CONNECTING SLEEVE FOR OIL ASSORTMENT PIPES AND METHOD FOR APPLYING IRON-ZINC COVER AT THREADED PORTIONS Russian patent published in 2005 - IPC

FIELD: mining industry.

SUBSTANCE: device has body with two threaded portions, on which protective layer is applied of alloy including iron and zinc. Iron and zinc are present in alloy in relation from 0.0638 to 03330 for thickness of covering layer of 20-100 micrometers. Micro-hardness of cover determined from method of restored print of four-sided pyramid is within limits of 3360-5250 MPa. Such cover may be received on threaded portions of connecting sleeve by method of diffusive zinc-plating. Zinc-plating is performed in container filled with diffusive mixture containing mixture of zinc powder having graininess of 0.1-0.5 mm and quartz powder with graininess of 0.15-0.70 mm. Process of diffusive zinc-plating is performed by isothermal exposure to temperature of 430°-450°C during 1.5-3 hours with following air cooling. Before filling container with diffusive mixture it is stirred for granting smooth form to mixture particles.

EFFECT: higher durability and impermeability.

2 cl, 1 tbl