Process Equipment and Plant Design
A stuffing box is used for

Facilitating smooth opening and closing of a valve
Absorbing the contraction/expansion of pipeline due to temperature changes
Prevention of fluid leakage around moving parts
Reducing the resistance of fluid flow

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Process Equipment and Plant Design
In a shell and tube heat exchanger for a given heat transfer surface area, smaller diameter tubes are favoured as compared to larger diameter ones ; because the smaller diameter tubes

Are less prone to fouling
Can be fitted into a smaller shell diameter hence the cost of the heat exchanger would be less
None of these
Are easier to clean

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