The CWI Part B practical: what the replica kit, Book of Specifications, and gauges actually are

Part B is the part of the American Welding Society (AWS) Certified Welding Inspector (CWI) exam that first-timers understand the least, which is exactly why one company built its whole business on selling a Part B kit and a guide for it. This walkthrough gives you the neutral version: what the Part B practical actually is, what the replicas and gauges and the Book of Specifications are, what the vision requirement means, and the honest answer to “do I need to buy a replica set”. We sell no kit, so we have no reason to tell you that you must.

What Part B is, in one paragraph

Part B is the hands-on practical. You inspect molded plastic weld replicas using real inspection gauges, working against a supplied document called the Book of Specifications, and you must score at least 72 percent (checked 2026-07-23). Critically, you are the inspector, not the welder. Part B does not test whether you can lay a bead. It tests whether you can measure, judge, and apply an acceptance criterion to a weld that someone else made, under time pressure, using the tools of the trade. That reframe alone helps: nobody is watching you weld.

The replicas: molded plastic, not real steel

The “welds” you inspect are molded plastic replicas, cast to reproduce real weld profiles, discontinuities, and defects: undercut, overlap, porosity, cracks, incorrect profiles, and so on. They are consistent from candidate to candidate, which is the point: everyone inspects the same standardized specimens so the exam is fair and repeatable. You handle them, measure them with gauges, and decide, against the supplied acceptance criteria, whether each feature passes or fails.

Because they are plastic replicas rather than hot steel coupons, the surprise for first-timers is not danger, it is workflow: knowing which gauge to reach for, how to seat it, and how to read it quickly. That is a learnable motor skill, and it is learnable in advance.

The Book of Specifications: your acceptance criteria

The Book of Specifications is a document supplied to you at the exam that contains the acceptance criteria you must apply to the replicas: the allowable limits for each type of discontinuity, the dimensions that pass and the ones that fail. You are not expected to have it memorized. You are expected to use it: read the criterion, measure the feature, compare, and record your judgment. AWS makes the Book of Specifications available so you can familiarize yourself with its structure before exam day, and doing so is free and worth it, because time lost hunting through an unfamiliar document is time you do not have. It functions for Part B much the way the code book functions for Part C: the skill is fast, confident navigation, not recall.

The gauges: the inspector’s toolkit

You use real welding-inspection gauges to measure the replicas. Depending on the specimen these include tools such as a fillet weld gauge, a Cambridge or bridge cam gauge, an undercut gauge, and a Hi-Lo gauge, used to measure things like fillet weld size, weld reinforcement, undercut depth, and misalignment. The gauges are provided at the exam. The failure mode is not “I did not own the gauge”, it is “I had never handled this gauge before and fumbled it under the clock”. Getting time with the gauge types in advance, so seating and reading them is reflex, is the single highest-value bit of Part B preparation.

The vision requirement: book the eye exam early

Part B is a visual-inspection test, so AWS gates it on your eyesight. You must pass an eye exam proving near-vision acuity of Jaeger J2 at 12 inches (about 30 centimeters) or better, plus a color-perception test, performed within one year of your exam by a licensed medical professional and kept on file (checked 2026-07-23). Corrective lenses are allowed. AWS will not release your results without a completed visual-acuity record on file. This is the requirement people leave to the last minute and then scramble over. Book the eye exam early and get the signed form filed. It is a hard gate, not a formality.

The question everyone asks: do I need to buy a replica set?

No, you do not need to buy a third-party replica kit to sit Part B. The specimens, the gauges, and the Book of Specifications are provided at the exam. A whole cottage industry sells replica sets and Part B guides, and they are selling into a real anxiety, but the honest statement is that the exam furnishes what you need on the day.

What genuinely helps, and what that anxiety is really about, is format familiarity. Part B fails people through format shock far more often than through inability. So the useful spend, if any, is on getting hands-on with the format before exam day, which can come from:

• Practicing with the free AWS Book of Specifications so its structure is familiar.
• Any hands-on time you can get with the actual gauge types, whether through an employer, a local training facility, or a course that bundles Part B practice.
• The in-person Part B practice included in a full seminar, which is one of the few things a seminar bundles that self-study cannot easily replicate. Whether that is worth the seminar price is a separate decision, covered neutrally in the seminar-versus-self-study guide.

Buying a plastic replica set is optional and, for many candidates, unnecessary. Practicing the format is not optional if you want to pass Part B on the first try. Those are two different things, and the sellers blur them on purpose.

Where Part B fits, and what it costs

Part B is one of three parts, and you need 72 percent on each independently; a strong Part A or Part C does not carry a weak Part B. See the CWI exam guide for the full structure and the how hard is the CWI exam guide for why each part fails a different person.

On cost, Part B is the one part whose fee is not set by AWS. It is administered by an Authorized Training Facility (ATF), and the ATF sets the Part B practical fee, so there is no single official number for it. That is why our cost table and cost calculator label the Part B fee as provider-set and tell you to contact your ATF, rather than printing a fabricated figure. Budget for it, and ask your ATF directly.

Sources: the AWS Certified Welding Inspector certification pages, the AWS Visual Acuity requirement, and the AWS Book of Specifications information at aws.org (reviewed 2026-07-23). The Part B format, the 72 percent passing score, and the vision requirement are set by the American Welding Society and can change; the Part B practical fee is set by the Authorized Training Facility, not AWS. Confirm current details before you pay. This site is independent, is not affiliated with AWS, and sells no seminar, course, exam seat, or replica kit.