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Abstract

ASME SA 106 Grade B pipe material or more familiarly known as API 5L Grade B Pipe in the oil and gas industry is widely used in distribution pipes with quite high pressure and temperature, especially in gas and steam distribution lines. During operation, damage and leakage often occur due to earthquakes and other external loads. The strength of the resulting welded joint and the selection of the appropriate welding method are strategic issues to be studied and researched. This study aims to determine the hardness and strength of the welded joint of 6 inch schedule pipe 80 API 5L Grade B using a combination Gas Tungsten Arc Welding (GTAW) and Shielded Metal Arc Welding (SMAW) welding process and setting welding parameters with different current variations for 6 layers design. The electrode used is ER 70S-6 for root pass welding using the GTAW process, and the SMAW process uses the E 7016 electrode for hot pass and cover pass welding, the groove used is the singgle V groove with an angle of 60 degrees. The tests carried out are non-destructive testing, tensile testing and hardness tests. The results of the study showed an increase in the value of tensile strength reaching 499 Mpa, yield strength reaching 364 MPa and elongation is became 13%. The hardness test show that the highest hardness is in the weld metal area with an average hardness reaching 68.10 HRC, then in the Heat Affected Zone (HAZ) area with an average value of 63.55 HRC and the average hardness value in the parent material or based metal area reaches 61.00 HRC. These results indicate the combination welding method between GTAW and SMAW process are suitable to be applied for joinning API 5L or ASME SA 106 Grade B pipes material.