AlMgSi 5.0 pipe for a bolt action mechanism?

[Heimo]

an alloy consisting of magnesium and aluminium is called magnalium.
(with your explosive interests you should know, DYI, altough I doubt its functionality in HE's)

I'm not sure about the Silicon yet... I think it has something to do with the hardness and strength.

this pipe can consist of anything from 0,2%Mg-1,5%Mg and 0,2Si-1.5%Si
with the balance being Al.

Silicon is added to Aluminum alloys to increase hardness and improve machining characteristics. I know Mg also increases the hardness of Al alloys, but I think the purpose of Mg in this alloy is more to modify grain structure of the material...

in the foundry world we call a Al/Mg alloy Almag, it requires special care since it can easily catch fire (no surprise there )

[FighterAce]

Going a little bit off topic.... still related to that alloy tho

I was thinking about that 5x safety factor for 40 bar....I realized that a AlMgSi0.5 pipe would be perfect for a pump cylinder - the 2nd stage of the pump.
If I wanted the second stage to bring the pressure very high I'd need to use a small ID.... so lets say pipe dimensions are 10x2mm. Thats a 6mm ID and a 2mm wall thickness.

I calculated the max pressure for my weight and would be about 240 bar. But I'm not going that high... not yet anyways.

Could anyone please calculate the max pressure of that Al pipe 10x2 or even link me to the needed formula/calculator. I tried to use some of the online calculators but I didn't really know what to enter under "Allowable Stress".

Also... how would I go about attaching the aluminum cylinder to the rest of the pump? Welding or threads?
I guess the 2mm wall is too thin for threads... If its not, how much would I need to decrease the pressure to stay safe if we assume the threads will become a weak spot?