The Ship Repair Man Story
Understanding Your Generator’s Nomenclature and Signals
Real Life Incidences
- On a container ship, there was a planned generator maintenance. But the engineers should have checked what spare parts they had on board. While doing the maintenance, they realized they needed to replace a “big end bolt” part because it was stretched out and not working well. However, they didn’t have a spare one on the ship. So, they had to stop the maintenance and wait until the next port to get the new part. This delay cost the company more money because they needed more power to use the refrigerated containers on the ship.
- Before they could do the maintenance on the generator, they needed some special tools to remove a part called the main bearing. But they needed to check if these tools were working correctly. When they tried to remove the main bearing, they realized an essential nut for one of the tools was missing. They couldn’t use the tool without this nut and had to make a new one in the ship’s workshop. This took extra time and delayed the whole maintenance process.
- Many ships need help with essential tools and measuring equipment. These tools are used to make sure everything is working correctly. But sometimes, they need to be taken care of or appropriately checked. When required to measure things, they can only be found if they are recovered or broken. This causes delays because the company needs help getting the necessary measurements.
Delaying the maintenance of a ship’s generator is a serious problem and can lead to significant losses for the company. It’s essential to be organized, check the tools, and have spare parts ready to avoid these costly delays.
Consequences of Neglecting Proper Tagging Out and Assembly Procedures
- While ensuring the generator was safe to work on, we forgot to use a particular tag to keep the lube oil priming pump switched off. This pump got power from an emergency switchboard. When there was a blackout, someone accidentally turned on the lube oil priming pump for the “open” generator, and this caused oil to spill all over the generator platform. Cleaning up the mess and regaining power took a lot of time.
- When we were doing maintenance on the engine and opening the cylinder head, a lot of water suddenly got into the crankcase. We figured out that it happened because we didn’t open the vent cock, which would have let the water drain properly from the cylinder head and jacket.
- On a tanker ship, there was a terrible accident. A high-pressure pipe for a hydraulic jack burst, and a crew member got seriously hurt. Later, we realized we had used too much pressure when opening the cylinder head. It was way more pressure than what was needed, and that’s what made the pipe burst.
- When we were running the engine, we got lucky. We noticed that all the big-end bolts were getting loose. It turned out that we needed to understand something called the tightening unit. It was supposed to be in kgf-m, but we were using N-m, and that’s why the bolts were coming loose.
Mistakes like these can be dangerous and cause a lot of trouble. Paying attention to all the little details when working on a ship’s engine is essential to keep everyone safe and avoid delays.
Consequences of Neglecting Proper Tightening and Misusing Special Tools
- When we were trying to open the cylinder head, one of the four hydraulic nuts got stuck and wouldn’t budge, even when we increased the hydraulic pressure to 940 bar (the required pressure was 920 bar). To fix this, our experienced chief engineer had us tighten all the nuts back to their recommended pressure and then try opening the stuck nut with a force of up to 950 bar. It finally came loose at 950 bar and was then retightened to the correct pressure of 920 bar. Afterward, we opened all four nuts together using the recommended hydraulic pressure.
- We encountered a problem when removing the piston from a three-piece connecting rod. We should have used a tool called the liner holding tool. As a result, when we pulled the piston out with a chain block, not only did the piston come out, but the entire liner came out of its place because the piston was stuck inside it.
- We encountered an issue while removing pistons from a MAN B&W engine with three-piece straight-cut connecting rods. The big end part of one unit could freely rotate. When we tried to remove the significant end bearing of one team, we rotated the crankshaft using the turning gear without checking the big end housing of the other units. Unfortunately, one of the big end assemblies got stuck in the engine frame, causing a crack near the crankcase door. Repairing the structure cost the company a significant amount of money, running into thousands of dollars.
These incidents highlight the importance of following proper procedures and using the right tools in engine maintenance to prevent costly and potentially dangerous mishaps.
Consequences of Neglecting Spare Parts Testing and Overhaul Procedures
- We had a spare cylinder head that had been overhauled a while ago, and we decided to use it to replace one unit’s cylinder head without pressure testing it. The engineer in charge assumed that the previous engineer must have tried it after overhauling, as there was no test record. However, as soon as we started the generator, the cylinder head began to leak due to a crack in the valve jacket. Fixing this issue required additional person-hours to replace the faulty head with a pressure-tested one.
- We discovered severe cracks and pitting in the liner of one of the units. We removed the damaged liner using a liner removal tool to replace it with a new spare liner. However, it got stuck in the jacket frame when we tried to fit the new liner back in. This happened because we had not cleaned the jacket properly before fitting the new liner. Mud deposits in the jacket started sticking to the O-ring, eventually damaging the new O-ring. To resolve the issue, we had to remove the entire liner again, clean the jacket, and renew the O-ring.
