Which of the following statements is true regarding bevel and J-groove welds?

Bevel and J-groove welds are commonly used in situations where the joint configuration requires effective penetration and fusion between the two pieces of metal being joined. The characteristic shape of these welds allows for better access for the welding torch or electrode and promotes thorough melting of the base materials.

The statement regarding the bent leader is relevant to the welding process. A bent leader typically refers to a setup that helps guide the welding arc more effectively when working on joints that require a specific angle of approach. This can be quite important for ensuring proper penetration and the quality of the weld in bevel and J-groove configurations.

The other statements are either misleading or incorrect; for example, bevel and J-groove welds certainly do penetrate the joint when executed correctly, as penetration is a critical aspect of a successful weld. These types of welds can be applied in various positions, not limited to horizontal, and do not require multiple reference lines for commonly accepted practices in their application.