What Is SNT-TC-1A? The Employer-Based NDT Certification Model Explained

SNT-TC-1A is the document behind most NDT certifications in North America — but it isn't itself a certification. Here's what it actually is, why the employer (not ASNT) does the certifying, and how it stacks up against CP-189, ISO 9712, ACCP, and Canada's CGSB-derived scheme.

That employer-based structure is precisely what distinguishes SNT-TC-1A from every scheme it gets compared against — CP-189, ISO 9712, and ACCP all shift certification authority (fully or partly) to a body other than the employer. The comparison section below covers each one directly.

SNT-TC-1A gets compared against three other schemes most often. Each comparison below links to the full deep-dive.

Atlantis NDT runs ASNT Level III-led SNT-TC-1A training and offers independent Level III consulting for employers building or reviewing their own Written Practice.

What this page covers

• What SNT-TC-1A Actually Is
• Why SNT-TC-1A Is an Employer-Based Qualification Model
• Levels I, II, and III at a Glance
• SNT-TC-1A vs Every Other NDT Personnel Scheme
• SNT-TC-1A vs Canada's CGSB-Derived Scheme
• Frequently Asked Questions
• The Full SNT-TC-1A Cluster
• Ready to Start Your SNT-TC-1A Pathway?

Key points covered

• Performs specific calibrations, conducts specific examinations, and records results following written instructions. Works under Level II/III supervision.
• Sets up and calibrates equipment, conducts examinations to written procedures, interprets and evaluates results against acceptance criteria, and reports results. The standard production-inspector certification.
• Develops and approves written practices and procedures, interprets codes and specifications, trains and examines Level I/II personnel, and assumes technical responsibility for the NDT program.
• A more prescriptive ASNT standard: mandatory ASNT-administered general and specific exams, stricter documentation, and greater certification portability than SNT-TC-1A — but still employer-issued, not third-party.
• The international third-party central-certification model: an accredited body (not the employer) examines and certifies, and the credential is portable between employers. Dominant outside North America.
• ASNT's own third-party portable alternative — ASNT (not the employer) issues the certificate, so it travels between employers without a new written practice. Available at Level II and III only.
• No. SNT-TC-1A (ASNT's Recommended Practice No. SNT-TC-1A) is a guideline document. It is not issued to individuals and does not certify anyone by itself. Each employer writes its own Written Practice that follows SNT-TC-1A's recommendations, and it is the employer — not ASNT — that examines, qualifies, and certifies its own personnel under that Written Practice.
• The employer does. This is the single most confused point when SNT-TC-1A is compared to other schemes: under SNT-TC-1A the employer is the certifying agency, training hours and experience are logged against the employer's own Written Practice, and the resulting certification is not automatically portable to a new employer — a new employer's Written Practice governs from day one at the new job.
• SNT-TC-1A is employer-based: your employer's Written Practice governs your qualification and your employer issues the certificate. ACCP is ASNT's own third-party program: ASNT examines and certifies you directly, so the certificate is portable between employers without a new Written Practice. See the full comparison for exam structure and levels covered.
• SNT-TC-1A is an employer-administered Recommended Practice dominant in North America. ISO 9712 is a third-party central-certification standard, in which an ISO 17024-accredited certification body — not the employer — examines and certifies, and the certificate is portable between employers. See the full comparison for recognition by region and recertification cycles.
• Both are used. Canada's federal NDT personnel standard is CAN/CGSB-48.9712, Canada's adoption of ISO 9712 — the standard document is published by the Canadian General Standards Board, but certification is administered by Natural Resources Canada's National NDT Certification Body (NDTCB). ASNT SNT-TC-1A is separately accepted for US-headquartered operators and cross-border crews. See the CGSB comparison section below.
• CP-189 (ANSI/ASNT CP-189) is a more prescriptive ASNT standard than SNT-TC-1A — it mandates ASNT-administered general and specific examinations rather than letting the employer write its own, and produces a more portable credential. Both remain employer-issued, unlike ISO 9712 or ACCP. See the full SNT-TC-1A vs CP-189 comparison.
• SNT-TC-1A explained: ASNT's Recommended Practice for NDT personnel qualification, why it is an employer-based (not ASNT-issued) model, Level I/II/III at a glance, and how it compares to CP-189, ISO 9712, ACCP, and Canada's CGSB-derived scheme.
• SNT-TC-1A, snt tc 1a, what is SNT-TC-1A, employer-based certification, ASNT SNT-TC-1A, CP-189, ISO 9712, ACCP, CGSB, NDTCB
• ASNT SNT-TC-1A, ANSI/ASNT CP-189, ISO 9712, ASNT ACCP, CAN/CGSB-48.9712
• ASNT's Recommended Practice for personnel qualification and certification in nondestructive testing, defining an employer-based model in which the employer — not ASNT — issues the certification following a written practice aligned to the document.
• Guideline document — ASNT does not issue SNT-TC-1A certificates to individuals

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