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

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