tailieunhanh - MECHANICAL PROPERTIES OF STRUCTURAL STEELS

The seat or seal rings provide the seating surface for the disk. In some designs, the body is machined to serve as the seating surface and seal rings are not used. In other designs, forged seal rings are threaded or welded to the body to provide the seating surface. To improve the wear-resistance of the seal rings, the surface is often hard-faced by welding and then machining the contact surface of the seal ring. A fine surface finish of the seating area is necessary for good sealing when the valve is closed. Seal rings are not usually considered pressure boundary parts because the body. | NIST NCSTAR 1-3D Federal Building and Fire Safety Investigation of the World Trade Center Disaster Mechanical Properties of Structural Steels William E. Luecke J. David McColskey Christopher N. McCowan Stephen W. Banovic Richard J. Fields Timothy Foecke Thomas A. Siewert Frank W. Gayle NIST National Institute of Standards and Technology Technology Administration . Department of Commerce NIST NCSTAR 1-3D Federal Building and Fire Safety Investigation of the World Trade Center Disaster Mechanical Properties of Structural Steels William E. Luecke J. David McColskey Christopher N. McCowan Stephen W. Banovic Richard J. Fields Timothy Foecke Thomas A. Siewert Frank W. Gayle Materials Science and Engineering Laboratory National Institute of Standards and Technology Retired September 2005 . Department of Commerce Carlos M. Gutierrez Secretary Technology Administration Michelle O Neill Acting Under Secretary for Technology National Institute of Standards and Technology William Jeffrey .