Vessel supports — choose the correct application: Saddle supports are primarily used to support which class of process vessels?
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AHorizontal cylindrical vessels
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BTall vertical columns
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CThick-walled vertical autoclaves
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DThick spherical pressure vessels
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ESquare-section silos
Answer
Correct Answer: Horizontal cylindrical vessels
Explanation
Introduction / Context:Mechanical support design must accommodate vessel geometry, weight distribution, thermal expansion, and external loads. Saddle supports are a standard solution for horizontal cylindrical vessels such as storage tanks, heat-recovery drums, and separators.
Given Data / Assumptions:
- Vessel is a right circular cylinder lying horizontally.
- Two saddles typically spaced symmetrically support the shell.
- Loads include self-weight, contents, wind/seismic reactions, and thermal growth.
Concept / Approach:Saddles cradle the curved shell, distributing bearing pressure and minimizing local stress concentrations. One saddle is often fixed; the other allows sliding to accommodate axial thermal expansion. Vertical vessels instead use skirts or legs; spheres use columns or skirts with different load paths.
Step-by-Step Reasoning:
Identify geometry: horizontal cylinder → shell curvature suits saddle contact.Support spacing determined by bending moment minimization and nozzle loads.Thermal expansion considered via sliding saddle or Teflon pads.Verification / Alternative check:Industry standards (e.g., Pressure Vessel Handbook) illustrate saddle supports on horizontal drums; vertical columns use skirts with anchor bolts.
Why Other Options Are Wrong:
- Tall vertical/thick vertical: use skirts or legs.
- Spherical: use column legs (multi-supports), not saddles.
- Square silos: flat-bottom or leg supports.
Common Pitfalls:Placing saddles too close to heads causing high midspan bending; ignoring nozzle-induced loads in support spacing.
Final Answer:Horizontal cylindrical vessels