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Valve Materials and Elastomers

Posted in: Engineering guides

06/14/2026

Valve material selection should not be based only on nominal pressure or valve size. Operating pressure, temperature,...

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Recommended Flow Velocities for Steam, Water and Air Lines

TECHNICAL DATA

Technical Reference for Piping Systems

The following values may be used as an indicative guide for preliminary checks of flow velocities in industrial steam, condensate, feedwater, cooling water and compressed air piping systems.

Proper flow velocity selection affects pressure drop, noise, erosion, water hammer risk, condensate transport and the operation of valves, steam traps, pressure reducing valves and control equipment.

Application	Recommended Velocity
Flash steam in condensate lines	15–25 m/s
Saturated steam lines up to 1 bar	≤ 10 m/s
Saturated steam lines 1 to 2 bar abs	10–15 m/s
Saturated steam lines 2 to 5 bar abs	15–25 m/s
Saturated steam lines 5 to 10 bar abs	25–35 m/s
Saturated steam lines 10 to 40 bar abs	35–40 m/s
Saturated steam lines above 40 bar abs	≤ 60 m/s
Superheated steam lines of low capacity	35 m/s
Superheated steam lines of medium capacity	40–50 m/s
Superheated steam lines of high capacity	50–65 m/s
Feedwater suction lines	0.5–1 m/s
Feedwater pressure lines	1.5–3.5 m/s
Cooling water suction lines	0.7–1.5 m/s
Cooling water pressure lines	1.0–5.5 m/s
Compressed air lines	15 m/s

Volume Flow Calculation in Pipes

The volume flow through a pipe can be calculated using the following equation:

V̇ = w × A = w × π × d² / 4

V̇: volume flow, in m³/s
w: flow velocity, in m/s
A: internal pipe cross-sectional area, in m²
d: internal pipe diameter, in m

To convert from m³/s to m³/h:

V̇_m³/h = V̇_m³/s × 3600

Engineering Notes

Excessive velocities may increase pressure drop, noise, erosion and water hammer risk. Very low velocities may lead to poor drainage, insufficient condensate transport or oversized pipework.

In steam and condensate systems, operating pressure, steam dryness, flash steam formation, back pressure, pipe slope, drainage points and steam trap selection should also be considered.

Related Equipment

Philippopoulos S.A. supplies equipment for industrial and marine steam, condensate, water and air systems, including isolation valves, control valves, pressure reducing valves, safety valves, steam traps, strainers, separators, condensate pumps and boiler house equipment.