Phone interview with HR rep was pretty easy, just a lot of "tell me about a time when... blah." (which everyone obviously makes up) Then they flew me to Houston for an interview with about 3 engineers and another HR rep. Right before that they had me take a test on this valve system which was pretty tough because I had never seen the stuff before. The first part of the interview was going over that test, explaining how you got to your answers. Then they had me explain everything on my resume and how it will help at their company. Then they went on to the "tell me about a time when... blah" questions again.