Hours, Examinations and the Written Practice Behind an Oklahoma City Certification
In the United States certification is employer-based. ASNT SNT-TC-1A is a recommended practice; the employer's written practice is the controlling document and may be more or less demanding. It sets training hours, experience hours, general, specific and practical examinations, and recertification intervals. Oklahoma City adds two harder layers: NAS 410 for Tinker and Boeing aerospace work, and ISO 9712 where a client demands third-party certification.
The question that costs Oklahoma City employers audit findings is not how many hours a Level II needs. It is which document the auditor will read. Under SNT-TC-1A nothing in the recommended practice itself binds you; your written practice binds you, and an auditor will hold you to the hours, examinations and intervals you wrote, even where you wrote something stricter than ASNT recommends. ANSI/ASNT CP-189 changes that relationship, because it is a standard rather than a recommendation and it requires your Level III to hold an ASNT Level III certificate rather than one you issued. NAS 410, which governs the aerospace work that dominates the metro through Tinker Air Force Base and Boeing, is invoked contractually and audited through Nadcap. ISO 9712 removes the employer from certification entirely and puts an accredited third party in the seat, though the employer still has to issue a written authorization to operate.
Source: ASNT SNT-TC-1A, Recommended Practice No. SNT-TC-1A, Sections 5 (written practice), 6 (education, training and experience), 7 (training programmes), 8 (examinations) and 9 (certification and recertification), including Table 6.3.1A; ANSI/ASNT CP-189, Standard for Qualification and Certification of Nondestructive Testing Personnel; ISO 9712, Non-destructive testing — Qualification and certification of NDT personnel, and ISO/IEC 17024 for the certification body; NAS 410, NAS Certification and Qualification of Nondestructive Test Personnel, audited through Nadcap AC7114; ASME BPVC Section V, Article 1, T-120; AWS D1.1 Clause 8.
| Method | Level I classroom hours | Level I experience hours in method | Additional Level II classroom hours | Additional Level II experience hours in method |
|---|---|---|---|---|
| Ultrasonic testing (UT) | 40 | 210 | 40 | 630 |
| Radiographic testing (RT) | 40 | 210 | 40 | 630 |
| Eddy current testing (ET) | 40 | 210 | 40 | 630 |
| Magnetic particle testing (MT) | 12 | 70 | 8 | 210 |
| Liquid penetrant testing (PT) | 4 | 70 | 8 | 140 |
| Visual testing (VT) | 8 | 70 | 16 | 140 |
Employer-based certification, and the document the auditor actually reads
The single most consequential fact about NDT certification in the United States is that the employer certifies, not ASNT. ASNT SNT-TC-1A is a recommended practice. It recommends; it does not require. The document that requires anything is your written practice, the one your Level III wrote and your management signed, and when a customer, a registrar or a Nadcap auditor arrives, that is the first thing they ask for. Everything after that is a comparison between what your written practice promises and what your records prove.
This inverts how most people expect the audit to go. Nobody will fault you for setting experience hours above ASNT's recommendation. They will fault you for writing 840 hours into your practice and producing an experience log that shows 600. Writing a stricter document than you can evidence is a self-inflicted finding, and it is more common in Oklahoma City than the reverse, because shops chasing aerospace work often copy an aerospace-grade practice into an energy-side business that cannot staff it.
The other recurring failure is the opposite: a written practice copied from the recommended practice verbatim, should statements intact. A document that says a Level II should have 630 hours of experience has committed to nothing, cannot be audited, and cannot be defended. A written practice must use shall, must name numbers, and must describe your actual process, including who administers examinations and where the question bank lives.
Training and experience hours, and what legitimately changes them
The table above sets out the SNT-TC-1A recommendations. Two distinctions inside it are routinely blurred. Training hours are organised instruction, delivered against a documented outline, with attendance recorded. Experience hours are hours spent performing the method under the direction of qualified personnel, logged against real work with dates and job references. Three years in the industry is not an experience log. An auditor asked to accept it will decline, politely, and write it up.
There is also a total-NDT-experience floor sitting alongside the in-method figure, which matters for a candidate certifying in a second or third method: the in-method hours can be met without the person yet having enough overall NDT experience to satisfy the practice. SNT-TC-1A permits reductions in experience where the candidate has completed relevant engineering or science study, and permits training hours to be adjusted where a Level III judges it appropriate, but every deviation must be written down and justified at the time, not reconstructed later.
The sequencing trap is worth naming explicitly. Experience accrued in a method before the candidate has completed the training for that method is contentious, and different customers treat it differently. If your Oklahoma City operation works for both an aerospace prime and an energy owner, decide your position, write it into the practice, and apply it consistently. Inconsistency between two technicians' files is what an auditor samples for.
The three examinations, and what a practical actually involves
Certification rests on three examinations. The general covers the physical principles of the method and is the part candidates prepare for most and worry about least. The specific is the one that fails audits: it must cover the equipment your company actually uses, the procedures your Level III actually wrote, and the codes your customers actually invoke. A specific examination bought off the shelf with no reference to your procedures is not a specific examination, and it is the most frequent personnel-file finding we see in the metro.
