The Steamboating Forum

My thinking is that if you are stressing any of these steels to such high levels then a change in design is in order. In the case of the valve rod where the failures I've seen were in bending, going up in size gives such a large reduction in stress it is a good choice. Since you have balanced the valves you will probably have no problem.

Lionel Connell wrote:Yes I agree, but as I stated in my last post, I cannot get it here so it is a pointless debate.

Just FYI.. Probably it doesn't make sense for steel because it's so heavy - but I have a standing offer for steamboaters that if you need a part (material, steamhose) that mcmaster sells you can't get locally I can buy it and send it to you as long as you reimburse me.

Done this a few times for braided steam hose.

-CB

Mike, I like the idea of using the 17-4SS and I have the facility to heat treat it myself, I just don't have any.
But as you point out, the best way is to reduce the cause of the stress i.e.balancing the valves and I will coat the valve faces with boron nitride which is super slippery, and/or to add a feature that shares the load i.e run the valve rod though the valve to a bush in the top of the steam chest so that the rod is supported at both ends rather than waving about in the breeze, all of which I have done. Changing one part for a stronger material only fixes the problems for that particular part, but reducing the stress by balancing the valve and coating the valve faces with a super hard slippery coating reduces the stresses on every other part in the valve train. Many birds with one stone.

I will add the pictures of the valves to my Facebook page in the next couple of days. Yesterday I added the pictures of the eccentric rods.

Cyberbadger, your offer is very generous and I will keep it in mind, thank you.

Cheers

Lionel