The following absolute roughness height values i micrometers (10^-6 m)
can be used in pressure drop component models.
Extruded Glass, Lead, Copper and Brass: 0 - 1.5
Extruded steel:
New: 20 - 100
Cleaned after long use: 150 - 200
Moderately rusty: < 400
Heavily rusty: < 3000
Galvanised steel: 70 - 150
Welded steel:
New: 50
Used and cleaned: 150 - 200
Moderately rusty: < 400
Cast iron:
New: 260 - 1000
New bituminised: 100 - 150
Rusty: 1000 - 1500
Concrete:
Smoothed: 300 - 800
Rough: 1200 - 3000
Planed plank: 200
Sawn plank: 700
Reference: VDI-Wärmeatlas 1977