We often receive inquiries from clients regarding the necessity of conducting a comprehensive pipe stress analysis and whether a more economical simplified analysis would suffice. Leveraging our extensive experience as leading pipe stress analysts, we have compiled a set of selection criteria based on the ASME B31.3 and industry standards. Before delving into these criteria, let’s first briefly define the various types of analyses.
TYPES OF ANALYSES
There are three categories of analysis that may be conducted depending on the size, temperature, and equipment connections of your line.
NO ANALYSIS REQUIRED
According to ASME B31.3, Section 319.4.1, formal analysis is unnecessary for a piping system that:
a) Duplicates or replaces a system with a proven track record without significant changes.
b) Can be adequately assessed through comparison with previously analyzed systems.
c) Consists of uniform size, no more than two points of fixation, no intermediate restraints, and falls within the limitations outlined in Eq. 16 of ASME B31.3 Section 319.4.1.
CATEGORY 1: VISUAL ANALYSIS
These lines are referred to as non-critical and are exempt from formal stress analysis. Piping designers should only verify, through visual inspection, that piping spans fall within acceptable limits and that the lines can expand or contract freely.
CATEGORY 2: SIMPLIFIED ANALYSIS
Lines in this category necessitate mandatory investigation, utilizing approximate methods such as the guided cantilever method, simplified computer models, or those specified in para. 319.4 of ASME B31.3. Any lines failing to meet the criteria during this evaluation must be upgraded to Category 3.
CATEGORY 3: DETAILED ANALYSIS
Lines falling into this category necessitate thorough analysis employing computer programs like CAESAR II, AUTOPIPE, and similar tools and shall meet the requirements of the specified piping code like ASME B31.3. Subsequently, formal documentation shall be issued based on the obtained results.
PIPE STRESS CRITICAL LINE SELECTION CRITERIA
Many companies have their own criteria and guidelines, which vary from project to project. The criteria below, generated using industry standards and ASME B31.3, only provide criteria covering most critical lines that may require formal pipe stress analyses and are provided for informational purposes only. It remains the responsibility of the professional piping engineer in charge to ensure that all lines are categorized correctly and verified safe to operate under the specified conditions. SimuMech does not accept any responsibility for damages resulting from the use of this criteria.
