Cast steel Y strainers  are typically used in applications where the amount of solids to be removed is small, and where frequent clean-out is not required.  They are most often installed in gaseous services such as steam, air, nitrogen, natural gas, etc.  The compact, cylindrical shape of the Y-strainer is very strong and can readily accommodate the high pressures that are common in this type of service.  Pressures up to 6000 psi are not unusual.  When steam is being handled, high temperature can be an additional complicating factor.