Hello, I am replacing an existing ASME Section VIII Division 1 column. The U-1 states it is designed to 240psig @ 650degF, but does not say anything about being designed for vacuum conditions. The SIS for the column states that it is safe to operate under full vacuum. The SIS is not a code document, but the U-1 is. This vessel is from the 1950s. Does anyone know if it didn't use to be a requirement to specify if a pressure vessel was rated for vacuum on the U-1? I have run into this before with a different column so am wondering which document to trust, the U-1 or the SIS. Thank you for your help!