Marine Diesel Insights

A mounth ago, I wrote an article regarding the damages observed in piston connecting rods . Shortly after that, we received a service request from a ship where it was reported that the connecting rod had bent and fractured the liner. In this article, I will discuss the findings, conclusions and preventive measures related to the incident on the ship we provided service for. The piston rod that has fractured by striking the liner [1] We visited a ship waiting at anchor to inspect the situation of a diesel generator following an incident. Upon arrival we observed that all the cylinder heads had been removed by the ship's crew from the engine and that the engine could not be rotated . The damaged cylinders were numbers 2 and 6 (firing order 1-4-2-6-3-5). In these cylinders, the piston rods had bent and struck the liners resulting in fractures and the engine was immobilized in this state. The ship's crew had attempted to disassemble cylinder number 6 but had not succee...

   To investigate the seizure of the crankpin bearing in generator No. 3 of a ship operating we conducted an on-site inspection aboard the ship to identify the root cause. The information provided was as follows: Disassembly and reassembly of covers and pistons are performed for maintenance purposes. After maintenance, the machinery is reassembled. The machine is started and operated for a continuous duration of 15 minutes. Engine connecting rod axial movement is inspected by opening the crankcase covers. An issue of overheating or failure is observed in crankpin bearing No. 1. Figure 1 - From left to right - No. 1 crankpin, No. 1 upper crankpin bearing, No. 1 lower crankpin bearing Firstly, the No. 1 piston connecting rod, which had been removed by the ship's crew, was tightened without the bearing in place. The inner diameter measurement was taken using a micrometer, and it was determined that there was an ovality of nearly 30%. Figure 2 - Example Demonstration of Conn...

  Introduction In diesel engines certain bolts are of utmost importance. To ensure that a bolt performs its function effectively it needs to be tightened to a predetermined torque within the elastic range. This torque value is provided by the manufacturer. In some cases tightening the bolt may require multiple steps. For instance in certain bolts after tightening they may need to be loosened and tightened again to achieve the desired tension and proper clamping force. In this article I will share some insight I’ve gained while I was trying to explore the reasons behind the “ tightening, loosening, and re-tightening ” steps provided in the tightening procedures by machine manufacturers. I am quoting a significant portion of the article from a comprehensive study conducted by A. Strozzi [1] and colleagues . In the other sections I have included the sources I used as much as possible. I have also tried to add some insights from my own experiences. Any mistakes made during the proces...