GTAW(GAS TUNGSTEN ARC WELDING)-

TIG WELDING IS AN ARC-WELDING PROCESS IN WHICH THE HEAT NEEDED FOR FUSION IS GENERATED BY AN ARC BETWEEN A NONCONSUMABLE TUNGSTEN ELECTRODE AND THE WORK.SINCE BOTH THE MOLTEN PUDDLE AND THE HOT TUNGSTEN ELECTRODE ARE SUSCEPTIBLE TO CONTAMINATION FROM THE AIR ,AN INERT GAS ATMOSPHERE OR SHIELD(USUALY ARGON OR HELIUM)IS USED TO KEEP AIR FROM THE ARC AREA.FILLER METAL MAY OR MAY NOT BE USED DEPENDING ON THE TYPE OF WEL AND THICKNESS TO BE WELDED.

PRO'S OF TIG-

1.IT PRODUCES HIGH-QUALITY WELDS IN MOST METALS AND ALLOYS,INCLUDING MANY "SPACE AGED" MATERIALS.

2.CAN BE USED ON A VARIETY OF THICKNESSES OF METAL

3.THERE IS NO SPATTER,SINCE NO METAL CROSSES THE ARC STREAM.

4.IT IS USABLE IN ALL POSITIONS

5.IT NEEDS LITTLE OR NO POST-WELD CLEANING.

WELDING MACHINES FOR TIG-

A SPECIALLY DESIGNED MACHINE CAN BE USED FOR TIG  WELDING.THESE TYPES OF MACHINES USUALLY CONTAIN A HIGH-FREQUENCY GENERATOR FOR AIDING ARC STARTING WHEN WELDING WITH ALTERNATING CURRENT.ALTERNATING CURRENT IS USED  FOR WELDING ALUMINUM AND MAGNESIUM.OTHER MACHINES USED FOR TIG ARE AC,DC,OR RECTIFIED CONSTANT CURRENT WELDING MACHINES AS USED FOR SHIELDED METAL ARC WELDING

TORCHES-

TIG TORCHES ARE SIZED BY CURRENT CAPACITIES.SOME TORCHES ARE WATER COOLED.

TUNGSTEN ELECTRODES-

TUNGSTEN IDENTIFICATION

TYPE                                                      COLOUR

PURE TUNGSTEN                               GREEN BAND

THORIATED 1%                                 YELLOW BAND

THORIATED 2%                                 RED BAND

THORIATED STRIPED                      BLUE BAND

ZIRCONIUM                                       BROWN BAND

                                     GAS TUNGSTEN ARC WELDING PROCEDURES                                                                  

METAL                          SPECIAL PROCEDURES          CURRENT                 GAS                        TUNGSTEN

CARBON STEEL                         INCLUDES STAINLESS                            DCSP            ARGON OR ARGON HELIUM      THORIATED POINTED END

NICKEL                                                                                                               DCSP      ARGON OR ARGON HELIUM     THORIATED POINTED END

TITANIUM                                                                                                          DCSP                             ARGON                    THORIATED POINTED END

ALUMINUM                      SHEETS,PLATES,CASTINGS                            ACHF     HELIUM OR ARGON HELIUM    ZIRCONIUM BALLED END

COPPER &                     SHEETS & PIPE                                                      DCSP     ARGON OR ARGON HELIUM   THORIATED POINTED END

COPPER ALLOYS       VERY THIN MATERIAL                                        ACHF                                  ARGON               ZIRCONIUM BALLED END