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Safety in welding & grinding

Safety in welding & grinding


Welding and Grinding


Objective


Introduction


Hazards in Welding activity


Hazards


Health Hazards


Portable DC arc welding

Measures


Welding


Measures


Terminal cover and Earthing connection


Preventive measures


Personal Protective Equipment


Recommended Filter shades


Auto - Darking welding filter


Protection against fumes and dust


Safety in Gas cutting


Introduction


DA & O2 Cylinders


Acetylene cylinders


Acetylene cylinders


Oxygen cylinders


Accessories


Regulators


Identification


Cylinder storage


Gas cylinder Rules - 1981


Unloading from Truck


Right operation


Right operation


Handling and use


Handling and use


Hazards


Flash Back & Back Fire


Reasons


Flash back arresters


Fire on cylinder


Explosion


Explosion limits


PPE's


How to Cylinder expire date identified?


Grinding Safety


Purpose of Grinding


Measures


Measures


Safe usage of DCD


Commonly used machines


Commonly used machines


Commonly used machines


Commonly used machines


Commonly used machines


Thank you






SAFETY IN WELDING

INTRODUCTION

Welding is an art of joining metals.
The faces to be joined are brought to plastic or liquid state and with or without the application of pressure the joint takes place. Sometimes, additional filler rod is used to complete the joint

HAZARDS IN WELDING ACTIVITY
* Bare Elec. Conductor
* Defective Insulators
* Exposed and Damaged insulators at Joints
* Exposed Terminals
* Improper Earthing
* Heat – Resistance
* Hot Spatters – FLY 
* Hot work in Flammable atmosphere
* UV / IR Rays
* Toxic Fumes

HAZARDS
* Fire
* Shock
* Health hazards

HEALTH HAZARDS

*
* Eye Damages
* Skin Diseases
* Inflammation of the lungs (chemical pneumonitis)
* Pulmonary edema (swelling and accumulation of fluids)
* Chronic bronchitis.
* Asphyxiation.

MEASURES

*Body of the welding M/c should be earthed.
*Terminals with lugs and well insulated with heat resistant tape.
*The cable should be free from joints atleast for a length of three meters from electrode holder to avoid shock hazard
*Switch off the Power when the M/c is not in use
*Do not operate with wet hands and on wet location.


MEASURES

*Other electrical cables should not be kept laid with welding cables, to avoid insulation damage.
*For the return lead only proper cable should be used. Using rods, angles, channels etc. Should be avoided.
*Use of well insulated Holder
*Remove / protect the flammable materials in near by location
*Cable should pose a trip hazard
*Work platform


PREVENTIVE MEASURES

* Elimination or substitution
* Modification of the process or engineering
* Local exhaust ventilation
* General dilution ventilation
* Personal protective equipment


PERSONAL PROTECTIVE  EQUIPMENT

Face Shield With Attached Helmet
Eye   - Goggles, Face-shield.
  - Din Value Of Black Glass 12 To 14 .
Hand  - Leather Hand Gloves (Heat     Resistant)
Body  - Leather Apron & Leg Gaurd.
Foot  - Safety Shoe.

RECOMMENDED FILTER SHADES

ARC  WELDING          SHADE NO.
Below Ø 4 mm ( UP to 175 Amps. )    11
Ø 4 to 5 mm     ( 175 to 300 Amps. )  12
Above Ø 5 mm. ( 300 to 500 Amps. )  13
GTAW WELDING
 Up to 40 Amps.   10
40 to 100 Amps.   11
100 to 175 Amps.   12
175 to 250 Amps  13
> 250 Amps  14


AUTO-DARKENING WELDING FILTER

* Darkens instantly when an arc is struck
Constant protection against UV/IR radiation
Both hands free
Increased accuracy and less rework =  high productivity
Always a clear view of the workpiece


PROTECTION AGAINST FUMES & DUST


SAFETY IN GAS CUTTING


INTRODUCTION

Compressed gases present a unique hazard. Depending on the particular gas, there is a potential for simultaneous exposure to both mechanical and chemical hazards. Gases may be

Flammable or Combustible
Explosive
Corrosive
Poisonous or a combination of hazards
Inert


Since the gases are contained in heavy, highly pressurized metal containers, the large amount of potential energy resulting from compression of the gas makes the cylinder a potential rocket or fragmentation bomb. 


ACETYLENE CYLINDERS

*Maroon in colour.
*Acetylene gas (C2H2) is dissolved in acetone (liquid) and stored at 250 PSI, in a specially designed cylinder.
*Acetylene cylinders has a volume of 8.5 m3.


