Failure Analysis and Integrity Management

Failure analysis and integrity management of mechanical equipment, piping and structures is one of the main business activities of CCPGE. For this purpose, we primarily utilize software such as ANSYS, AutoPIPE CONNECT and CAESAR II. Failure analysis and integrity management include FEA calculations of stress, deformation, fatigue and fracture characteristics of mechanical equipment, piping and stuctures, subjected to applied static and dynamic loads in a working environment. This provides technical reference for elucidating root causes of mechanical failure and also for improving designs of mechanical equipment, piping and stuctures. CCPGE has a successful track record for failure analysis and integrity management projects, and has also published numerous technical papers in international journals and conferences in this field.

Failure Analysis and Design Improvement of Cylinder Joint Structure

Pipeline integrity management is one of the main development areas in CCPGE. As pointed out by Dr. Duan, CCPGE’s pipeline integrity expert, at the CIPC 2021 (Beijing), that pipeline integrity management should be more than just a fitness-for-service assessment during a pipeline’s operating stage; it is actually a management strategy throughout the pipeline’s service life – from the pipeline’s design, construction to operation.

Pipeline integrity management includes many aspects. Dr. Duan pointed out that pipeline stress /strain based design, girth weld quality and environmental stress cracking are three of the most important aspects to be considered.

Pipe stress /strain based design

Typically, problems such as pipe float and uplift buckling caused by the changing ground conditions and operating conditions, as well as pipe-soil interactions and ratcheting makes stress predictions challenging. These problems can be resolved effectively by improving pipe stress /strain based design.

Girth weld quality

Fractures failure in girth welds has become a major integrity threat to pipelines. Mechanical semi-automatic welding, while improving production efficiency, also poses a challenge to the quality of welds. Workmanship compliance does not guarantee the safety of welding quality, the requirements for fracture toughness testing have also become increasingly critical.

Fracture Toughness Test

Environmental stress cracking

The current integrity assessment is mainly based on traditional fracture mechanics. For hydrogen pipelines, the assessment philosophy based on traditional fracture mechanics is no longer applicable. Some preliminary experimental results indicated that the fracture behavior of hydrogen pipeline materials is different from common pipeline materials. For example, Multiple fracture toughness values have been found which makes the current fracture criterion K <KIC no longer valid, the progression of fatigue cracks depends on loading frequency, etc. As a result, the pipeline integrity management system needs to be improved accordingly.

Progress of Fatigue Crack Depends on Loading Frequency

CCPGE has provided a week long pipeline integrity management training course to related subsidiary companies of Sinopec. At present, CCPGE is closely working together with national-class Labs in Canada to jointly conduct experimental tests and theoretical research on the design and integrity management development of hydrogen pipelines.