Pipe Fabricators Institute Standard PFI ES-3

[bryansonnier]

So i've showed the PFI ES-3 standard to a few welding shops and the general comment was "Dude, that kinda tight huh?" Is that a reasonable standard to hold shops to? These shops are welding 2" Cl1500 RFF flanges to valve bodies for us. We have had a couple valves come back from customers with complaints of crooked welds. Some were obvious and we've instituted QC policies to try and catch them in our shop before we ship. But we've gotten some push back from our welding shops that the standard is too tight. The standard, if i read it correctly, leads to a 1/2 degree tolerance for parallel on 2" 1500 flanges. RFF diameter of 3.62 by 1/32" out of parallel tolerance. Am i asking too much?

 

[akpipelineengr]

It's not asking too much of a good fabricator, but it is definitely something you will pay for and you need to decide whether your customers need or want to pay for it. For small diameter piping, that is a tighter tolerance than is probably necessary for most systems. On larger diameter or stiffer piping, misalignment can be a significant problem. 2" class 1500 could fall into either category, depending on the specifics.

[URL unfurl="true"]https://www.eng-tips.com/viewthread.cfm?qid=443951[/url]

[URL unfurl="true"]https://www.eng-tips.com/viewthread.cfm?qid=265410[/url]