Pipe Velocity & Erosive Limit Calculator — Piping Passion

Units

Inputs

Volumetric flow rate (Q)

NPS

Schedule

ID will show below.

Fluid density (ρ)

Water = 1000 · Light HC = 850 · Air STP = 1.2 · Compressed gas (50 bar) ~ 50

Service type (API RP 14E)

C-factor per API RP 14E paragraph 2.5. Note: API 14E was withdrawn in 2008 but values remain industry reference.

Result

Calculated velocity

—m/s

Erosive limit V_e (API 14E)

—m/s

Status

—

Pipe geometry

—

Formula & Method

V = Q / A where A = (π/4) × ID² V_e (SI) = C_SI / √ρ_kg/m³ (C_SI = 122 for C = 100 imperial) V_e (Imp) = C / √ρ_lb/ft³ (per API RP 14E, ft/s)

API RP 14E erosional velocity: empirical limit beyond which two-phase or solid-laden flow accelerates erosion of pipe walls and fittings. Originally for offshore production; widely applied to onshore as a conservative ceiling.

C = 100 — continuous service, no inhibitor, no solids
C = 125 — intermittent service
C = 150–200 — corrosion-controlled or solids-free systems

Typical design velocity ranges (rule-of-thumb):

Liquid pump suction: 1.0–2.0 m/s · pump discharge: 1.5–3.0 m/s
Liquid gravity / drain lines: 0.5–1.5 m/s
Compressible gas: 15–30 m/s common · check Ve and noise (> 60 m/s = noise issues)
Steam: 20–40 m/s saturated · up to 60 m/s superheated

Brownfield tip: when re-rating a line for higher flow, run this check FIRST. A pipe that handled 5 m/s of clean liquid for 10 years may not survive 8 m/s once you add inhibitor solids or change phase. The cheap fix is upsizing the line; the expensive fix is finding pinholes during turnaround.

⚠ For preliminary sizing only Results are based on nominal ASME dimensions and typical material densities. They do not account for manufacturing tolerances, coatings, supports, flanges, fittings, corrosion allowance, or actual site conditions. All final designs must be verified by a qualified engineer and validated against the applicable code edition. Piping Passion accepts no liability for decisions made using this tool.