Grease seals form the primary barrier in wireline pressure control equipment. Multiple flow tubes inject high-viscosity grease around the cable, creating a hydraulic seal. Elastomeric or brass bushings support the wire centrally while grease pressure exceeds well pressure, preventing blowouts during live-well interventions in high-pressure reservoirs. https://globalsealstech.com/product-category/oil-gas-seals/oil-free-lubricated-pump-seals/