Sc_sql_injection

I have doutful when I have to use this command.
I see it is necesary when using a field {field1} as parameter ,
but Have I use when are internal variable or a fixed string ?;
by example ;
“INSERT INTO T03PedidoCabeceraTemporal(formaEntrega,dir_ViaTipo,dir_CP,dir_permiso) values(‘recoger’,‘Calle’,1,‘N’);”;
would I have to put the string fixed in a variable and execute sc_sql_injection on them.

thanks