Hey engineers! Need some help finding a repair part.

WARRIORWELDING

WARRIORWELDING

Owner opperator Of WarriorWelding LLC.
Joined
Jan 6, 2008
Location
Chillin, Hwy 64 Mocksville NC
Fiberglass tank. Has epoxied threaded bungs. Threads are crossed up and damaged by very corroded fittings removed.
I have used some sort of double flanged fitting with gaskets in the past. I can't seem to source what i need. Willing to use parts in a non traditional way if a combination applies.
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Ideally the flange would allow bolts outside the removed unit. A inner backing flat flange. Gaskets for both sides. And one have a 2 inch FPT and another unit for 2.5 FPT.

We have some room to bush if a larger pipe flange is required to get into clean tank wall to drill.
Tank is fiberglass approximately 1/4 thick.
 
I have done this repair before many years ago but i don't know what I was supplied.

Edit. These are supply and one recirculation line. Not a pressurized situation or a place dead head pressure would be applied.
 
 
Lankford said:
Would a bulkhead fitting work?

Similar to this?

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I have seen and repaired those. One this year. They tend to not stay tight for the intended use. The flanges are also very narrow making a seal harder to attain on the very rough fiber glass inside the tanks. The one side is fed by a JIC flexible hose and tends to surge and vibrate. Isolating this line would cause damage from chassis flex and the tanks in this fashion do not tolerate hard plumbing or victolic fittings for the same reason and added weight.
 
braxton357 said:
It's a banjo bulkhead fitting, they make several styles. I might have some 4" ones laying around
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If its like what is posted below they usually fail.
 
Could you weld stainless studs into a 150lb stainless flange, drill 4 holes through the tank, install flange with studs from inside with a threaded flange on the outside? Sandwich gaskets inside and out?
 
What liquid, my main concern with a bulkead fitting is liquid being contained/ seal material compatibility.

You could also get a bondo brand fiberglass repair kit at auto parts or Lowe’s it’s just a ratio of a and b mixed if you want to glass in a new fitting it’s not that hard and sets up overnight.

If there’s enough thread and the liquid is petroleum based or water you can chase the threads with a tap and reinstall with permatex #2 sealant it will set up hard at the surface but remain soft where it gets no air
 
Shreddinlettuce said:
What liquid, my main concern with a bulkead fitting is liquid being contained/ seal material compatibility.

You could also get a bondo brand fiberglass repair kit at auto parts or Lowe’s it’s just a ratio of a and b mixed if you want to glass in a new fitting it’s not that hard and sets up overnight.

If there’s enough thread and the liquid is petroleum based or water you can chase the threads with a tap and reinstall with permatex #2 sealant it will set up hard at the surface but remain soft where it gets no air
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Water...lots.
 
awheelterd said:
Could you weld stainless studs into a 150lb stainless flange, drill 4 holes through the tank, install flange with studs from inside with a threaded flange on the outside? Sandwich gaskets inside and out?
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This is along the lines of what I used many moons ago. It was high density plastic though and off the shelf. Gonna look hard at some generic flanges and gaskets tomorrow.
 
WARRIORWELDING said:
If its like what is posted below they usually fail.
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That's why I said banjo brand, the ones you get from the farm store aren't nearly as good.

Banjo 3" FNPT Bolted Bulkhead Tank Flange BF300 | Zoro Banjo 3" FNPT Bolted Bulkhead Tank Flange BF300 | Zoro

Idk what size you need but they also sell different bolt through fittings like that as well.
I have done exactly what you're talking about--an npt bulkhead through a fiberglass tank--many times. I always rough up, fiberglass and epoxy over them too. If the threads are getting messed up from screwing things in and out they need to switch to a camlock or some other way of connecting hoses or you need a stainless BH
 
braxton357 said:
That's why I said banjo brand, the ones you get from the farm store aren't nearly as good.

Banjo 3" FNPT Bolted Bulkhead Tank Flange BF300 | Zoro Banjo 3" FNPT Bolted Bulkhead Tank Flange BF300 | Zoro

Idk what size you need but they also sell different bolt through fittings like that as well.
I have done exactly what you're talking about--an npt bulkhead through a fiberglass tank--many times. I always rough up, fiberglass and epoxy over them too. If the threads are getting messed up from screwing things in and out they need to switch to a camlock or some other way of connecting hoses or you need a stainless BH
Click to expand...
Much better fitting. The bolt diameter may not get us into clear fiberglass as far as I would like. I have contacted two of our poly tank suppliers. One engineer refused to make us something custom 😆.

The other said sure! As for on and off its a fire truck. One fitting chewed up the thread because it was ate up like the Titanic. The other is stupid access and "others" ruining the thread by several attempts to repair.
 
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