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"HP Rail"

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pdeaves

pdeaves

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At Paddington Hammersmith & City platforms earlier today I happened to see a reflective label station "HP Rail" with an arrow pointing both left and right beneath. It was mounted on the web of the further running rail (not electric rail) on the eastbound track. I don't know whether it was on any other rails.

What does HP Rail mean, please? Is isn't the same as a datum plate, is it? :)
 
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Ships

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Ploughman said:
Are there any considerations to bear in mind when using this HP rail?
eg. Welding for instance.
Click to expand...

I’m pretty sure you can’t weld repair HP switches, as such installation has to be centrally approved.

Standards stipulate you need to install 0 cant to 0 cant to prevent uneven wear on curves between the HP and grade A rail. This does give a bit of (I believe) unintended wiggle room on flat curves!
 
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civ-eng-jim

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Ships said:
Standards stipulate you need to install 0 cant to 0 cant to prevent uneven wear on curves between the HP and grade A rail. This does give a bit of (I believe) unintended wiggle room on flat curves!
Click to expand...

Which standard is that? Looking for it at the moment but can't find it...
 
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Boodiggy

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civ-eng-jim said:
Which standard is that? Looking for it at the moment but can't find it...
Click to expand...

I will try and locate standard for you but it is true and we had to adhere to it when installing a few years back at Linslade on UF, which was the first site to have it in Cen60.
 
Daniel Pyke

Daniel Pyke

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Ships said:
I’m pretty sure you can’t weld repair HP switches, as such installation has to be centrally approved.

Standards stipulate you need to install 0 cant to 0 cant to prevent uneven wear on curves between the HP and grade A rail. This does give a bit of (I believe) unintended wiggle room on flat curves!
Click to expand...

This advice was to prevent someone changing grades midway around a curve or putting a 260 grade plug rail into the middle of a HP335 curve. It does have some unintended consequences if you take the advice to the extreme. As I understand it exceptions are allowed if gone through the correct channels.
 
Daniel Pyke

Daniel Pyke

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Ships said:
I think anything over 260 grade A counts as HP rail. I guess that includes MHH, MHT, etc
Click to expand...
No no no no no!
HP335 is a specific grade with its own welding and performance parameters
MHH375 is another one
MHT is an old grade again with different weld parameters
They are all very different rails.
 
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civ-eng-jim

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My understanding is "Premium Hardened Rail" is the generic term for rails over 260R whereas, If I'm right in thinking, that HP/MMH/MHT et cetera are British Steel branded products.
 
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civ-eng-jim

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Daniel Pyke said:
No no no no no!
HP335 is a specific grade with its own welding and performance parameters
MHH375 is another one
MHT is an old grade again with different weld parameters
They are all very different rails.
Click to expand...

Do you get much call for the MHH 375 in the UK?
 
Daniel Pyke

Daniel Pyke

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civ-eng-jim said:
My understanding is "Premium Hardened Rail" is the generic term for rails over 260R whereas, If I'm right in thinking, that HP/MMH/MHT et cetera are British Steel branded products.
Click to expand...
Yes sort of. HP335 and MHH are British Steel products. MHT is an "old" British Steel product from quite a while ago.
There are other hard rails out there, 400HT for example but harder does not always mean more wear resistant at high hardness levels. I think the jury is still out on exactly why that is though.
 
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