During a routine stroke testing of a shutdown valve, it was found that the valve was not passing the test. A technician who checked the valve heard a hissing noise coming from a fitting on the valve stem that looked like a grease injection point.
The valve had historically been lubricated with grease through the stem injector fitting to aid the performance of the valve. This fitting had been wrongly assumed to be a grease injector fitting. The actual purpose for the fitting was to inject a sealant in the event of a lower stem seal failure. As technicians were unknowingly greasing the cavity between upper and lower stem seal, it caused the collapse of the lower stem lip seal, causing gas to migrate up to the injector fitting.
This is a lesson why we need to read OEM manuals!
Contribute to the surviving victims of Bhopal by buying my book "Practical Process Safety Management"
The valve had historically been lubricated with grease through the stem injector fitting to aid the performance of the valve. This fitting had been wrongly assumed to be a grease injector fitting. The actual purpose for the fitting was to inject a sealant in the event of a lower stem seal failure. As technicians were unknowingly greasing the cavity between upper and lower stem seal, it caused the collapse of the lower stem lip seal, causing gas to migrate up to the injector fitting.
This is a lesson why we need to read OEM manuals!
Contribute to the surviving victims of Bhopal by buying my book "Practical Process Safety Management"
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