Was asked to come in for an on-site interview at the Springfield, MA headquarters where I had several smaller interviews over the course of 3 hours. For the most part there was nothing out of the ordinary. Since the job involves a lot of travel, you will get the"are you willing to travel" question several times. From the engineers who interviewed me, they asked questions about a simple process flow diagram that they will ask you questions about - related to flow in a pipe and pressure gauge relative to one another. Just basic fluid dynamics questions. They also asked about any tinkering or construction work since they feel those people tend to do better with the smaller details of P&IDs.