Finding black pipe size

JoeyQ

Hello friends and happy holidays. My current job has nothing to do with hvac or steam. I am very fascinated by the "lost art of steam heat" book. Please forgive the elementary nature to my question. Sizing the particular pipes of a one pipe steam system is a very detailed process (I am familiar with the necessary concepts of steam velocity, the needed -A- dimension, finding the EDR for piping and radiator sizing. I understand the reference chart relating the pipe diameter with regards to steam / condensate direction. In short I must check everything and assume nothing is accurate just because it was installed.)

My question is in the pipes that are already installed. It should be schedule 40 black pipe. Is there a way of measuring the outside diameter with a caliper to find the size of the pipe, like acr copper tubing ? Is Teflon tape sufficient to seal steam ?

nicholas bonham-carter

Pipe sizes

If you do a search here for "pipe sizes", you will see in one thread a chart of the external diameters for various pipe sizes.

Checking the boiler size vs the EDR of your radiators is perhaps the most important part of your system survey, followed by examination of your main vents. If you had a 0-3 psi gauge, you could see the back-pressure of venting as the air is escaping. A higher pressure indicates the air having to be forced out, instead of being allowed to escape.--NBC

JoeyQ

Venting air

Thank you for the help on black pipe sizing. You threw me for a loop with the air venting, I think I understand. If the boiler matches the EDR perfectly, I can verify this by installing a 0-3 psig gauge where. At the end of the main vent close to the main air vent ? At the radiator vent with a tee? If everything is great within the system, would that mean the reading should be system pressure or should it never rise the gauge ? If the venting is forcing out the air, does that mean my vents potentially have the wrong size or restricted internally?

nicholas bonham-carter

Low pressure gauge

You could put the 0-3 psi gauge on a tee next the the pressuretrol.

The pressure is virtually the same throughout the system. Any pressure over a few ounces is an unneeded waste.--NBC