Earning your certified welder credential is a performance-based milestone — but the written knowledge behind every qualification test is just as important as the weld you lay down in the booth. Whether you are preparing for an AWS Certified Welder performance qualification, an ASME Section IX welder qualification, or an employer-specific weld test, the questions in this free printable PDF cover the core knowledge areas that evaluators expect you to understand: welding processes, joint types and positions, weld symbol interpretation, metallurgy, discontinuity identification, qualification variables, and shop safety. Download the file, print it, and work through each item away from a screen — many welders find that reviewing written content outside the shop helps lock in the vocabulary and procedures they apply daily without thinking about them.
Welding certification exams range from purely hands-on performance qualifications to written knowledge tests depending on the applicable code and employer requirements. AWS D1.1 Structural Welding Code, ASME Boiler and Pressure Vessel Code Section IX, and API 1104 Pipeline Welding Standard each define their own essential variables, test positions, and acceptance criteria. The questions in this PDF reflect the knowledge domains common across these codes so that your review is useful regardless of which standard governs your qualification. Use the PDF alongside our online practice tests for timed, scored sessions with immediate feedback on each question.
Most welding certification exams test knowledge of multiple processes even if the welder is being qualified on only one. Understanding why each process is selected for a given application — and what can go wrong — is fundamental to producing code-quality welds.
SMAW uses a flux-coated consumable electrode that simultaneously provides filler metal and a shielding slag as it burns. Electrode selection is one of the most heavily tested topics in any welding knowledge review. The AWS electrode classification system encodes critical information in the electrode number: E6010 means minimum tensile strength of 60,000 psi, all-position (1), DC reverse polarity (0), and a high-cellulosic sodium coating that produces a forceful, fast-freezing arc ideal for root passes on pipe and open-root groove welds. E7018 has minimum tensile strength of 70,000 psi, is an all-position electrode (1), and uses a low-hydrogen iron powder coating (8) that requires storage in a rod oven at 250–300°F to prevent moisture absorption — moisture in the coating is the primary cause of hydrogen-induced cracking in low-alloy and high-strength steels. Low-hydrogen electrodes must be kept in a heated container and should not be left exposed to atmosphere for more than the time specified by the applicable code (typically 4 hours for E7018 under AWS D1.1). E6013 is a general-purpose electrode suited for sheet metal and out-of-position work where appearance matters more than mechanical property requirements.
GMAW (MIG welding) uses a continuously fed wire electrode and an externally supplied shielding gas — most commonly 75% argon / 25% CO2 for short-circuit transfer on carbon steel, or 90–98% argon for spray transfer on thicker material. The three primary metal transfer modes are tested frequently. Short-circuit transfer occurs at low voltage and wire feed speed: the wire contacts the puddle and short-circuits repeatedly at 20–200 times per second, producing a small, controllable puddle suited for thin material and out-of-position welding. Globular transfer occurs at intermediate settings: metal transfers in large, irregular droplets that can cause spatter and are difficult to control in vertical or overhead positions. Spray transfer requires high voltage, high wire feed speed, and a high-argon shielding gas: metal transfers as a fine, axial stream of tiny droplets with minimal spatter, producing excellent fusion and appearance but only practical in the flat and horizontal positions due to the fluid puddle. Pulse-spray transfer is a modified spray mode that allows out-of-position spray transfer by cycling between high peak current (spray phase) and low background current (cooling phase).
GTAW (TIG welding) uses a non-consumable tungsten electrode and a separate filler rod fed by hand. Tungsten electrode selection depends on the base metal and current type. Pure tungsten (green band) is used for AC welding of aluminum and magnesium — the AC current's electrode-positive half-cycle provides cathodic cleaning to break up the aluminum oxide layer. Thoriated tungsten (red band, 2% thoriated) is used for DCEN (DC electrode negative, also called straight polarity) welding of steel, stainless steel, copper, and titanium — it offers excellent arc starts, a pointed geometry, and better current-carrying capacity than pure tungsten. Ceriated (gray band) and lanthanated (gold band) tungstens are non-radioactive alternatives to thoriated that perform comparably on DCEN. Tungsten preparation matters: for DCEN steel welding, the tungsten is ground to a pointed tip with grinding marks running longitudinally (toward the tip) to prevent arc wander. Contaminated tungsten — caused by touching the filler rod to the electrode or dipping the tungsten into the puddle — must be removed by breaking or grinding off the contaminated tip and re-grinding before resuming welding.
FCAW uses a tubular wire electrode filled with flux. Self-shielded FCAW (FCAW-S) requires no external shielding gas — the flux inside the wire generates all necessary shielding and slag protection, making it suitable for outdoor use where wind would blow away external shielding gas. Gas-shielded FCAW (FCAW-G) uses an external CO2 or mixed-gas shield in addition to the flux core, producing better mechanical properties and lower spatter than self-shielded variants. FCAW-G is not suitable for outdoor welding in windy conditions without wind protection because the shielding gas can be displaced. The AWS classification for FCAW electrodes follows a similar pattern to SMAW: E71T-1 indicates all-position (1), flux-cored tubular wire, requiring CO2 or mixed gas, suitable for single and multi-pass welds with a rutile-type slag.
