Mike , you have a good point but when you take a look at FIG. 127.4.4(C) "....(Minimum) welding dimentions required for socket welding components other than flanges.....This statement seems to only give (minimum) gap not maximum gap or minimum insertion. This is the closest statement to a minimum insertion rule but it just doesn`t` quite make it in my opinion. Like you said " all comments are welcome " Thanks for your interest, Have a good one!
Hi Mike
ASME B31.3, para 328.5.2 also addresses this, but by the use of pictures, (figures) very similar to those in B31.1. It would also seem to me that the 1/16" distance is neither a minimum or maximum. It is an "approximate" dimension. This means that something twice this value would not qualify as being approximately 1/16".
Lets look at this another way. If the collar of the fitting served no purpose, why do the manufacturers put it there? If I was making a fitting with a collar, into which a pipe needs to fit, I would make it the minimum size to meet code design requirements, with a small factor of safety. So, if you only need to have a 1mm insertion depth, (to allow proper weld penetration) why make it 20mm long? I would be loosing money!
Just as a matter of interest, we in South Africa also often radiograph these socket welds for quality control purposes. I have heard all the arguments about doing it right to begin with, then the radiography becomes superfluous, (Using the scribe method etc.) but if we take this line of reasoning, very little inspection would be required because we can just trust the welders and boilermakers to do everything right. Where I come from we have a saying: "Trust is good, check is better."
Regards
Niekie Jooste
Fabristruct Solutions