ASME B16.5:1998 pdf download PIPE FLANGES AND FLANGED FIT TINGS
2.3 Rating Temperature
The temperature shown for a corresponding pressurerating is the temperature of the pressure-containingshell of the flange or flanged fitting. In general, thistemperature is the same as that of the contained fluidUse of a pressure rating corresponding to a temperatureother than that of the contained filuid is the responsibilityof the user, subject to the requirements of the applicablecode or regulation. For any temperature below -20Fthe rating shall be no greater than the rating shownfor -20°F
2.4 Temperature Considerations
Application of the ratings in this Standard to flangedjoints at both high and low temperatures shall takeinto consideration the risk of leakage due to forcesand moments developed in the connected piping orequipment. The following provisions are intended tominimize these risks.
2.4.1 Flange Attachment. Socket welding andthreaded flanges are not recommended for service above500°F or below -50F if severe thermal gradients orthermal cycling are involved.
2.4.2 High Temperature Service. At temperatures in the creep range, gradual relaxation of flangesbolts, and gaskets may progressively reduce bolt loadsIt may be necessary to arrange for periodic tighteningof bolts to prevent leakage, Joints subject to substantiathermal gradicnts may require the same attention.When used above 400°F,Class 150 fanged jointsmay develop leakage unless care is taken to avoidimposing severe external loads and/or severe thermalgradients. For other classes, similar consideration shouldbe given above 750°F
2.4.3 Low Temperature Service. The usershould recognize that some of the material listed inthe rating tables undergo sufficient decrease in toughnessat low temperatures that they cannot safely sustainshock loadings, sudden changes of stress or temperature,or high stress concentrations.
2.5 SystemHydrostatic Test
Flanged joints and flanged fittings may be subjectedto system hydrostatic tests at a pressure not to exceed1.5 times the 100°F rating rounded off to the nexthigher 25 psi. Testing at any higher pressure is theresponsibility of the user, subject to the requirementsof the applicable code or regulation.
2.6 Welding Neck Flanges
Ratings for welding neck flanges covered by thisStandard are based upon their hubs at the welding endhaving thickncss at least equal to that calculated forpipe having 40.0 ksi specified minimum yield strength.(For higher strength pipe with thinner wall, see MSSSP-44.) The ratings also apply to such flanges usedwith components of unequal strength and unequal wallthickness when the attachment weld is made in accord-ance with the applicable code or regulation. See Figs12，13，and 14.
2.7 Multiple Material Grades
Materials for flanges and flanged fittings may meetthe requircments for more than one specification orgrade of a specification listed in Table 1A. In thatevent, the pressure-temperature ratings for any of thesespecifications or grades may be used provided thatmarking is in accordance with para.4.1.2(d).
3 SIZE
3.1 Nominal Size
The size of a flange or flanged fitting covered bythis Standard is its nominal pipe size, NPS. The diameterof a bolt is its nominal size. Use of “nominal” indicatesthat the stated siz or dimension is only for designation.not measurement. The actual dimension may or maynot be the nominal size and is subject to establishedtolerances.
3.2 Reducing Fittings
Reducing fittings shall be designated by the size ofthe openings in their proper sequence as indicated inthe sketches of Fig. 2.
ASME B16.5:1998 pdf download
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