Pipe Roughness Values
Pipe Roughness Values
Absolute roughness (ε) values for Colebrook-White friction factor calculations, with recommended design values by pipe material and service condition.
The absolute roughness (ε) values below feed the Darcy-Weisbach / Colebrook-White friction-factor method used for pressure-drop and hydraulic calculations. Use the recommended design value for your pipe material and service condition.
General Darcy-Weisbach default
Commercial steel / Carbon steel (new)
0.045 mm(0.0018 in)
Standard Moody chart reference; covers majority of general piping design cases
Fire protection default
Galvanized steel
0.15 mm(0.006 in)
Common for above-ground fire protection piping; distinct from carbon steel due to rougher zinc coating surface
Absolute Roughness (ε)
Smooth Pipes
Glass(แก้ว)
Range0.0015
Recommended0.0015
Treated as hydraulically smooth
Drawn tubing(ท่อดึงเย็น)
Range0.0015
Recommended0.0015
Copper(ทองแดง)
Range0.0015
Recommended0.0015
Brass(ทองเหลือง)
Range0.0015
Recommended0.0015
Lead(ตะกั่ว)
Range0.0015
Recommended0.0015
Aluminum(อะลูมิเนียม)
Range0.0015–0.002
Recommended0.002
PVC / CPVC
Range0.0015–0.005
Recommended0.005
Upper bound used to account for joints/scaling in service
HDPE / PE
Range0.0015–0.007
Recommended0.007
Upper bound used to account for joints/scaling in service
ABS / General plastic(ABS / พลาสติกทั่วไป)
Range0.0015–0.007
Recommended0.007
FRP / GRP (Fiberglass)(FRP / GRP (ไฟเบอร์กลาส))
Range0.005
Recommended0.005
Rubber-lined(ท่อบุยาง)
Range0.01–0.06
Recommended0.03
Midpoint of range
| Material | ε Range (mm) | Recommended (mm) | Notes |
|---|---|---|---|
Glass(แก้ว) | 0.0015 | 0.0015 | Treated as hydraulically smooth |
Drawn tubing(ท่อดึงเย็น) | 0.0015 | 0.0015 | — |
Copper(ทองแดง) | 0.0015 | 0.0015 | — |
Brass(ทองเหลือง) | 0.0015 | 0.0015 | — |
Lead(ตะกั่ว) | 0.0015 | 0.0015 | — |
Aluminum(อะลูมิเนียม) | 0.0015–0.002 | 0.002 | — |
PVC / CPVC | 0.0015–0.005 | 0.005 | Upper bound used to account for joints/scaling in service |
HDPE / PE | 0.0015–0.007 | 0.007 | Upper bound used to account for joints/scaling in service |
ABS / General plastic(ABS / พลาสติกทั่วไป) | 0.0015–0.007 | 0.007 | — |
FRP / GRP (Fiberglass)(FRP / GRP (ไฟเบอร์กลาส)) | 0.005 | 0.005 | — |
Rubber-lined(ท่อบุยาง) | 0.01–0.06 | 0.03 | Midpoint of range |
Metal Pipes
Stainless steel(สเตนเลส)
Range0.015–0.045
Recommended0.015
Lower bound; new pipe, smooth mill finish
Commercial steel / Carbon steel (new)(เหล็กกล้า Commercial/Carbon steel (ใหม่))
DefaultRange0.045–0.046
Recommended0.045
Standard Moody chart reference value - recommended default
Wrought iron(Wrought iron (เหล็กเหนียว))
Range0.045–0.05
Recommended0.046
Welded steel(เหล็กเชื่อมตะเข็บ)
Range0.045–0.09
Recommended0.06
Galvanized steel(เหล็กอาบสังกะสี)
DefaultRange0.15
Recommended0.15
Standard reference value - recommended default
Lightly rusted steel(เหล็กเป็นสนิมเล็กน้อย)
Range0.15–0.4
Recommended0.25
Use upper bound for critical/safety systems (e.g. fire pump suction)
Heavily rusted steel(เหล็กเป็นสนิมมาก)
Range1–4
Recommended2
Use upper bound for critical/safety systems
