STUDY OF IMPACT OF THERMODIFFUSION ZINCCOATING CHARACTERISTICS ON CASING PIPES THREAD CONNECTIONS MAKING-UP CAPABILITY

Abstract

One of promising areas of prevention of thread connections performance characteristics failure and of the irimprovement is considered to be application of anti-friction coating, as well as their quality upgrading. Selection of type of thread coating and method of its application, is considered to be an important stage for provision of a long-term operation of thread connection. In the process of casing pipes manufacturing, the use of couplings with thermodiffusion zinc coating becomes a frequent practice. In this article results of analysis of impact of ther modiffusion zinc coating on casing pipes thread connections making-up capability. A comparative making-upofahigh-torquecouplingt hread connection was performed (coupling Ø200,03 mm, pipe 177,8×9,19 mm, of structural alloy chrome-manganese high-quality steel), with thermodiffusion zinc coating applied within various production conditions. Make-up performance during the study was determined using a torque recording system with plotting a make-up diagram. An extended study was conducted to determine the coating characteristics such as microstructure, chemical composition of phase components, roughness and hardness of the thermodiffusion zinc layer. Analysis of the obtained data allowed to identify additional factors that impact the performance properties of threaded connections. In addition to assessing the quality of the coating using standard parameters (thickness and appearance), which are often used as key parameters in the production of casing pipes, it is advisable, if necessary, to additionally evaluate the roughness and microhardness of the coating. This study contributes to the expansion of knowledge in the field of thread coatings, their parameter and properties evaluation, in the context of ensuring make-up performance of casing pipe threaded connections.