SAW uses a continuously fed wire electrode and a granular flux that completely covers the arc — the arc is invisible during welding. SAW produces very high deposition rates, deep penetration, and excellent mechanical properties, making it the process of choice for heavy structural fabrication (shipbuilding, pressure vessels, bridge girders) and automatic seam welding of large-diameter pipe. Because the flux completely shields the arc and is partially fused into slag during welding, SAW is limited to flat and horizontal positions. Unfused flux can be recovered and reused, but flux that has been moistened must be dried in an oven before use. The combination of wire and flux type (analogous to electrode and coating in SMAW) must be qualified together as a combination — a change in flux classification is an essential variable under many codes.
Understanding the relationship between joint design, weld type, and qualification position is essential for both the written exam and the actual qualification test.
Five basic joint types appear on every qualification exam: butt joint (two pieces edge to edge in the same plane), T-joint (one piece perpendicular to the face of another), lap joint (two pieces overlapping in parallel planes), corner joint (two pieces at approximately 90 degrees with one edge meeting the face of the other), and edge joint (two pieces with their edges parallel and in the same plane). Each joint type can accommodate different weld types: groove welds are used in butt joints and T-joints where full penetration is required; fillet welds are triangular cross-section welds used in T-joints, lap joints, and corner joints where full penetration is not required or where geometry prevents it. Plug and slot welds are used to join overlapping members through holes or elongated slots in the top piece. The distinction between a complete joint penetration (CJP) groove weld and a partial joint penetration (PJP) groove weld determines the structural capacity of the joint and whether it qualifies for use in cyclically loaded or dynamically loaded structures under AWS D1.1.
Welding positions are designated by number and letter codes. For groove welds on plate: 1G is flat (plates horizontal, welding on top), 2G is horizontal (plates vertical, weld axis horizontal), 3G is vertical (plates vertical, weld axis vertical — both uphill 3G uphill and downhill 3G downhill), and 4G is overhead (plates horizontal, welding from below). A welder who passes a 3G test is qualified for flat, horizontal, and vertical positions; a welder who passes a 4G test is qualified for flat and overhead. A welder who passes both 3G and 4G is qualified for all four plate positions. For pipe, the positions are 1G (pipe horizontal, rolled), 2G (pipe vertical, axis horizontal — horizontal fixed), 5G (pipe horizontal, axis horizontal — fixed, all positions around the pipe without rolling), and 6G (pipe inclined 45 degrees — the most demanding position, qualifying the welder for all positions). A 6G qualification is the gold standard in the pipe welding industry and is required by most pipeline operators and refineries for production welders.
Reading weld symbols from engineering drawings is a knowledge area that appears on virtually every written welding exam. The AWS A2.4 standard defines the system used on most structural and fabrication drawings. A weld symbol consists of a horizontal reference line with an arrow pointing to the joint. Weld symbols placed below the reference line indicate welds on the arrow side of the joint; symbols placed above the reference line indicate welds on the other side. A weld symbol on both sides indicates welds on both sides simultaneously. The tail of the weld symbol (at the end opposite the arrow) contains specification, process, or detail references when needed. Common dimensions include weld size (placed to the left of the weld symbol), weld length (placed to the right), and pitch or center-to-center spacing for intermittent welds (placed to the right of the length, separated by a dash). A circle at the junction of the arrow and reference line indicates a field weld; a flag at that junction indicates an all-around weld. Exam questions frequently show a drawing with a weld symbol and ask you to identify the weld size, whether the weld is on the arrow or other side, or whether the weld is continuous or intermittent.
Welders are not metallurgists, but a practical understanding of what heat does to steel is critical for producing sound welds and avoiding cracking — which is both a quality failure and a safety hazard in structural and pressure applications.
The heat-affected zone (HAZ) is the area of base metal adjacent to the weld fusion boundary that has been heated to a temperature high enough to alter its microstructure but not high enough to melt. In carbon and low-alloy steels, the portion of the HAZ nearest the fusion line may be heated above the upper critical temperature, causing grain coarsening that can reduce toughness. Rapid cooling (quenching) from those temperatures can produce hard, brittle martensite — a microstructure that is highly susceptible to hydrogen-induced cracking (also called cold cracking or hydrogen cracking). Hydrogen-induced cracking is the most common serious weld defect in high-strength and alloy steel construction. The three conditions that must simultaneously be present for hydrogen cracking to occur are: a susceptible (hard) microstructure in the HAZ, the presence of diffusible hydrogen, and sufficient restraint stress. Eliminating any one of these three conditions prevents hydrogen cracking. Preheat addresses susceptibility by slowing the cooling rate, preventing martensite formation and allowing hydrogen to diffuse out of the weld zone before cracking can initiate. Preheat requirements under AWS D1.1 Table 4.5 are specified by base metal carbon equivalent (CE) and thickness — heavier sections and higher-CE steels require higher preheat temperatures. Interpass temperature requirements set a maximum temperature (typically 400–500°F for many structural applications) above which welding shall not continue, preventing excessive heat input that degrades toughness in multi-pass welds. Using low-hydrogen filler metals (E7018 in SMAW, ER70S-3/6 in GMAW, low-hydrogen flux in SAW) directly reduces diffusible hydrogen in the weld deposit.
