Expansion pipe Plumbing Fitting

[GoK4rtFanatic]

Hello, I was wondering if anyone could give me any insight on how I might go about welding a plumbing fitting to 16 gauge mild steel sheet metal. For reasons later on, I cannot use galvanized or stainless fittings. I could use aluminum or copper, but I was wondering how I should go about this. Can copper be joined to steel without brazing. Do they sell uncoated, non-galvanized, non-stainless steel plumbing fittings? If so I haven’t found any (obviously they would rust). I feel as if I’m asking about something that obviously doesn’t exist but I figured I may as well.

[mla2ofus]

Can you use common black pipe fitting? Just grind the surface on the fitting to be welded. You'll have to wash the weld from the heavier fitting to the 16 ga.

[scsmith42]

I would consider welding a threaded bung to the sheet metal, and then screwing the fitting into it. That way the fitting can be replaced if need be.

[Meltedmetal]

You haven't said what you are planning but there are steel fittings available or you could weld a black pipe nipple into a washer and weld or bolt the washer to the 16 ga. Or use bulkhead fittings.
https://www.fastenal.com/product/plu...FamilyId=25335
https://www.amazon.ca/Bulkhead-Fitti...756298&sr=8-15

[Willie B]

For many years I soldered galvanized fittings in place. No reason you couldn't solder brass, stainless, copper. Absolutely not OK for pressure application.
Second choice is buying a weld in bung.
I TIG stainless fittings.
Black iron welds easily.

Plumbing supply I deal with no longer carries galvanized fittings, I can't say why. Lead content is a concern, but lots of piping isn't for potable water. They've substituted stainless.
Black has traditionally been used for boiler work.

[albrightree]

The wording of question makes my mind melt down. The most important parts of the question are missing. "Plumbing fittings" is such a huge question mark ( Unions, couplers, nipples, valves, tees, elbows bungs bulkhead fittings etc, etc..) Can't use stainless or galvy , but alumimum, and copper is OK ?
What Temp. that the device will be subjected to ?
What Material the that the device will be exposed to (gas, water, oil, exhaust) ?
What Pressure it will be exposed to ?
Will the sheet metal be flat, curved, of formed ?

Your title mentions expansion pipe, and your handle is "GoK4rtFanatic" so I'm gonna stop trying to figure out the above mentioned, convoluted matrix above and ask. Are you making some sort of expansion chamber for a small motor ? I think some people might have done a few of these before.

I can think of over a hundred ways to answer the above question, but most probably won't work for what you doing. Soldering, brazing, welding, and mechanical bulk head fittings are all options, but are dependent on knowing the whole picture. Its an interesting riddle right now.

Thanks for sharing, pictures are always good too.

[GoK4rtFanatic]

Sorry for my illiterate babble in the original post. I have no idea what I’m looking for. I need a pipe fitting (no idea what the name would be) that is essentially other threaded conduit tubing that could connect to a small internally threaded brass fitting (around a 1/4 inch diameter). I say I cannot use galvanized or stainless. The truth is, and yes it sounds dumb, but I am slightly (ok, very) neurotic about the fumes released. Yes I realize no welding fumes are good, however I try to keep the ZnO and Cr6 out of the way. That being said I have no clue what fumes copper or aluminum bring to the table. That is why I pose the question. Are plain iron/ plain steel plumbing fittings (of any kind) sold? Logically it wouldn’t make sense as they would rust, but I figured I may as well ask. I figured my backup could be to de-galvanize a fitting with concentrated vinegar or muriatic acid. I would then take said fitting (whatever type that may be) and weld it over a hole drilled in one of the [two] sheet metal pieces. I would then tig weld the two pieces (of identical shaped sheet metal) on the sides, connect the plumbing fitting to my pressure washer and expand it into shape. I know it sounds very picky but I’m rolling with it.

I cannot add any pictures as there is nothing to see (unless you want boring math equations that may not be correct)
Yes I know I could probably find a pipe online, that is not the purpose of this project
Obviously welding between metals such as copper and steel (if it were to be done) would be done via tig brazing.

[albrightree]

No worries, sometimes its hard to figure out what someone else is thinking from a couple of paragraphs of writing. These fittings could be the helpful, or something similar. These are similar to the ones meltedmetal posted above.

https://www.mcmaster.com/weld-bungs/

Straight Adapters with Extension for Flat Tanks



Straight Adapters for curved Tanks



The ones Meltedmetal posted from fastenal are also listed in Mcmaster, and are much higher pressure, but you will need to find the right adaptor for attaching to a power washer.

Just be aware that after welding fittings , you may need to chase the threads, as some warpage may occur..

Best of luck with your endeavor

[psacustomcreations]

To the OP, why don't you just say you are hydroforming with a pressure washer?
There are plenty of YouTube videos showing the process. Plus plenty of pictures online.
Here is a video from Colin Furze:


Plus some pics



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[GoK4rtFanatic]

Yeah good point. I suppose I wasn’t sure how general of a term it was. I watched that video and that’s what inspired me to build mine. I’ll add pictures once all set up. May take awhile.

