In response to the increasing number of fatal accidents in the early part of the 20th century specifically as a result of the rapid development of steam-driven engines and the total lack of legally accepted standard practice, the demand for codes and standards providing a systematic approach to pressure technology was introduced.
Within the framework of these codes, it is clear that the primary reason for performing Pipe Stress analysis is to ensure the safety of process plant operating personnel and the general public. In support of this primary reason, it is therefore imperative the design of plant and equipment is evaluated in terms of the structural and operational considerations of process piping systems with particular reference to the analysis of the associated mechanical contributions considered via pipe stress analysis.
In providing for a safe working environment achieved through the optimal design of piping systems, the validity of stress analysis requirements may be substantiated with consideration as to whether the following parameters are a precursor to plant safety;
- To ensure the level of stress within piping systems complies with Code limitations
- To validate sufficient flexibility exists within piping configurations that maintains nozzle loads on equipment within the allowable limits of recognised
- To check that the level of stress on vessel nozzle connections are within vessel code
- To calculate loads at supports for incorporation into safe structural
- To review the possibility of leakage at joints
- To provide a check on the extent of piping displacement related to interference with other
- To investigate the effects of dynamic parameters such as mechanical and acoustic vibration, transient flow, compressor pulsation due to wave propagation, wave induced fatigue slug flow and relief valve reaction
- To qualify piping systems subject to elevated temperatures or pressure (external or internal) or systems with critical or hazardous service
Any combination of these considerations would not only direct iterative design more efficiently but also present sufficient justification to investigate a piping system by performing a stress analysis of commensurate degree of complexity and in turn provide both Code validation and design optimisation as an intended outcome.
CAESAR II software is the preferred computer program referenced and utilised on this course. Amongst numerous others on the market it has been developed to provide a structural analysis for piping systems using three-dimensional beam elements and while it is not as accurate as finite element solutions, the ease and efficiency of using this method provides sufficient accuracy in conservatively addressing Code requirements. It is important to note however that any stress analysis program is merely a tool and that only with a firm foundation of understanding of the fundamentals of stress can the processing of results be likely to engender realistic and practical value.
The objective of this course is to present the student with methodology in clearly and systematically building a foundation of understanding of the requirements for performing Pipe Stress Analysis.
The course is developed sequentially. First, a rigorous review of basic stress concepts typically encountered in undergraduate solid mechanics courses is undertaken. These concepts are then developed with specific reference to CODE compliance parameters so that the student becomes comfortable with the selection and use of various methods available in different codes for evaluating flexibility.
Next, the student is introduced to some fundamental material parameters and selection criteria along with various and typical piping components and their use. This review is followed by a study of restraint mechanisms and how their different functions are related to developing necessary control of deflections and loadings. This sequence of presenting the course objectives provides the groundwork in presenting the student with a working appreciation for the fundamental input parameters necessary to begin building and competently analysing pipe stress models.