Beginning the path: API 653 Questions

By Carlos Molina

What should you do in order to pass the API 653 exam? Well, you should read the standards well ahead, choose and write down the most questions and answers you can, and, if possible, take the course to reinforce knowledge. Regarding the Q&A´s, you should revisit them regularly using an spaced repetition software. 

The following 50 questions were extracted from the standards by me, or remembered by me or other students that took the exam before.

The format is a Q&A one, different from the multiple choice question format from other courses I have seen online. I prefer this method because it takes away all the clutter that leads to confusion when treating these standards. I advise you to copy this info and paste it in a spaced repetition software like Anki or Supermemo, as the Q&A format allows, and start studying right away.  You could choose to print flashcards too. When days pass by, you will see who you remember all of the information with no problem.

1. Q: What is the minimum thickness for a tank floor plate with no means for leak detection or secondary containment if an RBI program is not in place?

A: 0,1 inches Ref: Table 4.4 API 653

Don´t hesitate to keep reading if you are studying for the API 653 exam, as there is a downloadable  for you.

2. Q: When a full hydrostatic test is required, it shall be held for ________
A: 24 hours. Ref: 12.3.1 API 653

3. Q: How many radiographs shall be taken in a square 12” x 24” butt welded insert plate in a 1″ thickness shell?
A: 100% Ref: API 653

3a. Q: How many radiographs shall be taken in a square 12” x 24” butt welded replacement  plate in a 1″ thickness shell?
A: 1 in every vertical, 1 in every horizontal, and 1 for every corner. Ref: API 653

UPDATE 21/01/16: One reader pointed out to a mistake in this answer. The answer is: 1 in every vertical, 1 in every horizontal, and 1 for every corner.

UPDATE 4/03/2017: Other reader noted that radiography is 100% for an insert plate. Now I´ve posted 2 questions, one for insert plates and the other for replacement plates.

4. Q: Minimun number of radiographs that shall be taken to a circular butt welded insert plate in a shell 1/2″ thick?
A: 1 Ref: API 653

5. Q: How much time do you need to keep the radiographs of a reconstructed tank?
A: 1 year Ref: 13.2.3 API 653

These were examples of questions that have appeared in the exam in the past, with information taken from the standards of the body of knowledge

Part of the API 653 questions series

General and definitions. #2 in the API 653 questions series.

You cand Download all the 50 questions from Path #1 here in pdf format.



  1. In-depth explanation of standards
  2. Unsusbcribe at any time

{ 10 comments… add one }
  • Ken Konduah October 3, 2015, 3:17 pm

    This site is very useful. I am thinking of taking the course in Feb 2016. Could you please give me some guidance as to which area of these standards to study. You know they are a lot to read. Also do I need to read both APIs 650 and 653 before taking the course and the exams?

    • October 12, 2015, 1:59 pm

      Hi. Sorry for the late response. Some 70 or 80% of the questions come from API 653 and API 650. If you have time, you should definitely take time to read the standards, to get a feel of the structure of them. The standards by themselves will kick you out of reading the parts that contain tables and drawings. And understand ASME IX. Thanks

  • Jeffrey Thomasson January 20, 2016, 4:59 pm

    On question #3, wouldn’t the correct answer be at least 1 radiograph on the horizontal seam, 1 on each corner and 100% on the vertical joints?

    • Carlos F. Molina January 21, 2016, 2:40 pm

      Yes, there is a wrong answer. Actually, it would be 1 in every vertical, 1 in every horizontal, and 1 for every corner. It would be 100% of the verticals if thickness exceeds 1in.

      • Sriram March 5, 2017, 1:12 am

        I think your previous answer is right as the question asks about “Insert Plate” and not replacement plate. Maybe the question is not complete…

  • Ehsan January 27, 2016, 3:17 am

    Hi Carlos,
    On question 18 for crude oil tank with operating at 190F …. I really confused as there are 2 table one for Thick-film and one for thin film and both included 190F.

  • Don Stites March 2, 2016, 11:53 pm

    Like your site and appreciate the info. I have competed you paths 1-6 and found some errors. How Can I forward them to you?

    • Carlos F. Molina March 3, 2016, 10:22 am

      Yes, off course. I´ve been aware of some error since a long time ago, I just haven´t had time to make the corrections.

  • mohamed April 6, 2016, 10:28 am

    I’m in need to know the errors and the correction . .if any expert here prepare a list .. it will be appreciated.

    • Carlos F. Molina April 6, 2016, 2:01 pm

      Hi. My next post is a “list of errata” and 50 or 100 more questions. I will have it ready by sunday. Stay tuned. Thanks

Leave a Comment