Joining Cast Iron Pipe

Last Updated on Sat, 05 Aug 2023

Cast iron pipe is grouped into two basic categories: hub and spigot, and hubless.

The hub, or bell, and spigot joint uses pipe with two different end types. The hub end of the pipe has an enlarged diameter, thus resembling a bell. The spigot end of the adjoining pipe has a flat or plain-end shape. The spigot is inserted into the bell to establish a joint. Two methods of preventing leaks on bell and spigot joints are compression and lead and oakum. The compression joint uses a one-piece rubber gasket to create a leak-proof seal. As shown in Figure 2-9, when the spigot end of the pipe is placed into the hub containing a gasket, the joint is sealed by displacing and compressing the rubber gasket. Unlike welded pipe, this joint can absorb vibration and can be deflected up to 5° without leakage or failure.

The lead and oakum joint is made with oakum fiber and molten lead to create a strong, yet flexible, leak-proof and root-proof joint. When the molten lead is poured over the waterproof oakum fiber, which is a loose, oil laden,

hemp-like packing material, the joint becomes completely sealed. Water will not leak out and, when used underground, roots cannot grow through the joints. See Figure 2-10.

Hubless cast iron pipe uses pipe and fittings manufactured without a hub. The method of joining these pipe and fittings uses a hubless coupling that slips over the plain ends of the pipe and fittings and is tightened to seal the ends. Hubless cast iron pipe is made in only one wall thickness and ranges in diameter from \¥i' to 10". Figure 2-11 depicts the hubless cast iron pipe joint.

STAINLESS STEEL

STAINLESS STEEL

Figure 2-11. Hubless pipe coupling.

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