The API 653 Aboveground Storage Tank Inspector certification, awarded by the American Petroleum Institute (API), is the premier globally recognized credential for professionals evaluating the structural integrity, safety, and operational reliability of in-service atmospheric and low-pressure welded or riveted storage tanks. Accredited under ISO/IEC 17024 by ANAB, this certification validates an inspector’s technical competence in tank evaluation, corrosion rate calculations, bottom settlement assessment, repairs, and reconstruction protocols according to international energy standards.
Before applying for the exam, candidates must navigate API’s education and experience prerequisites, master the official Body of Knowledge (BoK), and prepare for the 2-part exam structure.
Important Note on Exam Administration:
Capgrow provides specialized exam preparation training, codebook navigation drills, and calculation practice. The final API 653 examination, candidate eligibility review, and official credentialing are administered independently by the American Petroleum Institute (API) via Prometric computer testing centers.
1. Eligibility Requirements & Prerequisites
API enforces strict eligibility criteria based on a combination of formal education and relevant industry experience acquired within the last 10 years:
- B.S. or Higher in Engineering / Technology (or 3+ years technical military service): Minimum 1 year of experience supervising or performing in-service storage tank inspection activities.
- 2-Year Degree / Certificate in Engineering/Technology (or 2 years technical military service): Minimum 2 years of experience in tank design, construction, repair, operation, or inspection (with at least 1 year in direct tank inspection).
- High School Diploma or Equivalent: Minimum 3 years of experience in tank design, construction, repair, operation, or inspection (with at least 1 year in direct tank inspection).
- No Formal Education: Minimum 5 or more years of experience in tank design, construction, repair, operation, or inspection (with at least 1 year in direct tank inspection).
2. Core Body of Knowledge (BoK) & Referenced Codes
The API 653 exam evaluates a candidate’s practical understanding of primary storage tank inspection codes, mechanical design standards, and damage mechanisms:
- API Codes & Standards:
- API Standard 653: Tank Inspection, Repair, Alteration, and Reconstruction (Primary Code).
- API Standard 650: Welded Tanks for Oil Storage.
- API RP 571: Damage Mechanisms Affecting Fixed Equipment in the Refining Industry (Selected mechanisms).
- API RP 575: Inspection Practices for Atmospheric and Low-Pressure Storage Tanks.
- API RP 576: Inspection of Pressure-Relieving Devices (Sections 4.3.2 & 6.7).
- API RP 577: Welding Processes, Inspection, and Metallurgy.
- API RP 651 & 652: Cathodic Protection & Lining of Aboveground Petroleum Storage Tank Bottoms.
- ASME Codes:
- ASME Section IX: Welding and Brazing Qualifications.
- ASME Section V: Non-Destructive Examination (NDE).
How Capgrow Supports Your Preparation:
Trainees enrolled in Capgrow’s API 653 Training receive structured codebook navigation manuals, practice calculation sets (corrosion rates, remaining life, minimum bottom/shell thickness, shell settlement, maximum fill height), and mock exam simulations to build confidence for exam day.
3. Final Exam Format & Delivery
The API 653 examination is a rigorous, 7.5-hour computer-based test delivered at Prometric testing centers worldwide:
- Question Breakdown: 170 total multiple-choice questions (140 scored questions and 30 unscored pretest questions).
- Two-Part Structure:
- Closed-Book Portion: 110 questions (2.75 hours) testing fundamental concepts, definitions, inspection procedures, and damage mechanisms.
- Open-Book Portion: 60 questions (3.75 hours) focusing on codebook lookup, complex calculations (minimum required shell thickness, tank bottom settlement evaluation, joint efficiency, MAWP), and scenario analysis.
- Digital Codebooks: Reference PDFs of allowed codes are provided directly on-screen during the open-book portion.
4. Practical Exam Preparation Tips
- Master Shell & Bottom Settlement Formulas: Practice solving edge settlement, planar tilt, and out-of-plane settlement evaluation formulas according to API 653 Annex B.
- Get Familiar with On-Screen Code Documents: Practice using PDF search functions, bookmarks, and tables of contents to quickly locate specific ASME/API clauses during the open-book portion.
- Study Corrosion Rate & Remaining Life Calculations: Practice calculating metal loss, corrosion rate, and internal/external inspection intervals for tank bottoms and shell courses.
5. Recertification & Continuing Development
To maintain an active API 653 license, inspectors must complete recertification steps every 3 years:
- 3-Year Work Requirement: Demonstrate active engagement in storage tank inspection (at least 20% of time spent performing or supervising tank inspection activities over 3 years).
- 3-Year CPD Hours: Complete 24 Continuing Professional Development (CPD) hours relevant to inspection and mechanical integrity.
- 6-Year Requirement: Complete an online, open-book web quiz covering code changes and updates over the prior six years.
For more information on certification, please refer here
