12c datapump on RAC - dump files are created with group of sysasm

My export files end up with a group of sysasm why is that ? when my oracle user which is orauser in this case has a gid of oinstall

$  id

uid=2499(orauser) gid=2501(oinstall) groups=2501(oinstall),2503(sysdba),2509(sysoper),2511(sysasm) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023

$ touch xx

$ ls -l

total 5

-rw-r--r--. 1 orauser sysasm    659 Nov 10 16:12 export.log

-rw-r-----. 1 orauser sysasm   4096 Nov 10 16:11 test.dmp

-rw-r--r--. 1 orauser oinstall    0 Nov 11 09:13 xx

Thanks

Steve.