Determine the actual burnt of metal (Internally or Externally)

[JHWC]

Hi All Experts,

Just a question, I am dealing with a burnt metal which is used in the track railway.

Recently, there was a burnt on the metal, probably due to arc flash or arc blast.

My questions are as follow:

1) Based on visual inspection, would we able to determine whether the burnt start from internally or externally?

2) Does metals accumulate "energy" and when it reaches it capacity, perhaps it conductivity level, it will start explode or start burning?

Thanks.

 

[Compositepro]

This must be an electric railway. It appears that there as a defect in the surface of the rail (the groove that goes across the top of the rail). I believe this groove would cause a momentary interruption of the current as the wheel went over this at speed. This would cause a spark every time a wheel went over it. The arc pitting is probably the result of thousands of sparks over time.

 

[IRstuff]

Looks to me like the rail was coated with something, possibly some sort of insulator, which was scraped off, allowing the arcing to occur.

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[JHWC]

Hi Compositepro, it is electric rail. The burnt occurred between 2 materials. The center material is a weaker materials (Insulated Rail Joint). Just wondering which one of the two will burn first.

Hi IRstuff, will check with the respective engineer if there is any coating coated. Just wondering, any recommended coating for arc resistance?

Thanks all.

 

[MintJulep]

Your ground cables have been stolen and one section of rail is not as well grounded as the other.

Thus when a train wheel passes over this insulated joint the wheel is shunting the two sections that have a voltage difference and you are getting an arc.

 

FWIW, the uniform groove across the top suggests this is the location of a flash butt weld joint.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[berkshire]

ironic metallurgist,
This looks more like a sheet metal cap on the rail or a machined grove, there is no evidence of a flash butt weld or thermit weld down the sides or bottom of the rail.
B.E.

You are judged not by what you know, but by what you can do.

 

[MintJulep]

It's an insulated rail joint.

 

[kingnero]

We need a better pic to see the situation completely.
I agree that the possibility of an insulated rail joint (IRJ) is the most probable.
I cannot see the reason why a thermite or FB weld would spark, as everything has the same potential.

IRJ's regularly fail in a similar way. The methor of repair is most likely a prefab IRJ that needs to be welded in track. On site prepared IRJ's don't achieve the same quality of prefab ones, and will most likely fail again in short order.

 

[JHWC]

Hi All,

This is IRJ. Attached some of the photos.

Wondering what could be some of the causes that create the burnt IRJ.

Is there any possibilities that would prevent from IRJ burnt? for example, fire resistance coating?

Thanks.

 

[JHWC]

Another photo attached.

 

[berkshire]

JHWC
From the pictures you have just posted, it would appear Mint Juleps answer is the most plausible. A voltage potential across the insulated joint sparked by a wheel bridging the joint, once you have ionized air there, the arc can sustain for a while.
B.E.

You are judged not by what you know, but by what you can do.