Integrity of straightened tube.!!??

[frederik]

Was thinking once tube is bent is that not always a weak point once straightened.

 

[longun]

If i remember correctly... only tube bent to a certain small degree are allowed to be straightened.

 

[scaffy 1980]

We cut all bent tube, it removes all risk of using a weakened tube on a job.

 

[NTSS]

As long as the tube is straightened using a cold rolled process, i.e no heat involved the tube will not be weakened, the severity of bend which can and cannot be straightened safely is like many things down to experience, if a tube to severely bent is put into a reeling machine the tube will become jammed, and/or the tube will become deformed ever so slightly. All tubes to severley bent or showing any signs of damage should have the damaged section of tube cut out and removed prior to straightening.

there is an argument that if a tube was continually bent and then straightened in the exact same place over and over again it would become weakened, in reality if this did happen the weakness would be revealed during the straightening process as the tube would break due to the stresses put in it during straightening, we had this several years ago when some poorly manufactured tube found its way into the British market, and by straightening the tube we were able to isolate the the poor quality tube for our customers.

Lenny

 

[Havespannerwilltravel]

I can remember there being a lot of welded long tube about many moons ago. 13 and 8 foots.

 

[Damo fraser]

I remember welded 20s when u cut them in the weld there was a solud spigot inside. I rememberthem being heavy as it was black steel then.dobt thibk you would get away with it now.

 

[allscaff]

Yes we had a load that come out of sgb back in the 90s like that all 10&11ft welded

 

[SWIFTY]

I remember welded 20s when u cut them in the weld there was a solud spigot inside. I rememberthem being heavy as it was black steel then.dobt thibk you would get away with it now.

Benchmark were using loads of wobbly welded galv with the spigot just before they went pop not very many years ago.

 

[NTSS]

When done properly welded tube is fine, In fact a good weld should always be stronger than the material it is welded to, one of the best methods used today is Fusion welding which does away with the need for an internal spigot, this method with full traceability and tracking seems to be getting very popular again with some major companies.

Benchmark never welded there tube together, they developed a joint system very similar to the Tube lock system where a specially made internal spigot is crimped to the 2 sections of tube.

Lenny

 

[SWIFTY]

I stand corrected Lenny it was crimped. Topping out felt a bit like fly fishing though.

 

[NTSS]

Yeah i know what you mean, I,ve watched the process they use and have to say that when 'new' they are very solid, however during the straightening process they did become a little loose! but they may well of perfected the process now!