The ornamental design for a butterflyvalvedisc, as shown and described.
FIG. 1 is a perspective view of a butterfly valve disc showing our new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a top plan view thereof;
FIG. 7 is a bottom plan view thereof; and,
FIG. 8 is a cross-sectional view taken along lines 8-8 in FIG. 2.
The dashed-dot broken lines shown in the figures are included for the purpose of illustrating bounds of the claim and form no part of the claimed design.