NDT Procedures for NOM-020-STPS
NOM-020-STPS names this requirement as "Records signed by personal certificado endorsing NDT results, and by an engineer with knowledge in the matter endorsing pressure tests (clause 13.2 f and i)". The Level III who approves them owns it, and a contracted Level III can author and sign it.
The finding auditors record against this document is: NDT results endorsed by a technician whose certification cannot be traced to NMX-B-482, its replacement, or a demonstrably equivalent scheme. The current designation is confirmed: NOM-020-STPS-2011, published in the Diario Oficial de la Federación on 27 December 2011 and in force from 27 June 2012, superseding NOM-020-STPS-2002, with an authorised alternative procedure published 9 December 2014 and continued validity confirmed by systematic review on 15 August 2022. It is the engine of the Mexican NDT inspection market because it makes periodic non-destructive examination or pressure testing mandatory rather than discretionary for Category II and III equipment. The employer classifies each item into Category I, II or III from fluid hazard, relief-device set pressure and volume, maintains a per-equipment file, and either contracts an accredited inspection unit or — for Category III only — constitutes its own Type B unit.
Source: NOM-020-STPS-2011 as published in the Diario Oficial de la Federación, Segunda Sección, Tuesday 27 December 2011, retrieved from the STPS document repository at asinom.stps.gob.mx and extracted; clauses 3.7, 4.19 to 4.21, 4.32, 4.41 to 4.43, 7 and Table 1, 13.1 to 13.6, 16, 17, 19 and 20, and Reference Guide III read directly. Status as vigente, entry into force on 27 June 2012, the authorised alternative procedure of 9 December 2014, and the systematic review confirmation of 15 August 2022 from the Sistema Nacional de Infraestructura de la Calidad catalogue at platiica.economia.gob.mx. NMX-B-482-CANACERO-2016 — full title, vigente status, DOF declaratoria de vigencia of 20 October 2016, CANACERO as issuing Organismo Nacional de Normalización, cancellation of NMX-B-482-1991, and its recorded international grade of 'no equivalente' — from the same catalogue. Limitation: the text of NMX-B-482-CANACERO-2016 itself was not obtained, so its internal qualification model is not characterised here beyond its recorded grade. Verified 21 August 2026.
| Item | What applies | Why it matters |
|---|---|---|
| Regime | NOM-020-STPS-2011, Recipientes sujetos a presión, recipientes criogénicos y generadores de vapor o calderas — Funcionamiento — Condiciones de seguridad | Enforced by Secretaría del Trabajo y Previsión Social (STPS); conformity assessed by unidades de inspección (statutory term until 2020: unidades de verificación) that are accredited by an accreditation entity and approved by STPS |
| Document | NDT Procedures | the method-specific instructions technicians actually work to, and the approval that makes them valid |
| Owner | the Level III who approves them | The signature an auditor traces back |
| Where it is checked | The unidad de inspección issues the dictamen de evaluación de la conformidad, carrying its accreditation number, the dates. | Usually against a sampled job, not in isolation |
| Common failure | Equipment misclassified into Category I or II to escape the Category III duties to have a unidad de inspección present and to notify STPS | The gap between the manual and the job file |
What must a ndt procedures contain under NOM-020-STPS?
It has to satisfy NOM-020-STPS as Secretaría del Trabajo y Previsión Social (STPS); conformity assessed by unidades de inspección (statutory term until 2020: unidades de verificación) that are accredited by an accreditation entity and approved by STPS enforces it: the method-specific instructions technicians actually work to, and the approval that makes them valid. The test is not completeness on paper but traceability — an auditor picks a finished job and works backwards to this document, so anything it claims must be demonstrable on that job.
Who signs the ndt procedures for NOM-020-STPS?
The Level III who approves them. Because this regime accepts employer-based certification, that role can be filled by a contracted Level III rather than a staff appointment, provided they are qualified in the methods they sign for.
How does a NOM-020-STPS auditor test this document?
By sampling. They take a completed job, find the technicians and equipment used, and trace each back through this document to the evidence behind it. A document that reads well but cannot survive that trace is the most common finding across every regime, not just this one.
How long must NOM-020-STPS records be kept?
For Category II and III equipment: the first pressure test or NDT is due before ten years from the manufacturing certificate or code stamp for new equipment that has one; equipment without that certificate or stamp, and all used equipment, is tested before entering service. Thereafter at least every five years, performed within the sixty calendar days before the end of each five-year period. The periodicity is determined by the employer's qualified personnel and may in no case exceed five years (clause 13.2 a). Dictámenes issued by a unidad de inspección are valid ten years for new equipment and five years for used equipment (clause 19.7). Boilers additionally require functional testing of safety shutdowns. Category III equipment requires a notice to STPS within sixty days of the dictamen. Retention is set by the regime and by the client contract above it, and the longer of the two governs. Firms that set one retention period for everything and document it fare better at audit than firms tracking different periods per record type and losing track.
Does a generic template satisfy NOM-020-STPS?
No. A downloaded template describes a generic firm, and the first question an auditor asks is whether the document describes THIS firm — its methods, its equipment, its people, its actual workflow. Templates are a starting structure; the content has to be the firm's own or the trace fails immediately.
What happens if this document is missing at a NOM-020-STPS audit?
It is a finding, and depending on the regime it can suspend the certificate rather than merely generate a corrective action. The related finding auditors record most often is: Equipment misclassified into Category I or II to escape the Category III duties to have a unidad de inspección present and to notify STPS
Where this sits in the NOM-020-STPS evidence pack
- Expediente del equipo — the per-equipment file, maintained for each item including Category I equipment
- Classification record placing each item in Category I, II or III under clause 7, based on relief-device set pressure, volume and whether the fluid is hazardous
- Registro de la última prueba de presión o exámenes no destructivos practicados a los equipos
- Resumen cronológico de las pruebas de presión o exámenes no destructivos
- Procedimientos for the pressure tests and non-destructive examinations, with the acceptance and rejection criteria applied to results
- Records signed by personal certificado endorsing NDT results, and by an engineer with knowledge in the matter endorsing pressure tests (clause 13.2 f and i)
- Dictamen de evaluación de la conformidad, or dictamen de evaluación de la conformidad con reporte de servicios where a Type C unit provided the services
- Aviso a la Secretaría for Category III equipment, filed within sixty days of the dictamen, together with the STPS-assigned número de control
- Registros de capacitación — theoretical and practical training records for workers who operate, maintain, repair and test the equipment (clause 17)
Personnel certification context
Clause 4.21 defines 'personal certificado' as a person with the technical capability and experience to perform, supervise, interpret and evaluate NDT results in accordance with NMX-B-482-1991, or the standards that replace it, or an equivalent. That replacement is NMX-B-482-CANACERO-2016, 'Industria siderúrgica — Capacitación, calificación y certificación de personal en ensayos no destructivos', issued by CANACERO and declared in force in the DOF on 20 October 2016. Crucially, NOM-020 names no accredited certification body for NDT personnel and its 'o equivalente' wording admits other recognised schemes, so an employer-based written practice supported by an outsourced Level III is defensible under the norm itself — unlike Brazil. Client contracts, notably Pemex, routinely override this.
Related: the NOM-020-STPS overview, outsourced ASNT Level III cover, written practice development, NDT procedure development, a programme gap assessment, interim Level III cover.