Masts need to be RIGID.
It depends on the size of the service to be installed. For a 200 amps service, a free standing mast is 2 inch rigid steel galvanized pipe and schedule 40 in strength.
A 770 Greenlee hydraulic pipe bender bend is used for rigid steel conduit from 2" to 4".
IT IS THE MOST USED ON UNDERGROUNG PIPE WORK
Mostly used for plumbing inside a house. -Personally, I prefer PEX, easier to install and lasts longer.
It's not used for making PVC resin, but it is used in processing it - they use it as a lubricant when making rigid PVC articles like pipe.
NO!! Black iron pipe has a special coating to resist the highly corrosive effect of natural gas. Galvenized pipe CANNOT be used for gas service.
A pipe,an fire extinguisher,rubber hose
Heavier Angle iron is often used as a structural element in building and bridges, while lighter angle iron is used for a variety of supports such as an adjustable bed frame. Pound for pound angle is more rigid than standard pipe.
mast
Flex pipe should not have been used in your pool construction underground. It may be against code in most cities. The use of rigid shcedule 40 or sch 80 PVC is standard.
One way is to use an electricians snake, can be bought at home depot I think they run about $20, It's a long flat steel wire on a reel that you can feed through the mast . then hook your wire on it and pull it through. I had once used 10 foot 1/2" PVC pipes glued together and slid inside the mast with all wires protected inside the pipe. I assume you are talking about an aluminum mast? If it's wood you may be out of luck. hope this helps
Water main coming into house usually 3/4" K copper pipe. Depending on local plumbing code, fitting usually is flared or soldered.