In the marine industry, the use of industrial borescopes to inspect cylinder head valves through fuel injector holes is a highly efficient and a non-destructive testing technique. It is widely applied in the maintenance and fault diagnosis of diesel engines, particularly large marine low-speed two-stroke or medium-speed four-stroke engines.
1.Yateks Q series application cases in Marine inspection
Recently, an international VLCC (Very Large Crater Carrier) successfully identified minor erosion on the sealing surface of an exhaust valve using the Q-Series industrial borescope, independently developed by Shenzhen Yateks Co., Ltd. Early detection allowed for timely replacement of the valve seat, preventing power loss due to gas leakage during navigation and damages to the turbo charger. Additionally, a cracked valve stem was discovered, enabling root cause analysis and preventing a potential major failure.
2.What are the daily inspection problems that may arise on marine?
It is very important for these inspections as the customer had failures in the past where a piece of the broken valve ended in the exhaust manifold and damaged the turbo charger turbine wheel and nozzle ring. When this happens a very costly turbo, charger must be replaced.
By performing borescope inspections (1000 hourly), we can detect any valve damages and minor cracks that could result in a failure.
When a piece of valve breaks, customer have the following parts to replace.
- Cylinder head and gasket kit
- Normally we have a damaged cylinder liner , so also the liner must be replaced
- Piston crown could also be damaged, so also the piston…
- Turbo charger – damage to nozzle ring & turbine wheel
So a very costly operation that costs approximately $50 000 (USD)
Therefore, the borescope inspection are crucial!
3.Typical Faults that can be found using the Yateks industrial borescope
（1）Oil seepage is visible at the damaged valve seat, with minor edge wear observed.
（2） Valve head margin erosion
After several inlet valve failures, we noticed that the valve always failed in the same manner, at the highest temperature exposure, we now inspect that area closely with the borescope to see any damages, as seen in the below image
(3) The valve stem is broken due to fatigue stress or improper assembly
（4）Damaged turbine wheel from broken off pieces of exhaust valve
Turbo charger with exhaust bellow connections visible, the broken valve pieces ends up in the turbine wheel and damaged the fins.
Turbo charger with exhaust bellow connections visible, the broken valve pieces ends up in the turbine wheel and damaged the fins
Broken valve pieces ends up in the turbine wheel and damaged the fins
Based on our experience, field maintenance personnel often need to perform batch inspections of cylinder head valves using borescopes. To improve efficiency, we recommend using a small O-ring as a depth guide to ensure the probe is inserted to the same depth each time, as shown in the figure below.
Yateks Industrial borescope has won high praise from customers for its efficient and accurate detection performance, and has always been a high-quality choice in the field of industrial inspection. If you have similar detection needs, please feel free to contact us!