Chlorine Hazards and Handling

Chlorine Handling
IS 4263  Code of Safety for Chlorine
Chlorine:
q  Chlorine gas is produced in large scale as co-product in the Electrolytic manufacture process of Caustic Soda.
q  Chlorine has many uses in industry as strong Oxidizer, Chlorinating agent, Bleaching agent and through addition reactions
q  It is mainly used in in pulp and paper, textile industries, in the manufacture of Hydrochloric acid, bleaching powder, PVC and wide range of chemical products such as insecticides, medicines, detergents, refrigerants, propellants, resins, explosives etc… and purification of water
Physical Properties
n  Physical state: Gas/Liquefied gas
n  Colour: Gas-Greenish Yellow
n              Liquid-Amber
n  Odour: Strong, Pungent, suffocating
n  Formula: Cl2
n  Molecular Weight: 70.91
n  Atomic Weight: 35.5
n  Relative Density (Air): 2.49 at 20 C
n  Specific Gravity (Liquid):1.41 at 20 C
n  Viscosity: 0.35 cp at 20 C
n  Boiling Point: -34.05 C
n  Freezing Point: -101 C
n  Vapor Density: 3.214 Kg/M3
n  Vapor Pressure: 6.7 Bar at 20 C
n  Liquid –Gas volume Expansion:457
n  Specific Heat: 0.236 K cal/gm/C
n  Latent heat of vaporization:63.2 K cal
n  Coefficient of cubical expansion:0.0021/C
n  Critical Pressure: 77.1 bar
n  Critical Temperature: 144 C
n  Chlorine is a greenish yellow colour gas with pungent odour.
n  It is two and one half times as heavy as air.
n  It is slightly soluble in water to a maximum of one percent at 9.6 C
n  Liquid chlorine is amber in colour
n  It is one and one half times as heavy as water
n  One volume of liquid chlorine vaporise and expands to 457 volumes of gas
REACTION
n  Chlorine reacts spontaneously with Hydrogen to form Hydrogen chloride
n  The reaction is slow in the dark but explosive in sun light or at temperature above 250 C
n  Chlorine reacts with ammonia and form dense white fumes of ammonium Chloride, under certain condition the reaction may produce Nitrogen Trichloride which is spontaneously explosive
n  Chlorine reacts with organic compounds  to form chlorinated derivatives
n  Some of these reactions particularly with hydrocarbons, alcohols and ethers may become explosives
n  Dry chlorine at ambient temperatures does not attack steel, copper and nickel but these metals are attacked at higher temperature
n  Wet chlorine cause rapid corrosion on these metals
Health Hazards
n  Chlorine is a poisonous gas that can cause severe injury to health or death if exposed to higher concentration.
n  The severity depends upon the concentration of gas and duration of exposure.
n  The common symptoms to exposure of chlorine gas Irritation of nose, eyes and throat, cough, pain behind the breast bone, laboured breathing, vomiting and increase in respiratory and pulse rate.
n  Massive inhalation of chlorine produce pulmonary edema, fall of blood pressure and cardiac arrest.
n  1-3 PPM      – Definite odour, irritation to eyes    
                          & nose
n  6 PPM        – Irritation to throat
n  30 PPM      – Intense Cough
n  40-60 PPM – Cause serious damage for  
                          exposure 30-60 minutes
n  100 PPM   –  Cause Lethal damage
n  1000 PPM –  Danger to life after few deep  freeze burns
Prolong exposure to very low concentrations of chlorine gas can cause permanent of reduction of pulmonary function and may result decease of Bronchi.
TLV = 1 PPM or 3 mg/M3
STEL = 3 PPM or 9 mg/M3
FATAL DOSE = 1000 PPM
Personal Protective Equipment
n  Essential protective equipment should be made available at all time near the Chlorine handling area.
n  The wearer should have thorough knowledge about the usefulness and limitations of the protective equipment.
n  Periodic training and exercises improve acquaintance with the equipment and gain confidence to the wearer.
n  PVC Full Suit
n  PVC Apron
n  PVC Hand Gloves
n  Gum Shoes
n  Goggles
n  Air Line Respirators
n  Canister gas masks
n  SCBA
First Aid
n  The victim should be moved to fresh air and provided free air circulation.
n  For mild exposure of chlorine gas, the person is encouraged to take stimulants such as tea, coffee, milk etc., cough mixture, throat lozenges such as Vicks, halls, jaggery.
n  For moderate exposure, if breathing is difficult give Oxygen
n  Position the patient with lie down the head and trunk elevated to 45-60
n  If breathing found apparently ceased, artificial respiration is to be started using acceptable methods like mouth to mouth resuscitation or with Ambu Bag
n  If liquid chlorine spilled on the body, the contaminated clothing shall be removed and the effected area washed with running water and mild soap.
n  If eyes are effected they should be washed with fresh water for fifteen minutes & refer to eye specialist.
n  No neutralizing agents are used. Ointments not apply unless ordered by physician
Fire & Explosion Hazard
n  Chlorine is not flammable material, but it does support combustion of many substances the same way as oxygen does. 
n  Chlorine reacts explosively or form explosive compounds with chemicals like acetylene, turpentine, ether, ammonia, fuel gas, hydrocarbons and powder metals
n  Chlorine forms explosive mixtures with Hydrogen and other fuel gas.
n  Chlorine cylinders, if exposed to heat, will explode due to rapid development of pressure. Similarly explosion can take place in chlorine vaporizers
n  Move chlorine cylinders immediately from fire areas.
n  Apply water to cool the cylinders.
Storage & Handling
n  Dry chlorine gas is liquefied and stored in the High Strength Steel Tanks.
n  The storage installation have to be approved and licensed under the STATIC MOBILE PRESSURE VESSELS (Un Fired) RULES 1981
n  The storage, handling, transporting and use of the cylinders should be carried out strictly in compliance with the Gas Cylinder Rules 1981 and other Statutory Regulations
n  Liquid chlorine is handled through Seamless Carbon Steel Piping
n  Store cylinders in clean, well ventilated, fire resistant area in an up right position and secure properly.
n  Do not store near elevators, gangways or ventilation systems
n  Storage temperature should not exceed 55 C
n  Do not store near turpentine, ether, hydrocarbons, other flammable, anhydrous ammonia or finely divided metals.
Materials of Construction
n  At ambient temperature Dry Chlorine gas or liquid does not appreciably attack steel or most other common metals
n  Dry chlorine reacts rapidly or even violently with Titanium
n  On the basis of cost and performance Steel is the metal, choice of handling dry chlorine from -29 to 149 C
n  For dry Chlorine schedule 80 pipe is used in sizes up to 15 cm dia and Schedule 40 is satisfactory for large diameter pipe.
n  At temperature above 149 C corrosion of steel increase rapidly, spontaneous ignition can occurs at above 251 C
Leaks Control
n  Chlorine gas detector have to be installed around the chlorine storage and handling area to raise the alarm in case of any leakage
n  The emergency team has to be alerted and correct steps to control the leak
n  Delay can lead to dangerous situations
n  Authorized persons equipped with appropriate respiratory protection has to be investigate the leak.
n  Ammonia torch is useful to identify the leak spot release 26C ammonia vapors (not liquid) from a squeeze bottle near the suspected area. If chlorine is leaking a white cloud will result.
n  If the leak is extensive the area is evacuated and down stream peoples are cautioned.
n  Personal approach to leak control shall be from up wind side.
n  If cylinder develop leak, it is to be positioned that leak spot occupies at top in such away only gas will escape rather than liquid
n  Water never be poured on the chlorine leaks
n  The leak cylinder should not be thrown into water or neutralizing solution pits
Spills
n  Small size liquid chlorine spills can be covered with burnt lime or Soda ash and little amount of water sprinkled on it.
n  Fluoro protein foam may be used on the large spills after containment in order to reduce the vaporization rate.
n  Chilled water spray or fog can be used on dispersion gas streams away from the leak containers and liquid spills.
Waste Gas Disposal
n  Suitable provisions must be made near the storage and handling areas to connect the waste gas streams with the neutralization systems.
n  Alkaline solutions of Caustic Soda, Soda ash and Hydrated Lime are used for Chlorine Gas absorption.
n  The proportions of alkalis and water recommended is
Container capacity
Caustic Soda and Water
Soda Ash and Water
Hydrated Lime an Water
Weight
Kg.
Weight
Kg.
Volume
Lts.
Weight
Kg.
Volume
Lts.
Weight
Kg.
Volume
Lts.
45
58
182
136
450
58
566
68
90
270
220
680
82
815
900
1160
3680
2720
9050
1160
11350

