The ornamental design for a structuralbeam for a screen enclosure, as shown and described.
FIG. 1 is a perspective view illustrating my design for a structural beam for a screen enclosure.
FIG. 2 is a front end view thereof.
FIG. 3 is a rear end view thereof.
FIG. 4 is a left side view thereof.
FIG. 5 is a right side view thereof.
FIG. 6 is a top view thereof.
FIG. 7 is a bottom view thereof; and,
FIG. 8 is another perspective view with environmental subject matter.
The broken lines shown in FIG. 1 and FIGS. 3-8 illustrate portions of the structural beam for a screen enclosure that form no part of the claimed design. The additional broken lines shown in FIG. 8 represent environment. The break lines shown in the center of the beam indicate a symbolic break in length. The appearance of any portion of the article between the break lines forms no part of the claimed design.