Michiel P. H. Brongers

Effect of Hydrostatic Testing on Ductile Tearing of X-65 Line Pipe Steel with Stress Corrosion Cracks

Abstract Hydrostatic testing is one method to confirm the integrity of pipelines containing colonies of stress corrosion cracks. Although this technique is widely used, a concern of the pipeline industry is the potential for ductile tearing damage of subcritical flaws. Objectives of the current study were to evaluate the influence of hydrostatic testing on the crack tip morphology and to determine the amount of ductile tearing that may occur for different hydrostatic testing conditions. Stress corrosion cracks were grown in compact tension specimens of X-65 line pipe steel in a near-neutral-pH stress corrosion cracking (SCC) environment. Simulated hydrostatic tests were performed at loads that corresponded to hoop stresses at and above the specified minimum yield strength (SMYS), resulting in applied J-integral values near to and above the J(Q) fracture toughness value of the material. Some specimens ruptured; some did not fail. Crack tip blunting occurred and the tearing extent was small and proportional...

Facility Integrity Management and Assessment of Associated Risk Conditions

This paper reviews the basic elements of a facility integrity management program and describes the process used to assess risk conditions related to a facility. The policies, goals and objectives of the program should be defined before implementing it. The location and details of the facility and all its equipment must be described and the information should be recorded in a computerized database. Important triggers for change management and the minimum features of change management are reviewed. Ensuring the competency and training of personnel responsible for integrity management is essential. The integrity management team must identify hazards associated and ways of controlling them. Once hazards are identified, risk assessment is performed and options for reducing risk are considered. Results of the risk assessment are then used to plan and execute activities of the integrity management program. Needed repairs or replacements are identified, planned and completed. Finally, the integrity management program should incorporate a continuous improvement process and information from investigations of incidents at the facility, at other company locations, and within the industry.Copyright

Failure Analysis and Fitness-for-Service Assessment of Nickel 200 Baffles in PVC Reactor

Visual inspection of Nickel 200 (Ni-200) baffles inside several Type 304L reactor vessels used to produce PVC revealed corrosion in the form of localized metal loss along the baffle’s length direction. Prior to recent process changes, these baffles had operated satisfactorily for about 8 years. The observation of metal loss raised concerns as to the cause of the corrosion, and the possibility of compromised structural integrity of the reactor baffles. A failure analysis was performed to characterize the nature and extent of the corrosion, based on scrape samples and cut-out samples. A Level 3 fitness-for-service assessment per API 579 was performed to evaluate the urgency for repairs. Laboratory corrosion testing was then done to further investigate the influence of pH, oxygen, and temperature, on the corrosion susceptibility of the Ni-200 material in this application.Copyright

Review of Test Methods for Evaluating Hydrogen Embrittlement Susceptibility of Materials

For several decades, engineers and technicians responsible for safe transport and storage of hydrogen, in both the government and industry sectors, have had to contend with the problem of hydrogen embrittlement. Today, the problem of hydrogen embrittlement must be considered anew with the systems and environments emerging with the developing hydrogen fuel cell industry. This paper discusses several methods to test for the susceptibility of metallic materials to hydrogen embrittlement. The objective of this review is to assist engineers and designers in selecting hydrogen embrittlement test methods to simulate actual manufacturing and/or operating conditions while using appropriate specimen geometries. Reviewed are standard test methods from American Society for Testing and Materials (ASTM) International, British Aerospace Series (BSEN), and General Motors Engineering sources. These include constant load, rising step load, slow strain rate, inclined wedge, bend, disk pressure, and cantilever beam test methods. Information is provided on load and displacement characteristics, uses, a brief description, and required equipment for each test.Copyright