Welding S Number. 3 A group of spot welds may be located on a drawing by intersecting center lines. S Numbers were assigned to those materials which were acceptable for use by the ASME B31 Code for Pressure Piping or by selected Boiler and Pressure Vessel Code Cases but were not included in section II of ASME Boiler and Pressure Vessel BPVC.
However per ASME Section IX These assignments are based essentially on comparable base metal characteristics such as composition weldability brazeability and mechanical properties where this. Fillet Example Length of Weld Not Defined. There are a wide variety of welding blueprint symbols that represent all different types of welds.
Another important fact is you can use 304 and 316 welding rods for 304 stainless steel.
The S Numbers purpose was identical to the P Number. V Groove Numbering Example. If you are interested in a welding career you might have already looked into the welding tools and equipment that are used. However the third digit indicates the position of the rods for welding.