Front-Back Cleats versus Side Cleats

[schulzr]

I know this might be dumb q, but why wouldn't the end front to aft cleats also sit on top of base to top cleats, especially if ends are as long as side?

Sorry if it sounds confusing, (but I know what I'm trying to say!!!)

I'm assuming it's for structural stability, but I wanted to hear specifics from someone else.

[Admin]

Hi Schulzr - welcome to the forums!

I assume your question concerns light-duty containers such as D6251/601s.

The cleating arrangement on this type of container allows for similar strength from any angle but specifically, when set upright, it adds to the stacking strength. If all the upper cleats on the sides and ends went the full length of the panel, you can have a structural deficiency in the area between the bottom edge of those upper horizontal cleats and top edges of the cleats directly underneath them. Consider that by the standards, relatively thin panelboard is allowable and if used in this type of construction, you have a greater chance of structural failure if a heavy load is placed on top of the container. In theory, the sides and ends would buckle outward. This scenario generally assumes the load placed on top of the container is of the same length and width as your container.

Also, conceptually the container has similar strength from any angle. If the container were rolled (or bounced) across the floor, no panel is weaker than any other.

All that being said, the strength of this style is dependent on many conditions and there are many companies that build small containers using load bearing corners (the construction style you are questioning) rather than interlocking corners (as the specs suggest). An alternate argument is that load bearing corners are stronger because if, for example you use interlocking corners and your container is 8' front-to-aft and someone places a 2' front-to-aft, 1000# container dead center on top of yours, your upper end cleats are not supported by your vertical end cleats.

In the end, everything should be considered: panelboard thickness, overall size, weight, load type and all transportation conditions including things like container heights.

[schulzr]

This makes sense......thank you......

[schulzr]

Another question regarding D6251, it says that strapping is required when skids are used. I couldn't find where it talks about placement of strapping.

I'm assuming based on diagrams I've seen that two are placed outside of and parallel with each runner over the cleats. The notch requirement is for running a strap across the other (perpindicular) way?

[Admin]

Without reviewing the spec, I think it's implied that strapping should run around the sides rather than the ends.

There are different thoughts here as well... The strapping should not go under the skids, but should only go around the body of the container. Doing it that way though, a forklift fork could get caught in the strapping and break it or damage the container so some people will cut a strapping notch at the bottom front and back of the skids and wrap the strapping around the whole thing. This also has a downside though. First, it is more labor intensive and if a crate get pushed sideways, it could get caught on something such as the edge of a dock leveler and, again, cause damage.

Unless specified in an RFQ or for a government job, strapping is rarely used on these smaller containers and was intended to allow for a reusable top. This concept was conceived before some of the newer alternate fasteners were invented so often times, these alternate fasteners are used instead.

[schulzr]

I never thought to put them under the skids....occasionally we "band" around the body of box between the skids. I've been encouraging my guys to put them towards the outside of the skids, and was wondering if it specified to do so in the spec. (When I tell my guys to do something a certain way, I like to say the spec says to do so). Sometimes the runners on boxes we reuse have the skids all the way to the sides so you have to band inbetween.

I probably should have started my thread by stating that I have been supervising a shipping department for an aerospace company for about 2 years and although most of our requirements are "commercial" packing, I want our guys to get in the practice of packing, crating, etc to ASTM or Mil Spec methods unless of course it impacts cost significantly.