Piping Flexibility (Thermal) Analysis


Piping System Stress and Flexibility (vibration diagnostics and design) was previously known as M.11 in API 618, 4th edition. As defined by API 618, a piping system flexibility analysis (also called thermal analysis) calculates forces and stresses that result from thermal gradients, thermal transients, pipe and fitting weights, static pressure, and bolt-up strains. Applications include a wide range of facilities such as refineries, LNG, Offshore Platforms, Gas Plants, Oil Sands Facilities, and Pipelines.

This study is particularly important for reciprocating compressor facilities when:

  • The cooler is remotely located from the compressor. The long lengths of hot piping may experience high thermal stress
  • Systems with high discharge temperatures
  • Systems with extreme ambient conditions


  • This analysis calculates piping stresses resulting from thermal cycles, pipe and fitting weights and static pressure.
  • The standard analysis includes the main process piping only.
  • Vessel nozzle loads can be calculated to ensure stress is within design limits. Typically this is additional scope as it may be done by the vessel designer.
  • Evaluate the stress due to thermal cycles, weight and static pressures in the piping as per all industry piping codes, such as B31.3, B31.8, BS826, BS7159, FDBR, DNV, Stoomwezen and others.
  • Calculate loads on equipment (for example: coolers, pumps, compressors) to meet manufacturer’s or industry standards.
  • Recommend pipe layout, pipe support and clamp designs.
  • This study also includes seismic analysis of piping.
 Piping Thermal Piping


  • The standard analysis assumes steady state operation.

Customer Benefits

  • System designed to ensure safe operation
  • Extend equipment longevity and minimized maintenance costs through appropriately balanced thermal and dynamic support requirements
  • Minimize number of pipe layout and support revisions when BETA conducts the piping flexibility study and the API 618 DA2 and DA3 mechanical studies

BETA Advantages

  • Experts in the latest analytical tools for conduction thermal studies such as ANSYS, CAESAR II, NozzlePRO and other applicable software packages.
  • Practical recommendations based on experience with more than 2000 compressor projects
  • Identify and resolve design conflicts between thermal and dynamic structural requirements
  • Depth of engineering resources to support any size project
  • Competitive pricing

Tips for Piping Analysis

The same consultants performing the mechanical Finite Element analysis should also complete the thermal piping analysis. This will avoid conflicting stiffness assumptions for supports. For example: mechanical analysis will specify high stiffness supports, while piping engineers will want flexible supports.