The practical is where competence becomes visible. A candidate is given specimens containing known discontinuities, sets up and calibrates the equipment, performs the examination against a written procedure, and records what they found. Grading covers detection, but it also covers whether the calibration was correct, whether the procedure was followed, and whether the report is usable by someone who was not there. Candidates who find every flaw and write an incoherent report fail, and they should, because on a real job that report is the deliverable.
Administration matters as much as content. Examinations should be drawn from a documented question bank, administered under controlled conditions, graded by or under the authority of the Level III, and the actual papers retained. The SNT-TC-1A grading recommendation is a composite of at least 80 percent with no individual examination below 70. Write your threshold down and never grade around it for a technician you need on a job Monday.
CP-189: the standard that removes your discretion
ANSI/ASNT CP-189 covers similar ground to SNT-TC-1A and is frequently confused with it, but it is a different kind of document. CP-189 is a consensus standard, not a recommended practice, so its requirements are minimums rather than suggestions. Where a customer invokes CP-189 contractually, the discretion your written practice enjoys under SNT-TC-1A largely disappears, and your programme has to meet the standard as written.
The most significant difference concerns your Level III. Under SNT-TC-1A an employer may examine and certify its own Level III, and many do. CP-189 does not permit that: the Level III must hold ASNT NDT Level III certification, obtained by examination through ASNT. For an Oklahoma City company whose Level III has been employer-certified for a decade, a customer invoking CP-189 is not a paperwork exercise, it is a qualification project with a lead time.
CP-189 also tightens the documentation expectations around the qualification programme itself, and it is used in sectors where a customer wants to remove the employer's latitude entirely. If you are bidding work in nuclear, defence supply or certain regulated markets, read the quality clauses before the pricing clauses. The cost of compliance is real, and it is a decision to make before award rather than after.
ISO 9712: central certification, and what it does not authorize
ISO 9712 works on a completely different model. An independent certification body, accredited to ISO/IEC 17024, examines the candidate and issues the certificate. The employer is not in the loop. Certification is granted for a level, a method, and a defined industrial or product sector, on the basis of training delivered by a body the certification body recognises, documented experience, a vision examination, and general, specific and practical examinations with a minimum score required in each part rather than a composite.
The certificate belongs to the individual and travels with them between employers, which is exactly why it is demanded on international projects and by EPC contractors working to European or Middle Eastern client specifications. For an Oklahoma City technician contemplating overseas work or a role on an export-oriented fabrication contract, ISO 9712 is often the credential that opens the door that an employer-based certificate cannot.
The point that gets missed, consistently, is that an ISO 9712 certificate does not by itself authorize a person to work. The employer must still issue a written authorization to operate, specifying the scope, the equipment and the procedures the individual is authorized to use. Certificate validity runs for five years, with a renewal step at that point requiring evidence of vision and continuing work in the method, and a recertification step at ten years that reintroduces examination. Diarise both. A lapsed ISO 9712 certificate cannot be quietly extended by an employer the way an internal certification sometimes is.
NAS 410 and Nadcap: the Oklahoma City aerospace layer
Oklahoma City's industrial base is not only energy. Tinker Air Force Base is the metro's largest single employer and one of the Air Force's air logistics complexes, performing depot-level sustainment on engines and airframes. Boeing maintains a substantial Oklahoma City presence supporting that sustainment work. The FAA's Mike Monroney Aeronautical Center sits at Will Rogers World Airport alongside commercial airframe maintenance operations. The result is a dense supplier ecosystem in which aerospace personnel requirements reach companies that also serve refineries and pipelines.
NAS 410 governs NDT personnel for that work. Like SNT-TC-1A it is employer-based, but unlike SNT-TC-1A it is prescriptive, it is invoked contractually rather than adopted voluntarily, and it is audited. Nadcap AC7114 checklists drive that audit, and personnel qualification records are a standard finding area: training outlines that do not match delivered hours, experience logs without traceability, vision examinations administered late, and Level 3 authority that is not documented the way NAS 410 requires.
For a shop straddling both markets, the practical answer is a decision, not a compromise. Either write one written practice that meets the stricter requirement in every clause where the two documents differ, and live with the higher cost across all work, or run two clearly separated programmes with separate records, separate examinations and unambiguous scoping of which technician is certified under which. What does not work is a single practice that gestures at both. Auditors find that immediately.
Vision, recertification, interruption and recovery
Vision requirements are simple and are failed more often than anything else on this list, because they are administrative. Near-vision acuity is demonstrated by reading a specified Jaeger type and size at not less than twelve inches, in at least one eye, corrected or uncorrected. Colour contrast differentiation is required where the method depends on it, which in practice means penetrant and magnetic particle work above all. Both are examined annually under SNT-TC-1A, and an expired vision examination invalidates the certification that rests on it.