OXYGEN CYLINDERS  

*Oxygen is a colorless, tasteless, and odorless gas and is slightly heavier than air.
*Oxygen cylinder is black in colour.
*Oxygen stored at 2200 psi
*Oxygen cylinders has a volume of 6.9 m3




ACCESSORIES

*Spark Lighter
*Cylinder Key
*Nozzle cleaner
*Wire Brush
*Tongs


 IDENTIFICATION

Never rely on the color of the cylinder for identification. Color coding is not reliable because cylinder colors may vary with the supplier. Additionally, labels on caps have little value because caps are interchangeable. 

CYLINDER STORAGE

* Well ventilated room
* No open flame in the store
* No materials that are prone spontaneous combustion
* Should not be stored in direct sunlight.

GAS CYLINDER RULES- 1981

Oxygen, acetylene, & LPG cylinders shall not be stored together.
Provide two foam type fire extinquishers in storage area.
Licence to be obtained from the Chief Controller of Explosives if:
    (a) The total quantity of LPG is 100kgs or more. 
    (b) The No. of acetylene cylinders are more than 15.
     (c) The No. of oxygen cylinders are more than 50. 

UNLOADING FROM TRUCK

*Never drop
*Use wooden Ramp and coir matters (50cm thick)
*Keep the top of the cylinder up
*Roll the cylinder keeping it upright 

RIGHT OPERATION

*Fix the DA and oxygen regulator to the respective cylinders after ensuring free from dirt or grease.
*Connect the cutting hoses to the regulators and cutogen with hose clamps. Blue or black hoses for oxygen and red for DA.
*Open the cylinder and check for leakage by soap water test at the joints. The same to be followed for the oxygen cylinder. Close the cylinders .


RIGHT OPERATION

*Purge the oxygen line and then the DA line one after the other and close the valves.
*Open the DA regulator, the torch valve and light the gas. Then open the oxygen valves to the required pressure.
*After cutting start closing from oxygen and then DA.

HANDLING AND USE

If a leak cylinder is discovered, move it to a safe place.

Under no circumstances

should any attempt be made to repair
a cylinder or valve. 

An open flame shall never be used to detect leaks of flammable gases. Hydrogen flame is invisible, so "feel" for heat. 

HANDLING & USE

*Use of cradle
*4-leg bridle sling
*D-shackle and lifting lug
*Use of trolleys
*Avoid Rolling & Manual carrying


HAZARDS

Flash back.
Back fire.
General fire.
Explosion.

FLASH BACK

- Retrogression of the fire upto the  cylinder.
BACK FIRE

- Retrogression of the fire in the cutogen.

REASONS

*Overheating of Nozzle
*Defective Nozzle
*Nozzle blocked.
*Nozzle close to the job.
*Job close to the ground.
*Pressure difference between flame pressure and the hose pressure.

FLASH BACK ARRESTERS

Flashback arrestors are designed to prevent flashback

FIRE ON CYLINDER

*Try to put out the fire
*Close the valve if it gets put out
*Otherwise inform fire dept. and keep on cooling the cylinder with water
*Never pour water on hot cylinder

EXPLOSION

Reasons:
Fire on cylinder (pouring water on hot cylinder)
Cylinder exposed to external heat
Rough handling
Cylinder without cap


PPE’s

*Helmets with face shields
*Black glass - din value 4 to 5
*Leather gloves
*Leather apron
*Safety shoes


Grinding Safety

PURPOSE OF GRINDING

v To remove excess material from work piece to
   get required SIZE , FINISH and FORM
v To get the SURFACE  QUALITY
   requirements of work piece

WHAT IS A GRINDING WHEEL

A MULTIPOINT Cutting tool comprising  of selectively sized ABRASIVE GRAINS,held together by means of a BONDING MATERIAL called BOND with suitable SPACING of grains in between.

MEASURES

ž
žVisually inspect all grinding wheels. Also, the use of “ring testing” or “vibration testing” is required for many grinding wheels.
žNever use a damaged Machine and Grinding wheel.
žCheck the machine speed against the maximum operating speed of the grinding wheel.
žInspect the machine and its guards.
žDo not force a grinding wheel onto the mounting arbor. If the wheel does not fit, don’t use it.

Don’t over-tighten the mounting nut or mounting screws.
Wear all required personal protective equipment.
Allow the grinding wheel to run at operating speed for one full minute before using the grinding wheel.
Do not allow anyone to stand in front of or in line with the grinding wheel during this test
Ensure for work rest
Area to be demarked and kept clear of materials

SAFE USAGE OF DCD

Commonly used machines
AG5 – 5 inches wheel
AG7 – 7 inches wheel
AG9 – 9 inches wheel





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