A little windy.
I will try to get the piping standard we used and see if there is a reference to any particular code/standard. I do remember early on that the gap requirement was reinforced by several incidents at a competitor's plant and later two incidents at a sister site. All our piping internal standards were at or mostly above code requirements even though we were not a Code state and there no incentives other than the commitment to have piping systems you could live with and not worry.
You are correct when you mention the added cost. When we had an internal RT Crew and most of the piping was bent on a slab eliminating fittings the cost was negligible. When we went to RT by contract and low bid contractors, instead of resident, the cost was raised considerable and quality went south. We had started to lower the % RT requirements when we discovered the welder/fitter quality was terrible, not only could the welder not weld, but the fitters were using the sockets as a crutch. While we were attacking this problem the permissible reportable spill was lowered by 90%. Also with any vaporized DP/DPO heating medium there was ever present danger of a vapor or mist explosion or fire a big problem as the majority of the piping was located in an occupied building. Our piping standards also require a vacuum, pneumatic pressure test, and He Leak test prior to commission.
I still say that RT is not the cost it’s the rework that drives the cost escalation. It was our group’s
opinion why should we lower our piping standards, proven, to the lowest common denominator of the industry.