In plumbing practice, lead caulked joints are commonly used for making joints in which type of pipes?

Introduction / Context:
This question comes from basic civil engineering and plumbing practice. It asks where lead caulked joints are typically used. Joints are critical in piping systems because they must prevent leakage and withstand internal pressure. Knowing which joint type is associated with which pipe material helps you understand traditional plumbing techniques and answer exam questions correctly.

Given Data / Assumptions:

• The options list earthenware, galvanised iron (G.I.), stoneware, and cast iron (C.I.) pipes.
• The question focuses on lead caulked joints, a specific traditional joint type.
• Basic awareness of common pipe materials and jointing methods is assumed.

Concept / Approach:
Lead caulked joints are associated historically with cast iron (C.I.) pipes. In this method, the socket of one cast iron pipe receives the spigot of another. A packing material such as tarred yarn or hemp (oakum) is first driven into the annular space, followed by molten lead poured into the joint. After cooling, the lead is caulked (hammered) to compact it and produce a watertight and pressure resistant seal. This method is especially useful for pipes carrying water or sewage under moderate pressure. Earthenware and stoneware pipes, used in drainage, are commonly joined using cement mortar or flexible rubber ring joints. Galvanised iron pipes are usually joined with screwed threads and fittings, not with lead caulked joints. Therefore, cast iron pipes are the correct answer.

Step-by-Step Solution:

Verification / Alternative check:
Civil engineering and plumbing textbooks list various types of pipe joints: socket and spigot joints, flanged joints, screwed joints, and others. They describe lead caulked joints in detail under cast iron pipes, showing diagrams with oakum and molten lead in the socket. For earthenware and stoneware pipes, they mention cement joints and rubber ring joints. For galvanised iron pipes, they discuss threaded joints with fittings. These references consistently associate lead caulked joints with cast iron pipes, confirming option D as the correct answer.

Why Other Options Are Wrong:

Earthenware pipes used mainly for low pressure drainage is wrong because these pipes are generally joined using cement mortar or rubber ring joints, not with molten lead.

Galvanised iron (G.I.) pipes used for light water supply is incorrect because G.I. pipes are normally connected using threaded joints, unions, and fittings rather than lead caulked socket joints.

Stoneware pipes joined with cement mortar or rubber rings is wrong as an answer because, like earthenware, stoneware pipes typically use cement or flexible joints, not lead caulking.

Common Pitfalls:
Students may focus only on the word pipes and forget to match the specific joint type to the correct material. Another pitfall is to assume that any older type of pipe might use lead joints, leading to confusion between earthenware, stoneware, and cast iron. To avoid these mistakes, remember that lead caulked joints are classically associated with cast iron (C.I.) pipes, while ceramic pipes use cement or rubber ring joints and G.I. pipes use threaded connections.