In this paper a new low cost, wireless unpowered sensor will be discussed that is designed to monitor the conductivity of concrete, which may provide information on the ingress of chloride ions during the life of the structure. A method of extracting temperature information from a previously developed corrosion sensor will also be presented. During a recent test, both a wireless corrosion sensor and a wireless conductivity sensor were placed in concrete and monitored throughout the duration of the curing process. Analysis of the data shows it is possible to determine temperature information based on the corrosion sensor response, allowing wireless in-situ temperature monitoring of the concrete during the cure. Monitoring curing temperature using the same sensor which would later be used for long-term corrosion detection would help reduce the cost of such a monitoring system.

Prototype sensors have been developed to detect the onset of corrosion in steel reinforced concrete using non-invasive techniques. These sensors are designed to be extremely simple and low cost. The sensors are embedded in the concrete and are powered and interrogated through the use of inductively coupled magnetic fields. A new conductivity sensor is proposed, based on the design of the corrosion sensor. The conductivity sensor design is examined using circuit simulations and initial experimental results. Both sensors could be used together in a corrosion monitoring system.

The long-term reliability of a threshold corrosion sensor is demonstrated using data collected during two series of exposure tests. The sensors were embedded in concrete and interrogated in a wireless manner using inductive coupling. The frequency signature of the sensor changes after a steel sensing wire corrodes, providing a convenient and noninvasive technique for determining when a threshold amount of corrosion has occurred in a reinforced concrete structure.In the first series of exposure tests, the sensors were embedded in concrete prisms, which were exposed to a variety of temperature and moisture conditions over a six-month period. In the second series of tests, the sensors were embedded in reinforced concrete slabs. The slabs have been subjected to sustained loads and alternating wet and dry cycles for the past year. Data from both test series indicate that the threshold sensors are functioning as designed.

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That the manufacturing and fabrication process can introduce low fracture toughness and cause brittle failure in steel has been documented in well-known studies. These include failure of Liberty ships during World War II and, more recently, weld failures in steel moment frames during the 1994 Northridge earthquake. In both of these cases, the manufacturing and fabrication process introduced stress states that reduced fracture toughness and caused brittle failures.Control of the manufacturing and fabrication process to maintain sufficient fracture toughness remains a challenge for the Oil and Gas Industry. In this article, we will review an incident of a brittle failure of a pressure vessel. The head of the pressure vessel, which was operating as a low-pressure separator, detached about its circumference at a pressure much less than the vessel's maximum operating pressure. A root cause analysis of the incident identified the performance gaps and root causes from the vessel's service conditions, manufacture, and fabrication that combined to cause the brittle failure.This article examines the performance gaps that lead to the failure and their root causes. The effect of the root causes on the vessel's mechanical properties is discussed. Further, the performance gaps are related to material and fabrication guidelines in the ASME Boiler & Pressure Vessel Code. Finally, recommendations for correcting the performance gaps are offered.