BH92 Welding at cylinders falling apart

[Ackman]

Anyone know of a thread that addresses the terrible weld quality on my 2018 BH92? The amount of oxidation is completely ridiculous compared to everywhere else on my tractor. Granted I live in heavy salt air but I don't see any degradation that compares to this.

 

[GreensvilleJay]

The weld is great, it's the grade of steel of the 'port adapter' or whatever they call the piece

 

[NvRudder]

Anyone know of a thread that addresses the terrible weld quality on my 2018 BH92? The amount of oxidation is completely ridiculous compared to everywhere else on my tractor. Granted I live in heavy salt air but I don't see any degradation that compares to this.
View attachment 78413

Remove the hose, remove the 90 degree fitting, install flush-type pipe plug.
Grind/file/sand to remove the corrosion...primer & paint (multiple coats) so the welded port is protected from the elements...
Reinstall fitting and hose...good to go!

 

[Vlach7]

Wire brush and orange paint, save what you can.

 

[fried1765]

Wire brush and orange paint, save what you can.

OSPHO.... BEFORE..... repainting!

 

[mcmxi]

Anyone know of a thread that addresses the terrible weld quality on my 2018 BH92? The amount of oxidation is completely ridiculous compared to everywhere else on my tractor. Granted I live in heavy salt air but I don't see any degradation that compares to this.
View attachment 78413

Looks like a classic case of a galvanic couple. The bung might be a standard 10XX (mild) series steel and the elbow looks like it's stainless steel. As was mentioned, nothing wrong with the weld.

 

[GreensvilleJay]

yup... basic battery.... 2 disimilar metals(ss + Fe) and electroyte (salt water)

 

[Ackman]

Thank you all for the help. Hopeful - but not optimistic- I can get the elbows replaced without removing the rest of the crumbling welds.
I visited a buddy who has a 30 year old Woods backhoe. His welds and fittings are pristine- paint is faded but not a drop of rust or corrosion anywhere. Arrrgh!

 

[Mark_BX25D]

Thank you all for the help. Hopeful - but not optimistic- I can get the elbows replaced without removing the rest of the crumbling welds.

When are you going to post a picture of these "crumbling welds"?

I'm sure we'd all like to see them.

 

[lugbolt]

Thank you all for the help. Hopeful - but not optimistic- I can get the elbows replaced without removing the rest of the crumbling welds.
I visited a buddy who has a 30 year old Woods backhoe. His welds and fittings are pristine- paint is faded but not a drop of rust or corrosion anywhere. Arrrgh!

Never seen it on Kubota either. Makes me wonder a lot of things.

I had a bachoe show up in a crate once, salesman said put it on a tractor. Upon uncrating, a big word written in indelible pen across the side of the boom, "POROUSITY", with an arrow pointing to the main weldment. I reckon that one got out of the factory.

 

[fried1765]

When are you going to post a picture of these "crumbling welds"?

I'm sure we'd all like to see them.

Agreed!
There are NO "crumbling welds" in the picture posted!

 

[lynnmor]

Kubota gets cylinders from several suppliers, perhaps this one came from China, or maybe its just a piece of cheap Chinese steel.

 

[Vlach7]

My L47 has pipe wrap tape on every hydraulic fitting going into the rams, not one bit of rust, helps that I live in the driest place on earth, wonder if that helps keeping the different metals from touching for electrolysis?

 

[mcmxi]

yup... basic battery.... 2 disimilar metals(ss + Fe) and electroyte (salt water)

I'm going to be picky here because I had a career replacing zinc plates on vessels as a diver/welder and a career in a corrosion lab as a research engineer. This is a galvanic couple with direct contact between the bung and elbow with the bung acting as a sacrificial anode. A battery stores energy and there's no storage of energy in this case so it's not a basic battery.

Zinc plates on steel hulls of ships work in the same way. The couple is immersed in a salt solution in the case of ocean going vessels, and the zinc plates are consumed preferentially to the steel hence the term sacrificial. In both cases, the active metal drives the potential of the more noble metal above it's pitting potential thereby protecting it.

By the way, the noble metal in the couple drives the potential of the less noble metal below it's pitting potential. This is why many water utilities select specific alloys to hook up to your homes water supply. They have no problem with your pipes and fittings being sacrificed, but have no intention of there's doing the same.

 

[mcmxi]

My L47 has pipe wrap tape on every hydraulic fitting going into the rams, not one bit of rust, helps that I live in the driest place on earth, wonder if that helps keeping the different metals from touching for electrolysis?

Your environment is the reason, not the PTFE.

