Features: 1.Provided with weak nitrile rubber sealing ring and used for sealing and protecting combination of union steel pairs. 2.Recommended for connection of manifolds and pipe lines, vehicle-mounted system and mud transportation and also can be used as non-pressure seal union. 3.Suitable for air, water, oil and gas service. 4.Made of high quality steel by forging and finishing cut.5.Adopts some end connections of pipeline thread, tubing thread, butt-weld.