ema Audit Preparation for Inspection Companies
A ema audit runs in 7 stages, beginning with recepción de la solicitud — application received and reviewed for completeness.. ema, operating as an Entidad de Acreditación under the Ley de Infraestructura de la Calidad; sectoral aprobación is granted separately by the regulating dependency — for pressure equipment under NOM-020, the Secretaría del Trabajo y Previsión Social tests the system by sampling finished work backwards to the records.
ema is the accreditation body that turns a Mexican inspection firm into one whose dictámenes a regulator will recognise. It accredits unidades de inspección against NMX-EC-17020-IMNC-2014, the Mexican adoption of ISO/IEC 17020:2012, applying ILAC P15 as guidance. Two things routinely trip up foreign firms. First, accreditation alone is not sufficient for regulated work: issuing a dictamen under a NOM also requires aprobación by the relevant dependency, and STPS publishes the directory of accredited and approved units. Second, since the Ley de Infraestructura de la Calidad took effect the statutory term changed from unidad de verificación to unidad de inspección — the activity is unchanged, and ema's own procedures still carry both names. What separates firms that clear an audit from firms that collect findings is not the quality of the documentation but whether it describes what actually happens. The finding recorded most often is: Type declared as A while the unit also inspects for a related party, breaching the independence conditions that type requires
Source: ema, 'Manual de Procedimientos — Evaluación y Acreditación de Unidades de Verificación (Organismos de Inspección) con base en la norma NMX-EC-17020-IMNC-2014 / ISO/IEC 17020:2012', extracted and read directly, including its definitions of renovación (4.33), testificación (4.44) and vigilancia (4.46) and its surveillance, reevaluation and witnessing intervals; the procedure cites ILAC P15, 'Guía de aplicación de la ISO/IEC 17020 para unidades de Verificación'. Types A, B and C and the accredited-plus-approved requirement from ema's application guides for the same standard and from NOM-020-STPS-2011 clauses 4.41 to 4.43 and 19. Terminology change from unidad de verificación to unidad de inspección under the Ley de Infraestructura de la Calidad, published in the DOF on 1 July 2020; cancellation grounds from Article 59 of that law. Limitation: ema's own website returned HTTP 403 from this environment on 21 August 2026, so the public accredited-body directory at catalogo.consultaema.mx was not consulted and no counts or named accredited firms are stated. Verified 21 August 2026.
| Stage | What happens | What it tests |
|---|---|---|
| Stage 1 | Recepción de la solicitud — application received and reviewed for completeness. | Where the paperwork is tested against itself |
| Stage 2 | Inicio del proceso de evaluación and designación del grupo evaluador — a lead technical evaluator plus evaluators covering each area. | Where the paperwork is tested against practice |
| Stage 3 | Evaluación documental of the management system and technical procedures against NMX-EC-17020-IMNC-2014 and the applicable ema application guide, general or by. | Where the paperwork is tested against practice |
| Stage 4 | Evaluación en sitio — verifying personnel technical competence by demonstration, reviewing records, auditing metrological traceability of equipment, validating methods and. | Where the paperwork is tested against practice |
| Stage 5 | Testificación — ema observes the performance of the inspection process. | Where the paperwork is tested against practice |
| Stage 6 | Dictamen — the relevant evaluation committee or technical opinion commission decides to grant, deny, reduce, suspend or cancel the accreditation. | Where the paperwork is tested against practice |
| Stage 7 | Aprobación by the regulating dependency where the scope covers a NOM, after which the unit appears in that dependency's directory. | Where the paperwork is tested against practice |
| Renewal | ema's procedure sets surveillance (vigilancia) at 12-month intervals, which may be conducted in the two months before or after the due date. The first surveillance evaluation is performed on site and preferably before 12 months from the accreditation date, with an outer limit of 18 months measured from that date for initial accreditations. Reevaluación must be carried out before the four-year cycle completes, counted from the last reevaluation decided by the relevant evaluation committee or technical opinion commission. Testificación must be repeated within no more than four years of the last witnessing. Renovación — a full re-evaluation against an expiry date — applies where a dependency requires the accreditation to carry one. Under Article 59 of the Ley de Infraestructura de la Calidad, accreditation or approval can be cancelled for issuing documents with false or erroneous information, repeatedly refusing requested services, express renunciation, serious breaches of obligations, or altering issued documents. | Diarised from the certificate date, not the last audit |
How long does ema audit preparation take?
