Reconditioning of TGME-206 Boiler Damaged by Through Cracks and Estimation of Its Serviceability

Abstract

Aspects of the process of repair of drums, which are virtually irreplaceable boiler units, are very important, especially under the conditions of intense wear and exhaustion of the service life of power equipment. Problems of reconditioning and estimation of the after-repair serviceability of TGME-206-type boilers damaged by through cracks in the zone of the recirculation hole are described. A brief characteristic of the boiler and the steam drum and a detailed description of the damage are presented. The defects are eliminated by mechanical removal of the damaged metal. Control of the repaired zones and of undamaged zones confirms the absence of defects in the metal. Analysis of the results and computation of the cyclic endurance show that the appearance of cracks at a relatively early operation stage is caused by permanent disturbances of the operating conditions of the recirculation line. The processes of repair welding of the drum and subsequent local heat treatment (high-temperature tempering) are described. According to strength computations and a study of the condition of the metal, the reconditioned boiler should operate safely for at least two more years.