JJAV1983:
That looks like a side boom for a pipe laying tractor to me. Ah…, now you tell us, you seem to indicate that it might be a piece of oil field equip. or some such, a boom, to be mounted on the back of a straight , flat bed, work truck for Geotech. drilling operations. It always flabbergasts me that people assume that there should be an exact/specific std. for every imagined design concept or piece of equip. I suspect that some significant percentage of these booms have been designed and built in contractors shop yards, maintenance or machine shops. I’m sure there are some of these booms commercially available. I would look around and see how they are generally designed and built. I would look at some boom stds., and the like for some guidance, along with our regular structural steel and welding stds. Do have a few good textbooks on Engineering Mechanics, Strength of Materials, Welding Design, and Machine Design on hand. And with that, I would be perfectly comfortable using first principles and just plane good engineering design, detailing and welding design and detailing to build something like this. Good clean detailing, welding and fabricating are just as important as some std. preset allowable stress/strength, give or take a few percent and some reasonable safety factors. You have to set your load limits, conditions of use, lifting arrangements, etc., based on the base truck, the boom mech. equip., and your field conditions, otherwise, those are really quite variable.