Variable list

Variables

Absolute roughness K in mm for various materials
Drawn glass, lead, copper and brass tubes		0 – 0.0015
Drawn steel tubes	New Cleaned after long service Moderately rusted or slightly fouled Heavily fouled	0.04 (0.02 – 0.1) 0.15 – 0.20 ≤ 0.40 ≤ 3.0
Galvanized sheet steel Galvanized steel tubes	Smooth (air ducts) Normally galvanized	0.07 0.15
Welded steel pipes	New New bituminized Used, cleaned Uniformly rusted Slightly fouled Heavily fouled	0.05 (up to 0.1) 0.05 0.15 – 0.20 ≤ 0.40 1 – 1.5 2 – 4
Riveted steel pipe		0.9 (0.5 – 10)
Cast iron pipes	New New bituminized Slightly rusted Fouled	0.26 (up to 1) 0.10 – 0.15 1.0 – 1.5 1.4 – 4.0
Concrete conduits	Smooth finish Rough	0.3 (up to 0.8) 1.2 (up to 3)
Fibrous concrete pipes	(Eternit; Toschi)	0.05 –0.1
Wooden boards	Unplaned Planed	0.7 0.2
Brickwork	Normal bonds	1.3
Plastic tubes		≤ 0.0015