing entered the ground. Having the cutting edge soil shoe on the inside also lessened the friction between spoil accumulation on the inside of the pipe and the pipe wall.

To pipe ram in the stiff Kentucky clay, a 1/2-inch schedule 80 lubrication pipe was welded to the top of the casings and fed into the front of the leading edge, allowing the crew to pump polymer to the inside and outside of the front edge. This lubrication made ramming the steel casing faster and facilitated the job of spoil removal.

Murtco’s crews used the 16-inch HammerHead to ram in the 20-inch casings and used the 8-inch pneumatic impact tool to push in the single 12-inch casing. The crew worked five days to complete all five pipe rams, hitting their marks on the exit side every time. ”

Written By: Richard Yach — Technical Writer Des Moines, Iowa
Provided By: Vermeer Manufacturing Company — Pella, Iowa