API 936 or API 653: Which Certification a Welder Can Actually Sit First
API 936 has no experience or education prerequisite — API states it is open to applicants with any experience in the petroleum and petrochemical industries, as well as applicants wanting to gain industry experience. API 653 requires one to five years under an authorized inspection agency, one year of it performing inspection. A welder with no logged inspection time can sit API 936 now and API 653 later.
The two certifications sit at opposite ends of the entry problem. API's programme page for API 936 states the certification is open to applicants with any experience in the petroleum and petrochemical industries, as well as applicants wanting to gain industry experience — no diploma, no logged hours, no employer sign-off before you sit. API 653 runs on a four-tier education-and-experience table topped by a hard requirement that the experience was acquired within the last 10 years while employed by, or under contract with, an authorized inspection agency, with at least one year supervising or performing inspection activities. Tank erection time on a construction crew fails that test, because a fabrication contractor is not an authorized inspection agency. That single clause, not the exam difficulty, is what blocks a field hand from API 653 and leaves API 936 open.
Source: API Individual Certification Programs pages for API 936 Refractory Personnel and API 653 Aboveground Storage Tank Inspector; API ICP published schedules and fees table; API Standard 936, Fourth Edition, June 2014; API Standard 653, Fifth Edition, November 2014, section 3 definitions; BLS 2025 wage data published via O*NET OnLine.
| Candidate background | API 936 requirement | API 653 requirement | Gap the candidate must still close for 653 |
|---|---|---|---|
| No formal education, 5+ years welding | No published education or experience prerequisite | 5+ years in AST design, construction, repair, operation or inspection under an authorized inspection agency | One year supervising or performing inspection activities |
| High school diploma or equivalent | No published education or experience prerequisite | 3 years, of which one year must be inspection activities | The same one-year inspection gate, plus employment by an AIA |
| Two-year degree or certificate in engineering or technology | No published education or experience prerequisite | 2 years, of which one year must be inspection activities | The same one-year inspection gate |
| BS or higher in engineering or technology | No published education or experience prerequisite | 1 year supervising or performing inspection activities | The inspection year only |
| Recency rule on experience | None published | Experience must fall within the last 10 years | Older field time expires and must be re-earned |
| Exam format | 85 questions, 3.25 hours, closed book, 75 scored | 170 questions, 7.5 hours, closed-book and open-book portions, 140 scored | Substantially heavier study load |
| Initial certification fee, API member / non-member | $450 / $625 | $875 / $1,125 | — |
| Recertification fee, API member / non-member | $320 / $430 | $745 / $855 | — |
The prerequisite gap is the whole answer
API publishes a four-tier education-and-experience table for API 653: one year for a BS or higher in engineering or technology, two years for a two-year technical degree or certificate, three years for a high school diploma or equivalent, and five or more years for no formal education. Every tier carries the same floor beneath it — at least one year supervising or performing inspection activities as described in API 653. API 936 carries no such table at all.
For a welder or a construction-side field hand, that difference decides the order of operations. The API 653 no-education tier looks generous until you read the qualifier attached to it: the experience must have been acquired within the last 10 years while employed by, or under contract with, an authorized inspection agency. Five years of pipe welding at a fabrication shop earns nothing against that requirement. Five years of the same welding inside an owner-operator's inspection organization earns most of it.
So the answer to which is reachable is not close. API 936 is sittable this quarter by anyone willing to study a 49-page standard. API 653 becomes sittable only after a deliberate year inside an inspection organization. Anyone mapping that year should read the companion route in our welder-to-NDT-inspector career path for 2026, which covers the same transition from the method-certification side rather than the API side.
What API 653 means by an authorized inspection agency
Section 3 of API 653 defines an authorized inspection agency as one of four organizations that employ an API-certified aboveground storage tank inspector: the inspection organization of the jurisdiction in which the tank is operated; the inspection organization of an insurance company licensed or registered to write aboveground storage tank insurance; an owner/operator who maintains an inspection organization for activities relating only to its own equipment and not for tanks intended for sale or resale; or an independent organization or individual under contract to and under the direction of an owner/operator.
Read that list against a construction résumé and the problem becomes concrete. Tank erectors, fabrication shops, scaffolding crews, coating contractors and rigging outfits sit outside all four categories. The fourth category is the door that opens for most people making this move: an independent inspection contractor working under an owner/operator's direction. Getting hired there — as a helper, a technician, a UT hand — is what converts field time into qualifying time on the application form.
