Refinery - II M&I SD Oct-Nov 2018

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Chennai Petroleum Corporation Limited (A group company of Indian Oil)
Technical - Inspection
15-F-02 A: SCHEMATIC SKETCH OF REPLACEMENT PORTIONS
2.2.4 15-F-02B VACUUM HEATER
Coil Arrangement:
Chennai Petroleum Corporation Limited (A group company of Indian Oil)
Technical - Inspection
Description Number of tubes Tube size Tube MOC
4.5” OD X 6.01 mm Thk. -26 nos.
2 Passes X 28 tubes/ each pass
Radiant HC Coil
6.625” OD X 7.11 mm Thk.-1 no. A 335 Gr.P9
Total-56 tubes
8.625” OD X 8.18 mm Thk.-1 no.
40 studded tubes +
Convection HC coil
4.5” OD X 6.01 mm Thk.- 48 tubes A 335 Gr.P9
8 plain tubes
Brief History:
In 2007 decoking short shutdown, the carburized/holed out arch roof casing plate at west manway location was
replaced & ceramic fibre lining was renewed at that location. Due to severe bowing/oxidation scales & high
surface hardness, 3 nos. of radiant coils were replaced.
Emergency shutdown was made on August 2011 due to convection tube leak due to carburization on account of
inner side coke deposit. In total, 26 nos. out of 42 nos. of convection tubes were replaced. Utilizing this
opportunity 2 nos. of radiant tubes were also replaced due to bulges & low thickness. Complete arch roof plate
was replaced & ceramic module was relined.
In 2012 M&I shutdown, Bottom, middle & top bank intermediate tube sheets were replaced as recommended
earlier due to multiple cracks along with end tube sheets. Stack tip retainer ring alone was replaced. Addition of
top two rows convection studded tubes; all burner replacement with low NOx type & burner floor plate along with
refractory replacement jobs were taken up as a part of revamp project activities. 10 nos. of radiant tubes were
removed and 6 nos. new tubes (with increased size) were added.
CRUDE DISTILLATION UNIT
(CDU/ VDU-II PLANT-15, 17, 18)
- Convection section return bends
Convection section
replacement.
return
bends replacement.
(South side)
(South side)
Ref-II vacuum section was taken on emergency shutdown in Nov’ 2016 due to convection shock tube leak in 15-
F-02B. Failure was attributed due to internal coke formation & localized overheating due to absence of velocity
steam provision at the shock tubes. Bottom bank all 8 nos. of tubes were replaced & recommended to
reintroducing velocity steam connection. External carburization/dis-coloration was noticed on 5 - 6 nos. of
radiant tubes (earlier dis-coloration was noticed on-stream) & same was recommended to monitor. Radiant
internal brick lining was renewed for the top 3 rows only & external patches were provided on shell external
surface. Partial arch roof replacement with module was carried out.
Upon completion of decoking radiant bottom, arch roof, convection and stack manways were opened & inspected.
Following major jobs were carried out.
9 nos. of Radiant tube replacement.
Replacement of 8 nos. of convection shock tubes & 4 nos. return bends due to low thickness.
Radiant Shell casing (EL + 7424 m to EL +12148 m) replacement along with refractory renewal.
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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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