A brief history of pipe materials development in the United States
Water is vital, and readily available, good quality water determines the growth of cities and nations. With the world population growing from 1 billion people in 1850 to more than 8 billion today (2021), water demand has increased proportionally.
The collection and transfer of water from remote sources to population centers has evolved from the early canals and aqueducts to extensive pipe systems. Much of these early water distribution systems in the US and much of the world are 75 to 100 years old or older. These systems leak heavily (more than 20% of all treated water is lost to leaks in municipal systems in the US, and as much as 40% is lost in some cities). and breaks are common; Approximately 250,000 water pipe breaks are recorded in the United States each year.
The history of water pipe materials in the United States
Early pipe materials used to distribute water included lead, clay, and wood, both wooden sticks and hollowed-out trees. Wooden pipes can still be found in municipal systems. There are still hundreds of thousands of leads for lead pipes in the US as well. Cast iron pipes were in use as early as the early 19th century when Philadelphia installed cast iron pipes to replace wooden pipes as early as 1810. Various linings and coatings have been used over time to reduce corrosion of cast iron, including cement or coal tar linings and coal tar coatings.
Ductile iron was introduced in AWWA standards in 1965 and largely began to replace cast iron due to its greater strength and ductility. Ductile iron also required an inner lining and an outer corrosion protection. Nowadays it is common practice to install ductile iron pipes in a polyethylene sleeve.
The most common water pipe sizes are 150 mm (6 inches) to 600 mm (24 inches) in diameter, with household and business service connections varying from 25.4 mm (1 inch) to 150 mm (6 inches). This article mainly focuses on this part of the market and the industry. Installation practices range from traditional cutting and masking to relining existing pipe and directional drilling. The choice of the type of pipe can be determined by the required method of installation. Many of the more recent pipe developments deal with these practices.
Modern pipe materials and technological advances
Over the past 50 years, significant improvements and changes have been made to the types of water pipes to address these issues. The market share of pipe materials has changed, reflecting changing requirements as well as construction or installation methods. The biggest change has been the introduction, use, and acceptance of non-metallic material for water pipe applications, particularly PVC (polyvinyl chloride) and HDPE (high density polyethylene). These types of pipes and materials have improved in recent years.
Plastic pipe types were widely used after the end of World War II. Many of these systems are still in use today and work well. Compared to the products made today, these pipes were primitive. Improvements in raw material, connections and fittings have made these systems very durable and made the connections very tight. Most of these improvements are presented in the current ASTM standards under ASTM F17, Plastic Pipe. and AWWA C906 / C901 water supply and water supply lines.
Advances in plastic pipe technology
PVC pipes were mainly made with sealed bell and tenon joints. Recent developments have resulted in butt welded joints, similar to the HDPE practice.
In the case of polyethylene pipes, the material, the connections, the available diameters and the performance have changed significantly. Regarding the PE resins used to make PE pressure pipes, the resins used in the 1970s would likely no longer meet the performance requirements of non-pressure pipes such as sewer and culvert pipes, much less the capabilities of current resins to achieve chemical resistance , Initial strength, long-term strength or impact strength. Even so, miles of pipes made to previous standards are still very good in the water service.
Perhaps the biggest change to water pipe distribution systems was the development of butt fusion equipment to make pipes that are virtually seamless. Bell and tenon joints occasionally have defects due to poor installation, sealing defects, and cracks due to overbells. They also require a larger diameter at the joint which reduces the slip lining capability. Butt fusion joints are no larger than the pipe and can be used to shim existing pipes or in directional drilling rigs. These joint failures are extremely rare and far less common than bell and tenon joints.
For water supply pipes, the AWWA C906 / C901 PE4710 HDPE pipe is widely used in urban water distribution systems for horizontal directional drilling, drilling, pipe bursting, compression grade pipe lining, trenchless installation practices, and local repairs.
With water systems nearing the end of their effective lifespan, leaks and water losses becoming a bigger problem, and actual pipe failures increasing every year, the need to address this infrastructure becomes more critical. New systems will rely on more plastic pipe products for their durability, water resistance, and long term strength.