Papers by Author: Jorge Luis González

Abstract: Hydrogen embrittlement is a common problem for the integrity of oil conducting pipes. In this work, we estimate the rate of hydrogen penetration into an API 5L steel pipe welded by electric arc. The hydrogen penetration was estimated by means of data taken from ultrasonic measurements. As expected, the steel pipe becomes more brittle as the hydrogen penetration rate does so. A simple diffusion model was developed. The model confirms the strong dependency between the rate of penetration and the mechanical damage to the material.

Abstract: This paper describes a technique to fabricate instrumented composite cylinders made by the filament winding process and based on the insertion of Bragg grating sensors contained in an optical fiber, so that real time monitoring of the temperature and strain response can be made. The main advantage of this method is that, for the first time, the strain response of the wound layers as a function of time and temperature can be monitored during fabrication without alteration of the composite structure, since the sensor is a filament itself. The sensor data reveals the existence of several phenomena related to the manufacturing process and material response. The results show that during the curing stage of the fabrication of the composite cylinders there is a dimensional contraction without change in temperature which indicates that a material transformation occurs, and also that at the last stage there is a residual compressive strain which may affect the in-service behavior of the composite cylinder.