- After completing a thorough overhaul, we started the generator for the running-in process. To our surprise, we noticed that the exhaust temperatures for all the units were still higher than expected. We still needed to maintain and clean the air cooler element during the overhaul.
These situations show how crucial it is to do necessary tests and maintenance when using spare parts and engine pieces. If you don’t, it can cause more work problems, making it take longer to get the generator working well again.
Ensuring Proper Maintenance and Checks for Smooth Generator Operations
- A critical incident occurred during the generator’s d’carb process when a previously overhauled cylinder head was used as a spare. After a successful d’carb, one unit suddenly started making a loud knocking sound, leading to an immediate shutdown of the generator.
- When they looked closely, they found that the stick that held the valve had broken. This made the valve go into the engine’s burning chamber. This not only damaged the piston top but also the cylinder head itself. The root cause of this catastrophic failure was traced back to the excessive clearance between the valve and the guide, which hadn’t been checked during the d’carb process. This led to the valve fluttering and ultimately breaking.
- During the crucial running-in process of a generator, an alarming issue arose when the crank pin-bearing temperatures for all units were noted to be excessively high. Additionally, traces of white metal were discovered in the sump oil. Upon further investigation, it was revealed that the bearing shells used as replacements were all undersized. This oversight in incorrect bearing shells resulted in elevated temperatures and potential damage to the engine components.
- Following the standard procedure of measuring crankshaft deflection before and after the d’carb, a third engineer noticed that two out of the eight units showed higher deflection values. This finding was immediately reported to the Chief Engineer. Upon closer examination, it was determined that the hydraulic nuts on the bearing keep of the affected unit were in a loose condition.
These situations show why properly caring for and checking a generator is crucial. Doing these critical tasks helps prevent big problems, expensive damage, and time when the generator can’t work. It’s a reminder that maintaining a generator is essential to keep it running well.
Avoiding Common Pitfalls in Engine Maintenance
- During routine maintenance, the decision was made to replace the crank pin-bearing shells for all the engine units. While this seemed like a straightforward task, a crucial mistake occurred. The upper and lower shells were correctly inserted, but the crankshaft was rotated using the turning gear before the big end bolts were tightened. Unfortunately, this rotation caused the bearing shell to shift and become misaligned. The problem was only found when they looked inside the engine, and they had to fix it immediately.
- Another incident occurred while fitting the connecting rod to the piston, where the small end of the connecting rod should fit into the piston bore using a gudgeon pin. In an attempt to do this, the crew decided to insert the connecting rod without attaching the bottom half, using manual lifting. However, due to the weight of the connecting rod, it slipped and caused damage to the serration surface. This error necessitated replacing the connecting rod with a spare one.
- After successfully fitting the cylinder head and tightening it with the recommended torque, the maintenance team rushed to complete all the connections as quickly as possible. Unfortunately, they overlooked a critical step. They failed to test for water leaks by opening the water supply. After all the connections were finalized, the jacket cooling water was opened, revealing leakages in two units. Consequently, the team had to disassemble all the links again to rectify the leakages.
With these events, we learn about the importance of good care. They show us that being careful and paying attention to small details is important. Avoiding misalignment, mishandling, and oversight ensures smooth and error-free maintenance processes.
Avoiding Operational Blunders in Engine Maintenance
- While running the engine, a problem arose after 2-3 startup attempts when the engine shut down due to low lube oil pressure. The root cause of this issue was neglected maintenance: the lube oil filters had not been replaced before starting the engine for running in. This oversight resulted in dirty filters, causing a drop in oil pressure.
- Following a successful d’carb of the engine, an engineer officer began the process of opening valves for various systems. While handling the freshwater system, the officer initially opened the outlet valve in the correct sequence. However, when attempting to open the inlet valve, they operated it too quickly. This sudden action caused a significant drop in jacket water pressure within the running generator, leading to an emergency shutdown and blackout.
- Many ships have experienced damage to the turning gear and flywheel gearwheel due to the sudden start of a generator without removing the turning gear and with the safety interlock not engaged. This oversight has resulted in accidents and damages, including cases where a tommy bar was accidentally left in the flywheel before starting the generator.
- On one ship, the d’carb procedure was extended for an extended period. However, when it came time to restart the generator, no one had drained the starting airline. This oversight allowed water to pass from the starting airline into the cylinder head through the starting air valves, causing complications.
These situations remind us of the importance of being careful and precise when caring for engines. If we don’t do regular maintenance, handle valves correctly, remove turning gear, or pay attention to safety measures, it can lead to expensive problems, accidents, and power disruptions. Doing things correctly and paying attention to the small details are essential to prevent these mistakes during engine maintenance.
