1/2 in. FPT Black Iron FPT Floor Flange

Hi, Don - The diameter of the piece is 3.5". The top-to-bottom measurement (around the thread area) is 9/16". The 4 securing holes in the base are 1/4" and are 1-13/16" apart when measuring in a square pattern. They're 2-9/16" apart when measuring on the diameter. Thanks.

You may be looking for a "gas appliance stub out."

These are built very tough. I used them to make some heavy duty book shelves that hold quite a bit of weight. The bigger concern would be that you need to make sure you find a good stud to mount them into, and then putting some lockthread on the threads to prevent the bar from rotating. You will probably only be able to get one screw in the top and one in the bottom hole since the holes on the left and right will be wider than the stud.

It states to use 5/8 in Flat head screws. I needed something sturdier, and went with 1/4 in. Carriage bolts. 5/8 in. Carriage bolts were too thick for the holes.

Yes. I have it and there is no marking saying otherwise anywhere on the packaging or item. Fun fact: if it is sold in America and doesn't say the country of origin on it, it's from America.

the holes are 4 on 2.5" dia. circle.

Sorry Jim. I cannot answer that. In order to calculate the withdrawl force of your screws you will need to know the diameter fo the screw, (#8), the length of the screw and the description and specific gravity of the material that you driving the screws into. There is a lot of informaiton on the internet regarding how to find your answer. Take a look at https://www.engineeringtoolbox.com/wood-screws-allowable-withdrawal-load-d_1815.html

Be easier to drill a hole in the wall use longer pipe to go through the wall. Cut pipe to allow for half inch of threads from where it exits the wall and however much more is needed to mount the airhose connection to the pipe. Then cut threads on the pipe and screw one of these on back against the wall lag bolt or screw the flange to the wall.

10 per American National Standard Pipe standards

No, this piece should be ready to go as is. Be warned, some of the pipes however may need the grease cleaned off. Just depends on what size pipes you need to buy.