Joining Cast Iron Pipe and Threaded Pipe Fittings

by | Jun 7, 2023 | News

Defnition Of Cast Iron Pipes

Cast iron pipe has been used for plumbing systems for over 100 years and is still commonly used today due to its durability and corrosion resistance. Cast iron pipe can either be hub and spigot or threaded and is typically joined using threaded fittings.

Hub and spigot cast iron pipe is joined using compression gaskets and hub bands. The spigot end of the pipe fits into the hub of the fitting and a rubber compression gasket seals the joint. Then a cast iron or stainless steel hub band is threaded onto the fitting hub and tightened around the pipe to compress the gasket and create a secure seal.

Threaded Cast Iron Pipe

Threaded cast iron pipe is joined using threaded fittings like elbows, tees, couplings, and adapters. The common threaded fittings used for cast iron pipe are referred to as “drain-waste-vent” or “DWV fittings.” These fittings feature a tapered pipe thread designed specifically for cast iron and PVC drainage pipe.

When joining threaded cast iron pipe, the fittings and pipe ends must be cleaned and properly lubricated before threading. Pipe joint compound or Teflon tape is applied to the fitting threads to provide a good seal and prevent corrosion. The cast iron pipe is then threaded into the fitting by hand or using a pipe die and threading machine.

Sealing Cast Iron Pipe Joints

Properly sealing cast iron pipe joints is critical to prevent leaks and ensure the longevity of the plumbing system. Cast iron pipe is prone to corrosion so using the correct fittings, pipe sealant, and tightening fittings properly will help keep the plumbing system functioning reliably for many years.

With proper installation and periodic inspection and maintenance, cast iron pipe joined with either hub and spigot joints or threaded fittings can provide decades of dependable service.

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