Saddles or Tees

[homerphish]

Is there a method, or are there formulas out there which can help determine whether or ot a saddle can be used instead of a tee at certain branch connections?

 

[metengr]

Yes. You have two basic options; you can obtain any good pressure vessel or piping design handbook OR use one of the ASME B31 Piping Codes (I am most familiar with B31.1 Power Piping Code).

To summarize, any time you provide an opening in a main pipe run to accommodate a branch connection, the opening weakens the pipe. Thus, when installing a branch connection you need to be sure that the opening is sized or reinforced to assure strength.

The method of determining reinforcement is by areas. An area calculation is performed for the original opening in the main pipe run. This is based on diameter and intersection angle.

After this area is determined, the calculated areas are obtained from margin provided in the
A1 - pipe wall (nominal-minimum)
A2 - pipe branch (nominal - minimum)
A3 - attachment weld area

If the sum of the above areas (A1+A2+A3) is LESS than the calculated area of the opening, reinforcement is required to assure strength. Reinforcement can be obtained by a saddle (which would be additive to areas 1-3) or by other suitable methods -thicker pipe branch or full penetration weld., etc.

Keep in mind that I provided only a very brief description.