. Tentative revised boiler safety orders. ckness of the head 5Xr (2) d = Si P where d = unstayed distance from shell in inches T = thickness of head in sixteenths of an inch P = maximum allowable working pressure in lb. per sq. in. NEW INSTxiLLATIONS, PART I, SECTION I, POWER BOILERS 57 In water-tube boilers, the tubes of which are connected to drumheads, the area to be stayed shall be taken as the total area of thehead less the area of an annular ring of width d measured fromthe inner circumference of the drum shell. 215 When the tube heads of drums of water-tube boilers are30 in. or less in
. Tentative revised boiler safety orders. ckness of the head 5Xr (2) d = Si P where d = unstayed distance from shell in inches T = thickness of head in sixteenths of an inch P = maximum allowable working pressure in lb. per sq. in. NEW INSTxiLLATIONS, PART I, SECTION I, POWER BOILERS 57 In water-tube boilers, the tubes of which are connected to drumheads, the area to be stayed shall be taken as the total area of thehead less the area of an annular ring of width d measured fromthe inner circumference of the drum shell. 215 When the tube heads of drums of water-tube boilers are30 in. or less in diameter and the tube plate is stiffened by flangedribs or gussets, no stays need be used if a hydrostatic test to destruc-tion of a boiler or unit section built in accordance with the con-struction, shows that the factor of safety is at least five. 216 Stays shall be used in the tube sheets of a fire-tube boilerif the distance between the edges of the tube holes exceeds themaximum pitch of staybolts for the corresponding plate thickness. Fig. 16 Method of Determining Net Area of IrregularSegment of a Head and pressure given in Table 4. That part of the tube sheet whichcomes between the tubes and the shell need not be stayed, if thedistance to the nearest tangent common to two tube holes whenmeasured on any radius of the tube sheet that intersects the tangentbetween the holes, does not exceed this maximum pitch by morethan 3 in. The tube holes to which a common tangent may bedrawn in applying this rule shall not be at a greater distance fromedge to edge than the maximum pitch referred to. 217 The net area to be stayed in a segment of a head may bedetermined by the following formula: ^ J / V ; — = area to be stayed, sq. in. 3 \ {H-d-2) where II z= distance from tubes to shell, = distance given by formula in Par. — radius of boiler head, in. 58 REPORT OF BOILER CODE COMMITTEE, 218 When the portion of the head below the tubes in a horizon-tal return
Size: 2577px × 970px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectsteambo, bookyear1919
