neqsim-pipe-wall-thickness-screening

name	neqsim-pipe-wall-thickness-screening
calculation_basis	screening
version	0.1.0
description	Educational process-pipe wall-thickness screening using the public ASME B31.3 hoop-stress (Barlow style) equation. USE WHEN: a task needs a public, screening-level minimum wall-thickness estimate and a check against a nominal schedule wall before detailed piping or pipeline mechanical design.
last_verified	2026-06-18
requires	{"python_packages":[],"java_packages":[],"env":[],"network":[]}

Pipe Wall Thickness Screening

Use this skill for public, educational pressure-piping wall-thickness screening. It estimates the minimum pressure-design wall thickness using the open ASME B31.3 internal-pressure equation, adds a corrosion allowance, and compares the result to a nominal wall so an agent can flag piping that may be under-walled before detailed mechanical design.

When to Use

• When a user asks whether a nominal pipe wall is adequate for a design pressure.
• When an agent needs a quick wall-thickness triage to scope a piping or pipeline study.
• When examples must run without confidential piping classes, project material certificates, or company piping specs.

Inputs

• design_pressure: internal design pressure in bar gauge.
• outer_diameter: pipe outer diameter in mm.
• allowable_stress: allowable stress S of the material in MPa at design temperature.
• weld_joint_factor: longitudinal weld joint quality factor E, default 1.0 (seamless).
• coefficient_y: temperature coefficient Y, default 0.4 for ferritic steel below 482 C.
• corrosion_allowance: corrosion and mechanical allowance in mm, default 3.0.
• nominal_thickness: nominal wall thickness in mm for the comparison.

Outputs

• pressure_design_thickness_mm: minimum pressure-design thickness t.
• required_thickness_mm: t plus the corrosion allowance.
• nominal_thickness_mm: the supplied nominal wall.
• thickness_margin_ratio: ratio of nominal to required thickness.
• wall_thickness_warning: ok, watch, or inadequate.
• assumptions: public assumptions used by the placeholder model.

Engineering Method

The Python class PipeWallThicknessModel uses the open ASME B31.3 internal-pressure equation only:

• the pressure-design thickness uses t = P D / (2 (S E W + P Y)), where W is taken as 1.0 in this screening form.
• the required thickness adds a configurable corrosion and mechanical allowance.
• the margin ratio compares the supplied nominal wall to the required thickness.
• the warning is a simple rule-based label aligned with ASME B31.3 and ISO 13703 pressure-design intent.

This is educational and screening-only logic. It does not include mill tolerance, bend thinning, external pressure or collapse, longitudinal or combined stresses, supports, or fatigue. It is not a piping code calculation, a vendor method, or a replacement for validated mechanical design and a qualified piping engineering review.

Python Usage Pattern

from pipe_wall_thickness_screening import PipeWallThicknessModel

model = PipeWallThicknessModel()
result = model.evaluate(
    design_pressure=100.0,
    outer_diameter=323.9,
    allowable_stress=138.0,
    nominal_thickness=12.7,
)

print(result.wall_thickness_warning)
print(result.required_thickness_mm)
print(result.thickness_margin_ratio)

Related NeqSim Functionality

For validated wall-thickness and pipeline mechanical design, redirect to existing NeqSim classes:

• neqsim.process.mechanicaldesign.pipeline.PipelineMechanicalDesign — pipeline wall thickness and mechanical design (DNV-OS-F101 style).
• neqsim.process.mechanicaldesign.separator.SeparatorMechanicalDesign — vessel wall thickness for separators (ASME VIII Div.1 style).
• neqsim.process.mechanicaldesign.MechanicalDesign — base mechanical-design framework with material data sources.

This skill is a public ASME B31.3 triage layer that decides when to invoke those validated design classes.

Validation Checklist

• Pressure, diameter, and allowable stress are positive and in the stated units.
• Example inputs are public and synthetic.
• Tests cover adequate, watch, inadequate, and invalid-input cases.
• Results are described as educational screening indicators.
• Real design is redirected to validated methods, ASME B31.3, ISO 13703, and qualified review.

Common Mistakes

Symptom	Cause	Fix
Thickness looks too thin	Allowable stress taken at ambient not design temperature	Use the code allowable stress at design temperature
Margin always passes	Corrosion allowance set to zero	Use a service-appropriate corrosion and mechanical allowance
Wrong Y coefficient	Using ferritic Y at high temperature	Use the ASME B31.3 Y table for the material and temperature

Limitations

• No proprietary piping classes, material certificates, or company piping specs are included.
• No mill tolerance, bend thinning, external pressure, or combined-stress checks are performed.
• No branch reinforcement, flange rating, or fatigue assessment is included.

References

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