Seamless Equivalent Criteria

Owned by Former user (Deleted)
Dec 11, 2015
2 min read

Deciding if a selected material needs to look for a seamless equivalent

  1. Material allowable stress line comes from Table 1A or 1B in Section II, Part D
  2. Material includes a note G3 or G24 if from Table 1A.
  3. Material includes a note G14 if from Table 1B.
  4. Material has a product form that includes pipe, tube, or fitting.
  5. Material has a product form that includes welded.

Determining the seamless equivalent

  1. If the material needing a match has the G5 note (90% yield note), the match has to have the G5 note.
  2. The ratio of allowable stress of the material needing a match to the match itself must be between 0.8 and 1 for all temperatures.
  3. The match may not have allowable stresses at higher temperatures than the material needing the match.
  4. The match must have the same SC II, D allowable stress table, set of units, min yield strength and min tensile strength. 
  5. Items 1 and 4 are hard criteria that must be met in all cases when DesignCalcs finds a seamless equivalent. An additional series of attempts to find a match for the material will be performed. The first pass will also gauge whether the following are the same between the material requiring the match and the match itself:
    1. nominal composition
    2. uns
    3. type/grade
  6. In addition, the matches must contain tube or pipe in the product form if the material requiring the match contained tube or pipe in the product form. The product form must also contain seamless.
  7. If only one match is found, that material is assigned a seamless equivalent and is removed from the list of materials needing an equivalent. If multiple matches are found for a material, DesignCalcs takes the following steps until the matches have been narrowed down:
    1. All the criteria from 1-6 are used and the Spec must be the same. 
    2. All the criteria from 1-6 are used and the special criteria for materials containing the W5 note is added.
    3. All the criteria from 1-6 are used and the Class/Condition/Temper must be the same.
    4. All the criteria from 1-6 are used and the product form criteria is made more strict.
  8. If DesignCalcs cannot find a match for the material, it will attempt the following exclusions until a seamless equivalent is discovered:
    1. All the criteria from 1-6 are used except for type/grade.
    2. All the criteria from 1-6 are used except for type/grade, and the max allowable stress temperature for the match may be less than that of the material requiring the match.
    3. All the criteria from 1-6 are used with the exception that the max allowable stress temperature for the match may be less than that of the material requiring the match.
    4. All the criteria from 1-6 are used, but the product form criteria is looser. 
    5. All the criteria from 1-6 are used except for alloy/designation/uns number.
  9. At this point, if a match has still not been determined, the criteria from steps 1-5 are put back into place in their entirety and the potential match that is closest in the book to the material requiring the match is assigned as the seamless equivalent.