Using older edition for replacement part
Using older edition for replacement part
(OP)
Hello all,
Does anyone know if it is permissible, or an interpretation exists, for constructing a new part, a tube bundle for example, using an older edition of Section VIII Div. 1 for design? More or less for limited dimensions that would have to be met. If permissible, or such a code case exists, I would imaging that the material would have to use the properties and values of the older Section II. My gut tells me this is a long shot, but I am still posting it. Thank you in advance.
Does anyone know if it is permissible, or an interpretation exists, for constructing a new part, a tube bundle for example, using an older edition of Section VIII Div. 1 for design? More or less for limited dimensions that would have to be met. If permissible, or such a code case exists, I would imaging that the material would have to use the properties and values of the older Section II. My gut tells me this is a long shot, but I am still posting it. Thank you in advance.





RE: Using older edition for replacement part
Regards,
Mike
RE: Using older edition for replacement part
Why would you consider using an older Edition of the ASME Code to manufacture a replacment part? The latest Edition of the Code, approved by your Juridsiction, is usually the route to go for most replacement parts. Why? Because as the Code committes gain expierence with newer and existing materials and designs, these enhancements soon become revisions, which improves the Code.
RE: Using older edition for replacement part
RE: Using older edition for replacement part
RE: Using older edition for replacement part
This type of work (replacement part fabrication and installation) should fall under the NBIC or API, and is not addressed in ASME B&PV Code directly. ASME B&PV Code is a construction code for new boilers and pressure vessels. It can be used to manufacture replacement parts in-kind or under an alteration using an in-service inspection, repair and alteration Code like the NBIC or API.
For either case, there is no requirement to use the original edition of the code of construction for fabrication of replacement parts. There is an interpretation for this in the NBIC (I can't recall at the moment what the interpretation number is for this). Original code of construction does NOT imply edition and addenda, it simply refers to the code of construction used for the item.
RE: Using older edition for replacement part
RE: Using older edition for replacement part
I did a project where a high pressure Hx with a 24" tubesheet designed and built in the '60's became a 27" thick tubesheet when it was replaced. That surprised me, but I took note. And to think, I had walked by that original unit many times in my life.
rmw
RE: Using older edition for replacement part
I also have seen the opposite where components that were engineered to earlier editions of the Code had such large design margins that they still remain in service to this day!
This is not to say that current Code rules are less safe. What seems to have occurred over time is that fewer and fewer unknowns have been squeezed out and more FEA and other forms of analysis have allowed designers to sharp-shoot designs to the point where items can be predicted to be replaced. I myself appreciated the added margins used by our Code forefathers. However, in today's climate every penny counts and that means designs are to the ragged edge.
Bottom-line for replacement parts the designer needs to look at current rules and compare with past rules to decide what will be safe for service.
RE: Using older edition for replacement part
Amazing advances in analysis, however our ignorance of actual field conditions is little changed.
Regards,
Mike
RE: Using older edition for replacement part
That is what surprised me about this top point heater in a supercritical plant at ~750 MW. When it was being designed and built, I was still designing and building stuff with a slide rule so I know its designers were too. I fully expected everything to shrink somewhat and even asked the engineers who did the calcs on the replacement (kitted it - reused only the shell and the channel and replaced everything else in between, tubes, tubesheets, zones, skirts, etc.) and as stated it went from a 24 inch TS to a 27 inch thick. That cost me 6" of surface on ~1500 tubes. The zones got larger, too. I was taken by surprise.
I have been involved in rerating stuff because when it was designed it had so much extra meat in it that with modern codes and calc methods, all that extra meat allowed a rerate.
So go figure.
rmw
RE: Using older edition for replacement part
Regards,
Mike
RE: Using older edition for replacement part
rmw