Onerous Grating Spec
Onerous Grating Spec
(OP)
We have a client who is requiring that the cross bar (you know the twisted bar on 4" centers) on bar grating not stick up above the bearing bar at all. My understanding is most vendors make this flush with + or - 1/16" tolerance. The client has been very specific that he won't accept grating that has cross bars that exceed plus zero on the height above the bearing bar. We got a sample from a vendor and sure enough the cross bar was about 1/16" (or so) above the bearing bar which didn't surprise me at all. Has anyone ever heard of such an onerous spec? How in the world are we going to find a vendor who takes this serious? Should it be taken seriously? IMO, we should have never accepted this condition but it's too late now.






RE: Onerous Grating Spec
RE: Onerous Grating Spec
RE: Onerous Grating Spec
RE: Onerous Grating Spec
RE: Onerous Grating Spec
Michael.
"Science adjusts its views based on what's observed. Faith is the denial of observation so that belief can be preserved." ~ Tim Minchin
RE: Onerous Grating Spec
You can turn the grating upside down, but the compression flange (side?) of the bars would be unbraced. This would need to be accounted for and you would not be able to use the load tables provided by the manufacturer.
RE: Onerous Grating Spec
Let's see what else was asked? Oh, not I don't know why they wrote the spec. this way. I suppose they feel it would be less likely to slip. I'm not saying I agree. I think serrated grating is too agressive as it is. I'm just postulating.
I spoke to one grating manufacturer and asked if they would be able to conform to this requirement. They said "no". Evidently its a highly automated process where they crank this stuff out like nobody's business and they aren't willing to guarantee the cross bar will never stick up above the bearing bar. I can't say that I blame them.
RE: Onerous Grating Spec
RE: Onerous Grating Spec
RE: Onerous Grating Spec
If they won't relent, fire-retardant FRP is an option. Anti-slip in this case is provided by means of glass granules embedded in a gel coat on the top surface- another dandy thing if you ever have to kneel on it or godforbid fall on it...
RE: Onerous Grating Spec
I don't think they can go back to the owner at this point and say what you have in the spec will cost extra. They own what they bought. If they didn't pay attention to the spec it's unfortunate, but they own it. It sounds like the contract was already awarded.
RE: Onerous Grating Spec
One approach would be to ask them if they know of any commercially-produced grating or of any grating company that meets their spec. IE, ask them if this product really exists, as you can't find it. If the answer is "no", then you start working on alternate materials.
Fegenbush- agree with your comment on the load design, it would depend on the details as to whether that would work, and might be difficult to show that it would work. On the plus side, grating is small enough, it wouldn't be too hard to load-test a piece and see.
RE: Onerous Grating Spec
RE: Onerous Grating Spec
But now for the good news. I have found a vendor who claims they can do it. It will cost a little extra, probably about 10%, because of the extra time and care they have to take. The proof will be in the pudding.
Moltenmetal, I agree with you about serrations. That's a nasty surface to kneel down on. I've taken my clipboard and put it on the grating then kneeled down on it in the past to avoid the pain.
RE: Onerous Grating Spec
RE: Onerous Grating Spec
Could you buy the less expensive grating, and have a machine shop mill the high spots off the top? Half of them may not need it, and some part of those that do need some machining won’t need the full 1/16th removed over the full surface.
RE: Onerous Grating Spec
Lion06, I wasn't sure if the OP was an engineer and it was early on in the project and they were going off an RFP spec, or a vendor provided an agreed-upon spec. In the latter instance, you're correct, they're stuck with providing what was specified.
RE: Onerous Grating Spec
Dik
RE: Onerous Grating Spec
RE: Onerous Grating Spec
RE: Onerous Grating Spec
RE: Onerous Grating Spec
I have an application where I was going to use grating upside down to support a sheet of stainless steel and then run a plastic modular conveyor belt on top. (I need a flat surface, and raised cross bars might be a problem.) But the grating manufacturer says that I cannot use bar grating upside down or it will crack at the cross bars because the welds aren't good enough to handle the tension. (they are only good in compression.) If that is true, then my proposal won't work and I'm running out of options.
RE: Onerous Grating Spec
moltenmetal - while I sympathize with bleeding knees, I'd rather bloody my knees than slip off an elevated platform and bounce down 65 treads on the way to the ground.
RE: Onerous Grating Spec