METHOD OF HIDDEN ARC WELDING OF STEEL STRIP Russian patent published in 2013 - IPC B23K9/18 B23K33/00 

FIELD: process engineering.

SUBSTANCE: invention relates to production of large-diameter steel pipes by welding, primarily, spiral pipes. One-pass hidden arc welding is made on sheet inner and outer surfaces. Special requirement to welding consists in setting cross-section of produced weld joints. Cross-section area S₁ of inner weld seam satisfies the equation S₁/t²≤0.35, cross-section area S₂ of outer weld seam satisfies S₂/t² ≤0.45 while the sum of said areas makes 0.40≤(Si+S₂)/t²≤0.80. Note here that t is steel sheet thickness (mm), S₁ is inner seam cross section area (mm²) except for area of the section of inner seam metal cross-section covered by metal of pouter seam after outer welding, and S₂ is cross-section area of outer seam metal (mm²). Besides, width of welded bead measured on steel sheet surface and at 0.4t therefrom is set.

EFFECT: sufficient weld penetration, high impact toughness in thermal influence zone.

5 cl, 4 dwg, 6 tbl