Root Cause Analysis (RCA): Ruined Demineralization (Demin) vessel internals threaten indefinite Ammonia plant shutdown.
| Article Type: | Root Cause Analysis (RCA) |
| Category: | Mechanical |
| Equipment Type: | Pipelines and Miscellaneous Problems |
| Author: | S. Raghava Chari |
Note: This root cause analysis (RCA) is from real-time scenarios that happened in industries during the tenure of two or three decades ago. These articles will help you to improve your troubleshooting skills and knowledge.
Demineralization Mixed Bed Vessel Problem
Wrong operation internals destroyed demineralization (De-min) mixed bed vessel need readying within 8 hours because of the following:
- De-min tank level will last max 9 hours only
- Demin water production not resumed within 8 hours will shut down the 1500 T/d NH3 plant
- Not meeting the hard won international orders involves heavy financial & image loss
- NH3 plant shutdown (SD) and restarts are time & efforts intensive, thermally stresses the plant equipment and shortens their lives
Constraints
- No spare parts available
- Rush Air freight from Japan takes minimum 2 months
Authors Improvisation
below described is the Authors Improvisation:
- Scouted the local market and made a vendor deliver in an hour the readily available 2” CPVC pipes; pipe-caps, 10 Nos. hand held drilling machines, 50 Nos. ½ mm drill bits and PVC glue 2 cans
- Shop crew cut 80 mm long rings out of the damaged laterals’ usable portions
- They machined the ring bores to to slide fit on 2” CPVC pipes. They glued the rings to the pipes cut to lateral lengths and the caps at the other end
- All – mechanics, electricians, and instrument mechanics – drilled numerous ½ mm dia holes all over the CPVC pipe guided by a wrapped round ½ mm brass strainer sheet.
- Homemade two in one lateral and distributor assembly (LDA) making progressed
- Field crew went on inserting the readied LDA in the demin vessel central vertical pipe sockets. Thus the demin vessel was ready for resin charge in 5 hours!
- Operation crew charged the resin and mechanical crew boxed the vessel. The demin vessel was ready in 7 hours, though the allowed time was 9‑hours!
With a vigorous prayer, operators started de-mineralization. As good quality as before demin water surprised all. The doom predicted ‘exerts’ grudgingly congratulated the author.
Author improvisation benefits:
Below listed the Author improvisation benefits:
- Demin water production resumption in 7 hours averted the 3 months or even longer ammonia plant shutdown, missed export deliveries’, penalties, and the debuting company’s image loss etc.
- Laterals and distributors several hundred dollars purchase saved
- A ready solution to handle future mishaps if any was in hand
The author made LDAs were still in service when he retired 5 years later.
Author: S. Raghava Chari
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