tapping a steam boiler?

Hi,
I have an old steam boiler that I want to install an electronic Low Water Cut Off into. Unfortunately there is no opening in the side of the boiler where the probe can go. The probe requires a 3/4" NPT tap which would require a 29/32" hole. I imagine I can carefully drill the hole in the side of one of the sections and then cut the threads. What type of drill bit should be used to do this? I know I would use cutting oil to keep it from building up heat while drilling. Should it be drilled in increments of increasing size? Not sure if this is a terrible idea or if there are alternatives to get my LWCO installed with some kind of remote setup.

The boiler is a 120,000 BTU natural gas Sears / Dunkirk that I believe was manufactured in 1979. Serial Number 7911104.

Suggestions appreciated.

Thanks!
David Sorkin

If it is a steam boiler there should be a gauge glass. You can install a tee in the lower tapping for the glass and install your probe in it.

John

Thanks for the reply John. I had also thought of doing that but wasn't sure if it would be safe enough. Do you know if that is a recognized installation method or if there was ever an inspector in my house they would get a good laugh at my expense from it? I like this idea because besides not having to drill a hole in the boiler it would also allow me to easily change the height of the probe if I need to make adjustments.

Thanks!

Here are some pictures, note probe in lower right of photo.

Follow up - I spoke with Hydrolevel (manufacturer of the LWCO) and they confirm the installation of the probe into the riser pipe.

Many thanks!