Steam Pipe Drip Legs

Overview

Engineering reference data for Steam Pipe Drip Legs in fluid mechanics.

Key Formulas

Reynolds Number

$Re = \frac{\rho v D}{\mu}$

Ratio of inertial to viscous forces — determines flow regime.

Bernoulli's Equation

$P + \frac{1}{2}\rho v^2 + \rho g h = \text{const}$

Conservation of energy for steady, inviscid, incompressible flow.

Continuity Equation

$A_1 v_1 = A_2 v_2$

Conservation of mass for incompressible flow.

Darcy-Weisbach

$\Delta P = f \frac{L}{D} \frac{\rho v^2}{2}$

Pressure drop due to friction in a pipe.

Variables

Recommended Drip Leg Dimensions

Example: For an 80 mm (3 in) steam pipe, the recommended drip leg pocket diameter is 80 mm (3 in) with a pocket depth of 700 mm (28 in).

Drip Leg Placement Guidelines

Steam traps and drip legs should be installed at the following locations to ensure proper condensate removal:

• On horizontal pipes, every 30 to 50 m (100 to 150 ft).
• In front of pressure reducing valves to protect the equipment from condensate damage.
• In front of control valves to prevent damage from condensate accumulation.
• In front of normally closed valves to avoid condensate buildup that could damage the system upon valve opening.
• At the bottom of vertical risers to collect condensate flowing downward.
• At the end of steam mains (dead ends) to drain condensate from the line.

Interactive Charts

References

• Original Source