For cast iron washers used in piping, what are the dimensions for 12" pipe?

For a 12-inch pipe, the standard dimension for cast iron washers is 3/4 inch by 3 1/2 inches. These dimensions are critical to ensure proper sealing and support within the piping system, especially for private fire service mains.

The specific sizing helps in maintaining a secure fit around the pipe, which is essential to prevent leaks and to manage the hydraulic loads that may be exerted on the connections. When washers are improperly sized, there can be a failure in the sealing capability, potentially leading to serious issues such as water damage or compromising the integrity of the fire service mains.

In the context of NFPA 24, having the correct specifications for components, including washers, illustrates the importance of adhering to established standards to ensure effective operation and safety of fire protection systems. Using the properly sized washer helps to ensure compliance with these regulations and facilitates optimum functionality of the fire service main.