Maintenance & Reliability
The modern maintenance culture attempts to predict failures before they reach a severity that affects the equipment’s performance. This modern philosophy makes the classic time-based maintenance model inefficient. Despite many papers and studies on this topic, many organizations reject change and still hold to the classic model. This is because change upsets the order, the rituals. Some organizations have essentially been institutionalized, valuing their methods more than they value their production. This paper attempts to apply the organizational change methods developed in the business environment by John Kotter of the Harvard Business School to an industrial maintenance organization.
ArcelorMittal USA operates various continuous casters that produce a wide spectrum of steel grades. These casters were built in the 1980s or earlier when the knowledge of the effects of specific nozzle designs on the resulting slab surface temperature in the secondary cooling zone was not as sophisticated as today. Today, procedures such as off-line nozzle testing using an impact pressure measurement for spray footprint analysis, heat transfer coefficient (HTC) measurement with realistic casting conditions, and off-line and on-line slab surface temperatures calculations with implementation of directly measured HTCs are the most important steps in the process of analyzing the effect of nozzles used for secondary cooling at ArcelorMittal USA. The results of these types of analyses achieved by close cooperation within R&D, Operations, Quality and Operation Technology departments produce slabs with improved surface quality. This type of analysis can determine which sprays are performing poorly and lead to significant improvements in slab quality. Examples of this complex approach for Indiana Harbor and Burns Harbor casters will be discussed to show improvements in secondary cooling efficiency and slab quality.
This paper presents an approach to discover patterns in big data sets and applying methods of artificial intelligence (AI) for interpretation. The paper will present the use of AI to identify the main refractory wear mechanism in the hot spots and to predict the refractory behavior. Further, this intelligent system is applied to analyze and compare different maintenance philosophies. As an example of the impact on daily operations in steel plants, a daily report is presented, which provides all the necessary key information when a refractory-related decision is to be made. The paper also examines and discusses the operational impact and future applications.
There are various reasons for modernizing electrical equipment. This paper will discuss multiple types of modifications to plant electrical systems, including scope of equipment and services that should be considered. Process requirements may dictate upgrading motor and drive ratings. Site physical conditions may suggest one implementation approach while production requirements dictate a different approach. The following discussion is intended as an overview of electrical modernization considerations and to assist in the justification and planning process.
This paper will present testing that revealed a dramatic reduction in fatigue life due to bearing material containing carbide segregation. The phenomenon of carbide segregation within steel will be explained, and the fracture mechanism demonstrated that causes bearings to fail prematurely. When carbide bands are present in bearing steel microstructure, the wear resistance of the material significantly decreases. Once the bearing is installed in the application, microcracks can form along the carbide bands. Through the stresses induced during cyclic fatigue, the microcracks formed beneath the surface of the steel grow and coalesce, which eventually results in premature spalling and bearing failure.
Adding oxygen into air for blast furnace (BF) ironmaking has positive and negative effects. The positive effects are increasing BF production by reducing bosh gas volume for controlling the blast pressure and maintaining the raceway adiabatic flame temperature (RAFT) above the lower limits for desired rates of fuel injections. However, the negative effect is reducing the sensible heat from the hot blast (air + oxygen) for given blast temperatures and the same total oxygen inputs. In this paper, the effects of oxygen enrichment on BF coke rate and on upper limits of fuel injection rates will be discussed, along with the minimum RAFTs for BFs with different injection fuels.