Recertification under SNT-TC-1A runs at intervals not exceeding five years for all levels, achieved either through documented evidence of continuing satisfactory performance or through re-examination. Your written practice must state which route you use and what evidence supports it. Under ISO 9712 the pattern is different: renewal at five years on vision and continuous activity, recertification at ten years that brings examination back for Levels 1 and 2 and a structured credit or examination route for Level 3.
Interruption of service is the clause most written practices handle badly. Define the break, in the method, that triggers re-examination, and apply it. When a technician has been off a method for eighteen months and the practice says twelve, the honest response is re-examination with the real dates recorded. It costs a day. Back-dating costs a customer approval, and in the aerospace supply chain running through this city it can cost an accreditation.
Who imposes what across the Oklahoma City market
Oklahoma City employers and their customers arrive at personnel requirements from four directions. Aerospace sustainment work around Tinker, Boeing and the airport MRO operations brings NAS 410 and Nadcap. Energy work — the Cushing storage hub an hour up the road, the refineries at Wynnewood, Ponca City and Ardmore, and the gathering and processing infrastructure across the Anadarko Basin — brings SNT-TC-1A adopted through your written practice, usually with an owner supplement naming specific methods and codes. ASME code fabrication shops inherit Section V Article 1, which requires personnel qualified in accordance with the employer's written practice built on SNT-TC-1A or CP-189. Structural steel and bridge work brings AWS D1.1 Clause 8, where the visual inspector's qualification and the NDT technician's certification are separate matters that get conflated.
A technician building a career here should read that list as a sequence rather than a menu. Certifying in one method against one employer's practice is a job. Building a portfolio — a working method at Level II, a second method, documented experience across both aerospace and energy specimens, and a credential that survives changing employers — is a career. That is the difference between being fully utilised and being seasonal.
Atlantis delivers NDT training and certification preparation to ASNT SNT-TC-1A and ISO 9712 at Level I, II and III across UT, RT, MT, PT, ET, VT, PAUT and TOFD, classroom, on-site corporate or blended, and ASNT Level III consulting to write, repair or audit a written practice before your customer does it for you. Affordable, accessible, fully customizable. Contact info@atlantisndt.com for a consultation or a scoped quote.
Is API 510, 570 or 653 inspector training part of this offer?
No. Atlantis does not deliver API 510, API 570 or API 653 inspector certification training and is not the API inspector of record for any client. Those are separate individual certifications administered by API with their own body of knowledge and examinations. What we deliver is NDT qualification and certification preparation at Level I, II and III to ASNT SNT-TC-1A and ISO 9712 across UT, RT, MT, PT, ET, VT, PAUT and TOFD, plus ASNT Level III consulting on written practices and examinations.
What must an Oklahoma City employer's written practice actually contain?
It must describe how you qualify and certify people, in enough detail that an auditor can test compliance. That means responsibilities by level, education, training and experience requirements per method and level, how examinations are prepared, administered and graded, grading thresholds, the vision requirement and its frequency, certification and recertification intervals, what triggers re-examination after an interruption of service, records retained and for how long, and the identity and authority of the Level III who signs. Copying SNT-TC-1A verbatim including its should statements produces a document that commits to nothing and audits badly.
How are the general, specific and practical examinations weighted?
SNT-TC-1A recommends a composite grade of at least 80 percent, with no individual examination below 70 percent. The general examination covers method principles. The specific examination covers your equipment, your procedures and the codes you actually work to, which is why a generic vendor examination rarely survives an audit. The practical is hands-on: the candidate sets up, calibrates, performs on specimens containing known discontinuities, and records results. ISO 9712 grades differently, requiring a minimum in each part of the examination.
Does a NAS 410 certification satisfy an SNT-TC-1A audit, or the reverse?
Neither automatically satisfies the other, and treating them as interchangeable is a common Oklahoma City mistake because so many shops here serve both aerospace and energy customers. NAS 410 is invoked contractually and audited through Nadcap, with prescriptive hours and specific Level 3 provisions. SNT-TC-1A is a recommended practice your written practice adopts. A shop doing both either writes one programme that satisfies the stricter requirement in every clause, or maintains two clearly separated programmes with separate records.
What happens when a technician's certification lapses or service is interrupted?
Your written practice must say, because nothing else will. Most practices set a maximum interval without performing the method after which re-examination is required, and set recertification at intervals not exceeding five years, achieved either by evidence of continuing satisfactory performance or by re-examination. The recovery path for a genuine lapse is re-examination against the current written practice, documented with the real dates. Back-dating a certificate to close a gap is the fastest way to lose a customer audit, and in aerospace it puts an accreditation at risk.
Which certification does a Tinker or Boeing supplier in Oklahoma City need?
Read the purchase order and the quality clauses attached to it. Aerospace sustainment work flowing from Tinker Air Force Base, Boeing's Oklahoma City site or the airframe maintenance operations at Will Rogers World Airport typically invokes NAS 410 for personnel and Nadcap AC7114 for the process, with the prime's own supplement layered on top. Energy customers in the same metro will typically invoke SNT-TC-1A through your written practice, sometimes with an owner supplement. The certification you need is the one your contract names.