Valve Stem Protectors

[kuboman]

They put them on the industrial tires but not the ag tires.

 

[94BULLITT]

My Bobcat CT235 had them on all 4 tires the L4240 just has the on the front but the rear valve stem does not stick out that bad.

 

[Gary Fowler]

If I were to weld on the stem protectors, I would let out the air pressure but leave the water in to keep the rim cooler so it doesnt damage the tire bead. Put the stem on bottom dead center and weld away. Water wont boil and make steam to increase pressure till all of it gets hot which its not going to do with the small amount of welding to be done. I have welded on pressurizes pipe, vessels, tanks etc with fluid in them and high pressures without a problem but you do have to not overheat the metal to the point of weakening it enough for the pressure to blow a hole in the hot metal which is why I suggested that you reduce the pressure. A professional welder would not even need to let the air out to weld those on.

 

[dstig1]

LD1 - glad you posted those vids. I was about to do it otherwise...

Gary - there is a slightly different issue here. The heat from welding heats up the air in the tire which then can cause the rubber in the tire to start a chemical reaction that runs away creating ever more heat until it all blows up. It isn't about weakening the metal so much as the unintended side effect nobody thinks about.

 

[My Hoe]

LD1 - glad you posted those vids. I was about to do it otherwise...

Gary - there is a slightly different issue here. The heat from welding heats up the air in the tire which then can cause the rubber in the tire to start a chemical reaction that runs away creating ever more heat until it all blows up. It isn't about weakening the metal so much as the unintended side effect nobody thinks about.

dstog1.

That sounds scary. But I'm surprised I've never heard of this effect.

Can you please provide more information on this phenomenon? Like the name of the reaction/process? And an explanation of how it works? Link?

Thanks,

My Hoe

 

[LD1]

From another website:

The most common cause of tire explosion involves pyrolysis of a section of rubber compound, usually the tire’s inner liner, due to a heat/energy source. The most common sources of heat/energy are:
• Equipment contact with high voltage power lines
• Tire or equipment fires
• Application of heat to tire components, such as welding and heating with a blow torch or overheated brakes
• Lightning strike
Pyrolysis of rubber produces flammable gases such as methane, styrene, butadiene, hydrogen, and other hydrocarbons. An explosion will occur if all of the following conditions exist concurrently:
• There is an explosive concentration of flammable gases.
• There is an adequate concentration of oxygen to support combustion of the flammable gases.
• There is an ignition source.
• There is sufficient molecular energy to sustain the explosive reaction..

 

[LD1]

More:

Pyrolysis is defined as the irreversible chemical decomposition of a material under the sole action of heat.
In the case of a tire, degradation of the rubber takes place. This phenomenon occurs:
n when the temperature inside the tire reaches 185°C
n in the absence of oxygen (inflation with nitrogen does not eliminate the phenomenon of pyrolysis)
n in a few seconds.
Also, this phenomenon leads to a degradation of the tire’s chemical and mechanical properties, which
can occur gradually and whose effects can be cumulative following several overheating events.

 

[Gordon Gould]

Thanks LD1 - That explains things very well. A lot more than than just hot air. Isn't it.

 

[Gary Fowler]

If I were to weld on the stem protectors, I would let out the air pressure but leave the water in to keep the rim cooler so it doesnt damage the tire bead. .

That is why I suggested leaving the water in the tire to keep everything cool. You dont need a lot of welding to hold these on just a couple of tacks which isnt going to heat up the air to any higher temp than running down the road. If no water in the tire, put some wet rags as close to the weld area as possible to keep it cool and just run a 1/4" weld at a time and cool in between passes.
You will burn off all the paint inside if not immersed in water which could cause some rusting around the area from inside out. Best thing would be to break the bead on that side and compress the tire enough so you can brush off the old burned paint and repaint it after welding.
I forget a lot of times that some of the welders on TBN dont always have my welding skills, but it is still a pretty simple tack weld job to do and with water in the tire, in my case I would just weld it on without depressurizing and clean the slag, paint and call it good. Rims look to be about 1/8" thick so burn thru is not going to be a problem for a welder with stick and Mig would be super easy.

 

[crazyal]

My plan was to lay the tire on it's side and debead the tire on one side so I could just use a board or something to keep the tire away from the steel. I figure it'll be a good time to replace the stem anyway if you don't have tubes.