API RP 2201 "Procedures for welding or hot tapping on equipment in service", normally lower system pressure as much as you can, qualify a procedure simulating the internal pressure and select a properly NDE (i.e. UT) depends of your application

In response to all, I appreciate all the input. To further clarify what i am dealing with, the line is 6" schedule 40 pipe, it is located between the compressor and 3 wells that tie into it, the leak is right about half way between the compressor and the first well tie in, which is approximately 1/4 of a mile either way, the only valves they have for blow down purposes and isolation, is at the compressor and the wells. The company man indicated to us that there was usually about 30lbs of pressure on the line under normal conditions, at times as much as 150lbs. we do have all the monitoring devices required, the last repair i made on the line we had approx. 2 to 5 lbs. flowing through the line throughout the repair with a man for fire watch, and one with a weed burner to make sure that the fire did not go out. the cutting and prepping was done with a torch beveler, and 4 1/2" grinder, i did use 5p and did leave the top open until i got the root and hot pass in then sealed off the top, however the reason i asked about the rod in my original question is because, the closer to the bottom of the pipe i got the harder it was to keep the arc going, the flame was burning the flux off faster than i could move, so when i got to that point i switched to 3/32 7018 and went from the bottom up and tied into where i left off with the 5p, i don't know what an inspector might think of that, but it worked well,experience has taught me that there are times and applications where bending the rules on welding procedures, is almost a necessity, thats where common sense and experience pay off, you can't teach that in a classroom, unfortunately, anyway there's the long and short of it. Thanks Steve.