CWI Part C: the open-book code exam, and why it is a speed test, not a memory test

Part C is the part of the AWS Certified Welding Inspector (CWI) exam that candidates most often misjudge, because the words “open book” make it sound like the easy one. It is not. Part C is where prepared candidates who never practiced against their actual code book run out of time and fail a part they knew the material for. This guide explains what Part C actually is, which code you sit it on, why it is a navigation test rather than a memory test, how to budget your time, and how it differs from the Book of Specifications you meet in Part B. We sell you no seminar and no code book, so we have no reason to talk the difficulty up or down.

What Part C actually is

Part C is the open-book code-application exam. You are given inspection scenarios and you apply one specific welding code, the code you registered for, to decide whether something passes, fails, or is handled a certain way under that code. You may use the code book during the exam, and you must score at least 72 percent to pass, scored independently of Part A and Part B (checked against the AWS certification pages on 2026-07-23). You are the inspector reading the rule and applying it, not recalling the rule from memory. The skill being tested is whether you can find the right clause and read it correctly, fast, under a clock.

The one code you register for, and why the edition matters

You do not sit Part C on welding in general. You sit it on one code that you choose when you register, from the set AWS offers: AWS D1.1 (structural steel), AWS D1.2 (structural aluminum), AWS D1.5 (bridge welding), AWS D15.1 (railroad), AWS D17.1 (aerospace), API 1104 (pipeline), or the ASME package (Section IX with B31.1 and B31.3 piping). Whichever you pick becomes the entire world of your Part C exam.

The trap here is the edition. Part C is pinned to a specific published edition of your code, and bringing the wrong edition turns an open-book exam into a book you cannot use, because clause numbers and acceptance criteria move between editions. Which code fits your work, and exactly which edition each Part C is currently pinned to, is its own decision covered in the code book and edition guide. Get that right before you buy the book, not on exam morning.

Part C is not Part B: the code book is not the Book of Specifications

First-timers routinely confuse the two open-reference parts, so here is the clean distinction:

• Part B, the practical, hands you a specially prepared document called the Book of Specifications, plus molded plastic weld replicas and real inspection gauges, and asks you to measure and judge those specimens against that supplied document. The Book of Specifications is a controlled, exam-only reference; it is not a real published code, and there are no replicas in Part C. The full walkthrough is in the Part B practical guide.
• Part C, the code exam, hands you nothing physical to inspect. You bring your real, published code book, the one you registered for, and you apply it to written scenarios.

Both parts let you reference a document, and both are timed, but they test different skills: Part B tests measurement and judgment of physical specimens against a supplied spec, and Part C tests navigation and application of a real code. Keeping them straight matters, because they fail different people and you prepare for them differently.

Why open book is a trap: it is a speed test

Because you may use the book, Part C does not reward memorization, and it does not have to be gentle on time. There are more questions than a slow reader can comfortably finish, so the exam is really measuring how fast you can navigate your code book. The candidates who fail Part C almost never fail on knowledge. They fail because they treated the open book as a safety net and never learned where anything is, then burned four minutes hunting for a clause that a practiced candidate lands on in thirty seconds.

Speed on Part C comes from one thing: repetition against your actual code book until finding a clause is reflex. You want to know the table of contents and the index cold, to have your common tables tabbed, and to recognize which kind of question sends you to which part of the book before you have finished reading it. That fluency is not something you can fake on the day, and it is the whole game.

Budgeting your time

Treat Part C as a time-management exercise as much as a welding exam:

• Know your pace before exam day. Time yourself answering practice code questions against your real book. If a typical question is taking you several minutes, that is your warning, and the fix is more navigation practice, not more reading.
• Tab and index the book in advance. Physical tabs on the acceptance-criteria tables, the figures, and the sections you hit most often turn a page hunt into a direct flip. Confirm your exam allows the tabbing you plan to use.
• Answer the fast ones first. Bank the questions you can resolve quickly, then return to the ones that need a deeper dig. Do not let one stubborn clause eat the time that three easy questions needed.
• Never leave a question blank. An open-book part is still scored on answers given; if the clock is running out, put down your best read and move on.

The 72 percent bar, scored independently

Part C is scored on its own, and you need 72 percent on it regardless of how you did on Parts A and B. A 90 on the closed-book fundamentals does not carry a 68 on the code exam, because there is no averaging across parts. That independence is why Part C deserves dedicated practice even if your fundamentals are strong: your weakest part is the one that decides your result, and for a lot of otherwise-ready candidates the weakest part is code-navigation speed. The retake rules also turn on this, because you must attempt all three parts before you can re-sit any one you failed.

How to practice Part C

The honest plan for Part C is short and specific:

1. Pick your code and pin the edition first. Everything else depends on it. Use the code book and edition guide so you buy the right book in the right edition.
2. Practice navigation, not reading. Do not read the code cover to cover. Drill finding specific clauses and tables until it is reflex, and learn the book’s structure so questions route themselves.
3. Time everything. Practice under the clock so pace, not knowledge, stops being your risk.
4. Decide your prep path with real numbers. A full seminar bundles code-application practice, but self-study with a well-tabbed book works for many candidates; the neutral seminar-versus-self-study guide and the cost calculator turn that into a figure for your situation.

Where Part C fits, and what comes next

Part C is one of three parts you must each pass at 72 percent. For the full exam structure and a study arc across all three, start with the CWI exam guide. For the closed-book fundamentals part and the eleven content areas it draws from, see the Part A fundamentals guide. For the hands-on part with the replicas and gauges, see the Part B practical guide. And for an honest, part-by-part read of what trips candidates up, see how hard is the CWI exam. If your work suits a specific code, a matching endorsement can both open jobs and, at the right time, count toward recertification: see the endorsement matrix.

Sources: the AWS Certified Welding Inspector certification pages at aws.org, reviewed 2026-07-23. The open-book format of Part C, the seven code options, the requirement to register for one specific code and edition, and the 72 percent per-part passing score are set by the American Welding Society and can change; confirm the current details on the official application before you pay. Part C is pinned to a specific published edition of your chosen code: verify the current edition before you buy the book. This site is independent, is not affiliated with AWS, and sells no seminar, course, exam seat, or code book.