Weld Inspection: Visual Inspection and What a CWI Looks At

What the work looks like

Weld inspection is the quality-control role that verifies welds made on structural, pressure, and pipeline work meet the applicable code (AWS D1.1, ASME Section IX, API 1104). About 80 percent of weld inspection is visual. The rest is nondestructive examination (NDE): ultrasonic testing (UT), radiographic testing (RT), dye penetrant (PT), and magnetic particle (MT). An inspector who can only do visual is still extremely valuable; adding one or more NDE methods takes you to senior rates.

The gold-standard credential is the AWS Certified Welding Inspector (CWI). Pay for CWIs runs $35 to $75 per hour, with field QC inspectors on shutdowns and pipeline jobs making $150,000+ per year including travel and per diem.

Job titles: Visual Welding Inspector, Quality Control Inspector, CWI, Senior QA/QC Inspector, NDT Technician.

Safety and tools

The visual inspection checklist covers pre-weld, in-process, and post-weld:

Pre-weld:

• Material: correct grade (stamped or traceable to heat number), no laminations, correct thickness.
• Joint prep: bevel angle within tolerance, root face and gap within tolerance, surfaces clean (no rust, mill scale, oil, or paint).
• WPS posted: correct process, filler metal, amperage, preheat documented.
• Welder qualification: current WPQ for the process and position.

In-process:

• Preheat achieved before arc strike (measure with Tempilstik or IR gun).
• Interpass temperature (do not exceed the WPS max).
• Interpass cleaning (slag, spatter removed before next pass).
• Current and voltage within WPS range.

Post-weld:

• Bead profile: acceptable convexity and concavity.
• Undercut: less than 1/32 inch on primary members, less than 1/16 inch on other members (per D1.1).
• Porosity: none visible in primary-stress welds.
• Cracks: none allowed.
• Fillet weld leg size: measured with a fillet gauge.
• Weld length: measured and matched to the drawing.
• Arc strikes: not allowed on structural steel outside the weld.
• Reinforcement (crown): within code limits (typically 1/8 inch max on groove welds).

NDE methods at a glance:

• UT: ultrasonic pulse into the weld, echo indicates discontinuity depth and size. Works for internal flaws.
• RT: radiograph (X-ray) produces a film or digital image. The slow, expensive, gold-standard method for internal flaws.
• PT: dye penetrant on surface-breaking cracks. Fast and cheap; nonferrous-compatible.
• MT: magnetic particle on ferrous surface cracks. Fast.

Tools: high-impact flashlight, inspection mirror, fillet gauge set (VWAC, Bridge Cam, or Palmgren), weld profile gauge, depth gauge, thermometer or Tempilstik for preheat, calipers, tape measure, camera for documentation, laminated copy of D1.1 Table 6.1 (visual acceptance criteria).

Your first exercise

Find a finished weld (any shop, any beam, any bracket). Visually inspect it against the D1.1 criteria: leg size, undercut, porosity, arc strikes, completeness, convexity. Document what you see, pass or fail, and why.

That observation skill is what CWIs get paid for. The certification comes later; the eye comes first.

Where to go next

Build on Weld Inspection with Welding Fundamentals (Introduction to Welding), Stick Welding (Introduction to Stick Welding), Pipe Welding (Introduction to Pipe Welding), Structural Welding (Introduction to Structural Welding), Blueprint Reading, Metallurgy for Welders, and AWS Certified Welding Inspector (CWI) exam prep. NDE specialties: UT, RT, MT, PT (ASNT SNT-TC-1A Level I and II). Safety: Welding Safety (AWS Z49.1), Fall Protection, Confined Space Entry.