CWS (CWNP) cheat sheet

Arc flash protection: AWS/OSHA practice requires filter shade selection by amperage - SMAW at 100 A uses shade 10, at 200 A shade 12; GTAW at low amperage uses shade 8–10; raise one shade when welding in a confined space or with high-amp processes.

Ventilation decision rule: manganese-bearing consumables and stainless (hexavalent chromium) require local exhaust ventilation; general dilution ventilation alone is insufficient when the welder's helmet is inside the plume.

Fume exposure limits commonly cited: ACGIH TLV for manganese is 0.02 mg/m³ respirable (0.1 mg/m³ inhalable); hexavalent chromium TLV is 0.0002 mg/m³ - both far below iron-oxide nuisance limits.

Hot work permit rule: a permit is required whenever welding is outside a designated hot-work area; fire watch must remain 30 minutes after work ends (60 minutes where the standard or site rule specifies) and the area must be checked before leaving.

Oxygen-fuel gas safety rule: never use oil on oxygen fittings; acetylene line pressure must not exceed 15 psi (103 kPa); flashback arrestors are required at the regulator and torch on both lines.

Discontinuity vs defect: a discontinuity is any interruption in the weld's uniformity; it becomes a defect only when it exceeds the acceptance criteria of the applicable code (e.g., AWS D1.1, ASME Section IX).

Visual inspection is performed before, during, and after welding; surface porosity, undercut, and crater cracks are typically detected visually, while internal lack of fusion requires UT or RT.

Weld quality acceptance for AWS D1.1 statically loaded butt joints: complete joint penetration is required; undercut shall not exceed 1/32 in (0.8 mm) with a maximum 1/16 in (1.6 mm) depth for intermittent undercut.

Personal protective equipment baseline: leather gauntlet gloves, flame-resistant sleeves or jacket, safety glasses under the helmet, and hearing protection when the pre-use noise survey exceeds 85 dBA.

Deposition rate formula: DR (lb/hr) = 13.1 × E × I / (melting efficiency × melting point of the filler); for SMAW/E70 electrodes, a working approximation is DR = 0.0003 × I (amps) × operating factor, with operating factor typically 0.2–0.4 for stick welding.

Arc time vs total time: arc-on time is the time the arc is struck; total labor hours include fit-up, positioning, chipping, and breaks. Operating factor = arc time ÷ total paid time; improving it from 25% to 40% cuts labor cost per unit by roughly 37%.

Travel speed and heat input: heat input (kJ/in) = (60 × V × I) / (1000 × travel speed in in/min). Raising travel speed lowers heat input and reduces distortion but risks lack of fusion if the puddle is not wetting in.

Cost per foot of weld: material cost = (weight of deposited metal per foot) × (filler price per lb ÷ deposition efficiency), plus labor = (labor rate ÷ travel speed in ft/hr). Filler metal typically accounts for a smaller share than labor in manual processes.

Weld cost reduction levers ranked by typical impact: increase operating factor (fixturing, positioners), switch process (FCAW/GMAW deposition rates exceed SMAW by 2–4×), reduce over-welding (right-size the fillet leg), and reduce rework/scrap.

Fillet weld size rule: the required leg size is determined by the thinner part thickness per code tables; over-welding a 1/4 in fillet where 3/16 in is required adds roughly 78% more deposited metal (area scales with leg squared).

Productivity metric: pounds of deposited weld metal per labor hour; track it against a target derived from process, position, and joint type. A falling trend flags fit-up problems, excessive spatter cleanup, or arc instability.

Scrap and rework are the largest hidden cost drivers; a 2% rework rate on a job with 20% margin can erase profitability. Root-cause tracking by defect type (porosity, undercut, lack of fusion) is the control lever.

Labor standard adjustment: when a positioner or fixture converts a vertical-up weld to flat, deposition rate typically rises 30–50% and the operating factor improves, so standards must be re-baselined rather than using the same time per inch.

Weld procedure qualification rule: a WPS must be supported by a PQR (procedure qualification record) tested per the applicable code (ASME Section IX or AWS D1.1); the supervisor's role is to verify the welder is using the qualified WPS parameters, not to alter them.

Welder qualification vs certification: qualification is demonstrated by test (performance test); certification is the employer's written confirmation that the welder is qualified. The employer, not the welder, owns and signs the certification.

Continuous qualification rule: a welder's qualification lapses after a defined period (commonly 6 months for ASME) without welding with the qualified process; supervisors must track and log arc time to prevent lapses.

Progressive discipline sequence: verbal coaching → written warning → final warning → termination, with documented dates and specific behavior; skipping steps weakens the case and invites challenge.

Corrective action model: contain the defect, identify root cause (5 Whys or fishbone), implement the fix, verify effectiveness, and update the WPS or work instruction. Blaming the welder without a root cause is not a corrective action.

Safety leadership: supervisors must enforce PPE and hot-work permits consistently; inconsistent enforcement is a leading indicator of incident risk and undermines the credibility of the safety program.

Communication rule for shift handoff: pass along open nonconformances, in-process WPS parameters, and equipment issues in writing; verbal-only handoffs are a common source of repeated defects.

Training gap analysis: compare required skills (process, position, code) against the welder's qualified range; assign training or requalification where the gap is in a code-required parameter, not just in technique.

Performance feedback should be behavior-specific and timely: describe the observed action (e.g., 'travel speed increased above the WPS range on the last three passes'), its impact, and the expected correction.