Cylindrical storage tanks for general service: which roof shape is most commonly used?
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ACone (conical) roof
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BDome roof
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CUmbrella roof
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DFlat roof
Answer
Correct Answer: Cone (conical) roof
Explanation
Introduction / Context:Fixed-roof cylindrical tanks store water, chemicals, and many non-volatile liquids. Roof geometry influences structural efficiency, drainage, and fabrication complexity. Among roof types, the conical (cone) roof is widely used for ambient-pressure tanks due to its simplicity and effectiveness.
Given Data / Assumptions:
- Atmospheric or low-pressure fixed-roof service.
- Typical field-erected steel tanks per industry standards.
Concept / Approach:Conical roofs are easy to fabricate from plate segments, shed rain and snow effectively, and can be self-supporting or supported by rafters and columns. Dome roofs (spherical segments) are common for low-pressure or vapor-tight service but are more complex. Flat roofs are rare for outdoor storage due to drainage issues. “Umbrella” is a descriptive variant, not the standard default choice across industries.
Step-by-Step Solution:
Compare typical applications of cone, dome, and flat roofs.Identify the most prevalent in general fixed-roof service → cone roof.Exclude specialty cases (floating roofs for volatile products) not asked here.Verification / Alternative check:Vendor literature and tank construction standards consistently present conical roofs as the default for many ambient-pressure tanks.
Why Other Options Are Wrong:
- Dome: used, but not the most common across general services.
- Flat: drainage and ponding problems limit use.
- Umbrella: not a standard mainstream selection term.
Common Pitfalls:Confusing floating roofs (for volatile hydrocarbons) with fixed roof types; floating roofs are a separate category.
Final Answer:Cone (conical) roof