Читать книгу Petroleum Refining Design and Applications Handbook - A. Kayode Coker - Страница 40

1 1. Design temperature between −30 and 345°C is 25°C (−20° F and 650°F if 50°F) above maximum operating temperature; higher safety margins are used outside the given temperature range.

2 2. The design pressure is 10% or 0.69–1.7 bar (10–25 psi) over the maximum operating pressure, which-ever is greater. The maximum operating pressure, in turn, is taken as 1.7 bar (25 psi) above the normal operation.

3 3. Design pressures of vessels operating at 0–0.69 barg (0–10 psig) and 95–540°C (200–1000°F) are 2.76 barg (40 psig).

4 4. For vacuum operation, design pressures are 1 barg (15 psig) and full vacuum.

5 5. Minimum wall thickness for rigidity: 6.4 mm (0.25 in.) for 1.07 m (42 in.) diameter and under, 8.1 mm (0.32 in.) for 1.07–1.52 m (42–60 in.) diameter, and 9.7 mm (0.38 in.) for over 1.52 m (60 in.) diameter.

6 6. Corrosion allowance 8.9 mm (0.35 in.) for known corrosive conditions, 3.8 mm (0.15 in.) for noncorrosive streams, and 1.5 mm (0.06 in.) for steam drums and air receivers.

7 7. Allowable working stresses are one-fourth the ultimate strength of the material.

8 8. Maximum allowable stress depends sharply on temperatureTemperature (°F)−20–6507508501000(°C)−30–345400455540Low-alloy steel, SA 203 (psi)18,75915,65095502500(bar)12901,070686273Type 302 stainless (spi)18,75018,75015,9506250(bar)129012901100431