Before commissioning,
Example: NPS 4, Sch 40 (OD = 114.3 mm, wall = 6.02 mm), carbon steel (SA-106 Gr. B), ( S = 138 ) MPa @ 200°C → Max P ≈ 9.3 MPa (1350 psi).
Piping hydraulics dictate how a fluid behaves as it moves through a processing plant. Understanding these core fluid behaviors is the first step in successful system design. Fluid Properties Density (
The you are modeling (e.g., hydrocarbons, water, superheated steam) Before commissioning, Example: NPS 4, Sch 40 (OD = 114
Using the trial diameter, pipe length, and estimated number of fittings, the engineer calculates the total system pressure drop using the Darcy-Weisbach equation and minor loss methods. If the pressure drop is too high, a larger diameter is selected. If it is too low (and capital costs are excessive), a smaller diameter is evaluated. This economic optimization is a core hydraulic skill.
In turbulent flow, the friction between the fluid and the pipe wall depends on the relative roughness of the pipe. The Darcy Friction Factor (
| Service | Velocity Range (m/s) | Reason | |---------|----------------------|--------| | Liquid (general) | 1.5 – 4.5 | Balance erosion & ΔP | | Suction to pump | 0.6 – 1.5 | Avoid cavitation | | Steam (low press.) | 20 – 40 | Economic ΔP | | Gas (compressed) | 10 – 30 | Noise & ΔP control | | Erosive slurries | < 3 | Prevent wear | Understanding these core fluid behaviors is the first
): Fluid particles move in chaotic, cross-current patterns, causing higher friction. Friction Loss and Head Loss
Seamless steel pipes usually have a manufacturing thickness tolerance of . The calculated must be divided by 0.8750.875 to find the nominal schedule thickness. Selecting Pipe Schedule
Common classes include: .
Process Piping (Refineries, chemical, and pharmaceutical plants).
When completing Module 3, an engineer should be able to answer:
). It is calculated using the or found visually on a Moody Diagram . Minor Losses in Fittings and Valves If it is too low (and capital costs
) , which determines whether the flow is laminar, transitional, or turbulent:
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