If this were my piece of equipment I would clean off as much loose rust as possible, treat with Ospho like @fried1765 suggested, and paint the bung with a good quality paint (enamel or similar) and allow the paint to extend up onto the elbow a little to "seal" the interface between the elbow and bung. The OP could get many happy and trouble free years of service using that approach.

 

[Henro]

I'm going to be picky here because I had a career replacing zinc plates on vessels as a diver/welder and a career in a corrosion lab as a research engineer. This is a galvanic couple with direct contact between the bung and elbow with the bung acting as a sacrificial anode. A battery stores energy and there's no storage of energy in this case so it's not a basic battery.

Zinc plates on steel hulls of ships work in the same way. The couple is immersed in a salt solution in the case of ocean going vessels, and the zinc plates are consumed preferentially to the steel hence the term sacrificial. In both cases, the active metal drives the potential of the more noble metal above it's pitting potential thereby protecting it.

By the way, the noble metal in the couple drives the potential of the less noble metal below it's pitting potential. This is why many water utilities select specific alloys to hook up to your homes water supply. They have no problem with your pipes and fittings being sacrificed, but have no intention of there's doing the same.

Just a simple question, but don't you need a conductive liquid of some type for the galvanic action to take place?

If so, would the poor performance of the paint be the root issue, since had the paint remained intact, there would be no path for a galvanic loop? Unless the paint was conductive I suppose...

Just asking, because I remember being in a meeting (couple decades ago) with various disciplines, talking before the meeting started, and galvanic corrosion came up, and being electrical, I asked the metallurgist why brass valve fittings can be used with black iron pipe (or something similar) and he simply said, there is no liquid involved...(I remember the part about the liquid, forget the other details actually).

In the example with the ship, the seawater is the liquid. With the OP's tractor, I guess it would be rain, or excessive washing of the tractor...the tractor does look pretty clean! LOL

 

[mcmxi]

Just a simple question, but don't you need a conductive liquid of some type for the galvanic action to take place?

If so, would the poor performance of the paint be the root issue, since had the paint remained intact, there would be no path for a galvanic loop? Unless the paint was conductive I suppose...

You do, and the OP mentioned living in an environment with lots of chlorides so he must be near the ocean.

I would say that the root cause is the choice of materials, since with better materials the failure of the paint is only cosmetic and won't cause functionality issues. That said, the paint definitely failed, and one of the problems with sacrificial anodes is that they are very much surface area dependent. Tiny voids in the paint can lead to much higher corrosion rates at those voids leading to significant pitting. You can imagine that this is a major concern for painted fuel tanks.

 

[fried1765]

Just a simple question, but don't you need a conductive liquid of some type for the galvanic action to take place?

If so, would the poor performance of the paint be the root issue, since had the paint remained intact, there would be no path for a galvanic loop? Unless the paint was conductive I suppose...

Just asking, because I remember being in a meeting (couple decades ago) with various disciplines, talking before the meeting started, and galvanic corrosion came up, and being electrical, I asked the metallurgist why brass valve fittings can be used with black iron pipe (or something similar) and he simply said, there is no liquid involved...(I remember the part about the liquid, forget the other details actually).

In the example with the ship, the seawater is the liquid. With the OP's tractor, I guess it would be rain, or excessive washing of the tractor...the tractor does look pretty clean! LOL

Similar issue occurs with electrical terminals when using (dissimilar) aluminum wire.
Absolutely no liquid is present, but without NOALOX treatment, the aluminum wire (dissimilar metal) will corrode, until it becomes disconnected, often causing a fire.

 

[mcmxi]

Similar issue occurs with electrical terminals when using (dissimilar) aluminum wire.
Absolutely no liquid is present, but without NOALOX treatment, the aluminum wire (dissimilar metal) will corrode, until it becomes disconnected, often causing a fire.

Being a bit picky again, it might appear that no liquid or electrolyte is present, but there has to be in order for corrosion to occur. High humidity (in excess of 70% R.H.) combined with sulfates and/or chlorides from outgassing from the battery, the enviroment etc., form the necessary electrolyte, even if not obvious. In order for electrons to move, ions have to be present in an electrolyte.

 

[fried1765]

Being a bit picky again, it might appear that no liquid or electrolyte is present, but there has to be in order for corrosion to occur. High humidity (in excess of 70% R.H.) combined with sulfates and/or chlorides from outgassing from the battery, the enviroment etc., form the necessary electrolyte, even if not obvious. In order for electrons to move, ions have to be present in an electrolyte.

"picky"?
I have never found any moisture in household electrical boxes, or main service entrance, but over the years many houses have been consumed by fire, determined to be caused by the aluminum/dissimilar metal corrosion issue.