foreach my $key ( keys %part_file ) {
    $key =~ s/[^A-Za-z0-9]/Junk alert!/g;
    print "Key-$key-\n";
}

##</code><code>##

Key-P123-
Key-P334-
Key-P925-

##</code><code>##

Key-P123Junk alert!Junk alert!-
Key-P334Junk alert!