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
Reducing the resistance of fluid flow
Prevention of fluid leakage around moving parts

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Process Equipment and Plant Design
In a shell and tube heat exchanger, triangular pitch arrangement as compared to square pitch arrangement

Facilitates easier shell side cleaning; hence is more suitable for handling high dirt factor shell side fluid
Creates relatively lower turbulence on the shell side resulting in lower shell side heat transfer co-efficient
Results in higher shell side pressure drop
Can accomodate less number of tubes for a given shell diameter

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