Underwater Stuffing Box Sealing Element Wear Reduction

The sealing element is constructed as a composite structure with an inner core made of wear-resistant material (such as ceramic or hardened metal) and an outer layer of soft sealing material. This composite design allows the soft outer layer to provide effective sealing against the drill string while the hard inner core resists wear from rotational contact, thereby simultaneously achieving both good sealing performance and long service life.

The sealing element is designed with flexible segments or a bellows-like structure that allows it to dynamically expand and contract radially to adapt to different drill pipe diameters and tool joint sizes. The inner hard-wearing core maintains its shape and wear resistance, while the flexible outer structure provides the necessary adaptability, enabling the same sealing element to accommodate various pipe dimensions throughout the drilling operation.

The sealing element is divided into multiple axial segments or zones, each designed to handle specific tool joint diameters. When a larger diameter tool joint passes through, only certain segments experience increased wear while others remain protected. This segmentation allows the sealing element to accommodate tool joints of varying sizes without suffering uniform wear across its entire length, thereby extending its useful life while maintaining drilling continuity.

The invention replaces traditional mechanical bearing systems with a hydrodynamic or hydrostatic lubrication system where a film of drilling fluid or specially formulated lubricant is maintained between the sealing element and the drill string. This fluid film eliminates direct metal-to-metal contact and rotational wear without requiring complex mechanical bearings, thereby extending the sealing element's life while keeping the system relatively simple and avoiding additional lubrication infrastructure.