Metric and Imperial Units

The above welding stress equations may be used with both imperial and metric units. As with all mathematical calculations care must be taken to keep consistent units throughout. Examples of units which could be adopted have been provided below:

Notation

• a = weld throat thickness, in or mm
• D = tube/pipe outside diameter, in or mm
• d = effective tube/pipe inside diameter , in or mm
• M = bending moment, lb.in or Nmm
• Zw = modulus of weld section, in³ or mm³
• σ = stress in weld, psi or MPa