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Need some “engineering” advice mid project

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Need some “engineering” advice mid project

Postby Josh MacD » Sat Feb 10, 2018 10:32 pm

I’m building a fire pit ring for the backyard out of 14 gauge steel. It’s two rings rolled so they can be the inner and outer circumference and a ‘donut’ for the top. I’ll add a gas fire element and some glass rock to the top.

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I have two questions
1: I tacked small sections as I worked the rolled pieces around the top ‘donut’. Do I need to go back and fill in the voids without welding? It will be outside but I’ll do a rust treatment and seal it. Nothing needs to be water right once I seal it. I just don’t know if it’s a structural or cosmetic issue.

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2: knowing that I’ll be doing a rust and seal treatment, do I need to do anything to deal with the blue tint and minimal scaling on the outside? I welded the inside.

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3: I plan to put feet on the inner ring and, for ventilation purposes, elevate it up 2” or so. Knowing that the weight of the rocks will be over the inner rings feet, is the outer ring heavy enough to sag and pull that too ‘donut’? It’s 17” tall and the ring is 7” wide with an OD of 37.5”. If it’s likely to sag up could add some inner bracing to ‘marry the two together’

Thanks in advance for all of the amazing input from this forum.
Hobbyist MIG welder with 75/25 gas on a Lincoln SP-140 in my garage/workshop/gym/storage space. Very new and still learning.

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Re: Need some “engineering” advice mid project

Postby Coldman » Sun Feb 11, 2018 5:42 am

Expansion and contraction due to heating and cooling could crack the tacks. If it wad me I’d be substantially welding it with filler


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Re: Need some “engineering” advice mid project

Postby tungstendipper » Sun Feb 11, 2018 8:24 am

I agree with Coldman. If your worried about sag, put some plates inside,vertical, above each foot, connecting the I.D. to the O.D.. I would worry someone would want to rest their feet on it and melt their shoes. It looks contemporary and I like it!

BTW....what are you going to use to seal it?
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Re: Need some “engineering” advice mid project

Postby Josh MacD » Sun Feb 11, 2018 9:29 am

Based on a recent post on another project I might use Flood Penetrol to seal it rather than my plan for rattle can. Does that sound like a good idea?

And I’ll definitely be reinforcing the tacks now. Maybe I can make th feet out of 1/4” angle iron and run it as a continuous length that rises from the ground, attaches to the ID for 3-4” down low then angles out and attaches to the OD up high. That could act like a truss and transfer weight directly to the feet.

Does the blue and scaling need attention? I struggled with settings and may have had things too hot while I welded
Hobbyist MIG welder with 75/25 gas on a Lincoln SP-140 in my garage/workshop/gym/storage space. Very new and still learning.

"Service is the rent you pay for room on this earth" - Shirley Chisholm
Josh MacD
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Posts: 23
Joined: Wed Apr 26, 2017 10:57 am
Location: Phoenix AZ


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