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PRELIMINARY INVESTIGATION REPORT

DC #5 SHELL PLATE LEAK

1.0 Event

Date : 05th November 2011

Time : 10:20 am

Heat No. : 5055443

A. DC# 5 shell plate below KT3 leak; happen during

tapping. The root cause of leakage was the bricks bad

condition consequence from water leaking of panel WCP 1-9

at 15 October 2011 and loose of coupler supply water WCP

1-11 on 05 November 2011. Tap temperature high due to

over arching worse the bricks condition.

B. History of Incident

Date Heat No. Event

04.10.2011 5054917Slag penetrate below KT3Patching with castable and gunning

15.10.2011 5055097 Panel WCP 1-9 leak

27.10.2011 5055204 F/hose cooling block KT8 leak

29.10.2011 5055338 Panel ECJ and RCP leak

01.11.2011 5055377 Tap temp 1651 C,O2 ppm 288 ppm

03.11.2011 5055405 Tap temp 1628 C,O2 ppm 556 ppm

03.11.2011 5055413 Tap temp 1630 C O2 ppm 745 ppm

03.11.2011 5055422 After hot repair Tap temp 1628 C O2 ppm 577 ppm

04.11.2011 5055432 Over shoot tap temp 1647C ladle preheater

04.11.2011 5055433 Gunning 1698kg

04.11.2011 5055438 Gunning 1528kg

05.11.2011 5055443Coupler W/return WCP 1-11 looseShell plate leak during tap

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2.0 Preliminary Causes

Based on our investigation, the leakage happens due to :-

1. The bricks area under KT 3 was very bad condition. The bricks

heavy erosion due to effect of water leaking from WCP 1-9 at

15 October 2011 and water leaking from loose coupler WCP 1-

11 at 05 November 2011.

2. Temperature high up to 1651oC due to overarching. Furnace

operation increases the temperature for ladle parking, ladle

preheater and after hot repair. The S.O.P required normal tap

temperature only 1610oC and 1630 oC for ladle preheated.

3. DRI was very low quality with high silica content 3 % required

furnace to use high amount of CaO 3500 per heat.

3.0 Equipment Damages

i) Shell Plate under KT 3

ii) Bricks area KT 3

iii) Bottom furnace Sensor and Cable

iv) Limit switch Tapping lock post

v) Hose cooling busbar

vi) Bottom electrode

4.0 Preventive Measure

1. To focus gunning at the high erosion bricks consistently.

2. Detail Check furnace condition once stoppage/onpeak schedule.

3. Dont delay the gunning activity schedule for safe mode.

4. Change the high erosion bricks or collapse bricks as quick as

possible.

5. DR plant must plan for high quality DRI on the future consistently.

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5.0 Cost Of Damages

Shell Plate repair RM x

New Bricks RM xBottom electrode RM x

Bottom furnace Sensor and Cable RM x

Busbar cooling hose RM x

Tapping lockpost limit switch RM x

Man Power RM x

Total Cost RM xxxx

Prepared by, Checked by,

Mohd Zakaria Khamis Mr. Abd Rahman Che Min

Mohd Nasuha Abd Halim

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ATTACHMENT

Picture 1: Shell plate leak below KT3

KT3 KT8

Leak area

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Picture 2: Brick condition below KT3 after incident

KT3

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Picture 3: Below furnace