Single year column and multiple weeks columns into single year/week column with PIVOT
This sounds more like an UNPIVOT to me.  

SELECT SalesTable.Pk, CrossApplied.WeekYear, CrossApplied.Value
FROM SalesTable
CROSS APPLY (VALUES ('01'+CAST([Year] AS CHAR(40)), Week1),
                    ('02'+CAST([Year] AS CHAR(40)), Week2),
                    ('03'+CAST([Year] AS CHAR(40)), Week3),
                    .......)
        CrossApplied (WeekYear, Value)


There are other ways to do an UNPIVOT but using CROSS APPLY is my favorite.  I give a more general example here.