Preparation of Materials, Tools, Equipment, and Work Area
This domain tests readiness before welding: material identification, joint preparation, cleaning, fit-up, tungsten preparation, equipment checks, and work-area control.
Core rules
- Verify base metal against the drawing and material certificate, including grade and heat number. Keep carbon steel, stainless steel, and aluminum tools and consumables separate.
- Clean the joint and adjacent surfaces. Remove oil, grease, paint, moisture, rust, and oxide. Degrease before brushing aluminum; use a dedicated stainless wire brush to remove aluminum oxide.
- Cut and bevel to the WPS or drawing. Check bevel angle, root face, root gap, alignment, and tack welds. Tacks must be made with approved filler, be crack-free, and have tapered ends for tie-in.
- Prepare tungsten by grinding longitudinally on a dedicated wheel, using the correct diameter and tip shape for the current and joint. Match collet, collet body, and ceramic to the electrode size.
- Check torch parts, gas hose, regulator, flowmeter, ground clamp, and water cooler. Set up ventilation, screens, fire blankets, and cable routes; keep the work area dry and clear.
Worked example
A stainless steel pipe root is to be GTAW welded. The fitter cleans the bevel with acetone, brushes it with a stainless-only wire brush, confirms the heat number, sets the root gap and alignment, and tacks with ER308L filler. The welder then installs a purge dam and monitors oxygen inside the pipe. Using a carbon steel grinding wheel or brush would transfer iron and cause contamination and corrosion.
Traps that cost marks
- Mixing stainless and carbon steel brushes or grinding wheels.
- Cleaning aluminum without removing oxide.
- Leaving tacks cracked or unt tapered.
- Grinding tungsten across the wheel instead of lengthwise.
- Failing to check gas leaks, cable damage, or work-area fire hazards.