When is Pipe Stress Analysis Required?

When is Pipe Stress Analysis Required (Past)

Pipe Stress Analysis has been a necessary and invaluable component to verify whether the designs meet the ASME B31 standards as well as verifying the loads on equipment.  ASME (American Society of Mechanical Engineers) B31 codes are indirectly mandated by Canadian legislation through its own CSA standards and are recognized as being the authority in North America for industrial and commercial piping design and construction.  ASME calculations are based on conservative safety factors that take into account previous piping failures that have occurred world wide.  These accidents were reviewed using forensic investigation methods and engineering principles. 

Provincial safety organizations (ex., Ontario’s TSSA or Alberta’s ABSA, etc.) are charged with piping design registration and construction inspection to ensure the projects meet and are designed to the ASME B31 standards. 

Almost 10 to 15 years ago, most of the pipe stress analysis was generally required only for industrial piping. 

When is Pipe Stress Analysis Required (Present)

Pipe stress analysis has caught a tail wind, as it has been included in more and more project specifications, commercial projects and piping services that are sometimes not even required to be designed to ASME B31 standards.  In these situations it may be included for due diligence.

Lists of Reasons to Require a Pipe Stress Analysis  

The first group of items below indicate an in-house list of reasons that a project could use Pipe Stress Analysis, based on our experience.  The second group indicates an “industry standard” list. 

1. Pipe stress analysis can be performed to verify the following:

  • To verify compliance with ASME B31.1 or B31.3 codes;
  • To determine whether the pipe layout has sufficient flexibility for stresses and equipment allowable loads;
  • To calculate stress intensification factors for elbows and intersections;
  • To review WRC 107/297 pressure vessel nozzle stiffnesses;
  • To select spring hangers when pipe rigid supports lift;
  • To verify the effect of an expansion joint w.r.t its intended purpose;
  • To determine equipment nozzle loads (pressure vessels, turbines, pumps, heat exchangers, etc.) and verify compliance with allowable values based on industry or client standards (may also need to carry out FEA [3rd Party] using alternate software);

2. Pipe stress analysis is recommended by industrial standards for the following applications:

  • Piping ≥ 3″ dia. connected to rotating equipment
  • Piping ≥ 3″ dia. and at temperatures ≤ -20°F
  • Piping ≥ 4″ dia. for steam generators or fire tube sections
  • Piping ≥ 6″ dia. and ≥ 350 °F
  • All piping ≥ 16″ dia. at any delta T due to large F = P/A
  • Thin wall piping ≥ 18″ dia. with OD/t > 90 (FEA required to verify buckling)
  • All piping with temperatures > 600 °F
  • All piping with pressure > 1,500 psig.
  • All lines requiring expansion joints
  • AMSE B31.3 Category M Fluid Service (a very small quantity of fluid  exposure can produce irreversible harm to a human)
  • All Pressure Relief Systems (review pipe system as a minimum)
  • All Boiler feedwater lines, drain lines and blowdown lines
  • All piping subjected to external pressure or internal vacuum

Refer to our extensive list of projects that have been carried out sine the inception of Santamaria Engineering Inc.