Steam line size calculator Online & [Excel File]

In steam distribution systems, selecting the correct steam line size is critical for ensuring proper steam velocity, minimal pressure drop, and efficient energy use.
An undersized line increases velocity, causing erosion, noise, and excessive pressure drop. Oversizing adds unnecessary cost and heat loss.

To make this process easier, tools like the Steam line size Calculator using velocity use standard equations to determine the optimal internal diameter based on flow rate, velocity, and steam properties.

Steam Pipe Sizing Calculator

Steam Pipe Sizing Calculator

Calculate optimal pipe dimensions for steam flow systems

Flow Parameters

Steam Properties

Pipe Specifications

The formula used in the steam line calculator

Pipe Diameter

d = \sqrt{\frac{4}{\pi} \cdot \frac{m_s \cdot V}{3600 \cdot v}}

d = pipe inner diameter (m)
ms = steam flow rate (kg/h)
V = specific volume of steam (m³/kg)
v = allowable steam velocity (m/s)
3600 = converts hours to seconds

If you like to learn unit conversion, you can check Unit Converter tool for chemical engineers.

Pressure drop (Darcy–Weisbach equation)

\Delta p = \frac{\mu \cdot l \cdot v^2}{2 \cdot d \cdot V}

Δp\Delta pΔp = pressure loss (Pa)

μ = coefficient of friction
l = pipe length (m)
v = steam velocity (m/s)
d = pipe inner diameter (m)
V = specific volume (m³/kg)

For steam properties like specific volume and enthalpy, you can refer to our Saturated Steam Table Calculator.

Example

  • Steam flow rate = 1,000 kg/h
  • Steam pressure = 8 bar(g) → from steam tables, V=0.240 m³/kg
  • Allowable velocity = 30 m/s
  • Pipe length = 50 m
  • Friction coefficient (μ) = 0.005

Step 1 – Find Internal Diameter:

d = \sqrt{\frac{4}{\pi} \cdot \frac{1000 \cdot 0.240}{3600 \cdot 30}}
d≈0.053 m (≈ 53 mm ID)

Closest nominal bore: DN 50.

Step 2 – Find Pressure Drop:

\Delta p = \frac{0.005 \cdot 50 \cdot 30^2}{2 \cdot 0.053 \cdot 0.240}
Δp≈88 Pa (≈ 0.00088 bar)

Why Velocity Matters

  • Too high: noise, water hammer risk, erosion of fittings
  • Too low: excessive condensation, heat loss, poor heat transfer response
  • Recommended ranges:
    • Saturated steam: 25–35 m/s
    • Superheated steam: 30–40 m/s

To save you time, Chemical Tweak created a Steam Line Sizing Excel Calculator that uses these exact formulas.

Download Steam lize size

FAQ(steam line size)

1. How to calculate the steam flow rate through a pipe?

The steam flow rate can be calculated if you know the internal diameter of the pipe, the steam velocity, and the specific volume of steam at operating pressure.

2. What is Schedule 40 pipe for steam?

Schedule 40 is a standard classification that defines the wall thickness of a pipe for a given nominal size (DN or NPS).