How thick must backing be when using an ER70S-X filler metal?

The correct thickness for backing when using ER70S-X filler metal is typically 3/16". Backing is essential in welding, particularly in specific joint configurations where it provides support, retains molten weld metal, and helps prevent issues like burn-through or distortion.

ER70S-X is a type of filler metal that is often used for welding carbon steel. The AWS D1.1 code specifies requirements for different scenarios, including those for backing material, based on the filler metal used and the specific welding process. In this case, the recommendation for backing thickness is tied to ensuring adequate support and a secure weld pool.

Choosing the appropriate thickness, such as 3/16", aligns with the requirements laid out in the code, allowing for effective and efficient welds. This helps ensure that the joints maintain integrity and strength, conforming to the structural standards established by AWS D1.1. Thinner or thicker backing materials do not meet the intended performance standards or may cause complications in the weld quality.