I need to replace the emissions check valve and hose on the drivers side of my 99 blazer 4x4. It has 150k miles so everything is well rusted and fused together.

Can anyone offer any suggestions on the best way to remove the valve? I have heard removing the pipe it connects to, is an easy way, but when I tried to loosen those screws, I got the feeling that they were going to break off, so I stopped before I did any damage.