The City of Clairton hereby accepts and becomes subject to the
provisions of the Act of 1939, June 21, P.L. 626, § 1 et
seq. (72 P.S. § 5452.1 et seq.), and from the date of the
completion of such acceptance the objects, property and persons subject
to and exempt for taxation in the City of Clairton shall be designated
by and the assessment and valuation thereof for City purposes shall
be done only in accordance with the provisions of said Act and by
the officers designated thereunder.