Refinery - II M&I SD Oct-Nov 2018

Regenerator Air Grid:
Chennai Petroleum Corporation Limited (A group company of Indian Oil)
Technical - Inspection
ARL damage & bulging at few locations on the main header was noticed. ARL on few air grid nozzle tip portion
found damaged/missing. Most of the Air grid nozzle tip found eroded severely up to 10 mm out of projected length
of 80 mm. Tip of almost 70% of air grid nozzles found with mild erosion & most of the air grid nozzle end rings
(2.0 mm thick SS 304) found eroded/missing. As planned earlier, air grid replacement was planned after removal
of old cyclones.
Chennai Petroleum Corporation Limited (A group company of Indian Oil)
Technical - Inspection
Bulges were noticed at several locations on plenum chamber shell plate. Many lug supports found welded on the
plenum shell over a period of time (during each shutdown to hold/rectify cyclones).
The air grid with main header was cut & removed from its position in three segment. Subsequently all three new
segments fit up was done. During fit up mismatch was observed and the same was corrected by flaring of pipe
edge & matching the OD of the pipe and cleared. Final weld was cleared by after checking by visual, DP & spot
radiography (based on weld quality). Finally the removable type branch arm was fixed back & both plate flanges
were lip seal welded.
ARL (19 mm HT SS304 hexmesh & S Bars with RESCO AA 22S) was renewed at all 4nos. of field weld joints.
Additionally ARL was relined for approx. 0.5 m 2 in the existing retained portion. Additional ARL (with S bars) was
provided covering the air grid arm flange plates after welding.
3D view during erection
Two segments fit up stage
Lug support plates welded on plenum shell
Plenum Chamber:
Air grid erection in three segments
Both sec. cyclone outlet thermocouple sleeves (2" pipe) found cut at the top & fallen on
the gas pipe with severe bulges at several locations. Vibracast lining cracks were
noticed in the Plenum chamber internal lining & at the flue gas outlet duct from Plenum.
Minor cracks in the plenum external retainer plate were also noticed. Crack was also
noticed at few lug support to plenum joining location & retainer plate to plenum joint
location. ARL biscuits damage/dislodgment was noticed at many locations inside the
secondary cyclone outlet pipe (connected to plenum) towards inside of plenum chamber.
Minor cracks also noticed at the edge bar located at tip of the o/l pipe.
Condition of Plenum chamber shell & primary cyclone top flange
Tilting of primary cyclone top flange
towards regen. Cyclone
It was noticed that over a period of last 34 years of service, due to loading (of entire cyclones online &
supporting loads during shutdown maintanance) on plenum chamber skirt plate since inception (1984), both
the primary cyclone flange setup has come inward. Which got reflected in variation of centre to centre distance
between each primary cyclones during verticality verification (same was maintained in order to ensure free
verticality of each cyclone by adjusting the brazing bar length).
Refractory around the takeoff location of the thermocouple sleeves was removed. Old left over portion (damaged
already) was cut & new thermocouple sleeves (2nos) were replaced with 2” Sch 80 SS 304 pipes below the retainer
plate. Refractory around the sleeves was relined (hand packing) after welding few additional anchors. Missing
hexmesh was fixed/welded back at the dislodged location & ARL was relined with RESCO AA 22S. Weld repair was
carried out at the edge bar (tip of the outlet pipe).
FLUIDIZED CATALYTIC
CRACKING UNIT (FCCU – PLANT 16)
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Refinery - II M&I S/D Oct-Nov 2018 - Inspection Report
Refinery - II M&I S/D Oct-Nov 2018 - Inspection Report
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