The gathered dust shows the weld has little penetration, and much less strength than it should. Click photo to enlarge 3. If you're a beginning welder, find someone who welds for a living to attach your seat belt tabs and the mounting bracketry for your seat. If you're a beginner, find a pro to weld up your roll cage, too. Keep your belts short.
Seat belts stretch.
If you use long belts, they will stretch much more than short belts. Seat belt webbing loses strength over time, especially in sunlight, and should be replaced every two years. If you experience a hard impact, replace the belts. When webbing stretches severely, it becomes damaged, losing strength. The hardware can also be damaged in bad wrecks and thus should not be reused.