This industry comprises establishments primarily engaged in manufacturing oil and gas field and underground mining machinery and equipment. Manufacturing offshore oil and gas well drilling and production floating platforms--are classified in Industry 33661, Ship and Boat Building; Manufacturing surface mining machinery and equipment--are classified in Industry 333120, Construction Machinery Manufacturing; Manufacturing coal and ore conveyors--are classified in Industry 33392, Material Handling Equipment Manufacturing; Manufacturing underground mining locomotives--are classified in Industry 336510, Railroad Rolling Stock Manufacturing; and Manufacturing pumps and pumping equipment--are classified in Industry 33391, Pump and Compressor Manufacturing.