Failure Analysis of Ethylene Cracking Heater, ET-O-F-105 Tube

The study is to analyze failure of an ethylene cracking heater’s tube, from Ethylene (M) Sdn Bhd. The objectives of the research are to conduct relevant tests and experiments, analyze data obtained and suggest recommendations to avoid similar incident in the future. Visual Inspection revealed cracks and deformation on the tube. Inner surface of the tube experienced more failure compared to outer surface of the tube. It can be concluded that the failure was originated from the inner side of the tube. Non-Destructive Testing revealed the only three cracks detected. However, from the visual inspection, cracks can be detected. It can be concluded that, the failure was originated from the inner side and penetrated to the outer surface at some point where the failure is most severe. From Hardness Testing, at inner surface of the tube, where carburization was most severe, the average hardness was found to be higher than the middle section of the tube. Carburization is expected to the factor of this hardening. From Microscopy Examination, precipitates of small blocky type are found in the austenitic grains. Comparison between Microscopy Examination image with higher magnification and uncarburized Nickel-Chromium image revealed that high degree of carbide precipitation at the grain boundaries and blocky carbide particles in the matrix compared to the uncarburized Nickel-Chromium alloy. Chemical Analysis proved Carbon’s involvement at the surface of the tube. Fractography showed intergranular fracture of the tube. It can be concluded that the mode of failure of the radiant furnace tube was a combination of creep damage and carburization attack. Experimental data shows that the furnace tube had undergone carburization due to exposure to excessively high temperature and carbide formation from the reaction of carbon during service. To avoid similar incident in the future, it is recommended for Ethylene (M) Sdn Bhd to review all operating parameters of the furnace. As a long-term recommendation, it is also recommended for Ethylene (M) Sdn Bhd to replace Nickel-Chromium alloy with an Al2O3-forming alloys. It is recommended to further study the furnace system and analyze samples from other furnace units

Prospective observational cohort study on grading the severity of postoperative complications in global surgery research

Background The Clavien–Dindo classification is perhaps the most widely used approach for reporting postoperative complications in clinical trials. This system classifies complication severity by the treatment provided. However, it is unclear whether the Clavien–Dindo system can be used internationally in studies across differing healthcare systems in high- (HICs) and low- and middle-income countries (LMICs). Methods This was a secondary analysis of the International Surgical Outcomes Study (ISOS), a prospective observational cohort study of elective surgery in adults. Data collection occurred over a 7-day period. Severity of complications was graded using Clavien–Dindo and the simpler ISOS grading (mild, moderate or severe, based on guided investigator judgement). Severity grading was compared using the intraclass correlation coefficient (ICC). Data are presented as frequencies and ICC values (with 95 per cent c.i.). The analysis was stratified by income status of the country, comparing HICs with LMICs. Results A total of 44 814 patients were recruited from 474 hospitals in 27 countries (19 HICs and 8 LMICs). Some 7508 patients (16·8 per cent) experienced at least one postoperative complication, equivalent to 11 664 complications in total. Using the ISOS classification, 5504 of 11 664 complications (47·2 per cent) were graded as mild, 4244 (36·4 per cent) as moderate and 1916 (16·4 per cent) as severe. Using Clavien–Dindo, 6781 of 11 664 complications (58·1 per cent) were graded as I or II, 1740 (14·9 per cent) as III, 2408 (20·6 per cent) as IV and 735 (6·3 per cent) as V. Agreement between classification systems was poor overall (ICC 0·41, 95 per cent c.i. 0·20 to 0·55), and in LMICs (ICC 0·23, 0·05 to 0·38) and HICs (ICC 0·46, 0·25 to 0·59). Conclusion Caution is recommended when using a treatment approach to grade complications in global surgery studies, as this may introduce bias unintentionally