Engine failure by hydraulic lock
In this post on Engine failure by hydraulic lock, we will discuss a catastrophic Engine failure by Hydraulic lock inside the Cylinder.
This failure is the actual life incident on such failure; I had an opportunity to witness as an Adviser to an authorized agent of a Reputed Diesel Engine manufacturer.
History of Engine failure by hydraulic lock
This incident took place in 2020 in an automobile factory.
The Engine is of 3.8 MWe capacities. The machine was in EDG mode. During the power supply interruption by the government electricity supply, the Diesel generator operator attempted to start the engine.
During starting the Engine, the shift engineer heard an obnoxious sound from the Engine. The speed of the Engine was falling gradually, resulting in a frequency drop. The Engine was stopped immediately by an emergency stop.
He engaged the turning gear of the Engine. But the Engine was hard to turn, and the turning motor was unable to turn the Engine. The engineer informed his power plant Manager.
The shift engineer started inspecting the cause of this failure. He opened all the crankcase doors. On his further inspection, he observed that one connecting rod was in a stuck position. There was bent in the center of the connecting rod.
My involvement in the Engine failure by hydraulic lock investigation
The power plant Manager gave a call to me. I immediately rushed for the site and reached after a 1-hour journey from Delhi to Gurgaon. The factory was located on National Highway.
After reaching the factory, I started to investigate the cause of this catastrophic failure. I asked the engineers to dismantle the affected unit.
After the complete dismantling of the Engine following damages have been observed.
- Damage on valve driving gears, including Cylinder Liners. Cylinder liners have suffered vertical deep scoring marks on the total length of the working surface.
- Damage on Cylinder Heads.
- Damage on all the piston rings of the entire unit
- Damage on push road and valve guide housing.
- Damage of all the barrels and plungers of all the FIP.
- Damage of TC compressor Wheel and Nozzle Rings and other associated parts.
Reason for the failure
The probable reason for failure is due to the running the heavy ingress of water into the Cylinder Liners through leaky cylinder heads, causing the hydraulic lock in the affected cylinders and adjacent parts. Parts of High speed running Turbocharger were also subjected to heavy shocks, resulted in failure of components, and needed to be the replacement. Other parts like fuel injection equipment and Connecting rod bearings have also suffered damage.
My further analysis to ascertain the root cause of water ingress into the cylinders and engine crankcase, which was the cause of the catastrophic failure, is as mentioned below.
- Staff carried out the hydraulic test of the affected cylinder heads. There was leakage of water from the valve seat area in the vicinity of the channel.
- On further investigation and close observation observed the symptoms of a combination of cold corrosion from sulphuric acid and normal erosion from the particles in the exhaust gas.
- The origination of corrosion was due to the sulphuric acid from the sulphur contents. The corrosion starts when the surface temperature of the cylinder head is below the dew point of sulphur.
A complete list of damaged parts, with the parts that need replacement to make the Engine Operational, is attached herewith.
A picture of the damaged parts is reproduced below.
Recommendations to avoid future failures (Engine failure by hydraulic lock)
During the normal starting, the Engine follows the following starting procedure.
- Turn the Engine by keeping the indicator cocks in an open position
- Blow through the Engine with air and keep a close watch on the indicator cocks.
- Take the necessary action if water emerges out during air turning of the engine
- Never attempt to start the Engine if any fuel or water particles are seen from the indicator cocks.
It is mandatory to folow all the points mentioned in above engine starting procedures must be followed for the trouble free operation of the DG set. These points are crucial for the DG sets used as EDG operation.
An engineer with experience should be allowed to start the Engine.
It is always advisable to keep cool during the emergency situation. Creating panics will worsen the situation. In the light of my experience, I have seen that engineers commit mistakes after getting panicky.
Author’s Experience on Failures. (Engine failure by hydraulic lock)
In the recent past, the available fuel for the Diesel power plant is of inferior quality. Fuel contains a heavy amount of sulfur contents.
Heavy sulphur contents are the main cause of Machinery exhaust system failures. Cold corrosion takes place in the path way of exhaust gases. Heavy sulphur has been the threat to environment conditions. Sulphur produces sulphuric acid, which is harmful to the metals and results in cold corrosion leading to cylinder head getting punctured. Punctured cylinder heads are the reason for the ingress of water in to the combustion chamber and hydraulic lock
To reduce the SOx, most Diesel engine owners are using scrubbers. Even in shipping, also use of scrubbers is popular.
Catastrophic failures of engines due to the above reasons are causing production losses and increase the maintenance budget.
It has also been observed that some engine manufacturers are using inferior quality of material for the engine components to reduce the production cost and compete in the market.
If we go by the experience, we will observe that the engines with the same manufacturers were not experiencing such failures in the past with the same fuel quality. But this type of problem started emerging in the recent past only.
It is dangerous to compromise with the metallurgy of the engine components to reduce the Engine’s overall cost
The Cylinder heads water leakage due to cold corrosion is a recent development in the past few decades.
The author of this post has 45 years of years experience in the shipping and Indian Industries. The article is real life incident took place in one factory in North India..
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