Pipe materials expand or contract when subjected to changes in temperature. Most materials expand when they are heated, and contract when they are cooled. When free to deform, concrete will expand or contract due to fluctuations in temperature. The expansion and contraction with changes in temperature occur regardless of the structure’s cross-sectional area.
Cause for generation of stress in a Piping System:
• Internal/External Pressure
• Temperature change
• Occasional Loads due to wind, seismic disturbances, PSV discharge, etc.
• Forces due to Vibration.
Depending on the stress design basis the system is classified as stress critical or non- stress critical. All the stress critical system shall be stress analyzed using software system (eg.Caesar II) to keep the stresses within the allowable limits as per the code/standard. The types of loads to be considered in Stress Analysis
• Sustained Loads
• Thermal Loads at Various Operating Conditions
• Seismic Loads.
Sustained loads to be considered are as given below:
• Design pressure.
• Weight of Pipe and associated components such as Flanges, Valves, Strainer, Sight glass etc., mounted on the Piping System.
• Weight of Fluid/contents in the piping.
• Insulation and cladding weight.
• Hydro test loads, if applicable for the line.
• Snow load, if applicable.
TEC will commonly used following all industry Codes and Standards:
• ASME B31.1 Power Piping
• ASME B31.3 Process Piping
• ASME B31.8 Design, operation, maintenance, and repair of natural gas distribution and transmission pipelines
• API 610 Centrifugal Pumps
• API 676 Positive Displacement Pumps
• API 617 Centrifugal Compressors
• API 618 Reciprocating Compressors
• API 661 Air Cooled Heat Exchanger
• TEMA Heat Exchangers
and classification society guidelines requirements.
Pipe Stress Analysis using CAESAR II