js55,
English being not my mother language, sometimes I'm not able to express in writing or speaking what I'm really thinking.
Let's see.
You say that the 3X/4X figure is arbitrary, and you repeat "arbitrary". In my first posting, I said that it's usual in jobsites and prefabricating shops to use a figure pulled off the air consisting in 3 diameters, and I kept on saying that "pulled off the air" means that there's no sound technical reason to support it. So, we're saying the same thing.
You also say that the arbitrary figure is imposed by engineering firms, forgetting that in their isometrics there's no way of following what they themselves have imposed. So, when this situation shows up, they (the engineering firms) have nothing to do but approve the change. In my first posting, I said that firms with a high reputation like Exxon, Dupont etc. have issued piping specifications where they state distances between welds, BUT allowing changes with the previous client's approval. I kept on saying that, as usually there's no other way to do the job, the approval is always granted. So, we're saying the same thing.
Back in my days of erector engineer, I took part, as I said in my second posting, in endless and sometimes angry arguments between contractor and client's inspector about the minimum distance between welds. Those arguments happen because, to their knowledge (contractor and client), there's no widely accepted technical standard which states that. We must agree (and excuse me, Flash), that Australian standards are not as widely known as American or German ones.
So, I felt happy at knowing that Aussies have issued such a standard. It means that the best piping and welding engineers in Australia put their heads together and have decided what Flash has reported in his posting. And if it is good enough for the best Australian engineers, it is also good for me.
Maybe the Committee that writes the ASME Code for Pressure Piping can study the Australian standard and see the conveninence of incorporating it in ASME B.31. There will be no language barrier in this case.
Giovanni S. Crisi
Giovanni,
Perhaps we did have misunderstanding. The main crux of my post was my thinking that you were advocating a code imposed standard for weld proximity.
And while I have been involved in a few of those disputes myself (no fun at all-well, unless you win), I wouldn't wish resolution of disputes to be criteria for code inclusion. If thats what you meant.
If not, I apologize.
If Engineering firms wish to impose something, thats a different issue. But its also possible that continuing issuance of something that seems to have no technical basis may be the very cause of the disputes in the first place.
The result is, we are left with very energetic arguments and nobody really knows why.
js55,
I've understood your point.
Best wishes
Giovanni
Giovanni,
No problem.
thanks