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API 653 Aboveground Storage Tank Inspector Exam Guide & Preparation

API 653 Aboveground Storage Tank Inspector certifies your competency to inspect, repair, alter, and reconstruct aboveground storage tanks, based on API 653 itself along with API 650 (new tank construction), API 651 (cathodic protection), API 652 (internal linings), and API 575 (tank inspection practices).

Reviewed by Senior Metallurgical Inspection Engineer, 35+ years · Updated 16 Oct 2026

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API 653 – Aboveground Storage Tank Inspector

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EXAM ANATOMY: 170 (140 scored, 30 unscored pretest) ACROSS 5 BOK DOMAINS

API 653, 2026 Edition

API 650 New-Tank Construction Fundamentals 20%

API 653 In-Service Inspection Intervals 20%

Settlement Evaluation 20%

Cathodic Protection (API 651) 20%

Tank Inspection Practices (API 575) 20%

Overview Compare Eligibility BOK Breakdown Registration Sample Questions Materials Related Exams FAQs

Overview & Scope

API 653 Aboveground Storage Tank Inspector certifies your competency to inspect, repair, alter, and reconstruct aboveground storage tanks, based on API 653 itself along with API 650 (new tank construction), API 651 (cathodic protection), API 652 (internal linings), and API 575 (tank inspection practices).

Like API 510 and 570, it uses the same 170-question, 140-scored, 7.5-hour exam structure split into closed-book and open-book portions. What distinguishes API 653's body of knowledge is its reference-document spread: the exam draws from roughly nine codes and standards, but they're not equally weighted. API 653 itself, a document of around 40 pages, typically accounts for close to half the exam's questions, while the remaining eight reference documents, collectively over 1,000 pages, share the other half.

That weighting has a direct practical implication for how you should allocate study time: mastering API 653 itself pays off disproportionately compared to trying to memorize every supporting standard with equal depth. Settlement evaluation is one of API 653's more distinctive technical areas compared to API 510 or 570, since tanks sit directly on foundations and are uniquely susceptible to differential settlement over decades of service, in a way pressure vessels and piping simply aren't.

Whether you're looking for a structured API 653 course, self-paced API 653 online training, or simply a focused way to study for API 653 certification around a working schedule, EIM's API 653 training platform is built to fit all three.

Exam Code

API-653

Total Questions

170 (140 scored, 30 unscored pretest)

Format

110 closed-book + 60 open-book, 7.5 hours total

Reference Standards

API 653, API 650, API 651, API 652, API 575 (~9 documents total)

Certification Validity

3 years

Testing Venue

Prometric testing centers, worldwide

Auto-Qualifies For

None; API 653 does not grant automatic eligibility for any other API exam

Comparison

API 653 vs API 510, 570, and 571

API 653, 510, and 570 are equipment-specific: each tests code compliance, repair procedures, and inspection intervals for a particular asset type, storage tanks, pressure vessels, and piping respectively. API treats all three as separate, independently maintained credentials requiring equipment-matched experience; pressure vessel or piping experience does not substitute for storage tank experience on an API 653 application.

API 571 sits underneath all three as a mechanism-focused certification: instead of asking how to inspect a specific equipment type, it asks why any of that equipment degrades in the first place. Unlike API 510, holding API 653 does not by itself grant automatic eligibility for API 571, though many tank inspectors pursue it next to deepen their damage-mechanism knowledge.

Eligibility

Qualification & Prerequisites

Direct Qualification

Not applicable, there is no certification that automatically qualifies you to sit for API 653, and holding API 653 does not automatically qualify you for another API exam either.

Combination Route

Eligibility is a sliding scale based on formal education combined with documented aboveground-storage-tank experience, acquired within the last 10 years while employed by or under contract with an authorized inspection agency, per Annex D of the API 653 standard. Candidates with a relevant engineering degree need the least documented experience; candidates without a qualifying technical degree need considerably more.

