Failure analysis of submersible pump system collapse caused by assembly bolt crack propagation by stress corrosion cracking

The Recycling Potential of Submersible Sewage Pumps in the EU

“…Sewage pumps play an important role in wastewater collection and treatment because they have been among the main electromechanical equipment of these facilities around Europe for over 30 years [1][2][3][4][6][7][8][9]12]. Their operational life is around 15-20 years and thus a significant number of them are non-functional any more [2,[7][8][9][10][13][14][15][16]. The need for replacement of these pumps has increased the number of pumps that must be disposed of in the forthcoming years [17].…”

“…Another important consideration is that the life expectancy of sewage pumps (around 15 years, even if their maintenance, repair procedures and operation during these years follow the manufacturer directives, precautions and limitations) could be extended, with the ultimate result that a relatively small number of pumps will reach their end of life [3,[5][6][7][8][9][10][11][12][13][14][15][16][17]23]. Many of these facilities have been in operation for more than 15 years in Greece and around the EU, resulting in an increased number of sewage pumps becoming non-functional.…”

“…Here it must be noted that all products that were manufactured and distributed in the EU internal market from 2003 and onwards comply with the European directive RoHS (Directive 2002/95/EC). The previous note means that the products do not contain lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls (PBB) or polybrominated diphenyl ethers (PBDE) at levels exceeding the maximum concentration values [3,6,[8][9][10][11]15,18,19,24].…”

Design Optimization on 2 Vane Pump of Wastewater Treatment for Efficiency Improvement

“…Scholars both at home and abroad have made a deep study into the submersible pump, among which for the first time in 1979, Kratzer A [1] systematically summarized design and model selection issues of the sewage pump, and emphatically analyzed the lossless performance of various pump when discharging materials; J.A. Escobar [2] studied safety of the submersible pump by analyzing submersible pump system breakdown caused by stress corroded fitting bolt through X-ray fluorescence spectrum; Parviz Ali-Zadea [3] carried out study on submersible pump noise, analyzed the relations between interference level and noise level and provided a noise elimination plan; Hernandez -Solis, A and Carlsson, F [4] studied the relation between submersible centrifugal pump cavitation and motor power capacity, diagnosing cavitation and impeller damage of the submersible centrifugal pump by monitoring motor power capacity and current flow; Liu, Yingyuan [5] mainly studied the cavitation flow characteristics of the rotor pump and discussed several factors affecting the cavitation, including rotation speed, pressure difference and gap size and inlet pressure; Lee, Kyoung -Hoon [6] carried out experiments on the effects of cavitation flow instability of the double-blade axial inducer and observed the internal asymmetric cavitation and cavitation phenomenon of the inducer; Cudina [7] established correlation with pump cavitation through noise spectrum generated by cavitation, so as to test the cavitation; Domestic scholars Wang Songlin [8] and Wang Yushi [9], etc. verified the feasibility of the RNG k-ε model and the transport equation cavitation model through experiment, finding that pressure pulsation intensity under cavitation condition was 2 times as much as that under non-cavitation condition, and pressure pulsation under low flow condition was about 5 times as much as that under design condition; Zhu 88 Rongsheng and Wang Zhenwei [10,11], etc.…”

Analysis of Contact Angle for Metallic Materials in Wastewater Pumps

“…The paper includes a study on the influence of the contact angle on the dynamic corrosion resistance of the metallic materials used in the fabrication of the immersed wastewater pumps. The contact angle (the surface tension of the liquid on a flat surface) reflects the possibility of forming a boundary layer adhering to the active surface of the pump working area [3][4][5]. The limit layer (where the liquid has null speed) forms a relative protection zone for both erosion and corrosion.…”