CW Certified Welder cheat sheet

SMAW cellulosic electrodes (E6010/E6011) are commonly run on DCEP; basic low-hydrogen electrodes (E7018) require dry storage and are commonly run on DCEP or AC.

GMAW transfer mode depends on current density and shielding gas: short-circuit at low current, globular at intermediate current, and spray at high current with argon-rich gas.

FCAW-G uses an external shielding gas; self-shielded FCAW uses flux-generated shielding and is more wind-tolerant for field work.

GTAW uses DCEN for steel, AC for aluminum and magnesium to break surface oxide, and DCEP only for special thin work because electrode heating is high.

Process selection rule: windy outdoor carbon steel work favors SMAW or self-shielded FCAW; thin sheet or high-cleanliness joints favor GTAW; high-deposition flat work favors GMAW spray or FCAW.

A change in process, filler classification, shielding gas, polarity, current type, or transfer mode is an essential variable and may require requalification.

Filler metal must match the base metal strength and specification; using a different filler classification is generally an essential variable.

Preheat and interpass temperature control hydrogen cracking and are procedure essential variables for many steels; they are not substitutes for proper electrode storage.

Flat position (1G/1F): weld face approximately horizontal and deposited from the top; gravity helps hold the puddle and deposition rates can be higher.

Horizontal position (2G/2F): weld axis horizontal, weld face vertical; the puddle tends to sag, so lower current and controlled travel are used.

Vertical position (3G/3F): weld axis vertical; uphill welding gives deeper penetration and is often required, while downhill is a separate variable with less penetration.

Overhead position (4G/4F): welding from below the joint; use lower current, short arc, and fast-freezing electrodes or transfer modes to control the puddle.

Pipe 5G: pipe axis horizontal and fixed; welder progresses through flat, vertical, and overhead sections without rotating the pipe.

Pipe 6G: pipe fixed at 45 degrees and not rotated; it is the most severe common pipe test and typically qualifies all pipe positions when code permits.

Pipe 6GR: 6G test with a restriction ring near the joint; the ring limits access and is used for offshore or high-restraint qualification.

Position qualification is not automatically reciprocal: a test in a more difficult position may qualify easier positions only where the code explicitly allows it.

Pipe diameter is an essential variable; small-diameter pipe (commonly NPS 2 and smaller) has tighter curvature and requires more frequent angle changes than large-diameter pipe.

A plate qualification does not automatically qualify pipe; pipe curvature and fixed-position welding make pipe tests more restrictive in most codes.

Test coupon thickness sets the qualified thickness range; thicker coupons generally qualify thinner material, but thinner coupons do not automatically qualify thicker material.

Base metal grouping is based on composition, strength, and weldability; changing from carbon steel to stainless steel or aluminum usually requires separate qualification.

Backing, root gap, joint design, and groove type are essential variables; adding or removing backing changes root support and heat flow.

Small-diameter pipe is often tested in 5G or 6G because the welder must change body and electrode angle frequently around the circumference.

Large-diameter pipe allows longer continuous welds before repositioning, but diameter and wall thickness remain essential variables for qualification.

Aluminum requires removal of surface oxide by stainless brushing or chemical cleaning; GTAW AC provides cathodic cleaning during welding.

Cracks are generally rejectable in a welder qualification test regardless of size or location; the test weld must be repaired or replaced before evaluation.

Undercut acceptance depends on depth and length limits; excessive undercut reduces effective throat and is a code-rejectable defect.

Porosity acceptance is based on pore size, count, and distribution; scattered porosity within code limits may be acceptable, but clustered or aligned porosity often fails.

Bend tests evaluate ductility and fusion at the root or face; cracks or tears exceeding the code limit after bending constitute failure.

Tensile specimens must reach the minimum specified tensile strength of the base metal; failure below that value indicates an unacceptable test weld.

Visual inspection precedes mechanical testing; surface cracks, excessive reinforcement, and incomplete fusion visible at the surface can reject the weldment.

Excessive weld reinforcement concentrates stress and may exceed cap height limits; reinforcement is measured above the base-metal surface.

A discontinuity becomes a defect only when it exceeds the acceptance criteria; acceptance limits come from the applicable code, not from welder preference.