What schedule pipe to weld in fittings? 2

[Nitzey]

I am designing a plant to make emulsions. Much of the piping can be 2" and schedule 10 stainless steel welded pipe will be convenient for much of the piping. However, we have to feed three ingredients using quills and such things as an in-line pH meter needs to be installed. So, I need to install pipe couplings for the quills and incorporate the pH probe and my intuition says schedule 10 is too flimsy for this. So, what schedule should it be? Many thanks in advance.

 

[Fzob]

The minimum schedule used for threaded connections is 40.

 

[Nitzey]

Okay, but what I want to do is to weld in pipe couplings (for quills, temperature probes, pressure gages) into the main process line. So, the question is: what schedule for the main process (2 and 2 1/2") line?

 

[pmover]

nitzey,

the responsible engineer needs to use the appropriate piping code (B31.3, etc.) for the design of piping components. asking for which schedule to use implies you are not the responsible engineer; hence, the recommendation.

good luck!
-pmover

 

[moltenmetal]

Assuming the branch connections are designed and installed properly, you can install these sort of branches in any schedule of pipe. If you're designing this per B31.3, a branch connection must be attached by full penetration welds, and branches beyond a certain ratio of main pipe size to branch size require the use of reinforcement, which must be designed, or you must use a self-reinforcing fitting such as a thread-o-let. You can't just stick a coupling onto the pipe and fillet weld it in place if you're going to comply to a piping code.

If you use thread-o-let type self-reinforcing threaded branch connections for your quills and pH probe. and you follow the manufacturers' instructions, you will need to fill the entire weld bevel. Since the fittings are 3000# rated, that's a LOT of weld. On sch10S pipe, you'll end up with a lot of shrinkage- the pipe will become a banana. You'll get less on sch40S and less still on sch80S.

Of course you can also use reducing tees and avoid all this.

Which method and which schedule you choose will depend on many things. Important amongst these is the length of the pipe line, which will determine the cost of pipe versus labour to weld it etc.

 

[Nitzey]

Thank you moltenmetal. That is what I needed to know. And good thought about the reducing tee; it just never occurred to me.