[scsmith42]

Now that we know what you're doing we can give some better advice.

First off - stay away from plumbing fittings unless your life insurance is paid up. Typicaly black pipe fitting are not rated for the high pressure put out by a pressure washer. What you need are fittings for hydraulic systems, since they are high pressure.

Second - forget copper or aluminum, as they will be difficult to source and weld.

You don't need stainless either. Simply a high pressure steel fitting, such as these from McMaster. They can be MIG, TIG, or Oxy-acetylene brazed. Stick might be difficult due to the thin nature of the sheet metal.

https://www.mcmaster.com/bungs/high-...pipe-fittings/

I would have no qualms welding these to mild steel for the hydraulic forming purpose. If you're concerned, wear a respirator under your hood.

[GoK4rtFanatic]

So those would work great if they were externally threaded. I should have mentioned this. So I need to find externally threaded weld on bungs? The picture above (from the Colinfurze video) will show what the bung would thread in to.

[whtbaron]

I wouldn't get too worried about black pipe or plumber's fittings at pressures around 3,000 psi. Shortline ag manufacturers use them all the time on tractor hydraulics and they hold up just fine. Put about 30 yrs on a stonepicker with black pipe fittings and the only failure is when something ( like a big old rock) strikes them hard enough to damage them. Ditto for loader buckets, some disks, cultivators.... I'm sure we've had this discussion on another thread before. If you're worried about ending up with 2 female ends, run a short nipple between them.

[farmersammm]

I use "plumbing" fittings that are rated at around 3,000psi. The brown steel ones from the oil field supply. Same with ball valves, 3,000psi. The price really isn't much more. But being in the oil patch, they're probably more readily available than elsewhere.

A very interesting factoid..................A good number of hydraulic fittings (swivels, reducers, adapters) are made from 12L14 due to its excellent machinability.

[GoK4rtFanatic]

Great point about the two female ends, don’t know why that hadn’t crossed my mind. As for the pressure rating, I’d be much more worried about my weld breaking (kidding). I’ll get back (with more questions) after I purchase my dirt cheap pressure washer.

[CAVEMANN]

One thing to consider with hydraulic fittings is CADMIUM, they will probably be electroplated & it's not nice stuff, it's pretty easy to clean off with some muriatic acid, be prepared for flash rust.

[GoK4rtFanatic]

Thought cadmium was cycled out, no? I heard that’s some of the nastiest stuff to weld. I’ll try to avoid those.

[GoK4rtFanatic]

Can anyone identify this fitting? This is what runs off both sides of the high pressure hose.

[leightrepairs]

You need to measure the thread but it probably connects to this- https://www.homedepot.com/p/Powercar...1085/203353091

[GoK4rtFanatic]

Can anyone tell me the threads per inch on this fitting?

https://www.homedepot.com/p/Powercar...1087/203353080

[albrightree]

M22 threads per inch ?

Maybe this will help : https://www.mcmaster.com/standard-pipe-fittings/ and click on "How to Identify and Measure Fittings"

I think you weld a 3/8" bung on, and use the fitting that leightrepair listed from home depot so you can attach the gun end of the hose to thing your hydro forming.

[GoK4rtFanatic]

Sorry, finally got to measuring the fitting it is an m22 fitting with 1.5mm pitch. I am looking on McMaster carr but they are $4.25 a piece. I’m not unwilling to pay that much, however I was hoping to see if anyone would know of a store that might sell these as HD does not. A plumbing store might, however I do not know how to rig weld well enough to braze bronze or copper pieces.

[Welder Dave]

$4.25 is a good price for a odd ball fitting that would otherwise be hard to find. If Home Depot had them they would be double the price. That said, Home Depot is the last place to look for odd ball fittings. Still need be extra careful as there is a lot of pressure involved.

[psacustomcreations]

Sorry, finally got to measuring the fitting it is an m22 fitting with 1.5mm pitch. I am looking on McMaster carr but they are $4.25 a piece. I’m not unwilling to pay that much, however I was hoping to see if anyone would know of a store that might sell these as HD does not. A plumbing store might, however I do not know how to rig weld well enough to braze bronze or copper pieces.

Have you tried a Tractor Supply or Northern Tool store?
Northern in particular carries a lot of pressure washer parts.
$4.50 is cheap and at this point, what is your time worth?
You may save $0.30 at another location.

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[GoK4rtFanatic]

Okay fittings come thursday, but for now, I have cut the sheet metal into the exhaust shape. I can provide exact dimensions with a drawing if necessary but am beginning to have doubts about the pressure needed. I have the two sheets cut (congruent) out of roughly 1.5 mm plate (technically 0.065”). What I’m now questioning is will this 1600 psi washer I have be enough to expand this. I suppose there isn’t a straightforward answer so I’ll test it and post my results.