The clock matters as much as the employer. API requires the experience within the last 10 years, so a candidate who spent 2014 to 2018 inside an inspection organization and then returned to the tools has a window that closes. Anyone planning a delayed move should treat the qualifying year as perishable and apply while it is still inside the window.
What API 936 covers, and what it does not
API Standard 936, Fourth Edition, June 2014, is titled Refractory Installation Quality Control—Inspection and Testing Monolithic Refractory Linings and Materials, and runs 49 pages. It covers monolithic linings — castable, gunned, thick-layer plastic, thin-layer abrasion-resistant — and it qualifies materials, equipment and personnel by defined methods. The contents run through quality control elements, the separate responsibilities of owner, contractor, inspector and manufacturer, inspector qualifications, materials and anchors, qualification and testing, installation execution, curing, repairs and dryout.
What the card does not cover is equally important to state. It carries no authority over pressure vessels, piping, storage tanks or welding acceptance criteria. It is a narrow instrument aimed at one family of linings. That narrowness is precisely why API opens it without prerequisites: the exam tests knowledge of a single short standard, and that knowledge is learnable without a decade in the field.
Annex C of the standard is informative and is titled API Certification for Refractory Personnel, with Table C.1 listing minimum inspector competencies. Read that annex before committing money, because it states exactly what the certification asserts about the holder — installation quality control, as-installed sampling and testing, and dryout supervision, rather than fitness-for-service judgement on the equipment behind the lining.
The exams are not comparable in weight
API 936 runs 3.25 hours and 85 questions, of which 75 are scored and 10 are unscored pretest items. It is closed book throughout — no reference material is permitted in the room. Certification runs a three-year term, and API's recertification route uses an online open-book quiz of 25 questions covering code changes on a six-year cycle, with a four-hour completion window.
API 653 runs 7.5 hours and 170 questions, of which 140 are scored, split between a closed-book portion and an open-book portion that requires working from the standard and its referenced documents. The API body of knowledge for the exam pulls in API RP 571, RP 575, RP 576, RP 577, API 650, RP 651, RP 652 and ASME Sections V and IX alongside API 653 itself. Recertification runs three years and requires documented CPD hours plus continuing engagement in tank inspection work.
The fee separation follows the same shape. API's published ICP schedule puts initial certification at $450 for members and $625 for non-members on API 936, against $875 and $1,125 on API 653. Recertification runs $320 and $430 against $745 and $855. Those are API's figures, and they exclude preparatory courses, travel and the study time the open-book portion demands.
What each card opens on a job board
API 936 opens refractory inspection and third-party quality surveillance work, concentrated on FCC units, sulfur recovery units, reformers, fired heaters and CO boilers. The rhythm is turnaround-driven, arriving in shutdown windows rather than as a steady week-to-week load. Many refractory contractors and inspection firms treat the card as a condition of field assignment on a major turnaround, which is what makes it a hiring key even though its technical scope is narrow.
API 653 opens in-service external inspection, out-of-service internal inspection, repair and alteration oversight, and reconstruction work on aboveground storage tanks. The certified inspector signs the report, which is a different order of professional exposure and a different order of pay. Anyone wanting to see what that scope actually involves day to day can read our breakdown of how API 653 sets external, internal and settlement intervals, which walks the clauses an authorized inspector works to.
On earnings, BLS 2025 wage data published through O*NET puts the median for inspectors, testers, sorters, samplers and weighers at $48,570 a year against $53,750 for welders, cutters, solderers and brazers. Those national medians pool thousands of unrelated inspection roles and understate certified petrochemical work badly; our NDT inspector salary breakdown segments the bands that reflect this corner of the market.
The honest recommendation for a welder with no inspection time
Take API 936 first, and take it for the right reason. It is not a formal stepping stone to API 653 — no amount of API 936 field time converts into API 653 qualifying experience unless the employer happens to be an authorized inspection agency. What it does is put an API credential on the résumé, get a candidate onto turnaround inspection crews, and demonstrate to a hiring inspection firm that the person studies standards and passes closed-book exams.
The mistake to avoid is treating API 653 as a first purchase. API reviews the application against the qualification table before an exam is scheduled, so a candidate without the inspection year does not fail the exam — the application does not proceed to an exam at all. Money spent on API 653 preparation before the experience exists buys nothing but early familiarity with the standard.
