In what positions are WPS qualified when the qualification test welds are plug or slot welds made in the horizontal position?

When plug or slot welds are tested in the horizontal position, the qualification of the Welding Procedure Specification (WPS) is restricted to that specific position. This is because the weld's characteristics, including penetration and bead shape, can vary significantly with different positions.

In the horizontal position, the welders typically have certain advantages, such as better gravity assistance that helps prevent molten material from sagging or falling, which might not be the case in vertical or overhead positions. Consequently, if the initial qualification test is conducted only in the horizontal position, it does not provide data about the welding behavior in other positions like vertical, overhead, or flat. Therefore, the WPS is not automatically qualified for welding in those other positions unless additional qualifications are performed.

Thus, the correct answer highlights that the qualification is limited specifically to horizontal position welds when the test welds were performed solely in that position, reinforcing the importance of understanding how position affects weld quality and characteristics.