API STD 603-2013 pdf download.Corrosion-resistant, Bolted Bonnet Gate Valves—Flanged and Butt-welding Ends.
4 Pressure/Temperature Ratings 4.1 Pressure/temperature ratings shall be in accordance with those specified in the tables of ASME B16.34 for Standard Class for the applicable material specification and the applicable class. 4.2 Restrictions of temperature and concurrent pressure, or pressure and concurrent temperature (e.g. those imposed by special soft seals or special trim materials), shall be marked on the valve identification plate (see Section 8). 4.3 The temperature for a corresponding pressure rating is the maximum temperature of the pressure-containing shell of the valve. In general, this temperature is the same as that of the contained fluid. The use of a pressure rating corresponding to a temperature other than that of the contained fluid is the responsibility of the user. 4.4 For temperatures below the lowest temperature listed in the ASME B16.34 pressure/temperature tables, the service pressure shall be no greater than the pressure for the lowest listed temperature. The use of valves at lower temperatures is the responsibility of the user. NOTE Consideration should be given to the loss of ductility and impact strength of many materials at low temperature, ASME B31.3 Appendix A and ASME B31T may be used as guidance. 4.5 Double seated valves, in some design configurations, may be capable of trapping liquid in the center cavity of the valve when in the closed position. If subjected to an increase in temperature, an excessive build-up of pressure can occur, which may result in a pressure boundary failure. Where such a condition is possible, it is the responsibility of the user to provide or require to be provided adequate means (by design, installation, or operating procedures) for pressure relief of the center cavity. 5 Design 5.1 General 5.1.1 A valve body schematic is shown as Figure 1. The minimum body wall thickness, t m , at the time of manufacture shall be as given in Table 1, except as indicated in 5.1.2 for butt-welding valve ends.
5.3 Body Dimensions 5.3.1 Flanged Ends 220.127.116.11 Body end flanges shall comply with the dimensional requirements of ASME B16.5. Unless otherwise specified, raised face end flanges shall be provided. The Purchaser may specify a flange facing finish other than that specified in ASME B16.5. 18.104.22.168 Face-to-face dimensions shall be in accordance with ASME B16.10. Body end flanges and bonnet flanges shall be cast or forged integral with the body. 5.3.2 Butt-welding Ends 22.214.171.124 Butt-welding ends for valve sizes greater than DN 50 (NPS 2) shall conform to the requirements of ASME B16.25 and B16.34 for the bore specified for use without backing rings. Butt-welding ends for valves DN 50 (NPS 2) and smaller shall conform to the requirements of API 602. Conversion of a flanged end valve to a butt-welding valve for Class 300 and above may be permitted by agreement between the Purchaser and manufacturer. 126.96.36.199 End-to-end dimensions for butt-welding end class designated valves shall be in accordance with ASME B1 6.1 0, unless otherwise specified by the Purchaser. 188.8.131.52 Short pattern butt-welding end bolted bonnet valves are not permitted. 5.3.3 Body Seats 184.108.40.206 The inside diameter of the seat opening shall not be less than that specified in Table A-1 of Appendix A of ASME B16.34 for the applicable valve DN or NPS and pressure class. 220.127.116.11 Body seats may be separate or integral with the body. When hard facing is furnished, it shall be applied as a weld overlay of AWS A5.13 ECoCr-A or AWS A 5.21 ERCoCr-A, except as provided in 6.2.2, and shall have a minimum finished thickness of 1.6 mm (0.06 in.). 18.104.22.168 Where separate seat rings are provided, they shall be shoulder or bottom seated, and either threaded or seal welded in place, except that for DN ≤ 50 (NPS ≤ 2) rolled or pressed in seat rings may be used. Threaded seat rings may also be seal welded and shall be provided with lugs or slots to facilitate removal.