The 65, 55 and 45 refer to the nominal tensile strength of the as deposited weld metal in ksi.
Talking about ksi, let's considder something entirely different! Is there not a problem with the logic of the ksi units. The k refers to Kilo, which is a SI prefix while the si refers to square inch which is clearly imperial.
I am not trying to start a fight, merely pointing out what is surely an inconsistency. (Probably not very important, but an inconsistency none the less.)
Regards
Niekie
I worked for an electric utility for 22 years as a welding trainer. Our first class welders were qualified on OFW for pad welding boiler tubes. They welded 3" sch. 40 pipe in the 2G and 5G position as a test. We used RG65 wire, 1/8" for root pass and 3/16" for the covers. Believe me, it is a lost art, I loved teaching it. The welds produced were xray quality per ASMEIX. Most of the guys liked a No. 3 tip for the roots and a No. 4 on the cover but some stayed with the 3 for both passes. Use a lot of preheat, a lot of preheat, a lot of preheat and double up of the gloves!!!
A very slightly carburizing flame assisted in the wetting action, never go oxidizing or you will have a very very long day at the office.
Alan