Difficulty: Easy
Correct Answer: 1.5 to 2
Explanation:
Introduction / Context:
Hydrostatic testing verifies the structural integrity and leak tightness of pressure containment equipment before commissioning. Standards specify test pressures above design to create a safety margin and reveal fabrication defects without overstressing the material.
Given Data / Assumptions:
Concept / Approach:
Design pressure reflects maximum allowable operating pressure with code-mandated safety factors. Hydrotest uses liquid (usually water) to avoid stored elastic energy hazards of gas testing. A multiplier of roughly 1.5 times design pressure is commonly adopted for pressure vessels; some storage tank cases may approach up to 2 times depending on code and service, hence a practical band of 1.5–2 is recognized.
Step-by-Step Solution:
Identify typical vessel code guidance: test pressure ≥ 1.5 * design pressure (adjusted for temperature & allowable stress at test conditions).Acknowledge tank specifics: geometry and shell courses can shift exact multipliers; upper bound near 2 can appear in certain cases.Select the range that best captures Indian practice: 1.5 to 2.
Verification / Alternative check:
Project specifications and vendor data sheets across refineries and chemical plants in India align with 1.5–2× ranges, subject to code clauses and allowable stress ratios at test vs. design temperatures.
Why Other Options Are Wrong:
Higher multipliers (3–5 or more) risk plastic deformation; testing at exactly design pressure offers insufficient margin.
Common Pitfalls:
Ignoring allowable stress temperature corrections; not venting air pockets; testing with cold water on warm vessels causing thermal shock.
Final Answer:
1.5 to 2
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