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  #31  
Old 08-09-2018, 11:31 PM
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arizonian arizonian is offline
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Now I understand what you refer to as a cover plate.

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From what I understand, the compression side is less prone to failure than the tension side, so a guy could get away with a plate on the tension side.
Not quite. You ever tried to push a chain? It will buckle before you get very far, and in compression, you are fighting buckling. That same chain will take a hell of a lot of tension. Adding a cover plate on the tension side will move the neutral axis and help both sides, but best case is to add it on both sides and increase the cross sectional area and moment of inertia.
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  #32  
Old 08-10-2018, 09:47 AM
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Quote:
Originally Posted by Farmersamm View Post
Hell, I dunno……..I might be calling it the wrong thing.

To me, a cover plate is reinforcement of the flange by adding an additional plate top/bottom if possible, OR limiting it to the tension side of the flange if you can't get to the compression side.....or if you feel reinforcing the compression side is unwarranted. The idea being to reduce deflection, and hopefully add some carrying capacity.

From what I understand, the compression side is less prone to failure than the tension side, so a guy could get away with a plate on the tension side.

I'm sure it's a poor mans way to keep from deepening the web, and probably not the best bang for the buck if you're a purist.

From what I'd read, and hopefully understood, I decided to take the concept one step further. I added a simple strip of 3/16 flat to the tension side of the column on the rack. This just about doubled the thickness of that flange. Thinking was to resist the cantilevered load on the opposite side of the channel. It worked.

strips are hard to see in the pic, so I highlighted them in this pic.

Another way I've used them is reinforcing a bend in a beam. The bend was made by cutting a wedge out of the channel flanges, and welding the area together once the bend had been made. Same concept, thicken the flanges to offset any problems that might have been caused by splicing the flanges.

What I call a cover plate at a connection, might not, like I said, actually be a cover plate. This is illustrated in pic #3.

Thinking on this one...…..I want to resist any tendency for the beam (the tubing) to pull out of its connection. The stress I anticipated was/is in the Y axis (up and down). So, I've reinforced the flange at this point, and carried that reinforcement back a ways into the tubing sitting at the right angle to the beam. I didn't run the plate clear to the back edge because I didn't want to get too far from the neutral axis when welding...….it causes the metal to pull. Keeping your welds in the neutral axis goes a long way towards keeping the metal straight.

Anyways, I guess that's Okie engineering
Commonly I hear them called, fish plates, reinforcement, or fillet plate. But never had them called cover plates.

Cannot really see what you have in the first photo, except a nice looking dog.

Picture 2 I like the way you did the side plate, but would suggest that you
grind a radius at the 'pointy' ends. I generally try to cut mine at +/- 30°
from the center line unless you don't have room for it. On the top and
bottom plates looks like the end are cut at 90° to the long axis. That is a
problem. 90° welds in the middle of a load bearing member is where the
cracks will form (note I said will) then only question is when. When I was
welding for money 30-40% of the repairs I did were from poor designs and
cracking from vertical weld on load bearing member. The top and bottom
plates are not really needed and likely are a detriment to the overall
strength.

If you are but welding 2 structure members and you have a bend in the
structure. the #2 pic looks like the front corner of a trailer, and you have to
weld vertical, that is not all that bad. You are welding at the end of the 2
pieces. The ends will flex and minimize the induced stresses from the weld.
The stresses are induced as the welds cool, creating a compressive force.
Again at the end of 2 pieces it is not as bid a concern. I like the side plate.

However, lot of people will weld a cross member to the side rail and have
vertical welds on it this will be a fatigue and failure point down the road as
the weld cools on the side rail the compressive force induce significant stress
and will initiate and propagate a crack and eventually failure of the side rail,
seen it a lot!

In your picture number 3 you are setting up a failure.
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  #33  
Old 08-10-2018, 09:53 AM
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Top Picture:

So if you have to weld in the middle of a load bearing member, weld a
horizontal plate with 2 horizontal welds, I generally try to make the plate
twice as long as the rail is high. Weld is on with 2 horizontal welds.

Then weld your cross member to plate. Vertical welds are fine here
because the compressive forces are isolated from the main plate.

Bottom picture is how I reinforce a 90° joint to avoid any welds that are
90° to the load bearing member.
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  #34  
Old 08-10-2018, 12:15 PM
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An orifice will fix your jerky problem. It's the load check in the valve unseating and reseating with build up and loss of pressure.
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  #35  
Old 08-10-2018, 04:53 PM
Farmersamm Farmersamm is offline
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Quote:
Originally Posted by Dr Dean View Post
An orifice will fix your jerky problem. It's the load check in the valve unseating and reseating with build up and loss of pressure.
I had some sort of theory about proportioning, and glad someone actually knows what's happening.

I spent the good part of the morning trying to locate a simple $5 restrictor coupling. Guys over in Tulsa didn't have a clue what it even was.

One guy finally calls me back, and tells me he's got a whole box of the things. Said nobody ever buys them, and they were on a back shelf.

Anyways...…..they're "blanks"....drill your own hole to size it as needed.

I was shocked I couldn't locate one locally. I've seen the things a good part of my life.


I mean...…..they're not rocket science. https://www.farmandfleet.com/product...4-57af6c7a4733

K'kins 'n me goin' on a road trip
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  #36  
Old 08-11-2018, 07:40 AM
Farmersamm Farmersamm is offline
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Originally Posted by arizonian View Post
Sam, if you are running any sort of calculations, limit the yield to half of 36 ksi (18 ksi). If that doesn't pass muster, increase the cross section, shorten the span, etc. until your calcs come out less than 18ksi.

If you have a resource pile like I'm sure you do, does it include any drops other than A36? A516 Gr70 has an ultimate tensile strength of 70 ksi and yield strength of 38 ksi.

A992 wide flange, which is as common as dirt any more, has an ultimate tensile of 65 ksi and a yield of 50 ksi.

A500 GrB tube has an ultimate tensile of 58 ksi and yield of 46 ksi. Remember, these values are the minimum needed to follow ASTM specs. If you have MTRs (not likely), the tested value of that lot is listed and can be several points higher.
Most recent A500 delivery to my guy was, according to the MTR, rated at Class B>C. This is what they normally buy he said. He's a good guy, and hunted up the MTR's.

Tubing I'm using is probably, some of it, 7yrs old, and weathered. Some serious pitting in places. I need to throw a roof over my racks Either that, or use stickers between the layers in the stacks to allow the moisture to evaporate instead of staying trapped between the pieces of steel.

Bought about 2 grand worth of steel just before XMas last year, and haven't picked it up yet. They hold it for me, which is cool. Least it's staying dry till I get around to picking it up. Anyway...…..this time around, the guy is a little upset about it He actually doesn't physically stack my stuff in a corner, it just comes out of inventory when I go in to get it. AND ALL THE STUFF I BOUGHT WAS PRE-TARIFF INVENTORY
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