I understood that the spindle drop down should be maintained for at least 15 minutes by blocking after supplying air to the air cylinder.
The Instruction Book on the new ship says that the drop down time after changing the new seal-ring rings can be significantly shorter than 15 minutes, and that it should be tested after 500 hours of use. What is the reason for this? In general, the New Seal-ring would be in a good state of confidentiality.
Please give advice to the seniors.
New seals require a run-in time to reach the rated tightness. If after 500 RH the valve fails 15-minutes drop-down test this may mean on of the following:
- Pure quality of the installed new seals
- Seals installation procedure was not followed
- Metal sealing surfaces have defects (due to scratches, corrosion etc)
- Leaky non-return valve or its threads
The purpose of the drop-down test is to check the overall integrity of air-space under the air piston including the non-return valve. Leaky non-return valve leads to incomplete closing of the valve with subsequent troubles with compression, combustion and exh. gas temperature.
Thank you for the good information. My question has been solved. Good luck.
