What It Solves
The tool screens production piping for clean-service API RP 14E erosional velocity and adds a sand-loaded check where particle impact may control allowable velocity. It is most useful for early routing, line-size, and choke-point reviews before detailed erosion modeling.
API RP 14E Erosional Velocity
API RP 14E expresses erosional velocity as a C-factor divided by the square root of mixture density:
V_e = C / sqrt(rho_mix)
where V_e is in ft/s and rho_mix is in lb/ft3. Cite: API RP 14E, current edition.
| C Factor | Use |
|---|---|
| 100 | Continuous service, no sand |
| 125 | Intermittent service, no sand |
| 150-200 | Corrosion-resistant alloy |
| Derated | Sand present; API does not prescribe a value, so Petropt applies an engineering judgment multiplier |
Salama Sand-Laden Erosion
For sand-loaded service, Petropt includes the Salama empirical velocity limit:
V_e = D * sqrt(rho_mix) / (20 * sqrt(W))
D is pipe ID in inches and W is sand rate in lb/day. The basis is 0.1 mm/yr erosion rate, 250 micron particles, and bend geometry. Petropt scales the result for non-bend geometry such as tees or straight pipe and for non-default particle size. Cite: Salama, M.M., "An Alternative to API 14E Erosional Velocity Limits for Sand-Laden Fluids," OTC 8898 / Journal of Energy Resources Technology (1998).
Worked Example
Given: 4-inch ID pipe, gas-only flow at 1500 psia and 100°F, rho ~= 6 lb/ft3 for natural gas at these conditions.
Clean continuous service:
V_e = 100 / sqrt(6)
= 40.8 ft/s
With 100 ppm sand at 250 micron in an elbow:
Salama and the C-derate give a tighter limit,
typically about 20-35 ft/s depending on the selected basis.Petropt verdict: clean API 14E screening permits about 41 ft/s, but a sand-loaded elbow should use the tighter sand erosion constraint.
Limitations
API 14E is screening only. Final design for elbows and tees with high sand rates needs geometry-specific erosion modeling, often CFD-erosion. Salama is a 1998 empirical fit; DNV-RP-O501 has a more recent particle-impact model worth using for safety-critical sand-erosion design.
References
- API RP 14E, Recommended Practice for Design and Installation of Offshore Production Platform Piping Systems, current edition.
- Salama, M.M. (1998). "An Alternative to API 14E Erosional Velocity Limits for Sand-Laden Fluids." OTC 8898 / Journal of Energy Resources Technology.
- DNV-RP-O501, Erosive Wear in Piping Systems, current edition.
- Bai, Y. and Bai, Q. Subsea Engineering Handbook, Chapter 23. Elsevier, 2010; 2nd ed. 2018.