Sanity check, please?

EN24 cylinder, inside diameter 50 mm, outside diameter 95 mm, wall thickness 22.5 mm.

To be pressurised to 50,000 psi - that's the figure in the relevant literature, and it seems about right - its going to be a hot isostatic press. Effective actual wall thickness is about 17 mm. Not much margin here.

The cylinder is divided into a top and a bottom, and the high pressure area is 50 mm dia, so about 170,000 lb force, 80 tons, needed to keep the top in place.

Now to calculate the needed bolts (which hold together two collars holding the top and bottom parts). Allowing a 3x measure of safety, that's 240 tons yield strength, or 2.4 NM.

For grade 8.8, that's 8 x 24mm bolts - for grade 12.9, it's 8 x 20mm bolts.

Or have I slipped a decimal point, or messed up in the decimal/imperial conversions?


-- Peter F

Reply to
Peter Fairbrother
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MN. Doh.


Reply to
Peter Fairbrother

I calculate your clamping force as 152,171 lbs or 456,514 lbs with a 3X safety factor.

Assuming you use the bolts to 75% of their minimum yield strength I get the following number of bolts.

20mm metric fine 1.5mm pitch, grade 12.9 - 8.2 bolts 20mm metric coarse 2.5mm pitch, grade 12.9 - 9.1 bolts

I don't have the thread details for 24mm bolts. It's also often assumed that clamping load is only 75% of the proof stress not the yield stress which reduces the possible load by another 25% or so but you have a big safety factor built in anyway so you'd still be ok.

No slipped decimal points at least. Ballpark figures look fine. Torque settings and lubrication/friction values would have to be carefully calculated to not cut into the safety margin too much.

Reply to
Dave Baker

Here`s a link to the strengths of the various grades.

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