How Kalrez O-rings Seal So effectively So Long?

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:

1. Viton, the original O-Ring material temperature rating is lower than that of Kalrez
2. Maybe the vicinity fire had slightly deformed the DH annulus, the ORBRS sealing area
3. Maybe Viton deteriorates faster than Kalrez; hence it starts leaking within 3‑months.
4. Once the 250^o C gas leak starts  The rubber also attains the same temp and deteriorates still faster
5. 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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