Common Welding Processes Used In The Petrochemical Industry • SMAW (Shielded Metal Arc Welding) • GMAW (Gas Metal Arc Welding) • GTAW (Gas Tungsten Arc Welding) • SAW (Submerged Arc Welding)
Shielded Metal Arc Welding (SMAW) Electric arc between the flux covered electrode and the base metal
Benefits of the electrode coating •Arc stabilization •Provides gas shielding – decomposition of cellulose and limestone •De-oxidation of weld pool •Strengthens the weld – alloying elements •Increases deposition – adds filler •Oxide barrier for solidifying metal - slag •Thermal insulation of the cooling weld
Common defects associated with SMAW Porosity Cracks Slag Incomplete fusion Incomplete penetration Burn through Lack of fill Root concavity Undercut Excessive penetration
•The SMAW process is almost totally operator dependant
Gas Metal Arc Welding (GMAW) Electric arc between a continuously fed solid wire consumable and the base metal
Common defects associated with GMAW Porosity Cracks Incomplete fusion Undercut lack of fill Incomplete penetration
•The GMAW process is automated, semi-automated and machine.
Gas Tungsten Arc Welding (GTAW) Electric arc between a tungsten electrode, a solid wire consumable and the base metal.
Common defects associated with GTAW Porosity Tungsten inclusions Cracks Incomplete fusion Undercut
•The GTAW process is almost totally operator dependant
Submerged Arc Welding (SAW) Electric arc between a continuously fed solid wire consumable and the base metal submerged in a protective flux.
Common defects associated with SAW Porosity Cracks Slag Incomplete fusion
The GMAW process is automated, semi-automated and machine.
WELDING DEFECTS
Defects cause stress which can result in joint failure
Common causes of defects •Welder-technique •Cleaning •Joint preparation •Joint design
Film Handling And Processing Defects Scratches Finger prints Crimp marks Light Leaks Chemical Stains Roller Marks & Artifacts
Scratches
Chemical Stains
Light Leaks
Static Marks
Store film upright
Artifacts
Water marks
Crimp marks
CODES & STANDARDS in the petrochemical industry
What is the purpose for Codes & Standards? They ensure uniform practices throughout industry
Three common codes used in Saudi Arabia’s petrochemical industry ASME B31.3 Boiler and Pressure Vessel Code API 1104 Welding of Pipelines And Related Facilities
AWS D1.1 Structural Welding Code - Steel
ASME B31.3 and Appendix 4 Film interpretation acceptance criteria for Process Piping “onplot” facilities
API 1104
Film interpretation acceptance criteria for pipelines
AWS D1.1 Film interpretation acceptance criteria for structures
