CP Industries just got an expensive lesson in the unintended consequences of protectionism. Based in McKeesport, Pa., the company makes seamless vessels to store gases at high pressure — steel cylinders of up to six tons that it sells to the likes of the Navy, NASA and T. Boone Pickens’s Clean Energy. It has received the first bill from the 25 percent tariff that President Trump  placed on steel from China and a few other countries: $178,703.09 assessed on a steel-pipe shipment scheduled to arrive at the Port of Philadelphia on Thursday.