No. Helium hard drives are laser-welded shut. See http://www.seagate.com/files/www-content/product-content/ent... for the details about what parts are made out of what and the basic details of fabrication.
I'm not sure why I thought there was a rubber seal, I have vague memories of seeing an exploded view with one somewhere.
I'm not sure why I thought there was a rubber seal, I have vague memories of seeing an exploded view with one somewhere.