A Root Cause Analysis of Catastrophic Failure of Industrial Discharge Hopper Pipe | Chapter 8 | Engineering Research: Perspectives on Recent Advances Vol. 3

Several failures of the industrial pipes have been reported in the past and most of them are due to Stress Corrosion Cracking (SCC), sensitization and hydrogen embrittlement. Stress Corrosion Cracking is a delayed failure where corrosion environments such as condensed water, ammonia solutions, moist air, and solutions containing chlorides and nitrides play a major role. This work presents a detailed investigation and root cause analysis of the catastrophic failure of an industrial discharge hopper pipe. The hopper pipe investigated in the present work is made of austenitic stainless steel, 316 grade, a commonly used grade for valves, pipes and heat exchanger tubes. The pipe fractured in the transverse direction, leading to the failure of the discharge pipe. Visual inspection, dye penetrant test, chemical analysis, microstructural analysis, and fractography analysis were carried out on the failed part and it was concluded that stress corrosion cracking led to the failure of the hopper pipe. The pipe constantly being under exposure to industrial water and the presence of chlorine content in it made it susceptible to stress corrosion cracking. Transgranular fracture was clearly observed in the microstructure of the failed sample and spot EDX at the fracture location confirmed the presence of chlorine content. This indicates that the pipe has been subjected to corrosion because of service conditions/environment and any of those minor cracks would have opened up with the continued service operation, had the major transverse fracture not taken place. Further, fractography showed striations indicating fatigue loading. The work concluded that stress corrosion cracking was the root cause of failure. Cathodic protection or suitable polymer coating should be considered as the preventive measures to avoid stress corrosion cracking in future.

 

Author (s) Details

 

S. Rajole
Department of Mechanical Engineering, School of Engineering, Central University of Karnataka, Kalburgi 585367, India.

 

P. R. Sondar
Department of Metallurgical and Materials Engineering, National Institute of Technology Karnataka, Surathkal 575025, India.

 

S. Hiremath
Department of Mechatronics Engineering, Manipal Institute of Technology, Manipal 576104, India.

 

K. S Ravishankar
Department of Metallurgical and Materials Engineering, National Institute of Technology Karnataka, Surathkal 575025, India.

 

Please see the book here:- https://doi.org/10.9734/bpi/erpra/v3/3965

Stress Corrosion Cracking of Lean Duplex Steel in 3.5% Sodium Chloride Solution | Chapter 2 | Recent Trends in Chemical and Material Sciences Vol. 1

 Duplex stainless steels (DSS) offer a desirable combination of austenitic and ferritic characteristics and are widely utilised in petrochemical, pulp and paper, and other industries. They outperform standard austenitic stainless steels in terms of corrosion resistance, particularly chloride stress corrosion and chloride pitting corrosion, as well as strength. They are a good contender for the offshore oil and gas industry because of these factors. Weight loss measurements, electrochemical corrosion tests, and a slow strain rate test were used to explore the stress corrosion behaviour of duplex stainless steel in a 3.5 percent sodium chloride solution in this work (SSRT). After 1700 hours of weight reduction, there was no substantial corrosion. In a 3.5 percent NaCl solution, an electrochemical polarisation test revealed a consistent corrosion rate of 0.008 mpy and passivity in the range of 735–950 mV Vs SSC. In a 3.5 percent NaCl solution, a comparison of the slow strain rate test for duplex stainless steel revealed a similar stress-strain behaviour. The stress-strain behaviour of mild steel, on the other hand, exhibited a loss of roughly 25% elongation. The excellent corrosion and, in particular, pitting resistance of DSS was thought to be responsible for its ductility.

Author (s) Details

Muhammad Shahid
School of Chemical and Materials Engineering, National University of Sciences and Technology, Islamabad, Pakistan.

Ammer K. Jadoon
British Petroleum Ltd, UK.

Qanita Tayyaba
School of Chemical and Materials Engineering, National University of Sciences and Technology, Islamabad, Pakistan.

Hina Farooq
School of Chemical and Materials Engineering, National University of Sciences and Technology, Islamabad, Pakistan.

View Book :- https://stm.bookpi.org/RTCAMS-V1/article/view/2179