For slot welds, what is the minimum center to center transverse spacing, in relation to the slot width?

• A. The minimum shall be four times the width of the slot to be welded
• B. The minimum shall be two times the width of the slot
• C. The minimum shall be three times the width of the slot
• D. The minimum shall be equal to the width of the slot

Answer: (A)

When slot welds are used, spacing between them matters because it controls how heat-affected zones overlap and how the welds share the load. If the slots are placed too close, heat from adjacent welds can merge their affected areas, risking incomplete fusion, distortion, and reduced structural performance. A conservative separation keeps each weld's heat-affected zone distinct, preserves the effective throat of each weld, and maintains a reliable shear transfer along the joint.

That’s why the minimum center-to-center transverse spacing is four times the slot width. The centers are measured along the direction perpendicular to the slot length, from one weld centerline to the next.

So, the minimum spacing should be four times the slot width.