Structural piling pipe is a variation of steel used as a driven pile foundation. Having the capability to either be driven open end or closed end makes for a versatile foundation option. If driven open end, soil and other loose materials make their way into the pipe through the bottom. Pipes required to be empty for construction can simply apply pressurized water to remove the loose materials inside the pipe post driving. For closed end pipe piling, the bottom of the pile is covered with a steel plate or even a specially designed steel shoe.
Alternatively, some construction projects require the piling pipe to be filled with concrete. This is done in order to contribute increased resistance to corrosion. Some countries avoid this route altogether in order to cut costs. If this occurs, protection against corrosion is furnished by accounting for a sacrificial layer of steel or by utilizing a higher grade of steel pipe. When a concrete filled pipe piling corrodes, a majority of the load capacity of the pile remains intact from the concrete. In an empty pipe piling the structural load capacity would lost, therefore, no longer structurally sound.
Calculating the structural capacity of pipe piling is determined by the strengths of both the steel and concrete, if the piling is concrete filled. Depending on conditions of the construction site and/or building codes, a certain leeway is made for corrosion of the steel piling.
Generally made out of newly manufactured steel, pipe pilings for deep foundation construction can even be made from reclaimed steel. Typically the reclaimed steel is tubular casing that had been used previously in the exploration of oil and gas.
On some occasions, the piling is driven into soil that runs a high risk of corrosion. To slow down the corrosion process and protect the steel from rust, either a coal-tar epoxy or cathodic protection is applied. Although, corrosion of the pipe piling is calculated and accounted for when deciding on the size and which grade of steel pipe to use.
