Archive | 2019
Protecting machinery parts against the loss of surface
Abstract
Abstract Wear of machinery surfaces is a large contributor to maintenance load and plant downtime. In this chapter, the authors explore the possibilities of preventing and/or mitigating the consequences of various mode of wear by applying wear resistant coatings to wear surfaces. After examining basic wear mechanisms, hard-surfacing techniques such as shielded metal-arc (SMAW), oxyacetylene, tungsten arc, and other welding processes are listed and their advantages and disadvantages discussed. It is recommended that users must familiarize themselves with the work of the American Welding Association to understand the multiplicity of suitable electrodes available on the market. The different alloys used in hard-surfacing are described and their application listed. Special materials are examined such as ceramics, details of the detonation gun process, an example for high-velocity thermal spray coatings and a guide to selecting surface materials is offered. Additionally, the authors provide guidance for surface coating specification writing. Other methods of preventing wear of sliding surfaces are scrutinized, such as tungsten carbide coatings and industrial plating, including an example of chrome plating for reciprocating compressor cylinder liners to provide a hard surface with a low coefficient of friction. A good number of references and check lists complement this section on surface wear mitigation. The authors decided to add a section on the selection and application of O-Rings as these sealing devices are often subject to minute wear processes. After describing typical applications of O-rings around process machinery the following issues entering the application and selection process are discussed: Deterioration of O-rings in storage, the influence of temperature on life expectancy, undetected mechanical damage, chemical attack, and general compatibility with the process fluid. Extensive documentation in form of tables and pictorial material is provided to help the reader obtain an overview of application and selection of O-rings.