Search Results for ASTM A106 (seamless carbon steel pipe)

A felt guide roll fractured in-service on a paper manufacturing machine, damaging the belt as well as multiple dryer rolls, nearby felt guide rolls, and the frame of the machine. The investigation included visual and stereoscopic examination, chemical and microstructural analysis, microhardness and tensile testing, stress calculations, and vibration measurements. Based on the results, the roll fracture was attributed to high-cycle fatigue associated with a plug weld over one of the five threaded fasteners added to secure a balance weight inside the roll. The balance weight was installed to compensate for variations in wall thickness (i.e., weight distribution) of the pipe product used to make the roll. According to the investigation, resonance and vibration, which were initially considered, did not cause the failure.

A closed-loop hot water heating system at a museum in South Carolina was the subject of failure evaluation. The system consisted of plain carbon steel pipes (Schedule 40) made of ASTM A 106 or A 53 (ERW or seamless). The supply and return lines were made of the same materials. The fittings were mechanically threaded assemblies. Temperatures ranged from 150 to 155 deg F (65.6 to 68.3 deg C). Leaks in the system had reportedly initiated immediately after the building had been placed in service. The cause of corrosion inside the steel pipes was attributed to tuberculation caused by oxygen concentration cells and oxygen-pitting related corrosion. Both types of corrosion are due to the poor quality of the water and the lack of corrosion control in the water system.

This article discusses the effect of using unsuitable alloys, metallurgical discontinuities, fabrication practices, and stress raisers on the failure of a pressure vessel. It provides information on pressure vessels made of composite materials and their welding practices. The article explains the failure of pressure vessels with emphasis on stress-corrosion cracking, hydrogen embrittlement, brittle and ductile fractures, creep and stress rupture, and fatigue with examples.

This article discusses pressure vessels, piping, and associated pressure-boundary items of the types used in nuclear and conventional power plants, refineries, and chemical-processing plants. It begins by explaining the necessity of conducting a failure analysis, followed by the objectives of a failure analysis. Then, the article discusses the processes involved in failure analysis, including codes and standards. Next, fabrication flaws that can develop into failures of in-service pressure vessels and piping are covered. This is followed by sections discussing in-service mechanical and metallurgical failures, environment-assisted cracking failures, and other damage mechanisms that induce cracking failures. Finally, the article provides information on inspection practices.

A gas-fired, ASTM A-106 Grade B carbon steel vaporizer failed on three different occasions during attempts to bring the vaporizer on line. Dye penetrant examination indicated the presence of multiple packets of ductile cracks on the inside of the coil radius at the bottom of the horizontal axis coils. Visual examination of the inside of the tubing indicated the presence of a carbonaceous deposit resulting from decomposition of the heat-exchanging fluid. Subsequent metallographic examination and microhardness testing indicated that the steel was heated to a temperature above the allowable operating temperature for the fluid. The probable cause for failure is thermal fatigue due to the localized overheating. Flow conditions inside the tubing should be reexamined to ensure suitable conditions for annular fluid flow.

This article describes some of the welding discontinuities and flaws characterized by nondestructive examinations. It focuses on nondestructive inspection methods used in the welding industry. The sources of weld discontinuities and defects as they relate to service failures or rejection in new construction inspection are also discussed. The article discusses the types of base metal cracks and metallurgical weld cracking. The article discusses the processes involved in the analysis of in-service weld failures. It briefly reviews the general types of process-related discontinuities of arc welds. Mechanical and environmental failure origins related to other types of welding processes are also described. The article explains the cause and effects of process-related discontinuities including weld porosity, inclusions, incomplete fusion, and incomplete penetration. Different fitness-for-service assessment methodologies for calculating allowable or critical flaw sizes are also discussed.

Hydrogen damage is a term used to designate a number of processes in metals by which the load-carrying capacity of the metal is reduced due to the presence of hydrogen. This article introduces the general forms of hydrogen damage and provides an overview of the different types of hydrogen damage in all the major commercial alloy systems. It covers the broader topic of hydrogen damage, which can be quite complex and technical in nature. The article focuses on failure analysis where hydrogen embrittlement of a steel component is suspected. It provides practical advice for the failure analysis practitioner or for someone who is contemplating procurement of a cost-effective failure analysis of commodity-grade components suspected of hydrogen embrittlement. Some prevention strategies for design and manufacturing problem-induced hydrogen embrittlement are also provided.