How to generate 16 characters unique GUID in ABAP to use as a primary key

Hi,

Please help me in generating a unique 16 characters GUID which i can use it as a primary key in my custom table.

I have tried with "GUID_CREATE" and "CL_SYSTEM_UUID~CREATE_UUID_X16" but its  exporting parameters(EV_GUID_16) are returning 32 characters(alphanumeric hexdecimal value) which is transferring only first 16 characters by truncating the last 16 characters which is causing the duplicate GUID.

Atleast guide me how can i convert 16 length(32 characters hex value) raw text to 16 characters string which i can use it as primary key.

Thanks,

Babu