A. Good Companies provide both solid square shafts as well as pipe piles thus the selection is based on the project requirements and conditions, not on a product driven solution. The need for effective protective coatings is increased with a pipe pile because the tube is accessible to corrosion from the inside and the outside because of the hollow tube. Based on the general assumption that corrosion activity will be proportional to surface area exposed and inversely proportional to metal thickness, the shaft life of a solid pier is at least 85.8/4 = 28.60 times greater than that of the tubing. (Based on a 3/16 inch tube wall thickness).