What is the allowable stress for API 5L X70?

API 5L X70 is a high-strength steel commonly used in pipeline construction. The allowable stress for API 5L X70 can vary depending on factors such as temperature, material condition, and the specific requirements of the project or application.

In general, for pipeline design calculations, the allowable stress for API 5L X70 is typically determined based on the yield strength of the material. For API 5L X70, the minimum specified yield strength is 485 MPa (70,300 psi).

The allowable stress is calculated using a factor of safety applied to the yield strength. Common factors of safety used in engineering practices can range from 0.6 to 0.9, depending on the specific design codes and requirements.

Therefore, to determine the allowable stress for API 5L X70, you would multiply the minimum specified yield strength by the factor of safety chosen for the particular application. For example, if a factor of safety of 0.72 is selected:

Allowable Stress = Yield Strength / Factor of Safety
Allowable Stress = 485 MPa / 0.72
Allowable Stress ≈ 673 MPa

Please note that these values are provided for illustrative purposes and actual API 5L X70 allowable stresses should be calculated based on the specific design criteria and conditions of the project.