When Hot Riveting a mud ring do you form on the outside and pound on the inside? Or do you form on the inside and pound on the outside? Also what is the temperature of the rivets?

I think you will find it easier to buck them against the opposite side if you install them from the inside and set them from the outside. Ask your supplier about heat - most I've done were at bright red into straw, but they were for cabs and tanks, not pressure vessels.

dave

Generally, they are installed from the inside and driven on the outside. As Dave stated, this allows the use of an air buck, placed/wedged against the opposite side of the firebox, at the mudring. The air buck makes the rivet tight and solid in the hole better than a hand held buck or dolly bar. The air hammer has a die, or "snap" with a concave tip to form the rivet head.

Again, generally, these rivets are heated to a bright yellow heat, almost a white heat. Don't forget to properly calculate the extra length required to form the head.

In my opinion, rivets should be heated to between 1800° F and 2250° F and forming should be complete above 1350° F.

Spoken like an engineer. The guys in the shop don't use pyrometers to regulate the heat in the forge but they know when the rivets are hot enough. What are the colors that correspond with these temperatures?

Actually, you can use an electric furnace to heat to a predetermined temperature for very accurate control of the process. Probably a temperature controlled gas furnace would do as well.

Somewhere I have a blacksmithing book that relates color with temperature, just can't lay hands on it right now.

dave

When I helped do some boiler riveting, they had us heat the rivets until they just started to "spit", almost white hot.

-Hudson

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Follow this link for a short clip on the work in action.

http://www.youtube.com/watch?v=hsn_zKwFyq8

Brian

I would like to thank everyone for their responses. All of this info really helps out. It explains a lot and I would like to thank everyone for their input. If you have more to give please go ahead and post it.

Interesting article, and worthwhile information...don't drive spitting rivets.

This is why I signed up for RYPN! Every now and then we get a thread like this that is informative, useful and very valuable. Thanks to all who posted!