CWI Practice Questions — D1.1 Code Application
The CWI Part C exam tests your ability to navigate and apply a welding code under time pressure. These practice questions focus on D1.1:2025 code application — preheat lookups, fillet weld sizing, prequalification rules, and essential variables. Each answer cites the specific clause or table reference.
How to use these questions: Read the scenario, attempt your answer, then reveal the solution. Each answer cites the specific D1.1 clause or table. Use Flux above to ask follow-up questions about any topic you find challenging.
Preheat — Table 5.11
Table 5.11. E71T-1 is a low-hydrogen electrode, placing it in Category B. For Group II, Category B, thickness over 3/4 through 1-1/2 inch: minimum preheat is 50°F.Table 5.11. For Group II, Category A, 1 inch thickness: minimum preheat jumps to 150°F (65°C). This is a common exam trap — the only change is the electrode classification, but the preheat triples.Fillet Weld Size — Table 7.7
Table 7.7 Footnote A, when using a low-hydrogen process (E7018), T equals the thinner part joined (1/2 inch). For T over 1/4 through 1/2 inch, minimum fillet size is 3/16 inch. If the welder used a non-low-hydrogen process without preheat, T would equal the thicker part (3/4 inch), requiring 1/4 inch minimum.Table 7.7 Footnote A, T equals the thicker part (1-1/4 inch). For T over 3/4 inch, minimum fillet size is 5/16 inch. The 3/16-inch weld is undersized. Additionally, Table 5.11 requires 150°F preheat for Group I, Category A at this thickness (over 3/4 thru 1-1/2 inch) — but the scenario says no preheat was applied, which is also non-compliant.Prequalified WPS — Clause 5
Clause 5.3.2.2 specifically excludes GMAW with short-circuiting transfer (GMAW-S) from prequalification. The fabricator must qualify the procedure by testing under Clause 6. Spray transfer, globular transfer, and pulsed-spray GMAW are prequalified when all other Clause 5 conditions are met.Figure 5.1 (CJP groove welds), Figure 5.2 (PJP groove welds), or Figure 5.3 (fillet welds). Any deviation from these prequalified joint dimensions — including root opening, groove angle, root face, or land — requires WPS qualification under Clause 6.Essential Variables — Table 5.5
Table 5.5. A new prequalified WPS must be written for the FCAW process. However, since both E7018 and E71T-1 are low-hydrogen electrodes (Category B in Table 5.11), the preheat requirements remain unchanged.Table 5.5. However, because this is a prequalified WPS, no qualification testing is required — the fabricator simply writes a new prequalified WPS specifying the 3G position with appropriate parameters for vertical welding.ASME IX Crossover Questions
Clause 6 Part D welder qualification requirements. The welder must qualify separately under D1.1. In practice, many welders hold both qualifications.QW-250 series. Supplementary essential variables become essential only when impact testing is required by the construction code. D1.1 has only two tiers: essential (Table 5.5 for prequalified, Table 6.6 for qualified) and nonessential. There is no supplementary essential concept in D1.1."On the CWI Part C exam, time management is everything. You have 2 hours for 60 code-book questions. That is 2 minutes per question. If you cannot find the table or clause within 30 seconds, mark it and move on. Tab your code book with sticky notes for
— Field observation, CWI exam preparation practiceTable 5.11,Table 7.7,Table 5.5,Clause 5, andClause 6— these are the most-tested sections."
CWI Exam Tip: The Part C exam allows you to bring a tabbed, highlighted code book (no handwritten notes). Focus your preparation on rapid table lookup rather than memorization. Knowing WHERE to find the answer is more valuable than memorizing the answer itself.
Related Standards Guides
Frequently Asked Questions
Per D1.1:2025 Table 5.11, A572 Gr.50 falls in Group II. For FCAW (a low-hydrogen process, Category B), the minimum preheat for thickness over 3/4 through 1-1/2 inch is 50 degrees F (10 degrees C). If using a non-low-hydrogen process like FCAW-S with E71T-11, the steel moves to Category A, requiring 150 degrees F (65 degrees C) for the same thickness range.
Per D1.1:2025 Table 7.7, the minimum fillet weld size is determined by the thicker part joined (T) when using non-low-hydrogen processes without preheat, or by the thinner part joined when using low-hydrogen processes. For a low-hydrogen process (E7018, E71T-1, ER70S-6): T equals the thinner part (1/2 inch), requiring 3/16 inch minimum. For a non-low-hydrogen process without preheat: T equals the thicker part (3/4 inch), requiring 1/4 inch minimum.
No. D1.1:2025 Clause 5.3.2.2 specifically excludes GMAW with short-circuiting transfer (GMAW-S) from prequalification. Short-circuit GMAW has a higher risk of incomplete fusion, particularly on thicker materials, and requires WPS qualification by testing under Clause 6. The other GMAW transfer modes (spray, globular, pulsed-spray) are prequalified when all other Clause 5 requirements are met.
Changing from E7018 (SMAW, A5.1) to E71T-1 (FCAW-G, A5.20) is a change in welding process (SMAW to FCAW), which is an essential variable under D1.1 Table 5.5. This requires a new WPS. However, both electrodes are low-hydrogen and fall under Table 5.11 Category B, so the preheat requirements would remain the same. The new FCAW WPS can still be prequalified under Clause 5 if all other prequalification conditions are met, including the joint design matching Figures 5.1 through 5.3.
For a prequalified WPS under D1.1 Clause 5, position is listed as an essential variable in Table 5.5. Changing from 1G (flat) to 3G (vertical) requires a new or revised WPS. However, this does not require re-qualification testing because the WPS is prequalified. The fabricator simply writes a new prequalified WPS specifying the 3G position, with appropriate parameters for vertical welding (typically lower amperage, weave technique). For a qualified WPS under Clause 6, the welder must also be performance-qualified in the 3G position.