Stupid steam pipe questions

Taylor_4

I have to replace some steam pipes because I have to sister the joists that they go through. They appear corroded on the outside anyway. My stupid questions:

1. black pipe or galvanized? is there a difference between the big box and plumbing supply store in what they stock?

2. on connections, some here don't appear to like pipe dope, but I can't imagine silicon tape lasting. I've seen Exacto being recommended, but it's apparently impossible to break the bond (a feature?). I picked up a can of something called Real Tuff that looks promising.

3. I remember people advocating that you paint your pipes, can anyone comment on why this is recommended? This seems to assume non-galvanized.

Brad White

Some thoughts

1. Black pipe is preferable. Galvanized pipe is of any number of qualities and can flake off. Can you get away with it in a pinch? Sure, if that is all you have in a small area.

The best pipe has mill markings with ASTM numbers (A-53 being common for steel pipe). Schedule 40 is the weight you want for steam pipe, 80 for condensate if you can afford and find it. (Sch. 40 is fine really, but 80 is for longevity beyond your life.) There is seamless or ERW (electric resistance welded), notable by an internal seam. If you have that, try to keep it on top. Best bet is to buy from a supply house to assure quality.

2. Pipe dope has oils, at least most do. Good luck skimming such a system. Expando is the product you are thinking of, I bet. Not cheap when I priced it last. Mil-Spec teflon tape should be fine. Pressures are low, remember?

3. Painting- Well if you are not going to insulate (!) they look nice and radiate really well. I say insulate. If you must paint, your dining room needs attention, right?

ed wallace

pipes

avoid home depot for black pipes they sometimes sell over and undersized black pipes

Taylor_4

Thanks

Thanks for the info, I will talk to my local supply store.

I plan to insulate, but I thought there were not just aesthetic reasons for painting. Maybe protect from corrosion?

Taylor_4

Found an interestng thread by machinists on pipe threading

Thought people here might be interested in some of the observations. A couple of people mention NPTF (NPT for Fuel) which is designed to seal without dope or teflon tape, unlike NPT.

http://www.practicalmachinist.com/vb/showthread.php?t=157818