Hi Sunil/Sandeep,
It looks like you have two factors with Service Type.
P1-1hr
c1-1hr
c2-6hr
p2-12hr
c3-12hr
p3-24hr
You can have Service Type tied with priority and Service Type tied with request area (Category) at the same time if you use Ranking in Service Type.
Below is copy from menu Help >"Help on This Window..." of Service Type Detail page for Service Type Fields - Ranking.
"Ranking
Service types can be associated with various objects, such as contacts, organizations, categories, and priority codes. If different service types are associated with a ticket, the one that is used depends on the value in this field, where the one with the lowest number has the highest priority. For example, if an issue is opened and the Affected End User contact has a 12-hour resolution service type, which is ranked as 2, while the priority code has a 4-hour resolution service type, which is ranked as 1, the service type for the issue is 4-hour resolution.
You must enter a value of 1 or greater; values of 0 or negative numbers are not allowed."
Now, the next question what happen when a request with c2 and p2 as it is 6hr SLA and 12hr SLA. It should go for the c2-6hr not p2-12hr. The Ranking may give you the answer if 6hr has lower number of ranking. It also answers a request with P1 and c3. It should go for p1-1hr SLA not c3-12hr SLA if you have ranking setting accordingly.
Regards,
Chun (Derek) Li