Gas Safety

Gas safetyGas safety

In In

P&bs2P&bs2

introduction

THE FATAL ACCIDENT THAT HAS OCCURRED

IN BHILAI STEEL PLANT IS AN EYE-OPENER

FOR ALL OF US. WE MUST DRAW LESSONS

FROM THE INCIDENT. THIS PRESNTATION IS

TO RE-LOOK AT OUR SYSTEM, FINDING ANY

UNSAFE POSSIBILITIES AT OUR GAS AND

RELATED WATER NETWORKS AND TAKING

MEASURES ACCORDINGLY

CO GAS U-SEAL

AND

SEAL POT

Gas compositionGas composition

Constituents Unit COG BFG BOFMixed

Gas(BFG+BOF)CBM

CO2 % vol 3-4 23.3 16.2 22.38 1-2

CO % vol 6-7 26.9 69.3 32.4

N2 % vol 4-7 46.2 14.5 42.1

H2 % vol 52-59 -- -- --

CH4 % vol 24-28 -- -- -- 95-97

Other gases % vol 1.5-2.5 3.6 -- 3.14 2-4

Calorific Values Kcal/Nm3 4250 914 2000 10548300

(NCV)

Gas propertiesGas properties

SN COG BFG

Source

Coke oven gas, is the gas obtained when coal is heated in an air tight place

Blast furnace gas, a by-product of blast furnaces, is generated when the iron ore is reducedwith coke to metallic iron

Hazardous or Not

Categorized as hazardous/toxic gas

Categorized as hazardous/toxic gas

Colour Yellowish Colourless

Odour Pungent Odourless

DensityLighter than air (0.45 times lighter).

Heavier than air

Schematic arrangement of CO GAS U-SEAL AND drain POT & water supply lines

Schematic arrangement of CO GAS U-SEAL AND drain POT & water supply lines

Salient points of our cog water sealSalient points of our cog water seal There are one goggle valve at the COG inlet line at PBS2.There are one goggle valve at the COG inlet line at PBS2.

There are 2 drain pots in COG common header.There are 2 drain pots in COG common header.

There are total 3 U-seal one in each individual gas lines There are total 3 U-seal one in each individual gas lines taken from COG header.taken from COG header.

There are one drain-pot connected to each U-seal of There are one drain-pot connected to each U-seal of individual boiler.individual boiler.

Color code for gas line is yellow and color code for water line Color code for gas line is yellow and color code for water line is sea green.is sea green.

Our U-seal water line has been taken from ACW pump Our U-seal water line has been taken from ACW pump header.header.

Our U-seal water filling line is having U-seal to restrict back Our U-seal water filling line is having U-seal to restrict back flow of gas to water circuit in case of water pressure loss.flow of gas to water circuit in case of water pressure loss.

Backflow of gas in the drain-pot water filling line will be Backflow of gas in the drain-pot water filling line will be restricted by drain-pot water column itselfrestricted by drain-pot water column itself

CO GAS U-SEAL AND

SEAL POT

CO GAS U-SEAL AND

SEAL POT

CO GAS U-SEAL CO GAS U-SEAL

1. In main gas line the effective height of the U seal shall be 2.5 times of the working gas pressure.

2. The effective height of gas line is overflow point of the water pipe in gas line to the top of the U bend in gas line.

3. Inlet water line U seal is TO BE provided to avoid flow of gas in water line if the pumps gets dry or water line is empty.

U-SEAL facts

CO GAS SEAL POT

CO GAS SEAL POT

1. Drain pot is a device to collect the Condensate accumulated in gas pipe line.

2. It also helps in releasing the pressure in gas pipe line if the gas pressure becomes TOO high .

3. It works on the principal of U-Tube manometer.

• At Normal Condition P < 2000mm WC it remains in stable condition.

• When pressure rises above 2000 mm WC, then it throws out the water from the over flow outlet.

2000MmWC

P

Safety in

cable cellars

Cable galleries at P&BS2

1.below 33kV GIS room which handles 33kV cable, 6.6kV cable, 415V cable and 220V DC cable2.Second below Main LT Switchgear which handles 415V cable and 220V DC cable

Cable trenches in P&BS2

1.Near Boiler Area2.Near DM Plant3.Near Cooling Tower4.Near Cooling water Pumphouse

Use CO gas sensor to measure any presence of CO gas near cable trench before entering.

Incase of detection of CO gas, go away from the source of CO gas; preferably to an open area and inform control room in-charge and plant in-charge.

Ensure no steam is coming into the gallery/trench.

Keep someone outside the cable trench.

Keep walkie-talkie tied with you if possible.

Use 24V Lamp/Torches inside the trench.

Safety in cabale galleries & trenchesSafety in cabale galleries & trenches

Ensure running earthing in the cable trench and the connectivity with the earth grid. Use local earth in the cable tray.

Use mask, gum boot, hand gloves, helmet, and goggles.

