Welding Safety & Quality: OSHA Compliance, Defect Prevention, Inspection and Testing
The safety rules that actually get tested
Welding safety in the U.S. lives in OSHA 29 CFR 1910.252 (general industry) and 1926 Subpart J (construction). Two distance rules appear constantly and are easily confused. Combustibles must be moved at least 35 ft away from the work or protected by a tight, fire-resistive guard. Oxygen and fuel-gas cylinders must be separated by 20 ft or by a 5-ft-high barrier with at least a half-hour fire rating. Acetylene lines are limited to 15 psig and must never contact copper or silver. Cylinders stay upright, secured, valve caps on in storage.
Hot work permits, a fire watch during work plus 30 minutes after (longer if the site or NFPA 51B says so), and fume control under 1910.252(c) are standard items. Confined-space welding requires a 1910.146 permit. Eye protection follows the shade table: SMAW at 150 A calls for shade 10 or 11.
Quality: discontinuity versus defect
A discontinuity is any interruption in weld uniformity; it becomes a defect only when it exceeds the acceptance criteria of the governing code. Questions love to blur this. Match method to flaw: VT for surface and profile, PT for surface-breaking flaws in any material, MT for surface and near-surface in ferromagnetic steel, UT for internal planar flaws and laminations, RT for internal volumetric flaws. No method sees everything - RT misses tight planar flaws aligned with the beam, and UT struggles with some orientations and coarse grain.
Worked example
A welder runs SMAW at 150 A. The shade table band 100–200 A gives a minimum of shade 10, so shade 10 or 11 is acceptable and shade 8 is a citation. Similarly, before accepting or rejecting anything, name the code clause; the same porosity cluster may pass one acceptance class and fail another.