After sale of equipment Stock Information from Equipment Disappear

Hi All,

In our scenario we purchase equipment,

P.O >> Goods Receipt (maintaining serial number and generating equipment master)

Then in equipment master under serial data stock information is updated (Plant,storage location,batch,master batch,last movement date).

But when I sell this equipment the last movement date is updated and all other data disappear.

That I want prevent,because our batch-classification contains lot of information like engine no. engine serial,model etc.

How to prevent this so batch can stay as it is

Kapil