hi chek the below query

SELECT DATEADD(hh,SUM(DATEPART(hh,CONVERT(DATETIME,[ColName],108))), DATEADD(n,SUM(DATEPART(n,CONVERT(DATETIME,[ColName],108))),'1900.01.01') ) FROM dbo.[TableName]

But this will not work on the value like 0 if you can update your table values into 0:0 this is working,