Form 1 30cal TI tube thickness?

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fastfire
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Form 1 30cal TI tube thickness?

Post by fastfire »

What's the minimum safe wall thickness, this will not be welded.
I am making 416 ss 60deg clipped baffles and end caps -w- TI spacers and outer tube.
Shopping for tube materials now, I have 1.5" 416 rod for the baffles.

Haven't turned ti yet but have read up on it till my eyes bleed!
missilemantdi
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Re: Form 1 30cal TI tube thickness?

Post by missilemantdi »

There are likely other posts that answer the question of wall thickness

but....

Wall thickness depends on pressure inside of the suppressor which varies dramatically from one cartridge to another and varies with barrel length and other factors.

300 blackout subsonic will have lower pressures than say a 300 win mag.

Wall thickness will vary with actual tube material. What grade Titanium is the tube?
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cal50
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Re: Form 1 30cal TI tube thickness?

Post by cal50 »

I used .070" wall tube and 24 pitch threads for the end cap.

( Rifle length 16' barrel / .30 caliber can Grade 9 tube )
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fastfire
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Re: Form 1 30cal TI tube thickness?

Post by fastfire »

cal50 wrote:I used .070" wall tube and 24 pitch threads for the end cap.

( Rifle length 16' barrel / .30 caliber can Grade 9 tube )

Spacers or welded?

The answer I was looking for, Thanks.
At this time the highest pressure will be a .308 20+ inch barrel.
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cal50
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Re: Form 1 30cal TI tube thickness?

Post by cal50 »

Pressed and welded mounting end / muzzle end is threaded tube ID and end cap.

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Capt. Link.
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Re: Form 1 30cal TI tube thickness?

Post by Capt. Link. »

highest pressure will be a .308 20+ inch barrel.(Slow fire)
A turned id .070-.080 tube threaded 24-28 tpi end caps -.005 with Pressed baffles,spacers,-.003.

Using a coolent will help 10X w/ titanium.
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c5_nc
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Re: Form 1 30cal TI tube thickness?

Post by c5_nc »

fastfire wrote:What's the minimum safe wall thickness, this will not be welded.
I am making 416 ss 60deg clipped baffles and end caps -w- TI spacers and outer tube.
Shopping for tube materials now, I have 1.5" 416 rod for the baffles.

Haven't turned ti yet but have read up on it till my eyes bleed!
I used .060" Ti in mine, source was the Diversified Machine solvent tube at 1.500" OD 1.380" ID that had 24tpi ends, with a SS monocore it was 15.0oz at 9" long.

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fastfire
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Re: Form 1 30cal TI tube thickness?

Post by fastfire »

c5_nc wrote:
fastfire wrote:What's the minimum safe wall thickness, this will not be welded.
I am making 416 ss 60deg clipped baffles and end caps -w- TI spacers and outer tube.
Shopping for tube materials now, I have 1.5" 416 rod for the baffles.

Haven't turned ti yet but have read up on it till my eyes bleed!
I used .060" Ti in mine, source was the Diversified Machine solvent tube at 1.500" OD 1.380" ID that had 24tpi ends, with a SS monocore it was 15.0oz at 9" long.

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Nice!!! Do you have pictures of the monocore? We'd like to see that please.

Thanks
speed6
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Re: Form 1 30cal TI tube thickness?

Post by speed6 »

I take the tube thickness at the thread relief of the tube as my minimum thickness. Approximate the pressure in the blast chamber by using Boyle's law:

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P1 is peak chamber pressure, V1 is case volume (these can be had for your cartridge from wikipedia typically). V2 is the volume of the barrel AND blast chamber, where P2 is unknown. Solve for P2.

Then use thin-walled hoop stress equation to find stress in the tube at the blast chamber:

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You need to know the yield strength of your tube material and take some safety margin (I used 0.6 x yield at 100F) to make up for unknowns/assumptions and decrease in material strength at higher temps. IIRC, I arrived at 0.6 x yield because a) that is the criteria for ASME B&PVC allowable stress (tresca criterion) and b) Chro-moly material properties dont decrease THAT much at high temps and using 0.6 x "room temp" yield would still result in a strong enough part.

NOTE: TAKE ALL OF THIS WITH A HUGE GRAIN OF SALT. YOU ARE GETTING INFO ON PRESSURE VESSEL DESIGN FROM SOME RANDOM GUY ON THE INTERWEBS. USE AT YOUR OWN RISK.
speed6
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Re: Form 1 30cal TI tube thickness?

Post by speed6 »

Also, if you have quickload that would be a much more accurate method of determining pressure at the muzzle for a given cartridge/load. It takes into account factors that the (relatively simple) boyle's law doesnt.
c5_nc
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Re: Form 1 30cal TI tube thickness?

Post by c5_nc »

speed6 wrote:Also, if you have quickload that would be a much more accurate method of determining pressure at the muzzle for a given cartridge/load. It takes into account factors that the (relatively simple) boyle's law doesnt.
Does not apply to the tube I posted, but one of the solvent trap companies is producing Ti tubes marketed for form 1 conversions, They are running a course thread into .065" thick Grade 9 Ti. Also they are threading .65" into the tube for use with a .42" endcap, so .23" of threads are exposed on both ends of the tube in the blast chamber, and the wall thickness here is .026". No one has reported a failure yet and there appear to be a lot out there. Someone had ran a Hoop stress (?) calculation and said it passed with a safety margin of 1.

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