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1.6 ORIFICE AREAS AND DESIGNATIONS Pipe Flanges and Flanged Fittings
ValvesÑFlanged, Threaded, and Welding
End The standard effective oriÞce areas and the corresponding
letter designations are listed in Table 1. These effective areas
are valid only when used with the sizing equations contained
in API RP 520, Part I. 1American Society of Mechanical Engineers, 345 East 47th Street,
New York, New York 10017.
2American National Standards Institute, 11 West 42nd Street, New
York, New York 10036. 3NACE International, P.O. Box 218340, Houston, Texas 77218. 1
Copyright American Petroleum Institute
Reproduced by IHS under license with API
No reproduction or networking permitted without license from IHS Licensee=TECNA/5935100001
Not for Resale, 05/05/2005 09:50:16 MDT 2 API STANDARD 526 Table 1—Standard Effective Oriﬁce Areas
and Letter Designations
Designation Effective OriÞce Area
(square in.) D 0.110 E 0.196 F 0.307 G 0.503 H 0.785 J 1.287 K 1.838 L 2.853 M 3.60 N 4.34 P 6.38 Q 11.05 R 16.00 T 26.00 2 Design
Pressure relief valves discussed in this standard shall be
designed and manufactured in accordance with the applicable
requirements of Section VIII of the ASME Boiler and Pressure Vessel Code for pressure relief devices.
2.2 DETERMINATION OF EFFECTIVE ORIFICE
The minimum required effective oriÞce area shall be determined in accordance with API RP 520, Part I.
2.3 VALVE SELECTION
For valves described in this standard, inlet and outlet
ßange sizes and pressure-temperature ratings shall conform
to the data in Tables 2 Ð 15 for spring-loaded valves and
Tables 16 Ð 29 for pilot-operated valves. Inlet and outlet
pressure limits are governed by the ßange pressure/temperature limits or by the manufacturerÕs design limits, whichever
Center-to-face dimensions shall be in accordance with
Tables 2 Ð 15 for spring-loaded valves and Tables 16 Ð 29 for pilot-operated valves, with tolerances of plus or minus 1Ú16 in.
for valve inlet sizes up to and including 4 in., and plus or
minus 1Ú8 in. for...
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- Fall '13