Re: THREADED PIPING

What is the process? If you are installing a natural gas screw 150# piping installation, then yes you would need to provide a union, between the gas plug valve and regulator, for ease of removal in the event the regulator malfunction. On low pressure steam 150,or300# screw piping installation you would install unions on all control valves, and by-pass valves and, traps on the condensate.
On any screwed compress air piping you would also install unions down stream pressure of any valves between air regulators, on any 300# screw piping where the process is subjected to be more extensive flanges would be installed or what ever the engineer, calls for on the job specs. There are many times in field conditions where we as professional pipe fitter tradesman we must take it upon our self's to make a judgment case whether to use a union, flange, vic connection, with in the specs of the called out job material to make a threaded connection work. Always keep in mind as long as the connection is down stream of the pressure side with proper maintenance you shouldn't have many problems, always keep in mind the process piping.

                                          Edwin Mendez
                                      Pipe Fitting Pro L.U.597
                                           Chicago

[Non-text portions of this message have been removed] Received on Wed Aug 14 18:16:00 2002