Special Instructions
n  Never use chain, rope sling or magnetic device to lift the chlorine cylinders.
n  Never lift them by means of valve protection hoods.
n  Use a cylinder carrier to lift them.
n  Use new gasket when making connections and make sure connections are tight.
n  Use only 3/8” square box wrench not over 8” long, turning stem only one full turn anti clockwise for opening.
n  Never force the valve stem
n  Never use a hammer to apply force.
n  Never heat chlorine containers or valves or place them in hot water bath to increase discharge rate.
n  Be sure no water or other liquid is sucked back into Chlorine containers when nearly empty or due to pressure gradients.
n  Never leave container valves open, when chlorine is being not used.
n  Plug or cap the open end of the chlorine line immediately to keep out moisture.
n  Use flexible connection between the container and the chlorine piping system, preferably seamless copper tubing with a standard yoke and adaptor at the container end.
n  Use only valves, gauges, regulators, fittings, piping etc,.. Recommended for the Chlorine service.
Emergency Situations
n  Prevention is always better than control of leaks.
n  Many leaks can be prevented by practicing safety codes by the supplier as well as the consumer.
n  Human error is the common reason for gas leaks.
n  Leakages can be eliminated by right selection and placement of personnel, training, effective supervision and secondary checks.
n  Careful planning of leaks control program with crew, tools and protective devices is highly desirable.
n  Leaks can be effectively controlled by using the tools in the supplied tool kit.
Chlorine Tonner
n  Construction Code: BS-1500 part:1-1958 with head to shell joints as per BHOR – 1968
n  Material Specification: SA516 Grade 60
n  Type of Construction: Fusion welded
n  Internal Diameter: 760 mm
n  Outer Diameter: 784 mm
n  Shell Wall Thickness: 12 mm
n  Head wall thickness: 10.5/12 mm
n  Length: 2112 mm
n  Water Capacity: 800 Kg
n  Chlorine Capacity: 952 Kg
n  Tare Weight: 629 Kg
n  Gross Weight: 1581 Kg
n  Design Pressure: 19.9 Kg/Cm2
n  Design Temperature: 65 C
n  Test Pressure: 35.7 Kg/Cm2
n  Heat Treatment: Yes, 620 C for 60 minutes
n  NDT: All main seams 100 % radiographed


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