Re-rate of pre-1968 vessels
Re-rate of pre-1968 vessels
(OP)
Does anyone know the reason why vessels that were built to the 1968 or previous editions of the pressure vessel code cannot be re-rated using the current code?
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Re-rate of pre-1968 vessels
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Re-rate of pre-1968 vesselsRe-rate of pre-1968 vessels(OP)
Does anyone know the reason why vessels that were built to the 1968 or previous editions of the pressure vessel code cannot be re-rated using the current code?
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RE: Re-rate of pre-1968 vessels
RE: Re-rate of pre-1968 vessels
what is the material specification for your static equipment built to the 1968?
L S THILL
RE: Re-rate of pre-1968 vessels
RE: Re-rate of pre-1968 vessels
What environment will the material see?
RE: Re-rate of pre-1968 vessels
We have vessel fabrication drawings but no certified documentation for the vessel rating. There is not a U-1 and the nameplate is missing.
I am to perform the calculations to verify the rating of the vessel. I was under the impression that you had to use the code of construction if the vessel was built prior to the 1968 edition of the code. I now see that you just have to use the allowable stresses from that code.
The vessel is in pentane service.
RE: Re-rate of pre-1968 vessels
RE: Re-rate of pre-1968 vessels
Design, construction and welding to be in accordance to the 1952 edition of the ASME code for unfired pressure vessels.
RE: Re-rate of pre-1968 vessels
Can you elaborate what exactly happened in 1968 Edition ASME BPV Code to make NBIC to choose this edition as the cutoff year? I cannot find info about significant changes in 1968 Edition other than Div.2 was first published in that year. The new impact test rule was not implemented until 1987.
RE: Re-rate of pre-1968 vessels
Our only deviation from the original design is that for most of the equipment we require PWHT for all thicknesses due to service.
The only piece of equipment that presented any problem as to reevaluation of the original design was a Horten Sphere used to store anhydrous NH3 for several years.
RE: Re-rate of pre-1968 vessels
Why? Because from my recollection, the Bessemer steel-making practice (which produced plate steels with higher phosphorus contents and lower notch toughness) was phased out around the late 1960's and the basic oxygen furnace (blowing with oxygen instead of air) and electric arc furnace melting became the choice of most fabricators.
RE: Re-rate of pre-1968 vessels
RE: Re-rate of pre-1968 vessels
RE: Re-rate of pre-1968 vessels
2. In the old code, there is a 0.95 joint efficiency limit with full RT. When you rerate old vessels with latest software (with old allowable stresses), do you use E=0.95?
RE: Re-rate of pre-1968 vessels
Yes you should. In accordance with the requirements of the NBIC, you cannot take advantage of a higher joint efficiency for re-rating.