Hume steel pipes (also called cement-mortar lined and coated steel): Which description best matches Hume steel pipes used in water/wastewater conveyance?

Introduction / Context:
Hume steel pipes are widely used where the strength of steel is desirable but corrosion resistance and hydraulic smoothness of cement mortar are also needed. The combined system improves durability and water quality while maintaining manageable weight and constructability.

Given Data / Assumptions:

• Pipe consists of a steel cylinder for structural strength.
• Cement mortar lining inside improves hydraulics and corrosion resistance.
• Cement mortar coating outside enhances external corrosion protection.

Concept / Approach:
The defining feature of Hume steel pipes is the cement-mortar lining and coating applied to a steel shell. This sandwich approach reduces corrosion, limits tuberculation, and provides a smoother interior surface for reduced headloss.

Step-by-Step Reasoning:
Identify material core: steel shell.Identify internal protection: cement-mortar lining.Identify external protection: cement-mortar coating.Thus, correct description includes both internal lining and external coating.

Verification / Alternative check:
Manufacturer catalogs and design manuals list Hume steel pipes as steel cylinders with cement-mortar lining and coating; sometimes additional wrappings or coatings are added for aggressive soils.

Why Other Options Are Wrong:
Steel only / R.C.C. only: incomplete or incorrect.Only inside or only outside coating: partial description, not the standard system.

Common Pitfalls:

• Confusing Hume steel with purely R.C.C. (spun) pipes.
• Assuming only internal lining without external protection in corrosive soils.

Final Answer:
Both (c) and (d)