Cost analysis of pipes for application in sewage systems

The work described in this study is a preliminary effort to identify the most cost effective pipe material for application in sewage collection networks. Firstly, cylindrical concretes coated by epoxy (Ep), polyurethane (PU), and combination of epoxy and sodium silicate (Ep–SS) were tested to investigate coatings ability to protect concrete samples against corrosion. Secondly, the price of the cured concrete (CC) pipe by designed coatings was compared to that of a new concrete network. Economic analysis was then carried out to compare the prices of the CC and double wall corrugated high-density polyethylene (DWC-HDPE) pipes. The outcomes revealed that the designed coating materials were able to lengthen the concrete pipes service life. They acted as a barrier against the aggressive environment, and were able to reduce the corrosion rate in the piping system. By using the designed coatings, it was at least 1.5 times more economical compared to replacing it with new pipes. The CC pipes have been found to be more cost effective than DWC-HDPE pipes for pipes diameter larger than 600 mm. A computer program was provided based on the developed mathematical models which could aid engineers in nominating the proper pipe for optimum cost saving and performance.

► Ep, PU and Ep–SS coating materials could protect concrete pipe against corrosion.
► Designed coatings are able to lengthen concrete pipe service life.
► Using coating material is more economical than replacing sewer with new concrete pipe.
► CC pipes larger than 600 mm in diameter are more cost effective than DWC-HDPE pipes.
► We developed a computer program to assist engineers to select the proper pipe.