BODY OF KNOWLEDGE

What the Exam Actually Tests

Five domains, weighted by question share. This is the map the question bank is built directly against.

01API 650 New-Tank Construction Fundamentals

Shell course design, roof types, foundation requirements

02API 653 In-Service Inspection Intervals

Internal, external, and settlement-triggered inspection timing

03Settlement Evaluation

Edge-settlement and planar-tilt acceptance criteria, survey data interpretation

04Cathodic Protection (API 651)

Tank bottom external corrosion protection basics

05Tank Inspection Practices (API 575)

Floor, shell, and roof inspection practices

	Domain	Covers
01	API 650 New-Tank Construction Fundamentals	Shell course design, roof types, foundation requirements
02	API 653 In-Service Inspection Intervals	Internal, external, and settlement-triggered inspection timing
03	Settlement Evaluation	Edge-settlement and planar-tilt acceptance criteria, survey data interpretation
04	Cathodic Protection (API 651)	Tank bottom external corrosion protection basics
05	Tank Inspection Practices (API 575)	Floor, shell, and roof inspection practices

01. API 650 New-Tank Construction Fundamentals

Covers how new aboveground storage tanks are designed and built under API 650, including shell course thickness calculation, roof type selection (fixed cone, floating, geodesic dome), and foundation design. This forms the baseline an in-service inspector needs, since you can't properly evaluate a tank's current condition without understanding what its original design basis actually required, a shell that appears thin against general assumptions may still be well within its original design allowance.

02. API 653 In-Service Inspection Intervals

Tests how internal, external, and settlement-triggered inspection intervals are calculated from corrosion rate, remaining bottom life, and prior inspection history, and when each inspection type applies. A tank's internal inspection interval is typically governed by floor corrosion rate and coating condition, while external inspection frequency depends more on shell and roof condition; candidates are expected to apply the correct governing calculation for each, not treat all three interval types as interchangeable.

03. Settlement Evaluation

The most distinctive technical area in API 653: interpreting settlement survey data, typically a series of elevation readings around the tank's circumference, against API 653's edge-settlement and out-of-plane acceptance criteria to determine whether continued operation requires an engineering evaluation. Unlike a straightforward corrosion-rate calculation, settlement assessment involves curve-fitting survey data against a cosine-based acceptance profile, which is why this domain trips up candidates who understand the concept but haven't practiced applying the actual acceptance criteria to real survey numbers.

04. Cathodic Protection (API 651)

Enough working knowledge to evaluate whether a tank bottom's cathodic protection system, whether galvanic anodes or an impressed current system, is adequately protecting against external corrosion at the soil-to-steel interface. The exam expects you to interpret basic potential readings against protection criteria and recognize when a CP system's performance data suggests inadequate protection, not to design a CP system from scratch, that level of depth belongs to AMPP's dedicated cathodic protection certifications.

05. Tank Inspection Practices (API 575)

The applied field-inspection layer underneath API 653's formal requirements, covering practical inspection techniques for tank floors (including MFL and UT scanning methods), shells (visual and thickness survey), and roofs (structural condition and drainage). This domain connects the formal calculation-based requirements in the other domains to what an inspector actually does on a tank during a field visit, which technique to select, where to focus attention, and how to document findings.

Registration

How to Register and What to Expect on Exam Day

Candidates apply directly through API's Individual Certification Programs (ICP) portal, not through EIM or any third-party training provider. Exams are administered at Prometric testing centers worldwide during specified testing windows throughout the year.

API's 2026 fee schedule lists the official API 653 exam fee at $875 for API members and $1,125 for nonmembers, the same fee structure used across API's ICP inspector exams. This official fee covers only your Prometric exam seat; it does not include study material, a question bank, or structured exam preparation.

Who built this

Senior Metallurgical Inspection Engineer, 35+ years

This material was reviewed by a mechanical engineer with over 35 years in inspection, corrosion management, failure analysis and QA/QC across refineries in India and the Middle East.