Document work — the written practice, procedures and quality manual — takes weeks. What cannot be compressed is documented experience and records history: on-the-job hours accrue in real time, and calibration and certification history cannot be back-filled. Firms that start when the audit is scheduled rather than announced clear it without findings.
What does ema, operating as an Entidad de Acreditación under the Ley de Infraestructura de la Calidad; sectoral aprobación is granted separately by the regulating dependency — for pressure equipment under NOM-020, the Secretaría del Trabajo y Previsión Social look at first?
Records, not manuals. A manual states intent; records show practice. The usual opening move is to take a completed job and trace it back to the technician's certification, the instrument's calibration, the approved procedure and the report — and see whether all four reconcile.
What are the most common ema findings?
Type declared as A while the unit also inspects for a related party, breaching the independence conditions that type requires, Competence criteria for inspectors written generically rather than per inspection activity and method, with no authorisation records tying a named inspector to a specific scope, Metrological traceability gaps — calibration certificates without traceability to recognised standards, or equipment in use past its calibration date, Testificación allowed to lapse beyond four years from the last witnessed inspection. Almost all of them are evidence problems rather than capability problems: the work was done correctly and the proof was not kept, or was kept somewhere the firm could not retrieve during the audit.
Can a consultant attend the ema audit?
Yes, and it changes the outcome. Someone who has sat through the same audit at other firms answers in the auditor's own terms, produces the right record without a search, and stops a clarification turning into a finding. The firm still owns every answer — the consultant does not speak for it.
What happens after a ema finding?
A corrective action with a deadline, and evidence of closure at the next audit. Repeat findings are treated far more seriously than first ones, because they show the corrective-action system itself is not working.
Does ema require a pre-audit or gap assessment?
Not as a requirement, but the arithmetic favours it: a gap assessment finds the same evidence problems the auditor would, without the finding attached, and while there is still time to fix them. Firms entering their first ema audit blind typically collect findings that a sampling exercise would have caught.
What the auditor asks to see
- Solicitud de acreditación filed through ema's SAEMA system, naming a representante autorizado who accepts the accreditation requirements on the body's behalf
- Alcance de acreditación — the requested scope stating inspection activities, methods, and the NOMs or standards to be inspected against
- Documented management system meeting NMX-EC-17020-IMNC-2014, including the impartiality and independence declaration that establishes Type A, B or C
- Procedimientos técnicos de inspección for every method and activity in the requested scope
- Registros de competencia del personal inspector — competence criteria per activity, authorisation records, training and ongoing monitoring
- Registros de equipos y trazabilidad metrológica — calibration certificates and traceability evidence
- Formatos de dictamen and reporting templates carrying the accreditation number and the required dates
- A real inspection made available for ema to witness (testificación) before initial accreditation is granted
- Solicitud de aprobación to the regulating dependency, such as STPS for NOM-020, once accredited
Findings to close before the audit
- Type declared as A while the unit also inspects for a related party, breaching the independence conditions that type requires
- Competence criteria for inspectors written generically rather than per inspection activity and method, with no authorisation records tying a named inspector to a specific scope
- Metrological traceability gaps — calibration certificates without traceability to recognised standards, or equipment in use past its calibration date
- Testificación allowed to lapse beyond four years from the last witnessed inspection
- Dictamen templates missing the accreditation number, the date accreditation was granted, or the date of dependency approval that the NOM being assessed requires
- Issuing dictámenes under a NOM for which the unit is accredited but not approved
- Scope drift — inspecting against NOMs or standards outside the granted alcance
- Surveillance evaluation slipped outside the two-month window either side of the 12-month due date
Related: the ema overview, outsourced ASNT Level III cover, written practice development, NDT procedure development, a programme gap assessment, interim Level III cover.