State the strength equations of double parallel...................

Let t = Throat thickness (BD), s = Leg or size of weld, = Thickness of plate, and l = Length of weld, From Fig. 10.7, from above we find that the throat thickness, t = s × sin 45° = 0.707 s ∴*Minimum area of the weld or throat area, A = Throat thickness ×Length of weld= t × l = 0.707 s × l…….. If σt is the allowable tensile stress for the weld metal, then the tensile strength of the joint for single fillet weld, P = Throat area × Allowable tensile stress = 0.707 s × l × σt…….. and tensile strength of the joint for double fillet weld, P = 2 × 0.707 s × l × σt = 1.414 s × l × σt……..If τ is the allowable shear stress for the weld metal, then the shear strength of the joint for single parallel fillet weld, P = Throat area × Allowable shear stress = 0.707 s × l × τ and shear strength of the joint for double parallel fillet weld, P = 2 × 0.707 × s × l × τ = 1.414 s × l × τ …… The strength of the joint is given by the sum of strengths of single transverse and double parallel fillet welds. Mathematically, P = 0.707s × l1 × σt + 1.414 s × l2 × τ