Convert Varchar to Time

Question

I need my code to add the varchar CPUTM field + varchar CPUZIPTIM field which both has time values to see if greater than 2 hours. How do I do this when both fields are varchar. The value in CPUTM field is 
335:55:20.97 duration time.  My code is below.
CPUTM =     335:55:20.97 duration time
CPUZIPTM =     0:00:01.96 
duration time
select * FROM [SMF_DATA].[dbo].[System_Management_Facility]
WHERE ((convert(varchar(13), CONVERT(time, CPUTM) + CONVERT(time, CPUZIPTM))) > '02:00:00.00')

Answer 1

Well, there is no time span in T-SQL, so you need either to store it in the smallest necessary unit (seconds, milliseconds) or to convert ít on the fly.
E.g.
DECLARE @CPUTM VARCHAR(255) = '335:55:20.97';
DECLARE @CPUZIPTM VARCHAR(255) = '00:00:01.96';
DECLARE @T BIGINT = PARSENAME(REPLACE(@CPUTM, ':', '.'), 1) +
PARSENAME(REPLACE(@CPUTM, ':', '.'), 2) * 100 +
PARSENAME(REPLACE(@CPUTM, ':', '.'), 3) * 6000 +
PARSENAME(REPLACE(@CPUTM, ':', '.'), 4) * 360000 +
PARSENAME(REPLACE(@CPUZIPTM, ':', '.'), 1) +
PARSENAME(REPLACE(@CPUZIPTM, ':', '.'), 2) * 100 +
PARSENAME(REPLACE(@CPUZIPTM, ':', '.'), 3) * 6000 +
PARSENAME(REPLACE(@CPUZIPTM, ':', '.'), 4) * 360000;
SELECT @T / 360000,
(@T % 360000) / 6000,
(@T % 6000) / 100,
(@T % 100);