Preview

Sample Practice Questions

03: Settlement Evaluation

During an external inspection, a storage tank's settlement survey shows differential settlement exceeding API 653's acceptance criteria for that tank diameter. What is the correct next step?

A. Schedule the next routine external inspection as normal

B. Perform an engineering evaluation of the settlement before continued operation is approved

C. Immediately remove the tank from service with no further assessment needed

D. Ignore the reading if the tank passed its most recent internal inspection

Explanation: Exceeding API 653's settlement acceptance criteria triggers an engineering evaluation, it doesn't automatically mean shutdown, but continued operation can't be approved on inspection judgment alone.

Module 2 · Inspection Practice and Intervals

What is the hydrostatic test height of an in-service welded aboveground storage tank built to API 650, 8th Edition, 82 feet diameter, 40 feet tall with a minimum first course thickness of 0.197 in. The material of construction isA-516, Grade 70?

A. 40'

B. 36' -2"

C. 32' - 8"

D. 30' - 6"

Explanation: API 653, Minimum Thickness Calculation for Welded Tank Shell [4.3.3.2]- b Ht= [StE tmin./2.6 D) +l

Module 3 · Welding NDE Records and Readiness

Which of these statements is FALSE regarding settlement surveys during Hydrotesting (that occur after the initial settlement survey with the tank empty)?

A. Settlement shall be measured during filling (usually 25% intervals)

B. Settlement shall be measured when water reaches 100 % of test level

C. Excessive settlement as per Annex B shall be cause to stop the hydrotest

D. Excessive settlement as per Annex B shall require the foundation be repaired

Explanation: Ref (API 653, Section 12.5.2)  See API 650, 7.3.6.5 … Maximum filling rates

Module 4 · Joint Efficiency NDE Repairs and Reconstruction

Which of the following statements is FALSE regarding the Hot Tap installation procedure?

A. Repad to nozzle weld shall be installed (full penetration) with care taken to limit heat input

B. Pipe nozzles shall be cut to shell contour & beveled from outside for full penetration weld

C. Nozzle neck-to-shell weld shall be examined visually & MT/PT per API 653 Sect. 12 rules

D. After pipe is welded, repads shall be installed in 2 pieces (and welded horizontally)

Explanation: Ref (653, Par. 9.15.5) CLOSED BOOK … May be installed in 1 or 2 pieces

Module 5 · Essentials Materials and Welding II

Up to what thickness is a tank operating at 20 degrees F safe for use for unknown material?

A. 0.5 inch.

B. 1 inch.

C. 1.5 inch.

D. 2in

Explanation: API 653 1 Brittle Fracture Considerations (5.3.8/Figure 5.2)

Module 6 · Cathodic Protection and Tank Bottom Linings

Which of the following problems is most easily missed during the evaluation of an existing liner?

A. Coating holidays

B. Coating blisters

C. Cracking at areas of flexing

D. Permeation of lining with hydrocarbon

Explanation: R e f . 1 0 . 4 52. Tank liner variables Thin Thick Film Film 1. Lowest cost liner.  2. Easiest liner to apply  3. Less susceptible to mechanical damage  4. Most prone to crack with bottom flexing  5. During installation adequate surface preparation is important   6. During installation adequate climate conditions are important    7. Sometimes reinforcement is added to liner 8. Most often used with new construction   9. Most often used on existing tanks that experienced corrosion

Module 7 · Supplements

Which document provides an in depth review of the safety aspects to be considered when hot tapping or welding on in-service piping or equipment?

A. API 582

B. API 2201

C. API 2207

D. API 2217A

Explanation: Ref: Sect. 2 & Sect. 11.2  Hot Tapping & In-Service welding  API 2201

Resources

What's Included in the Self-Prep Package

API 653 Question Bank

Scenario-based questions mapped to the current API 653 Body of Knowledge, with a worked explanation for every answer.

API 653 Study Notes

Downloadable study material covering API 650 construction, settlement evaluation, and cathodic protection basics.

