Fitting the top back in a CO2 bottle

I have a 600g gas bottle which I unscrewed the top of to fit a dip tube.
Now I`ve got to put it back in but how do I do it?
Can someone please give me some advice on the best/safest way.

You'll need a recertification.

What firms do when checking up CO2 bottles.
Visual check on the outside. No dents, cuts or other damage? (scuffed paint and such doesn't count)

If not damaged,
Put the bottle in a well padded bench vice. Support it over the full length. Undo the valve, put in an inspection camera. No corrosion or other anomalies on the inside.
Screw the valve back in. Using a torque wrench and the data that goes with the kind of bottle and valve.
Hydrotest it.

Clean up the bottle, restamp and repaint it, add warning stickers and such. Add bill.(probably more expensive than buying a new bottle)


.

I just use a strap wrench to hold the bottle and a spanner to tighten the valve. I've never bothered getting it retested just for fitting a dip tube and tbh I doubt anyone else over here has- you should be alright. But don't let any moisture get into the bottle.

Thanks, how tight? It came out pretty easy.

I just do it up till it feels quite tight being careful not to over tighten it then listen for leaks when full. As Mario says there is probably data somewhere for exactly how tight it should be.

From Luxfer.

Straight-thread dimension Torque not to exceed

.625 – 18 UNF 50 lbf-ft (67.7 Nm)

Its tapered though.