Chang, Zhou, Michie
# 2006 Washington DC
MTD Pipeline LLC is a joint venture between Martin Marietta Magnesia Specialties LLC and The Dow Chemical Company. A nearly 30 miles of high density polyethylene (HDPE) pipeline project in northern Michigan is serving as the latest example of technology evolution for polyethylene (PE) pipe used in underground pipe applications. It offers a telling case study for a PE100 resin from The Dow Chemical Company. After the MTD Pipeline went on line between Manistee and Ludington, MI in October 2003, it marked a significant advancement for HDPE pipe and the completion of the largest PE100 project for smooth wall pressure pipe in North America - both in terms of continuous system length and pipe diameter. The project required the manufacture and installation of a 20-inch diameter SDR 11 pipeline to support the transport of brine solution. Trenchless installation was successfully used to cross rivers and highways with maximum pulling length of 3,200 feet. The operation conditions have a maximum temperature of 110oF (43oC) and maximum pressure of 150 psig. The project initially considered using steel pipe, PE3408 pipe or PE100 pipe. Due to the corrosion concerns, steel pipe was quickly eliminated. After extensive consideration of PE3408 and PE100 materials, PE100 pipe was chosen for this project due to many performance, installation and operation benefits. PE100 offered a 32% material saving and 25% flow capability improvement over PE3408 pipe, due to down gauging and the larger inside diameter. In addition, PE100 offers more than 500 times improvement in the resistance to slow crack growth as measured by the PENT test. PE100 pipe would not fail in rapid crack propagation (RCP) even during the cold winter in Michigan. Since PE100 has a larger inside diameter, the number of pump stations required was significantly reduced. In total, the combined savings from materials, installation and reduction of pump stations far exceeded $1 MM. After all, the PE100 pipe is expected to perform better in field service due to its higher pressure ratings, and outstanding resistance to both slow crack growth and rapid crack propagation.