API 653 Mock Test

Full-length practice exam mirroring the real closed-book and open-book split under timed conditions.

FAQs

Common Questions

What is the API 653 certification?

API 653 certifies competency in the in-service inspection, repair, alteration, and reconstruction of aboveground storage tanks, based on API 653, API 650, and several supporting standards. It's one of API's core inspector certifications and is frequently required for roles overseeing tank farms, terminals, and bulk storage facilities across refining, petrochemical, and pipeline operations.

How many reference documents does the API 653 exam cover?

Roughly nine, spanning API 653, API 650, API 651, API 652, and API 575, plus several supporting standards. API 653 itself, despite being the shortest document in the set at around 40 pages, typically accounts for close to half the exam's questions, which is why study time should weight toward it disproportionately rather than being split evenly across all nine documents.

How long is the API 653 exam?

7.5 hours total, including a short tutorial, 2.75 hours for the closed-book section, a 45-minute lunch break, and 3.75 hours for the open-book section. The open-book portion only grants access to the specific reference sections listed on that exam cycle's Publications Effectivity Sheet, not the full text of all nine documents.

How much does API 653 certification cost?

API's 2026 fee schedule lists the official exam fee at $875 for API members and $1,125 for nonmembers, the same fee structure used across API's ICP inspector exams. This covers only the official Prometric exam seat; EIM's API 653 course, question bank, and study material are priced and purchased separately.

What is unique about API 653 compared to API 510 or 570?

Settlement evaluation is the clearest technical distinction. Storage tanks sit directly on engineered or compacted foundations and are uniquely susceptible to differential settlement over decades of service, a failure mode pressure vessels and piping simply don't share, which is why API 653 dedicates an entire domain to interpreting settlement survey data against formal acceptance criteria.

Can I use my API 510 experience toward API 653 eligibility?

No, each API inspector certification requires equipment-matched experience specific to that credential, so pressure vessel inspection experience does not substitute for aboveground storage tank experience on an API 653 application. API treats 510, 570, and 653 as three separate, independently maintained certifications, not tiers of one broader qualification.

What does EIM's API 653 training include?

A structured API 653 question bank weighted to match the exam's real reference-document emphasis, downloadable study notes covering API 650 construction basics through settlement evaluation, and a full-length mock test that mirrors the real exam's closed-book and open-book format, all available as self-paced online training you can revisit as often as needed.

How is the API 653 open-book portion structured?

The same as API 510 and 570: 60 questions over 3.75 hours, with on-screen PDF access limited to the specific sections named on that exam cycle's Publications Effectivity Sheet. Candidates who haven't practiced navigating the reference material quickly often lose more time searching for provisions than they save by having access to them.

In Depth

Why API 653 – Aboveground Storage Tank Inspector Matters for Asset Integrity Careers

Because API 653 draws from roughly nine reference documents with uneven weighting, structured study material that reflects that weighting matters more here than for almost any other API exam, spending equal study time across all nine documents is a common and costly mistake. EIM's API 653 exam preparation is built around the exam's real weighting: heavier coverage of API 653 itself, with supporting question bank material for API 650 construction basics, settlement evaluation, and cathodic protection fundamentals from API 651.

Study notes are organized so settlement calculation, the area most distinct to this exam, gets dedicated worked examples rather than a single passing mention. If you're weighing API 653 training options, look specifically for a course or question bank that mirrors the real open-book, closed-book split, since API 653 mock test practice under that exact time pressure is what actually predicts exam-day performance, more than passive reading of any single reference document.

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API 653 – Aboveground Storage Tank Inspector

1 Year access, on any device.

Inside the bank

Orientation and Foundations82 Q
Inspection Practice and Intervals135 Q
Welding NDE Records and Readiness74 Q
Joint Efficiency NDE Repairs and Reconstruction166 Q
Essentials Materials and Welding II75 Q
Cathodic Protection and Tank Bottom Linings93 Q
Supplements352 Q

Plus 340 questions in full-length timed mock papers, for 1,317 in all.

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