ESCO Jack Stand Welds

Originally Posted by Darwin1138
Originally Posted by eljefino

Those bottom rungs "should" just be stiffeners under light load-- yes the legs will want to "split" away from center but they have solid welds up top with lots of contact. Still, I'm not a jack stand engineer, and can't recommend someone go against their better instincts and potentially compromise their safety.


The force that those stiffeners are resisting is:

F=(W/3)*Tanα*Cos30°

Where W is the weight applied to the jack and α is the angle between the leg and the vertical, which judging by the photo appears to be 30°

For a load of 6000 lbs that force is 1000 lbs Which i don't think is a small enough force to be dismissed like many here are suggesting, and I wouldn't trust that weld from the third photo to hold it.

Now, certainly you could make a jack stand without those components or even remove them just for kicks. In that case the force trying to rip apart the leg from the central support, or the force that the welds from the last photo will be resisting is:

F=(W/3)*Tanα

Which for our load of 6000 lbs is 1155 lbs

Are those welds strong enough to resist that kind of force?

Maybe, but even if the stand could work without problems without the cross members, I don't think they should be treated as "aesthetic enhancers" but as an integral part of the design.

In short, yes, those welds are wrong.



I don't believe you math is all-inclusive.

Those crappy welds are not holding 1000# max. I argue that the vertical welds are withstanding nearly 100% of the load, whereas the crappy welds are only there to stabilize the jack in place.

Also, based on the picture, the legs are square sections, which are incredibly rigid and have a very high bending modulus, meaning they're probably nearly as resistant to bending as the vertical welds themselves. Within the constraints of the load rating, I doubt those vertical welds nor legs will bend enough perceptibly, again meaning that the stabilizers (with crappy welds) won't see any strain due to the load, unless the load is cocked and the jack is wanting to twist.

I'm a nuke, NOT a structural engineer. This is all based on the limited welding and fab work I did out at sea as a NOVICE, as well as stuff I learned in the few structural classes I took in college.

To answer the original question the welds look awful.

The only suggestion I can offer would be to have the welds tested/inspected by a materials testing laboratory, which I estimate would cost $200 or so.

Or they could put the jack stand in a concrete cylinder testing machine and see if it would hold 6000#

I returned those esco stands and got these OTC 6 Ton. Less expensive and more robust. This little bit of material missing and some subpar welds, but I guess they all do at this point.

I'm not a welding expert, not sure how many on here are.

My understanding is that welding has two fundamental elements (surely many more, but these are the key ones pertinent here, IMO - credentialed welding experts please clarify if I'm wrong):

1) Welding melts the materials into each other, effectively resulting in one consistent material at the end. Phases and grain structure may change due to the heat, but it is in fact one consistent, integrated material.

2) Welding is contingent upon the materials to be welded together, but also a third material used to add to the joint, and form a "pool" of this material, which may actually be stronger or more important than the two materials being welded.

So all that said, I'm not sure that the welds are that bad, with a few exceptions.

Not bad because:
1) excess material being there is not a bad thing, and may be a good thing.

2) given that overlapping welded surfaces should undergo fusion to one another, and then the pool of additional material further strengthens the joint, the undercut of the cross pieces may be on purpose, to allow the creation of a pool.

Concerning because:
1) I see some pores in the finished product which I'm not qualified to know if these may be an indication of something worse underneath. They may or may not be a concern so I have to assume the worst for a safety item).

2) while the undercut of the cross pieces aren't a concern in and of themselves, the short length and lack of a full pool indicates that there may be a compromise of ultimate strength. Whether or not that ultimate strength is relevant here relative to the rated weight and application is TBD, as is the question of if these parts would ever get stressed to a level near even their current capability.

My suspicion is that these would be rated as sufficiently strong to hold the full weight with just the three legs. The combination of weld strength to the vertical central body (which looks ok minus that porous spot), and friction between the large round base pads and the surface underneath, would suffice. The other crossmembers simply add a margin of safety and some level of force transfer on uneven surface or twist condition. Think car sway bar. If disconnected, things aren't ideal but still ok... but stop using and fix or replace at the first opportunity.

Originally Posted by OCDoiler
I returned those esco stands and got these OTC 6 Ton. Less expensive and more robust. This little bit of material missing and some subpar welds, but I guess they all do at this point.


I'm still not clear that "subpar" welds actually have an objective standard of strength and more importantly, engineering reserve of strength (i.e. your 6000 lb stand is actually rated for 8000 or 10000 lbs each).

Also, with these you're trading pretty robust bar stock for folded (heavy) sheet metal that isn't welded that I can tell, at the butt joint. Yes the all in one folded design ensures that the cross members are truly all one piece with sufficient strength, but you still have one unfolding point, and less material in the base design.

Don't get me wrong, I have a set of USA made OTC stands that I really like. But it's not clear to me that one is truly better than another.

I'm with you on not being 100% clear regarding those welds. The OTC's I bought are welded on the inside. What's your thought on that missing bit of material around the circular area? Thanks