railway welders

[subarc boy]

local rag looking for welders with the following quals
sentinal qualified welder to tw1-4 5a & 5c rt1-3
mma1-5
anybody any idea what these are ?????

cheers

 

[markjabber]

This is thermit welding ( more of a casting process) to join rail sections, they also do arc welding to repair flaws in the rail and to join the com (3rd rail)

all are specialised to the rail industry

sentinel is the body that holds all rail competencies

 

[madkayaker]

Most likely network rail codes. http://www.ihsti.com/NoRCS/docs/brafas01/dept/elec pub/network_rail/nr_completed/Docs/catstp001.pdf

 

[snowcat]

Many moons ago I did a stint arc welding the 3rd rails in the london underground we were qual'd to a BS No. but being 15 odd years ago Iv long forgoton, We were tested in house and id assume you would be as well, Your also need a PTS cert and a clean D&D test, Railways are not much fun to work on, there ruin a good man.

 

[subarc boy]

cheers guys

 

[PTvor]

I thought it was mainly thermite welding and had been since the days of tram lines in the 20s.

Loads of other videos in Youtube.

I've got an old book in tramline engineering somewhere, and the process seems just the same as on Youtube.

As markjabber says, they also do some arc welding.

Puddle arc welding, which looks more like a casting process.

All very specialised.

 

[brightspark]

I thought it was mainly thermite welding and had been since the days of tram lines in the 20s.

Loads of other videos in Youtube.

I've got an old book in tramline engineering somewhere, and the process seems just the same as on Youtube.

As markjabber says, they also do some arc welding.

Puddle arc welding, which looks more like a casting process.

All very specialised.

u can tell thats not england 2 workers doin the job. christ they just done a new barrier crossing outside my house. its took 4 weeks on nights .14 blokes at most only 8 doin owt and even then they sat in there vans for ages

 

[Pete.]

I was watching them do thermit welding at Gravesend Station over the break. They fix the gap, align the rails, fit a mould, pre-heat with a torch, light a one-shot pre-filled pot and then after it's cast clamp a hydraulic shear over the rail to cut the excess off whilst it's still bright red hot. It's just following a proceedure, no 'welding' skill involved although it requires training, experience and good teamwork.

 

[wheresmejumper]

Puddle arc welding, which looks more like a casting process.

Sure isnt all welding, in a way

 

[PTvor]

Sure isnt all welding, in a way

Not to the extent of leaving a 1/2" gap and using moulded end pieces, then going at it with a succession of rods one after another to completely fill the gap.

 

[wheresmejumper]

Reduce the gap and you have an open butt, add a backing bar....not a million miles away
my point was all welding is a casting process

 

[aidank]

I thought it was mainly thermite welding and had been since the days of tram lines in the 20s.


As markjabber says, they also do some arc welding.

Puddle arc welding, which looks more like a casting process.

All very specialised.

is that standard arc welding is it ?

must be huge rods he is using he seemed to fill up that gap v quick

 

[lexi]

What is in the can then and how does it work?
The whole process please.

 

[PTvor]

Thermite is a mixture of a reactive metal powder, usually aluminium, and a metal oxide - iron oxide, chromium oxide etc, or mixture of metal oxides. It needs quite a lot of heat to start it. The aluminium burns by taking oxygen from the metal forming aluminium oxide and leaving the metal. It gets very hot - about 2500C - so the metal formed, iron, chromium whatever, is molten.

It has civilian uses, mainly in welding, but also is used for military incendiary bombs.

When I saw it done at school, it was with aluminium and chromium oxide in a small crucible. It was spectacular and there was a button of chromium left in the bottom of the crucible.

That's the basic process. I don't know what exactly they do with thermite for welding rails, but I'd guess it's fire once cartridges, and the metal oxides are chosen to produce weld metal of the right sort for rails.

 

[Jan]

Although I've worked on both private (NCB, steel works, quarries, etc) and public (British Rail) railways in my youth we never went into this kind of rail joining. Basically we just used fish plates with large nuts & bolts torqued up with metre+ long spanners. However the way I understand the physics of the situation it's essential that there must be some play in the joint. First you have hundreds of tonnes rolling over one end of a rail and back up to the start of the next to contend with. After this there is heat/cold expansion/contraction to take into account. Taken together you need a perfect melding of one rail to the next or it will fail pretty quickly. Even so the constant flexing will cause the joint to give way eventually and there's nothing you can do to stop it. Even before the advent of modern health & safety rules you wouldn't get platelayers to work on a 'live' rail. Time is money and the longer a line is out of use the more money it costs the owners/users. Doubtless thermite welding is the fastest way of getting a line back into use.

 

[PTvor]

Thermite welding was used for tram lines from early in the last century. I don't know how they coped with expansion, but it may not have been a worry as with railway lines, because the lines aren't as long.

They certainly used to leave a gap on railway lines and use fishplates because of thermal expansion likely to exert enormous forces and cause buckling. The gaps caused the biddly-dee sound, (Reginald Gardiner records).

Some time back I was talking to a civil engineer on a plane. He was retired, but I got the impression he'd mainly worked on railways. I asked him about welded rails and he said it was one of his favourite interview questions. He reckoned that welding long stretches of track became a prospect with the introduction of portable hydraulic rams which could exert hundreds of tons so they could stretch the rail just the right amount, so that it was under a bit of tension when it was cold but when it was hot, the expansion had already been compensated for by being stretched when cold.

 

[Jan]

Recalling the trams and tram lines that existed in my youth I seem to recall that

a) The lines tended to be supported either side by the road surface - cobbles, tarmac, etc
b) Summers didn't tend to be as hot back then. Which is fortunate as the tarmac of the day had lower melting point than the current variety.
c) Speeds were much lower and passengers on the old 'rattle traps' accepted a lower ride comfort.
d) Not every joint was welded.

Even so it was far from uncommon for trams to jump the tracks leaving the passenger to continue on foot until it could be remounted.

 

[Robotstar5]

He reckoned that welding long stretches of track became a prospect with the introduction of portable hydraulic rams which could exert hundreds of tons so they could stretch the rail just the right amount, so that it was under a bit of tension when it was cold but when it was hot, the expansion had already been compensated for by being stretched when cold.

The rails do expand/stretch due to use and will eventually buckle. The PW (permanent way) gang cut the rail and it will spring apart, the gap is measured and the ambient temperature taken then they use a table showing what the gap needs to be, the correct amount is trimmed off then hydraulic pullers as above are used to pull the gap up followed by thermite welding.