In water-supply engineering, which statements correctly describe asbestos cement (AC) pipes used for conveyance?
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AThey are light in weight and therefore easy to handle and transport on site
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BThey exhibit high resistance to corrosion in many soil and water environments
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CTheir joints are sufficiently flexible to accommodate deflection up to about 12° in alignment
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DTheir internal surface is very smooth, making them hydraulically efficient (low headloss)
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EAll the above
Answer
Correct Answer: All the above
Explanation
Introduction / Context: Material selection for pipelines balances hydraulics, constructability, durability, and cost. Asbestos cement (AC) pipes were historically popular for low-to-moderate pressure mains and laterals due to ease of handling and good hydraulic performance. This question checks recognition of their typical properties in traditional design literature.
Given Data / Assumptions:
- We consider conventional statements about AC pipes in civil engineering exams.
- Focus is on physical handling, corrosion behavior, joint flexibility, and hydraulic smoothness.
Concept / Approach: AC pipes are relatively light compared with metallic pipes, allowing faster laying with simpler equipment. They are inherently non-metallic and thus immune to electrochemical corrosion that affects iron/steel pipes. Gasketed push-on or similar joints offer some angular deflection, which helps in minor alignment adjustments. The bore is smooth, which lowers frictional headloss (favorable Hazen–Williams C).
Step-by-Step Solution: Confirm low mass per unit length enables easy transport and installation. Note corrosion resistance due to non-metallic composition; no galvanic action. Recognize joint flexibility allowing modest deflection (order of 10°). Acknowledge smooth internal surface yields high hydraulic efficiency. Thus, all listed statements are valid in standard references.
Verification / Alternative check: Historic specifications report high C-values and routine use where soil aggressiveness challenged metal pipes. Although many utilities have phased out AC due to health and handling regulations, the classical properties in exams remain as stated.
Why Other Options Are Wrong: Each single statement is correct; the most complete answer is therefore “All the above.”
Common Pitfalls:
- Confusing corrosion resistance with complete chemical inertness; AC can still be attacked by strong acids/alkalis.
- Assuming large curvature capability; joint deflection is limited and must respect manufacturer limits.
Final Answer: All the above.