New floor for a lorry's bed

[chevyman_de]

A friend of mine is going (read: needs) to replace the floor of his lorry's bed.
Size is slightly more than 2 x 3 metres, 2.5 or 3 mm thick steel.

He told me that the OEM plate was welded all around and he will do the same, more or less continuous welds on all edges. And of course some short beads to connect the plate to the subframe in between. I'm afraid with continuous welds of more than 2 and 3 metres length, the back of his lorry may turn into a banana, making hinges on the tailgate and the sides obsolete, sort of.

I've never made any welds that long, so I wasn't able to give advice from my own experience. How would you tackle this project?

 

[109party]

when i have done that sort of thing, its replacing boat panels, so we do tacks about 6inches long, so short six inch seams about 1.5 feet apart then just fill in the gaps when the whole thing has been tacked like thing just dont do it in one go, tack the fist panel in one place then work off that. donno if that makes sense

 

[Paul.]

If it really must be fully welded, then backstep, or preferably skip welding is the answer,
Have a look at this link, for some tips on distortion control.

 

[chevyman_de]

Thank you very much for your answers! Basically it's the way I would do it, but given the size of the part I was looking for confirmation from other welders. I don't want to give wrong info to a friend who's asking for help.