1st/2nd Grade Steam Engineer - Oral examination

1st Grade Steam Engineer - Part B paper 1- Desember 2003

1st Grade Steam Engineer - Part B paper 1- June 2003

Boiler Overhaul

Overhaul boiler dilakukan setiap 15 bulan untuk menyambung CF (Certificate of Fittness) atau + 3 bulan + 3 bulan (if approved) 

Langkah2

1)Turunkan firing, stop boiler operation dan cooling down

2) Buat isolation boiler system

3 Open man hole boiler

4)Lakukan boiler pre-inspection (internal)

5)Sekiranya didapati ada defect seperti crack, mesti repair dahulu

6) Buat mekanikal cleaning pada surface, tube dan furnace

7)Final inspection (internal)

8)DOSH inspection

9)Box-up

10)Filling boiler dengan feed water dan leak check

11)Sekiranya DOSH menghendaki Hydro test, blind semua flange dan ikut procedure HT test

12)Flushing all boiler water apabila selesai

13)Filling boiler dan dosing chemical Ammonia dan Hydrazine

14)Start-up boiler

15)Buat recommissioning dan safeguarding test (PSV, Level switch)

16)On-line operation

WATER HARDNESS

Hardness dipecahkan kepada Carbonate dan non-carbonate hardness
Hardness – Kewujudan Calcium dan Magnesium (dan mungkin iron, aluminium, manganese

CLASSIFICATION	Carbonate hardness	Non-bicarbonate Hardness
Calcium hardness	Calcium Bicarbonate Ca(HCO3)2 Calcium Carbonate CaCO3	Calcium Sulphate CaSO4 Calcium Chloride CaCl2
Magnesium Hardness	Magnesium Bicarbonate Mg(HCO3)2 Magnesium Carbonate MgCO3	Magnesium Sulphate MgSO4 Magnesium Chloride MgCl2

Boiler Explosion

Letupan yang berlaku didalam Furnace
Minor Explosion dipanggil sbg Puff, Flareback or fire blowback.


Biasanya disebabkan oleh:
- pengumpulan gas yang tidak terbakar (unburn fuel) didalam furnace
- Air/fuel ration in a explosive mixture
- Pembakaran yang tak sempurna
- ignition timing failure
- insufficiency purging process
- Fuel supply and control not in proper condition
- Loss of furnace draft


Kerosakan akibat daripada Furnace Explosion
Dinding boiler retak, mengelembong dan runtuh
Tube dan tube plate retak, longgar akibat dari gegaran
kerosakan pada plate baffle
kerosakan teruk seperti boiler explosion, drum sagging dan kerosakan boiler structure


Langkah2 asas bagi mencegah Furnace explosion:
Buat pemeriksaan boiler operasi secara berkala
Sekiranya burner stop tiba-tiba, pastikan fuel supply diberhentikan dan buat pemeriksaan dengan teliti
Pastikan burner dan peralatan yg berkaitan dgn burner sentiasa bersih dan memuaskan(working satisfactory)
Periksa interlock system secara berkala sekiranya boiler mengunakan induce dan force draft fan
Pastikan suhu dan tekanan air preheater, drying air dan fuel air mengikut suhu standard yg diperlukan
Jangan biarkan Pembakaran yg tak seimbang berterusan didalam furnace
Purge furnace dengan sempurna sebelum boiler firing

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Boiler failure

Reason for boiler Failure	Fire Tube	Water Tube
Mechanical, electrical fault/failure, maintenance testing	35%	19%
Boiler water trouble	17%	36%
Personnel	16%	13%
Corrosion and erosion	11%	9%
Installation and design deficiencies	10%	8%
Defective material	8%	3%
Other reasons- miscellaneous	3%	12%