Butt End Weld Joint Calculation Formulas

Butt end weld loaded with normal force

Normal stress

where:

	F n	normal force [N, lb]
	A	throat area of the weld [mm 2 , in 2 ]

Reference stress

where:

	σ 1	normal stress [MPa, psi]
	α 1	factor of the weld joint [-]

Butt end weld loaded with shear force

Shear stress

where:

	F t	shear force [N, lb]
	A	throat area of the weld [mm 2 , in 2 ]

Reference stress

where:

	τ	shear stress [MPa, psi]
	α 2	factor of the weld joint [-]

Butt end weld loaded with bending in the plane of welded parts

Normal stress

where:

	u	constant
	α 2	- for calculation in metric units u = 1000
	α 2	- for calculation in English units u = 12
	M 1 n	bending moment [Nm, lb ft]
	W	section modulus of throat area of the weld [mm 3 , in 3 ]

Reference stress

where:

	σ 2	normal stress [MPa, psi]
	α 1	factor of the weld joint [-]

Butt end weld loaded with bending in the plane perpendicular to the plane of welded parts

Normal stress

where:

	u	constant
		- for calculation in metric units u = 1000
		- for calculation in English units u = 12
	M 2	bending moment [Nm, lb ft]
	W	section modulus of throat area of the weld [mm 3 , in 3 ]

Reference stress

where:

	σ 3	normal stress [MPa, psi]
	α 1	factor of the weld joint [-]

Butt end weld loaded with combined loading

Resultant reduced stress

where:

	σ 1 , σ 2 , σ3	normal stress [MPa, psi]
	τ	shear stress [MPa, psi]

Reference stress

where:

	σ 1 , σ 2 , σ3	normal stress [MPa, psi]
	τ	shear stress [MPa, psi]
	α 1 , α 2	factor of the weld joint [-]

Butt end weld loaded with torque

Shear stress

where:

	u	constant
		- for calculation in metric units u = 1000
		- for calculation in English units u = 12
	T	torque [Nm, lb ft]
	W	section modulus of throat area of the weld [mm 3 , in 3 ]

Reference stress

where:

	τ max	shear stress [MPa, psi]
	α 2	factor of the weld joint [-]

Meaning of used variables:

A	throat area of the weld [mm 2 , in 2 ]
F n	normal force [N, lb]
F t	shear force [N, lb]
M 1 , M 2	bending moments [Nm, lb ft]
s	plate thickness [mm, in]
T	torque [Nm, lb ft]
W	section modulus of throat area of the weld [mm 3 , in 3 ]
α 1 , α 2	factor of the weld joint [-]