Windsocks shall be installed at plant facilities handling flammable gases, volatile liquids or toxic materials and also at helipads (may require lighting if night flights are intended). Windsocks are not required along pipelines except in hydrocarbon pump stations and major manifolding and scraping stations. Windsocks shall be mounted where they can be clearly seen from most ground-level points within the plant boundary; mounting shall be on the tops of structures or on a pole. More than one windsock may be required at a plant site.