BASIC ELEMENTS OF WELDING

BASIC ELEMENTS OF WELDING Current adjustment amps

Welding Machine Electrode holder

SAFETY IN WELDING The body of the welding machine should be earth The terminals of the welding cable should be provided with lugs and kept tight

The joint in the cable should be made with terminals kept tight and well insulated with heat resistant tape The cable should be free from joints at least for a length of three meters from electrode holder to avoid shock hazard Other electrical cable should not be kept laid with welding cable to avoid insulation damage

For the return lead only proper cable should be used using rods angles channels etc should be avoided

Never change electrode with bare hands or wet gloves when standing on wet floorsHAZARDS Fire Shock

Health hazards

Hazards to eye & face from welding brazing soldering and cutting operations Intense light and radiation from welding arc

Flying sparks

Metal sputter and slag chips

HEALTH HAZARDS

I. Exposure to toxic gases generated during welding may produce one or more of the following effects

II. In flammation of the lungs (chemical phenmonitis)

III. Pulmonary edema (swelling and accumulation of fluids)

IV. Chronic bronchitis

V. Asphyxiation

HAZARDS AT SITE Working over load

Working in confined spaces

Welding or cutting tanks or vessels

Tripping hazards

PREVENTIVE MEASURES Elimination or substitution Modification of the process or engineering

Local exhaust ventilation

Personal protective equipments

FACTORS TO BE CONSIDERED IN ASSESSMENTS Welding position Welding location

Duration exposure

GAS CUTTINGACETYLENE CYLINDERS

Maroon in color

Acetylene gas (C2H2) Is dissolved in acetone (liquid) and stored at 250 Psi in as specially designed cylinder

Acetylene cylinder has a volume at 8.5 m3

OXYGEN CYLINDERS

Oxygen is a colors less tasteless and odor less gas and is slightly heavier than air

Oxygen cylinders black in colour

Oxygen stored at 2200psi

Oxygen cylinders has a volume of 6.9m3

CYLINDER STORAGE

Well ventilated room No open flame in the store

10m distance from oxygen and acetylene cylinder No materials that are prone spontaneous combustion

Should not be stored in direct sun light

Cylinders containing oxygen shall be stored separate from cylinders fuel gages

Minimum 10 feet distance shall be maintained between the storage areas

UN LOADING FROM TRUCK

Never drop

Use wooden ramp and coir matters Keep the top of the cylinder up

Roll the cylinder keeping it up right

LIFTING CYLINDERS BY CRANE

Use of cradle

4leg bridle sling

D-shackle and lifting lug

USE OF CYLINDERS TROLLEY

Shifting cylinders at site

Avoid rolling & manual carrying

Use trolley

RIGHT OPERATION

Keep the cylinder up right away from hot jobs

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 and black hoses for oxygen and red for DA

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

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

Purge the oxygen line and then the DA line after the other and close the valves

CUTTING NOZZLEMAX. MATERIALS THICKNESS

(MS IN MM)SIZE OF NOZZLECUTTING OXYGEN PRESSURE IN KG/CM2

121/321.4

253/643.0

501/164.0

751/164.0

1001/165.0

1505/645.5

2003/327.5

2507/648.0

3001/88.0

HAZARDS

Flash back

Back fire

General fire

Explosion

FLASH BACK

Retrogression of the fire up to the cylinder

BACK FIRE

Retrogression of the fire in the cutogen

REASONS

When the blow pipe be comes hot

Nozzle close to the job

Nozzle blocked

Job close to the ground

Pressure difference between flame pressure and the hose pressure

IF A BACK FIRE OCCURS

EMBED PBrush

EMBED PBrush