Source: https://guthlabs.ai/docs/instruments/thin-wall-pressure-vessel-stress/implementation/

instrument implementation / implementation-contract

# Thin-Wall Pressure Vessel Stress implementation

A source-bound implementation contract for Thin-Wall Pressure Vessel Stress; deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-clean

**Evidence ID**: t4-094

**Effect**: Computation or source lookup only

## Input and validation requirements

The instrument should reject t=0 because both formulas divide by zero, and it should flag or reject t/r=0.1 because the thin-wall assumption is valid only for t/r<0.1. Signed-versus-magnitude pressure conventions can also reverse the reported stress signs.

## Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "inputs": {
    "p": 200000,
    "r": 0.5,
    "t": 0.01,
    "vessel_type": "cylinder",
    "units": "p in Pa; r and t in m"
  },
  "expected_outputs": {
    "sigma_hoop": 10000000,
    "sigma_long": 5000000,
    "stress_units": "Pa"
  },
  "working": "t/r = 0.01/0.5 = 0.02, which is less than 0.1. σ_hoop = pr/t = (200000 Pa × 0.5 m)/0.01 m = 100000/0.01 = 10000000 Pa. σ_long = pr/(2t) = (200000 × 0.5)/(2 × 0.01) = 100000/0.02 = 5000000 Pa."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/thin-wall-pressure-vessel-stress/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/thin-wall-pressure-vessel-stress/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/thin-wall-pressure-vessel-stress/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche4/tranche4-results.json`