Welding Required

[AshG]

Originally Posted by HandyAndy

Ash, did you type that long thread or pasted it????
how,s the build?
andy

i typed it out for another forum ages ago but saved it in notepad as i knew it would be usefull one day.

cracking on got the rad today so that will be going on this weekend. i have got about 10 jobs left on the list to do before i can sand blast and paint the chassis. then its on to floor and body pannels, pipes and wires, fuel tank, running gear, engine..............sod it i can't be bothered to type any more.

[davidimurray]

Generally - RHS (Rolled Hollow Section) is considered as a structural steel and as such will be less less strict tolerances then ERW (Electric Resistance Welded) or CDS (Cold Drawn Seamless). RHS will normally come in the 'black' form straight out of the mill whereas the others are likely to have been cold rolled and/or pickled to get rid of the scale. For our applications, the existance of the weld does not really make any difference. Typically ERW is so good nowadays that if you cut the tube and look at the weld under a microscope it is very difficult to distinguish the difference between the weld and the parent metal. Where you often will find differences will be when it comes to using these 'hollow' sections for pressurised pipework - as ERW ahs a lower 'joint' factor than CDS which reduces the overall pressure rating of the pipe - guess what I've been doing at work recently Interestingly, I did some work comparing the cost of ERW and CDS for a job at work and found there was no clear difference between the two, for some stuff one was cheaper than the other and for others the reverse applied. One other thing to bear in mind when ordering is that the tube is typically supplied in 'random' lengths - these are between 5.7m and 6.1m - it is easy to get caught out by this and assume they are 6m lenghts - been there done that

Cheers

Dave

[davidimurray]

What's the difference between Tube and Pipe?
The general term for pipe was that it was primarily used for carrying gas or liquid. It was not intended for structural use because the dimensions used in describing pipe was not dimensionally accurate. Measurement was referred to its inside diameter and wall thickness. The inside diameter was a true dimension, but over the years had become "nominal" (in name only) so that when pipe size was referred to, it was an approximate inside diameter measurement with the thickness described by the term "schedule".

Interestingly, or maybe not, Our Euro/British standard friends seem to have now standardised on the term Tube for any fluid/gas conveyance tubing!

[Land Locked]

Originally Posted by AshG

Handy little snippet if you fancy a read.



Cold formed....(Edited to save space)....measurement with the thickness described by the term "schedule".

Thanks for a very very useful post, now I know what I'm looking for.

[Land Locked]

The other welding question.

It would appear that the Sarf Efriken sevenesque people look with disdain on any form of welding except TIG. To them TIG is the the holy grail AND the only remotely acceptable way to weld a chassis. Yes TIG makes very pretty welds, but do we need to be that anally retentive?

[Tatey]

I dont think we do need to be that analy retentive. As if you're welding properly then the material should break before the weld does.

[AshG]

i started of with the mig on my chassis then wnet to tig then back to mig as the tig was to slow for someone impatient like me.

i only crack the tig out for little jobs like closing up the ends of the chsaais tubes these days. oh and it will come out again to do the ali fuel tank.

[RAYLEE29]

Hi, just a thought,
is it true that tig produces a more brittle weld than mig because of the intesity and concetration of tig welding?
I was told this by a fabricator years ago.
Ray

Done properly it's better as you can control the heat you are putting in as well as the filler rod, where mig is more brutal but then hairy chickens legs against bald mole legs

[RAYLEE29]

I would have used my tig for some of it but couldnt justify the argon bottle hire price and i get my co2 for a £1 a kilo.