These closures are intended to protect the threads, flares, tapered and straight surfaces of units from the intrusion of dirt, moisture and foreign matter during storage and shipment, and to "seal-in" the anti-corrosion fluid in hydraulic units in storage and shipment.

This specification covers caps and plugs (hereinafter referred to as closures) for the protection of thread and sealing surfaces, for prevention of intrusion of dust and moisture and for pressure sealing accessories and parts during storage and shipment.