Pipe under high external pressure

Hi,

We have a steel tube made of a material with yield limit 1000 N/mm2.
It is 250 mm long, outside diam. is 76 mm, inside diam. is 60 mm.
It is plugged at both ends.
Inside pressure is nearly 0 (zero) and outside pressure due to submersion is 69 MPa (MegaPascal).

Will this be safe?
How can I calculate what pressure that would be 'catastrophic' for the pipe?

 

google vacuum vessel calculations...

 

Did not find any (for me) useful help there.
I am sure there must be someone out there who knows a lot about this.
Hoping, hoping ... ;-)

 

http://www.deepsea.com/upwin.php

http://www.pveng.com/ASME/ASMEComment/ExternalPressure/ExternalPressure.php

 

Thanks for the pointers! The 2nd one looks promising.