The O‑ring backup ring set (ORBRS) change shutdown (SD) reduction from 10 to 1½ days won appreciation; yet the author continued his efforts to stop the continuing 3-monthly discharge head (DH) leaks, consequent 6 on stream days lost total NH3 and 70% lost Urea Production.
Constantly thinking about it, the author recollected Kalrez, Du Pont advertised new super sealing material.
The ad claim of Kalrez’s higher than Viton – the present O-ring material – upper temp limit, super long time-resiliency and inertness to all known chemicals characteristics.
After a detailed study, he was confident of its success; at least it won’t worsen the present situation.
However, the compressor vendor declined Kalrez O‑rings supply. He did not even give the O-ring dimensions, to get it from an O‑ring vendor citing deviation from his standard and proprietary information as the reasons.
Shining a powerful flashlight on the last supply shipping list reverse side, the author jotted down the blacked-out dimensions.
Kalrez O‑Ring from a US O-ring supplier and the usual PTFE backup ring at the DH never leaked!
Extending the new ORBRS quick-change method, bundles pre-TA assembled using bought-out stationary parts and available spare rotors reduce K‑601 each barrel overhaul times to just 36-hours, eliminating turnaround (TA) or shutdown pressures due to the Middle East and call center attracted depleting Rotating Machine Crew strength.
How Kalrez O-rings seal so effectively so long?
Below given are the author guessed possible reasons:
- Viton, the original O-Ring material temperature rating is lower than that of Kalrez
- Maybe the vicinity fire had slightly deformed the DH annulus, the ORBRS sealing area
- Maybe Viton deteriorates faster than Kalrez; hence it starts leaking within 3‑months.
- Once the 250o C gas leak starts The rubber also attains the same temp and deteriorates still faster
- The very slow deteriorating Kalrez O‑ring does not allow leaks starts maybe up to 4 years the overhaul intervals. Hence, its temperature never exceeds its rating.
The crew puts new elastomers at each 4‑yearly overhauls. Hence, no leaks seen ever.
Author: S. Raghava Chari
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