ASME B16.20:2017 pdf free download

ASME B16.20:2017 pdf free download
ASME B16.20:2017 pdf free download.Metallic Gaskets for Pipe Flanges
For all corresponding sizes and pressure classes, finished gaskets (including windings as well as inner and outer rings) shall be capable of meeting a maximum permissible leakage rate of 0.0137 mg/s·m (7.67E–10 lb/sec·in.). The circumferential length [meter (inch)] shall be calculated using the gasket outside diameter as shown in Tables SW-2.1-1 through SW-2.1-3. Testingshall be conducted atambienttempera- ture using an external calibration gas with a known methane concentration and a testgas flowrate of1 L/min.
(a) The testfixture shall have asurface finish perASME B16.5,becapableofshieldingthegasketso as to directany leakage to the monitoring probe, and be capable of applying a uniform load on the test gasket sealing element while internally pressurizing the gasket with methane (minimum 97% purity).
(b) Gasketstressduetotheuniformlyappliedloadshall be35 MPa(5,000 psi) forClass 150, 56 MPa(8,000 psi) for Class 300 and Class 400, and 70 MPa (10,000 psi) forClass 600 and above.
(c) Testpressure shall be 20 bar(290 psi) forClass 150 and 40 bar (580 psi) for Class 300 and above.
(d) Testpressure shall be maintained fora minimum of 4 h, after which time three readings shall be taken at approximately 5-min intervals; the average of these three readings shall be compared to the maximum permis- sible leakage rate.
Metal windings and filler materials shall be in accor- dance with Table SW-3-1. The inner-ring material should match the winding material unless the purchaser specifies otherwise. The centering ring may be carbon steel that is painted, metal plated, or otherwise coated to inhibit atmospheric corrosion.
Spiral-wound gaskets shall be marked with a colorcode that identifies the windings and filler materials. A contin- uous color around the outer edge of the centering ring shall identify the winding metal. The color identifying the filler material for NPS 1 1 ∕ 2 and larger shall have four intermittent stripes spaced approximately 90 deg apart on the outer edge of the centering ring. Smaller size gaskets shall have a minimum of two stripes 180 deg apart. The colors shall conform to those listed in Table SW-3-1.