If a groove weld has no size, what kind of penetration will it have?

When considering a groove weld that has no specified size, it typically implies that the weld is designed to have a significant depth of penetration. This condition leads to what is known as Complete Joint Penetration (CJP).

Complete Joint Penetration means that the weld penetrates entirely through the thickness of the base materials, ensuring that the weld metal bonds to both sides of the joint throughout its entire thickness. This is critical in applications where maximum strength is required, as it allows for the full area of the joint to be utilized.

In practice, design drawings or specifications that indicate a groove weld without a size requirement usually suggest that the intent is to achieve this maximum level of penetration for the weld joint. Thus, the performance and structural integrity expected from a CJP groove weld are typically adhered to unless otherwise specified.