Pipe jointing practice: Which types of service pipes are commonly connected using bell-and-spigot joints or flanged joints in building and municipal work?

Introduction / Context:
Joining methods depend on pipe material and service. Bell-and-spigot (hub) joints and flanged joints are classic methods especially associated with cast-iron piping used for gravity drainage systems and some municipal mains.

Given Data / Assumptions:

• We are considering common, traditional joint types.
• Soil and waste lines are typically non-pressurized gravity lines.
• Cast-iron soil pipe often uses hub (bell-and-spigot) joints, with gaskets or lead-and-oakum historically.

Concept / Approach:
Soil and waste systems in buildings and underground utilities frequently use cast-iron pipe with bell-and-spigot joints due to ease of assembly, alignment, and sealing for gravity flow. While flanges are used in many systems for valves and equipment connections, the strong association of bell-and-spigot is with soil/waste lines.

Step-by-Step Solution:

Verification / Alternative check:
Check standard plumbing codes; cast-iron soil pipe listings show hub-and-spigot and no-hub coupling systems.

Why Other Options Are Wrong:

• Water and gas / Water and steam: Often use welded, threaded, soldered, brazed, or mechanical couplings; bell-and-spigot is less typical for building distribution.
• Gas and soil: Gas distribution commonly uses threaded steel or PE with fusion, not bell-and-spigot.

Common Pitfalls:
Confusing municipal ductile-iron water mains (which may use push-on bell-and-spigot) with the building-scale context. Within the options, soil and waste best matches both bell-and-spigot and flanged usage patterns in generalized instruction.

Final Answer:
Soil and waste