For the past decades, natural gas (NG) has been playing a vital role in all aspects of development especially the use of natural gas to replace other sources of energy such coal and oil. The prime role of pipeline design is safety and therefore the integrity of the welded pipelines begins with good engineering design and construction practices that are based on working procedures. The design, construction, operation, and maintenance of piping systems involve understanding of piping fundamentals, materials, and specific design considerations, fabrication and installation, welding, examinations, and testing requirements to well-established standards and rules, because the products they carry can pose a significant threat to the surrounding population and environment. The causes of accidents around the world are due to various reasons such as corrosion; excavation damages; incorrect operation; materials/welding/equipment failure; natural force damage (heavy rains, floods) and sabotage.
Quality assurance and quality assessment of welded pipes play a crucial role in the safety of pipeline systems and of the public. In this presentation, we will discuss several issues related to the construction welding activities such as : high-low misalignment, unequal wall thickness transitions, high longitudinal stress/strain associated with lifting and lowering-in practices, inadequate tie-in and repair welding procedures, improper NDT performance and interpretation results and insufficient assurance of adherence to qualified welding procedures, which if improperly dealt during the construction activities can lead to defects and failures mechanism which in turn will inevitably trigger catastrophic incidents in natural gas pipelines.
