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Recommendations

7. Nitrogen cylinder to be stored at safe place. To avoid the hazards while lifting/shifting, storage place to be
developed in open area (preferably N-E corner of fire training ground.) so that vehicle (forklift/trolley/tractor)
to made available near storage place.

Case 16 Date: 22.05.2020 Time: 10:40 hrs.

Incident

MP Ethylene emergency vaporizer 67-E-001 was taken in line on 02.05.2020 and was in normal operation for
supply of ethylene to HDPE and MEG units. At 10.40Hrs on 22.05.2020, ethylene leak was observed along with
steam from shell of MP ethylene vaporizer, immediately MP Ethylene transfer pump was stopped and isolated.
Vaporizercircuit depressurized to flare.

Photograph showing crack in MP ethylene Photograph showing crack in MP ethylene
vaporizer shell from outside vaporizer shell from inside

Root Cause

1. Shell failure occurred due to leakage of ethylene from inlet header (Shell is not design to sustain cold ethylene)
As soon as cold ethylene came in contact with shell due to tube leakage, got sudden thermal shock which
resulted cracking of the shell).
2. Welding defect during fabrication and propagation of welding defect in long running duration. Tube leakage
has given further cooling to other tubes due to liquid ethylene expansion and might have resulted to weld
crack. Liquid ethylene temperature and pressure drop has given significantly chilling.

Recommendations

1. M&I schedule to be developed once in 5 years.
2. Ges detector installation to be relocate at height from grade level.

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