The carbon triple-bond is unstable under pressure, which can cause it to explode if stored above about 30 psi.
This is why acetylene cylinders are thin walled steel, and filled with a porous material. The porous material is filled with acetone. Acetylene dissolves nicely into acetone, so the gas is effectively stored in solution. It outgasses out of solution as it is drawn off during use, and generally creates only about 15 psi on its own (as long as you don't heat the cylinder).
But I digress. This is all probably more than this board wants to know, lol.