Ensure no insects/snakes inside.

Do not use metallic material for cleaning. Use wooden stick or bamboos.

Do not take flammable material.

Ensure both side entry of cable trenches are packed with fire retardant boards and packing material.

Do not touch open cables if found inside and immediately inform to the EIC.

Safety in cabale galleries & trenchesSafety in cabale galleries & trenches

ADDITIONAL MEASURES TO BE TAKEN THROUGH SOPS & SMPS

Always ensure overflow in the Drain-Always ensure overflow in the Drain-pot and pot and

Always ensure overflow in U-seal Always ensure overflow in U-seal when U-seal has been done for gas when U-seal has been done for gas isolation.isolation.

Whenever the overflow is not found Whenever the overflow is not found in a U-seal or Drain-pot, same to be in a U-seal or Drain-pot, same to be attended only after ensuring by a attended only after ensuring by a gas detector that there is no CO gas gas detector that there is no CO gas in the vicinity of U-seal or Drain-pot.in the vicinity of U-seal or Drain-pot.

..


Whenever a gas line is Whenever a gas line is isolated by U-seal for a isolated by U-seal for a maintenance job, in addition maintenance job, in addition to ensuring overflow, ensure to ensuring overflow, ensure that drain valve is closed that drain valve is closed with tag “DON’T OPERATE” with tag “DON’T OPERATE” or preferably keep the drain or preferably keep the drain valve locked.valve locked.


Whenever there is a total Whenever there is a total shutdown of all ACW pumps, it is shutdown of all ACW pumps, it is to be ensured through a gas to be ensured through a gas detector that there is no CO gas detector that there is no CO gas in the CW pump house before in the CW pump house before starting any job.starting any job.

Never keep any gas vent open Never keep any gas vent open during Thunderstorm. during Thunderstorm.


Whenever a job is to be Whenever a job is to be taken inside furnace ensure taken inside furnace ensure with gas detector that no CO with gas detector that no CO gas is present inside, also gas is present inside, also ensure O2 content is 21%. ensure O2 content is 21%. Keep a gas detector at Keep a gas detector at working place throughout working place throughout the job duration to be alert the job duration to be alert for any seeping CO gas for any seeping CO gas during the job.during the job.


Whenever a job is to be Whenever a job is to be taken in a confined place like taken in a confined place like Boiler Drum, Main Oil Tank, Boiler Drum, Main Oil Tank, LDO Storage Tank, LDO Storage Tank, Condenser etc, ensure that Condenser etc, ensure that O2% inside is 21% before O2% inside is 21% before starting the job.starting the job.


Don’t charge COG/BFG/BOF Gas Don’t charge COG/BFG/BOF Gas in an empty pipeline without in an empty pipeline without purging with N2 or steam.purging with N2 or steam.

Always ensure that Oxygen Always ensure that Oxygen content in the purged line is less content in the purged line is less than 2% before admitting Gas.than 2% before admitting Gas.


Never allow Boiler area, cable cellars to Never allow Boiler area, cable cellars to be used as resting place.be used as resting place.

Never allow use of any tapping in the Never allow use of any tapping in the water network of boiler area for water network of boiler area for washing or drinking.washing or drinking.

Cable cellars, Boiler area are to be Cable cellars, Boiler area are to be treated as restricted places with no un-treated as restricted places with no un-authorized entryauthorized entry

SummarySummary We have total 5 drain-pots and 3 U-seals in COG We have total 5 drain-pots and 3 U-seals in COG

networknetwork Drain-pot & U-seal overflow to be ensured alwaysDrain-pot & U-seal overflow to be ensured always During gas isolation by a U-seal it is to be ensured During gas isolation by a U-seal it is to be ensured

nobody opens the drain valves inadvertently.nobody opens the drain valves inadvertently. Though we have U-seal in the water filling line we Though we have U-seal in the water filling line we

should check the CO gas with detector at the place should check the CO gas with detector at the place of work if ACW system shutdown is taken.of work if ACW system shutdown is taken.

We should take requisite precaution as said while We should take requisite precaution as said while working in confined places, cable cellers etc.working in confined places, cable cellers etc.

We should never allow PBS2 Boiler area to be used We should never allow PBS2 Boiler area to be used as resting place.as resting place.

Any tapping of the water network in Boiler area Any tapping of the water network in Boiler area should never be used for washing or drinkingshould never be used for washing or drinking

Never Always

Never fail to anticipate

emergencies. Do not wait

until something happens to start the thinking process

Always study every

conceivable emergency and

plan exactly what moves to

make.

SAFETY RULES DURING AN EMERGENCY

Never Always

Never start to manage

emergency without

understanding what exactly

has happened

Always proceed to proper valves or

switches rapidly but without confusion in time of emergency.

You can better walking than

running.

SAFETY RULES DURING AN EMERGENCY

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Gas Safety