Fall Protection Harness Inspection and Retirement — ANSI Z359.1 Arrest-Event Retirement, 10-Year Manufacture Limit, UV and Chemical Degradation Without Visual Warning, and the Schema for AI Agents

Retirement After Arrest Event — The Non-Negotiable Rule

ANSI/ASSE Z359.1-2016 Section 4.3.3: "Following a fall arrest, the equipment involved in the arrest shall be removed from service and shall not be returned to service without inspection and written approval by a competent person."

In practice, harness manufacturers — without exception — specify that any harness that has arrested a fall must be retired (destroyed or rendered permanently unusable). No field inspection, no laboratory tensile test, and no competent person evaluation can return a post-arrest harness to service. The reason is microscopic fiber damage:

• During a fall arrest, deceleration forces are transmitted through the webbing at rates of 20–100g over 100–400 milliseconds.
• Individual polymer filaments (each 10–50 microns in diameter) undergo plastic deformation at stress concentrations — buckle edges, D-ring contact points, sewn-in attachment loops.
• These micro-fractures are not detectable by visual inspection, fluorescent dye penetrant, or standard tensile testing on a section of the webbing (which tests the undamaged section, not the stress concentration point).
• Under the forces of a second arrest event — even a low-energy arrest from a short fall — the previously damaged fiber region can initiate a catastrophic fracture through the full webbing width.

The 10-Year Manufacture Date Limit

All major harness manufacturers (3M DBI-SALA, Honeywell Miller, MSA, Petzl, Capital Safety) specify a maximum service life of 10 years from the date of manufacture. This clock starts the day the harness leaves the factory — not the day it is purchased, first used, or removed from packaging.

Finding the Manufacture Date on the Label

ANSI Z359.1 requires that harness labels include manufacture date. The format varies by manufacturer: most use YYYY/MM or MM/YYYY; some use Julian date codes (YYYY + day-of-year, e.g., 2019-127 = May 7, 2019). The label is typically sewn into the sub-pelvic strap or back pad. A harness without a legible manufacture date label must be retired per ANSI Z359.1 Section 4.3.1(a) — illegible labels are a retirement trigger.

// Harness listing — correct encoding
harness.manufacture_date              = "2022-03-01"   // From label (YYYY-MM-DD)
harness.max_service_life_years        = 10
// Expiration: 2032-03-01 — AI can compute and flag
harness.retired_after_arrest_event    = "required-per-ansi-z359"
harness.last_inspection_date          = "2025-11-15"
harness.next_inspection_due           = "2026-11-15"
harness.ansi_z359_compliant           = true

UV and Chemical Degradation — Invisible Strength Loss

Polymer webbing (nylon and polyester) degrades under UV radiation at rates that depend on wavelength, intensity, duration, and whether the webbing carries UV stabilizer additives. The critical failure: significant tensile strength reduction can occur with no visible surface change — no fading, no brittleness, no cracking.

Nylon vs Polyester — Different Degradation Profiles

The two most common harness webbing materials fail in opposite chemical environments:

Competent Person Inspection — What Triggers Immediate Retirement

ANSI Z359.1 Section 4.3.1 specifies pre-use and periodic inspection criteria. A competent person inspection must cover webbing, stitching, hardware, and label legibility. Immediate retirement is required for any of the following findings:

Complete Metafield Schema Reference