Flanges pressure ratings

The MAWP of the vessel cannot exceed the MAWP of the no valves, and pipe connected to the vessel. As discussed in Volui Chapter 9, pipe flanges, fittings and valves are manufactured in dan dustry standard pressure rating classes. Table 12-2 is a... 

Bag filters are perhaps the most widely used of these types of pretreatment equipment, and they are also commonly employed (and highly recommended) for sidestream application in HW boiler circuits. They are reliable and robust and tend to be available in an almost infinite number of permutations. When sizing, specification items to be considered include flow rates, vessel materials, housing and support-basket sizes, pipe sizes, connection threads and flanges, outlet positions, code and pressure ratings, gasket materials, bag shapes, bag materials, and micron ratings. 

Standard flanges are designated by class numbers, or rating numbers, which correspond to the primary service (pressure) rating of the flange at room temperature. 

Steel welding-neck flanges for nominal pressure ratings of 6, 10, 25, 40 bar. 

Note For pumps with flange and pressure ratings in excess of the minimum values in 2.2.2, the gland stud size and circle may increase. Larger studs shall be furnished only if required to meet the stress requirements of Section VIII or Section II of the ASME Code, or to sufficiently compress spiral wound gaskets in accordance with manufacturer s specifications. 

Test Conditions The shell pressure test for flanged fittings shall be at a pressure no less than 1.5 times the 38°C (100°F) pressure rating rounded off to the next higher 1-bar (psi) increment. 

In determining the MAWP, we are looking at components such as fittings, piping and vessels however, how components are fitted is also a concern in this equation. For instance, a vessel with a flange that is screwed on would have a different pressure rating than a vessel with a flange that is welded on. 

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