api 500 area classification pgjonline.com Category:energy industry Global Rank:2,772,016 visits:14.6K pages/Per:1.2 ocsgroup.com ocs group is a leading innovator in the oil and gas industry, providing commissioning, inspection, engineering, and training services globally. Category:energy industry Global Rank:4,235,618 visits:8.0K pages/Per:1.0 ADS