neqsim-pressure-drop-screening

name	neqsim-pressure-drop-screening
calculation_basis	screening
version	0.1.0
description	Educational single-phase line pressure-drop screening against a recommended pressure-gradient guideline. USE WHEN: a task needs a public, screening-level Darcy-Weisbach pressure-drop estimate and a check against NORSOK P-002 / GPSA style line pressure-gradient guidelines before detailed hydraulic design.
last_verified	2026-06-18
requires	{"python_packages":[],"java_packages":[],"env":[],"network":[]}

Pressure Drop Screening

Use this skill for public, educational line pressure-drop screening. It estimates a single-phase Darcy-Weisbach pressure gradient and compares it to a recommended pressure-gradient guideline so an agent can flag lines that may exceed standard hydraulic limits before moving to validated line sizing.

When to Use

• When a user asks whether a line pressure drop sits within recommended limits.
• When an agent needs a quick pressure-gradient triage to scope a hydraulic or debottlenecking study.
• When examples must run without confidential piping classes, project line lists, or company piping specs.

Inputs

• fluid_velocity: actual flowing velocity in the line in m/s.
• mixture_density: flowing mixture density in kg/m3.
• viscosity: flowing dynamic viscosity in Pa.s.
• pipe_inner_diameter: pipe inner diameter in m.
• length: line length used for the total pressure drop in m, default 100.0.
• roughness: absolute pipe roughness in m, default 4.6e-5 (commercial steel).
• guideline_bar_per_100m: recommended maximum pressure gradient in bar per 100 m, default 0.5.

Outputs

• reynolds_number: flow Reynolds number.
• friction_factor: Darcy friction factor from laminar or Haaland turbulent form.
• dp_per_100m_bar: screening pressure gradient in bar per 100 m.
• dp_total_bar: screening total pressure drop over the line length in bar.
• guideline_ratio: ratio of the pressure gradient to the recommended guideline.
• pressure_drop_warning: ok, watch, or high.
• assumptions: public assumptions used by the placeholder model.

Engineering Method

The Python class PressureDropModel uses open, published correlations only:

• the Reynolds number uses the standard Re = rho v D / mu form.
• the friction factor uses f = 64 / Re in laminar flow and the public Haaland explicit approximation of the Colebrook equation in turbulent flow.
• the pressure gradient uses the Darcy-Weisbach form dP/L = f (1/D) (rho v^2 / 2).
• the guideline ratio compares the pressure gradient to a configurable recommended gradient aligned with NORSOK P-002 and GPSA style line pressure-gradient guidelines.

This is educational and screening-only logic. It is not a piping standard, a line sizing method, a vendor method, a two-phase or transient hydraulic method, or a replacement for validated hydraulic design and a qualified process engineering review.

Python Usage Pattern

from pressure_drop_screening import PressureDropModel

model = PressureDropModel()
result = model.evaluate(
    fluid_velocity=12.0,
    mixture_density=50.0,
    viscosity=1.2e-5,
    pipe_inner_diameter=0.2,
    length=100.0,
)

print(result.pressure_drop_warning)
print(result.dp_per_100m_bar)
print(result.guideline_ratio)

If the optional neqsim Python package is available, the result records that fact so an agent can recommend moving to validated NeqSim hydraulic models (for example PipeBeggsAndBrills) for real pressure-drop calculations. If it is not installed, the example still runs with public placeholder logic.

Related NeqSim Functionality

For validated pressure-drop calculations, redirect to existing NeqSim classes instead of this screening placeholder:

• neqsim.process.equipment.pipeline.PipeBeggsAndBrills — Beggs and Brills multiphase pipe flow with elevation, holdup, and friction.
• neqsim.process.equipment.pipeline.AdiabaticTwoPhasePipe and neqsim.fluidmechanics flow solvers — rigorous single and two-phase hydraulics.
• neqsim.process.mechanicaldesign.heatexchanger.ThermalDesignCalculator — tube-side f L/D (rho v^2 / 2) pressure drop inside exchangers.

This skill is a public triage layer that decides when to invoke those validated models.

Validation Checklist

• Inputs are positive and densities, velocities, and viscosities are in SI units.
• Example inputs are public and synthetic.
• Tests cover laminar, turbulent, warning, and invalid-input cases.
• Results are described as educational screening indicators.
• Real hydraulic design is redirected to validated methods, NORSOK P-002, GPSA, and qualified review.

Common Mistakes

Symptom	Cause	Fix
Pressure gradient looks too low	Density taken at standard rather than flowing conditions	Evaluate density at line pressure and temperature
Friction factor looks wrong near Re 2000	Mixing laminar and turbulent forms at transition	Treat the transition band as approximate and validate with detailed hydraulics
Guideline never triggers	Guideline gradient set too high	Use a service-appropriate gradient per NORSOK P-002 / GPSA style limits

Limitations

• No proprietary piping classes, project line lists, or company piping specs are included.
• No two-phase, slug, flashing, or transient pressure-drop modelling is performed.
• No fittings, valves, elevation, or acceleration pressure losses are included.

References

• NeqSim repository: https://github.com/equinor/neqsim
• NeqSim Skills Guide: https://github.com/equinor/neqsim/blob/master/docs/integration/skills_guide.md