The working sequence is: sit API 936 now, use it to get hired by an inspection organization, log the inspection year deliberately with documentation, then apply for API 653. Add ASNT method certification in parallel, because a UT or MT ticket is what makes an inspection firm want to hire a welder in the first place, and that hire is the entire bottleneck.
Building the API 653 experience year deliberately
ASNT method certification is the lever that gets the door open. Under SNT-TC-1A the employer certifies the technician against its own written practice rather than a national body issuing the ticket, so there is no degree gate anywhere in the process — but there are documented classroom hours and documented on-the-job hours for each method, and they differ method by method. Our guide to ASNT certification levels and routes lays out how the levels stack and what each one authorises.
The on-the-job training log is what employers and auditors actually examine, and it is where most transitions come apart. Hours worked without contemporaneous records are hours that cannot be claimed later. Start the log on day one of the first inspection job, in the format described in our guide to NDT OJT hours log requirements, and keep it independent of any single employer's filing system so it survives a job change.
Run the API 653 study in the same period rather than after it. The open-book portion rewards familiarity with document navigation across API 650, RP 651, RP 652 and RP 575, and that familiarity is cheapest to build while working on tanks daily. By the time the twelfth month of inspection activity closes, the application and the exam readiness should arrive together.
Where Atlantis fits, and where it does not
Atlantis does not deliver API 510, API 570, API 653 or API 936 exam preparation, and nothing above should be read as an offer to. Those are API programmes with API's own qualification rules, and candidates apply to API directly. The guidance here exists because nobody was answering the question honestly for people coming off the tools.
What Atlantis does deliver sits upstream of the API route and is what makes a welder hireable into an inspection organization in the first place: ASNT method training across UT, RT, MT, PT, VT, ET, TOFD and phased array through our US training programmes, and outsourced ASNT Level III consulting for employers who need a Level III to write and sign the written practice their technicians are certified under.
For tank owners on the other side of the same problem — assets that need inspecting rather than people who need certifying — our API 653 tank inspector services supply certified inspectors and the reporting that goes with them. Both sides are affordable, accessible and fully customizable, with a demo or a quote available on request through contact.
Does API 936 require any prior refractory experience?
No. API's programme page states the certification is open to applicants with any experience in the petroleum and petrochemical industries, as well as applicants wanting to gain industry experience. There is no education tier, no minimum year count and no employer verification of field time before the exam. The exam itself is the filter: 85 questions in 3.25 hours, closed book, with no reference material permitted.
Why does tank construction time not count toward API 653?
API 653 defines an authorized inspection agency in section 3 as one of four organization types: a jurisdictional inspection organization, an insurer's inspection organization writing AST insurance, an owner/operator maintaining an inspection organization for its own equipment, or an independent organization under contract to and directed by an owner/operator. A tank erector or fabrication contractor sits outside all four, so its payroll time earns nothing.
What work does an API 936 card actually open?
Refractory inspection and third-party quality surveillance on monolithic linings — FCC units, sulfur recovery units, reformers, fired heaters and CO boilers. The work is turnaround-driven, so it arrives in concentrated shutdown windows rather than steadily. Refractory contractors and inspection firms commonly require the card as a condition of field assignment during a major turnaround, which makes it a hiring key rather than a career in itself.
Can ASNT Level II time count toward the API 653 experience requirement?
It counts when the employer is an authorized inspection agency, because API's requirement is about who employs you and what you do, not which credential you hold. UT, MT or PT work performed on aboveground storage tanks under an independent inspection firm contracted to an owner/operator is inspection activity. The identical work performed for a fabrication shop building new tanks is not.
Which certification is the better first step for a construction-side hand?
API 936, because it is the only one of the two that can be sat immediately. It is not a formal stepping stone — no API 936 time converts into API 653 qualifying experience by itself. Its value is that it puts an API credential on the résumé and gets a candidate hired by the kind of organization whose employment does count toward API 653.
Do you have to pass API 653 before proving the experience?
The order runs the other way. API reviews the application against the education-and-experience table before an exam is scheduled, so the experience gate precedes the exam rather than following it. Studying the standard early is useful; applying early without qualifying time under an authorized inspection agency simply returns the application. Build the year first, then apply.