Riveted steel(เหล็กหมุดย้ำ)
Range0.9–9
Recommended3
Wide range depends on rivet spacing/lap
| Material | ε Range (mm) | Recommended (mm) | Notes |
|---|---|---|---|
Stainless steel(สเตนเลส) | 0.015–0.045 | 0.015 | Lower bound; new pipe, smooth mill finish |
Commercial steel / Carbon steel (new)(เหล็กกล้า Commercial/Carbon steel (ใหม่))Default | 0.045–0.046 | 0.045 | Standard Moody chart reference value - recommended default |
Wrought iron(Wrought iron (เหล็กเหนียว)) | 0.045–0.05 | 0.046 | — |
Welded steel(เหล็กเชื่อมตะเข็บ) | 0.045–0.09 | 0.06 | — |
Galvanized steel(เหล็กอาบสังกะสี)Default | 0.15 | 0.15 | Standard reference value - recommended default |
Lightly rusted steel(เหล็กเป็นสนิมเล็กน้อย) | 0.15–0.4 | 0.25 | Use upper bound for critical/safety systems (e.g. fire pump suction) |
Heavily rusted steel(เหล็กเป็นสนิมมาก) | 1–4 | 2 | Use upper bound for critical/safety systems |
Riveted steel(เหล็กหมุดย้ำ) | 0.9–9 | 3 | Wide range depends on rivet spacing/lap |
Cast Iron & Lined Pipes
Cast iron, new(เหล็กหล่อใหม่)
Range0.26
Recommended0.26
Asphalted cast iron(เหล็กหล่อเคลือบแอสฟัลต์)
Range0.12
Recommended0.12
Old cast iron (rusted/in service)(เหล็กหล่อเก่า/เป็นสนิม)
Range1–3
Recommended1.5
Cement-mortar lined ductile iron(Ductile iron บุซีเมนต์)
Range0.1–0.25
Recommended0.12
Epoxy / Coating lined(ท่อบุ Epoxy / Coating)
Range0.005–0.03
Recommended0.01
| Material | ε Range (mm) | Recommended (mm) | Notes |
|---|---|---|---|
Cast iron, new(เหล็กหล่อใหม่) | 0.26 | 0.26 | — |
Asphalted cast iron(เหล็กหล่อเคลือบแอสฟัลต์) | 0.12 | 0.12 | — |
Old cast iron (rusted/in service)(เหล็กหล่อเก่า/เป็นสนิม) | 1–3 | 1.5 | — |
Cement-mortar lined ductile iron(Ductile iron บุซีเมนต์) | 0.1–0.25 | 0.12 | — |
Epoxy / Coating lined(ท่อบุ Epoxy / Coating) | 0.005–0.03 | 0.01 | — |
Concrete & Other
Smooth concrete (steel form)(คอนกรีตผิวเรียบ)
Range0.3–0.8
Recommended0.5
Rough concrete(คอนกรีตผิวหยาบ)
Range1–3
Recommended2
Asbestos cement(ซีเมนต์ใยหิน)
Range0.025–0.05
Recommended0.03
Wood stave(ท่อไม้)
Range0.18–0.9
Recommended0.5
Vitrified clay(ท่อดินเผา/เซรามิก)
Range0.3–1.5
Recommended0.6
Corrugated metal(ท่อเหล็กลูกฟูก)
Range45
Recommended45
| Material | ε Range (mm) | Recommended (mm) | Notes |
|---|---|---|---|
Smooth concrete (steel form)(คอนกรีตผิวเรียบ) | 0.3–0.8 | 0.5 | — |
Rough concrete(คอนกรีตผิวหยาบ) | 1–3 | 2 | — |
Asbestos cement(ซีเมนต์ใยหิน) | 0.025–0.05 | 0.03 | — |
Wood stave(ท่อไม้) | 0.18–0.9 | 0.5 | — |
Vitrified clay(ท่อดินเผา/เซรามิก) | 0.3–1.5 | 0.6 | — |
Corrugated metal(ท่อเหล็กลูกฟูก) | 45 | 45 | — |
How to use these values
Friction loss depends on relative roughness ε/D — absolute roughness ε divided by the pipe internal diameter D. Pick the recommended design ε for your material and service condition, then the Colebrook-White equation gives the Darcy friction factor f:
1/√f = −2·log₁₀( (ε/D)/3.7 + 2.51/(Re·√f) )
Data v1.0.0 · Updated 2026-07-03 · Sources: Moody Chart / Colebrook-White reference tables · Crane TP-410 · Cameron Hydraulic Data. Verify against the governing code edition for design use.