16133

14404

كارشناسي ارشد

جوشكاري

اصفهان : دانشگاه صنعتي اصفهان

1399

دوازده، 79ص. : مصور(رنگي)، جدول، نمودار

عباس بهرامي، عبدالمجيد اسلامي

احمد كرمانپور

مسعود عطاپور، احمد كيواني

1399/09/30

كتابنامه

مهندسي مواد

مهندسي مواد

1399/10/03

2656004

Isfahan University of Technology Department of Material Engineering Investigating the causes of destruction of superheater pipes in the boiler Mohammad Mahmoudian m mahmodian@ma iut ac ir Degree M Sc Language FarsiSupervisor Abbas Bahrami Prof Email a n bahrami@cc iut ac irAbdolmajid Eslami Prof Email m eslami@cc iut ac irAbstractOne of the reasons for the high cost of boiler failure is the unit s long term forced outages of thecircuit to replace or repair components After a field inspection and inspection of the boiler andsuperheater pipes the damaged and non damaged pipes were examined In the next stage quantumtests metallography elemental analysis fuzzy analysis phase analysis using XRD and EDS andhardness tests were performed on the pipes and the causes of the destruction of superheater pipesfrom the results of tests performed on the pipe Destroyed and compared these results with testsperformed on undamaged pipes were extracted Based on quantum tests performed on the four tubesexamined three tubes were in the creep resistant low alloy steels group chromium molybdenumsteels and one tube was in the austenitic stainless steels group which is an alloy of this tube Theyare used in the construction of superheater pipes By examining and performing various tests ondamaged pipes and comparing it with the results of examining undamaged pipes several mechanismswere involved in the destruction of superheater pipes By examining the damaged pipe the eventsthat happened to this pipe include swelling of the pipe at the site of rupture rupture of the pipe inthe mouth formation of deposits and oxide shells on the outer and inner surface of the pipe fractureof sediments and inner oxide shells And external at the site of pipe rupture reduction of pipethickness microstructural decomposition from ferrite perlite to ferrite and spherical carbides decarburization of the structure formation of cavities and bubbles and microcracks and grainseparation on the outer surface and hardness drop According to the mentioned cases the degradationmechanisms in the degraded pipe under study included overheating creep rupture abrasioncorrosion high temperature hydrogen damage thermal oxidation and microstructural decomposition Due to the higher temperature of the metal on the outer surface of the pipe than the inner surface andbecause the high temperature accelerates and increases the degradation in metals so the outer surfacewas more exposed to damage than the inner surface of the pipe Keywords Superheater Boiler Creep rupture Overheating Abrasion corrosion Hydrogen damage Thermal oxidation Microstructural decomposition

عباس بهرامي، عبدالمجيد اسلامي

احمد كرمانپور

مسعود عطاپور، احمد كيواني