Water pipes are used for a variety of applications, from the power industry to the process industry and utility services. Depending on their function, there are three main types of water pipes: pipes for drinking water, pipes for firefighting operations, and pipes for wastewater treatment.
Pipes for Drinking Water
Pipes for drinking water are designed to transport treated drinking water to consumers. These pipe systems typically consist of large-diameter main header pipes that connect entire towns, as well as smaller supply lines that provide water to individual streets or groups of buildings. The size of these pipes can range from 3.65 meters for giant mains or header lines, to 12 millimeters for individual outlets in buildings. Drinking water can be transported via gravity, and the quality of the water can be preserved with these piping systems.
Pipes for Firefighting
Pipes for firefighting are used to supply water to fire hydrants and other firefighting equipment. These pipes are typically made of steel or other fire-resistant materials, and must be able to withstand high temperatures and pressures.
Pipes for Wastewater Treatment
Pipes for wastewater treatment are designed to transport wastewater from homes and businesses to treatment facilities. These pipes are typically made of PVC, which is resistant to corrosion and can withstand the harsh conditions of wastewater. In some cases, these pipes may also be lined with a material such as rubber, to reduce the risk of leaking.
Metallic Pipes for Water Piping
Metallic pipes are a commonly used type of pipe for water piping applications, and come in several types and sizes. The most popular materials for metallic pipes are galvanized iron, steel, and cast-iron. These pipes are strong and durable, and can withstand high water pressure. Additionally, they have longer lengths than other pipes, which reduces installation and transportation costs.
Galvanized Steel or Iron Pipes: Galvanized steel or iron pipes are the most popular pipes for water and wastewater conveyance. Although they are gradually being replaced, they are still widely used around the world. However, when the water flow is slow or static, corrosion can occur and the water may acquire an unpleasant taste and smell.
Cast Iron Pipes: Cast iron pipes are a good choice for high water pressure applications. However, they are heavier than other pipes, which makes them difficult to transport and install in inaccessible places. Additionally, they come in shorter lengths, increasing the cost of layout and joining.
Copper Pipes: Copper pipes are mainly used for the distribution of hot and cold water. They are suitable for both underground and above-ground applications, but they must be covered with a protective sleeve if used underground due to their susceptibility to corrosive soil. Copper pipes are very expensive in comparison to other piping materials.
Concrete Cement and Asbestos Cement Pipes: Concrete cement and asbestos cement pipes are non-corrosive and very durable. Unfortunately, they are very heavy, making them difficult to handle and transport, which increases the cost of installation and transportation.
Plasticized Polyvinyl Chloride (PVC) Pipes: PVC pipes are lightweight, making them easy to handle and transport. They are flexible and come in long lengths, which lowers the cost of installation and transportation. However, when exposed to ultraviolet light, PVC can become brittle, so it must not be located in direct sunlight. Additionally, PVC can become soft and deform when exposed to temperatures over 65° C.
CPVC Pipes: Chlorinated polyvinyl chloride (CPVC) pipes are usually cream-colored or off-white and can withstand temperatures up to around 180 degrees Fahrenheit. They are commonly used in hot and cold-water lines for domestic service, as well as in hydronic heating systems.
PEX Pipes: Cross-linked polyethylene (PEX) pipes are good at resisting both hot and cold temperatures, and are commonly used in hot and cold water lines and hydronic heating systems. Additionally, they are lightweight and flexible, making them easy to install and transport.
Cost consideration for Water Pipes
When considering the total cost of a water pipe project, the installation costs make up the majority. Factors such as the weight of the pipe, ease of assembly, and strength must be taken into account when determining the cost. Additionally, water piping networks may be installed above or below ground.
Weight of the Pipe
The weight of the pipe can have an impact on the cost of the project. Pipes that are lighter in weight are easier and faster to handle, resulting in a lower cost.
Ease of Assembling
The method of joining the pipes can make a difference in the cost of a water pipe project. Bolting, welding, and threading are some of the ways to join pipes. Depending on the type of pipe, the choice of joining method can have a significant impact on the cost management.
Pipe Strength
The strength of the pipes should be taken into consideration when determining the cost of a water pipe project. Some pipes may require special bedding to withstand external pressure, whereas others may not.
Bury Water Lines
When burying water lines, the depth should be considered. Generally, water lines should be buried below the frost line to ensure that they will not freeze. However, it is important to check the local municipality’s building codes for guidance.
Water Piping in Sewage Networks
Water piping is an essential part of any sewage network, as it transports raw sewage from one point to another. Pipes used for this purpose are usually large in diameter, ranging from 160mm to 650mm, and are made from cast iron or a combination of PVC and HDPE materials. Despite their heavy construction, these pipes are vulnerable to corrosion caused by condensation and acidic gases such as hydrogen sulfide.
Preventing Corrosion in Sewage Piping
In order to protect sewage piping from corrosion, several methods can be employed. These include using inert materials, sacrificial linings, acceptable linings, providing ventilation to remove moisture, and periodic flushing of the network. The European Standards EN 1401 and EN 13476 are widely used for water pipes in sewage networks.
Fire Protection System Water Piping
Water piping is an essential part of fire protection systems used in industries and building services. Fire protection water pipes are usually made of carbon steel, which is able to withstand high temperatures. ASTM A795 is the steel pipe of choice for fire protection systems. The pipes usually come in 1” sizes and are painted red. Black steel is often used for traditional fire protection systems owing to its strength, durability, and extreme resistance to heat.
Advantages of Steel Pipes for Fire Protection
Steel pipes for fire protection have many advantages. They are lightweight and easy to fabricate in the field, and they have a low coefficient of thermal expansion. This makes them suitable for use in various sizes, shapes, and configurations. They also have a high melting point, which makes them ideal for fire sprinkler systems. Painting can also be done on steel pipes with no adverse effects.
Disadvantages of Steel Pipes for Fire Protection
The main drawback of steel pipes is their susceptibility to corrosion. They are prone to damage even during installation due to the presence of oxygen and water. Repairing leaking holes, removing loose scales and rust, and servicing obstructed pipes can become very costly. Corrosion also degrades the system flow characteristics.