Replace Press Fit Component

Please tell me you arn't simply removing a pressure relief valve from the system. You are replacing this valve with something else that perform the relieving function... right? Just in another location? The relief valve is there to prevent catastrophic failure of the system, and is likely a needed component.

You could get a good welder to weld a NPT bung onto that cast iron... but he needs to be a darn good welder.

Now for the important question:

What kind of pressures are you dealing with?

Thanks for your reply.

I'm not sure of the reasoning behind removing the valve, perhaps for testing or perhaps the valve is being moved, but I'm not sure. All I got was an email with two sentences asking me to come up with a concept for sealing the port.

As far as pressure, its a pressure relief valve designed to open at 50psi.

I originally thought a plug made of the same material (brass) and similar press fit force would be acceptable but then I realized the press fit calculation for the valve assumed a hollow diameter whereas a plug would only have outside diameter. This causes the dimensions of the plug to be different from the valve in order to get the same press force. I was wondering if this will affect the components as far as stress of perhaps something else I'm not thinking of.

I sure would ask a lot more questions before you commit to doing this. Too many open issues to proceed with confidence something bad's not going to happen.

Is it against the regulation if we fix a gate valve between the cylinder/tank and the PRV?.

Yes, it is against the regulations in my jurisdiction, but local regulations could vary. One way around this is a three-port valve that allows one of two relief valves to be isolated while leaving the other connected to the vessel.

To the OP, there are some cases in which a rupture disk or fusible plug can substitute for a relief valve, but it depends on specific circumstances and local Codes.

Without getting into the reasons why, or the regulations. Depending on the pressures you will be dealing with, freeze plugs that are pressed into cast iron engine blocks have worked well for decades.

Ah, that's a detail I forgot to mention. I looked at using something like a freeze plug or a a cup plug. But after looking at the details, the mating surface of the interference is only 4mm deep which makes for a very shallow cup.

Well, since the pressure relief valve is already in place, do you have to replace it?

My thought is to simply cut it off, remove the guts, thread the remaining brass cylinder and screw a plug into that. Or does it have to be flush with the cast iron?

If you could pull this off, you could probably use a common size brass bolt/screw as the plug.

I'll look into this. I'm not sure if this is a one-off for something like test or if this will be a change on the production line but I will check on it.

Thank you to everyone for your comments and input.