Black pipe question

cutter

I was checking at the local steel yards for pipe for my hot water system. They asked if I wanted A 500 or A 53. I think the A 53 is pressure tested. In another discussion on here it was suggested to only use USA pipe. I have bought USA butt weld caps and reducing couplings. I plan on measuring the inside diameter of the pipe and fittings to see what the difference is, if any. Don't know what I can do if there is a lot of difference in the inside diameter of pipe and fittings.
though.
Question is should I use pressure tested pipe or the other, or does it matter?
Another thought is when I weld fittings to the pipe I was thinking of cutting steel couplings in half and coping them, then welding them on. Or should I use weld-lets.
Any suggestions on my thinking?

nicholas bonham-carter

You could also cut 12 inch nipples in half and weld them to your header. I think any welding of two identical metals works better than say cast and steel joints.
What part of the piping is this for?--NBC

KC_Jones

Generally speaking A500 is for structural use and A53 is for "plumbing". If you told them you were doing pipe work for "plumbing" and they offered A 500 they don't even know their own product which is kind of scary to me. A500 is available in a lot more sizes because you spec wall thickness and diameter, A53 comes in standard pipe sizes and schedules. I don't have a chart in front of me, but I am not even sure if A500 comes in the sizes required to work with standard pipe fittings.

cutter

Thanks KC , This was a steel yard that I called. That only actual fittings is the Butt weld fittings that I have. The other fittings that I use I was planning on drilling holes and welding on fittings. I will use the A53, it is not that much more expensive. And I don't want to do it over again.

aircooled81

Just curious, what dimension pipes, mig tig or stick?
I was never proficient in welding anything stick below 3".

cutter

nicholas bonham-carter said:

You could also cut 12 inch nipples in half and weld them to your header. I think any welding of two identical metals works better than say cast and steel joints.
What part of the piping is this for?--NBC

Cast steel weld-lets are made for welding to pipe. At work years ago we welded them on with 7018 electrodes. What I call weld-lets might be called something else in another part of the U.S. This piping is on the supply and return headers of what I want to build. There are regular steel couplings that would weld on nice. the only thing I am worried about is if the welding would distort the threads. I don't have a 1" 1/4 pipe tap to fix the threads. If my welding skills have gone to pot I will have someone else weld it together for me. I would post a picture but it looks like I don't have that option for some reason.

cutter

aircooled81 said:

Just curious, what dimension pipes, mig tig or stick?
I was never proficient in welding anything stick below 3".

This is for a residential system, the pipe size's are all below 3". The weld-let or couplings cut in half would be 1 1/4" 1" and 3/4 inch and maybe a couple of 1/2". My thought was to use a Tig machine.

Back in vocational school in the early 70's I was really good at oxygen/acetylene welding smaller pipe. After school I did a little in the field. I have not welded any pipe in many years and my eyes aren't what they used to be. The idea was to do some re-fresher welds on similar size pipe.and see how I do. oxygen/acetylene is similar to Tig, just the heat source is different. I watched a couple of u-tube videos of laying the wire in the joint as it is being welded, so that was what I was going to try. Laying the wire is a little different than dipping the rod in the puddle. Do you have any suggestions?