Vansledge,
Since you didn't reference a code, the Farm Code would be the most logical choice.
Otherwise, here's what AWS D1.1 Structural Welding Code - Steel says about weld spacing...
4.12 Built-Up Members
4.12.1 Minimum Required Welding. If two or more plates or rolled shapes are used to build up a member, sufficient welding (fillet, plug, or slot type) shall be provided to make the parts act in unison but not less than that which may be required to transmit the calculated stress between the parts joined.
4.12.2 Maximum Spacing of Intermittent Welds
4.12.2.1 General. Except as may be provided by 4.12.2.2 or 4.12.2.3, the maximum longitudinal spacing of intermittent welds connecting a plate component to other components shall not exceed 24 times the thickness of the thinner plate nor exceed 12 in [300 mm]. The longitudinal spacing between intermittent fillet welds connecting two or more rolled shapes shall not exceed 24 in [600 mm].
4.12.2.2 Compression Members. In built-up compression members, except as provided in 4.12.2.3, the longitudinal spacing of intermittent fillet weld segments along the edges of an outside plate component to other components shall not exceed 12 in [300 mm] nor the plate thickness times 0.730 ✓E/Fy (Fy = specified minimum yield strength and E is Young's modulus of elasticity for the type of steel being used.) When intermittent fillet weld segments are staggered along opposite edges of outside plate components narrower than the width provided by the next sentence, the spacing shall not exceed 18 in [460 mm] nor the plate thickness times 1.10 ✓E/Fy. The unsupported width of web, cover plate, or diaphragm plates, between adjacent lines of welds, not exceed the plate thickness times 1.46 ✓E/Fy. When unsupported transverse spacing exceeds this limit, but a portion of its width no greater than 1.46 ✓E/Fy times the thickness would satisfy the stress requirement, the member shall be considered acceptable .
4.12.2.3 Unpainted Weathering Steel. For members of unpainted weathering steel exposed to atmospheric corrosion, if intermittent fillet welds are used, the spacing shall not exceed 14 times the thickness of the thinner plate nor 7 in [180 mm].