Discontinuities are departures from the ideal weld geometry or soundness. Whether a discontinuity constitutes a rejectable defect depends on whether it exceeds the acceptance criteria of the applicable code. Visual inspectors and welder qualification evaluators need to recognize discontinuities by appearance and understand their causes.
Cracks are the most serious discontinuity because they represent complete loss of continuity in the weld metal or HAZ. Hot cracks form at elevated temperatures from solidification shrinkage in the presence of low-melting-point impurity films (sulfur, phosphorus); they run along grain boundaries in the weld metal center line or crater. Cold cracks (hydrogen-induced) form below 300°F after the weld has solidified, typically in the HAZ within hours or days of welding. Porosity is gas entrapment in the solidified weld metal, appearing as spherical or elongated voids on a radiograph or cross-section. Causes include moisture on the base metal, electrode, or flux; oil or grease contamination; excessively long arc length (which aspirates atmospheric nitrogen and oxygen); and insufficient shielding gas coverage in GMAW or GTAW. Undercut is a groove melted into the base metal along the weld toe that is not filled by weld metal, reducing the effective throat and creating a stress concentration. It results from excessive current, incorrect electrode angle, or too-fast travel speed. Overlap (cold lap) is the protrusion of weld metal beyond the weld toe onto the base metal surface without fusion — caused by insufficient heat, too-slow travel speed, or incorrect electrode angle. Incomplete fusion is failure of the weld metal to fuse completely with the base metal or previous weld pass, typically caused by insufficient heat input, travel speed too fast, or incorrect electrode manipulation. Incomplete penetration is the failure of a groove weld root to fuse completely through the joint thickness — a critical defect in CJP groove welds intended to carry full structural loads.
One of the most practically important knowledge areas for working welders is understanding which changes in welding variables require a new qualification test versus which changes are permitted under the existing qualification. These variables are called "essential variables" — changing them voids the existing qualification because they are considered to materially affect the welder's ability to produce a sound weld in the new condition.
Under AWS D1.1, essential variables for welder qualification include: a change in welding process (e.g., from SMAW to GMAW), a change in position to one not covered by the current qualification, and a change in weld type from groove to fillet in certain circumstances. Under ASME Section IX QW-350 through QW-357, essential variables include: process change, deletion of backing (welding open root without backing when the previous test used backing), change in base metal P-number (beyond permitted ranges), change in filler metal F-number (beyond permitted ranges), and change in thickness beyond the qualified range. Non-essential variables — such as a change in electrode diameter, shielding gas flow rate (within the WPS range), or preheat temperature increase — do not require re-qualification but must be addressed in the Welding Procedure Specification (WPS) that the welder follows. The welder qualification records (WQR or WPQR) must specifically list the essential variables for which the welder was qualified and must be signed by an authorized representative of the employer.
Welding safety is not just an OSHA requirement — it is the foundation of a long career. Exam questions on safety test both knowledge of hazards and correct protective measures.
Arc flash and arc radiation are immediate hazards. The welding arc emits ultraviolet (UV) and infrared (IR) radiation that can cause arc eye (photokeratitis) from even brief unprotected exposure and can cause skin burns through exposed skin. The correct lens shade depends on the process and amperage: SMAW at 75–200 amps requires at least a shade 11 lens; GMAW typically requires shade 10–12 depending on amperage; GTAW at 50–150 amps typically requires shade 10–11. AWS F2.2 and ANSI Z49.1 provide complete shade selection tables. Bystanders and helpers must use appropriate protection — the term "welder's flash" affecting a bystander is a preventable injury. Welding fumes contain metallic oxides, fluorides, and other compounds that, depending on the base metal and filler material, can cause occupational lung disease over time. Hexavalent chromium (Cr(VI)) generated when welding stainless steel is a known human carcinogen; manganese from filler metal flux coatings can cause manganism (a Parkinson-like neurological condition) with chronic overexposure. Engineering controls — local exhaust ventilation (LEV) at the source, general dilution ventilation, and where necessary respiratory protection (air-purifying respirators with appropriate cartridges or supplied-air respirators) — are required by OSHA 29 CFR 1910.252. Confined space welding presents compounding hazards: oxygen-deficient or oxygen-enriched atmospheres (accumulated shielding gas can displace oxygen; accumulated acetylene or other gas can create explosive atmospheres), heat stress, and limited egress. OSHA's permit-required confined space standard (29 CFR 1910.146) mandates atmospheric testing before entry, continuous monitoring, a trained attendant outside, and a rescue plan. Never run an engine-driven welder inside an enclosed space — carbon monoxide accumulation can be fatal within minutes.
For timed, scored practice that simulates the pressure of a real written knowledge test, take our online certified welder practice tests — each question includes a full explanation so you understand the reasoning behind every answer, not just the correct letter. Use the printable PDF for review sessions in the shop, at lunch, or away from a screen, then return to the online tests to track your progress by topic and confirm that your weaker areas have improved before your qualification date.