The T-8-20 Task Group conducted a survey of plant practices and of the performance of materials of constrution in HF Alkylation Units. A Primary goal of the survey was to expand the limited body of the information on alternative ally performance in HF Alkylation units and to better define the susceptibility of steel to hydrogen induced cracking.
The aggressiveness of the atmospheric environment can be assessed by measurement of climatic and pollution factors, or by determination of the corrosion rates of metals and coatings. The latter is a low cost technique which has traditionally been employed at single isolated sites with different types of environments. This approach does not, however, adequately portray the levels of corrosivity across a city or region which can vary by an order of magnitude. A technique has been devised at the Commonwealth Scientific and Industrial Research Organization (CSIRO) in which specimens are exposed across a grid of contiguous sites and the results computer contoured to generate corrosivity maps. A new method of h hyperbolic interpolation of the data has been developed to model corrosivity approaching the coastline. The paper presents results from surveys around an industrial point source of S02, conducted over two different periods. The technique of corrosivity mapping was demonstrated to be a sensitive indicator of localized zones of enhanced corrosion, and the two maps reflected changed conditions in the plant's operation in the two periods. The paper also discusses corrosion mapping in countries other than Australia and examines the costs of such exercises and the potential savings they can provide.
When distress of a structure is evident, it is important to determine the nature of the degradation to select the best restoration strategy. This standard practice provides testing procedures and investigative techniques for the evaluation of masonry-clad steel frame buildings. The investigation and evaluation techniques described in this standard focus on degradation resulting from corrosion of the steel frame.
This standard provides the investigator, corrosion specialist, engineer, or owner a framework for evaluating the corrosion condition of a steel frame building beyond simple visual inspection and basic sounding techniques. Evaluation techniques that identify general and localized corrosion of masonry-clad steel frame buildings are provided.
This standard is intended for use by corrosion specialists, historic architects, structural engineers, and exterior building envelope consultants involved with evaluating corrosion of steel frame buildings and the subsequent effect on the masonry cladding. It also may be useful to owners of historic buildings whose service life may be affected by steel frame corrosion.
Direct current (DC) sources are a critical component of many cathodic protection (CP) systems. In order to assess the performance of these CP systems, momentary interruption of the DC current output is often utilized to help obtain true polarized potentials of protected structures1. This is achieved with a relay that is either integral to the DC current source or installed externally. Traditionally, these relays use a mechanical or mercury contactor, but solid-state relays are becoming more popular for their increased performance and reduced environmental footprint. Recent experience has indicated that interruption of current with an inductive load can damage solid state relays by momentarily exceeding their voltage rating. This has been observed by some CP technicians when they return to site to check on a previously installed interrupter, only to find it overheated and not interrupting. This study will examine the various sources of inductance in impressed current CP systems and discuss methods for mitigating the inductive effects during interruption. To demonstrate the effectiveness of these methods, an electrical circuit was created to mimic a cathodic protection circuit, and the effectiveness during interruption was measured using an oscilloscope.