ASME B16.4-2021 pdf download

ASME B16.4-2021 pdf download.Gray Iron Threaded Fittings.
General. ASME Standards are developed and maintained with the intent to represent the consensus of concerned interests. As such, users of this Standard may interact with the Committee by requesting interpretations, proposing revisions or a case, and attending Committee meetings. Correspondence should be addressed to: Secretary, B16 Standards Committee The American Society of Mechanical Engineers Two Park Avenue New York, NY 10016-5990 http://go.asme.org/Inquiry Proposing Revisions. Revisions are made periodically to the Standard to incorporate changes thatappear necessary or desirable, as demonstrated bythe experience gained from the application ofthe Standard. Approved revisions will be published periodically. The Committee welcomes proposals for revisions to this Standard. Such proposals should be as specific as possible, citing the paragraph number(s), the proposed wording, and a detailed description of the reasons for the proposal, including any pertinent documentation. Proposing aCase. Cases maybe issued to provide alternative rules when justified, to permitearlyimplementation of an approved revision when the need is urgent, or to provide rules notcovered byexisting provisions. Cases are effective immediately upon ASME approval and shall be posted on the ASME Committee web page. Requests for Cases shall provide a Statement of Need and Background Information. The request should identify the Standard and the paragraph, figure, or table number(s), and be written as a Question and Reply in the same format as existing Cases. Requests for Cases should also indicate the applicable edition(s) ofthe Standard to which the proposed Case applies. Interpretations. Upon request, the B16 Standards Committee will renderan interpretation ofanyrequirementofthe Standard.InterpretationscanonlyberenderedinresponsetoawrittenrequestsenttotheSecretaryoftheB16Standards Committee.
7.2.2 Thetransitioninwallthicknessfromoneendsize to another shall be in a manner that minimizes the addi- tion of stress caused by sudden changes in direction or wall thickness. 7.2.3 Proofofdesign shall be verified by a hydrostatic pressuretestmadeatambienttemperatureinwhichpres- sure is applied continuously for no less than 1 min and at no less than 5 times the pressure rating ofthe largestsize ofendconnectioninthereducingfitting. Testingis consid- ered successful only when no evidence of cracking, frac- turing, or leakage is exhibited after holdingfor atleastthe minimum time at or above the required pressure. 7.3 Tolerances The following tolerances shall be permitted: (a) Metal Thickness Tolerances. At no point in the cast- ings shallthemetalthickness belessthan90% ofthevalue given in Table 7.1-1, 7.1-4, or 7.1-5. (b) Center-to-End Tolerances. Permitted tolerances on the center-to-end dimensions ofthe fittings are shown in Table 7.3-1. Tolerances for end-to-end dimensions and lengths of couplings and reducers shall be twice those given. The largest opening in a reducing fitting governs the tolerances to be applied to all openings. These toler- ances do not apply to return bends and caps. 8 THREADING (a) All fittings shall be threaded according to ASME B1.20.1, and the variations in threading shall be limited to one turn large or one turn small from the gaging notch on the plug when using working gages. (b) The reference point for gaging internal fittings threads depends on the chamfer diameter. When the internal chamfer diameter exceeds the major diameter of the internal thread, the reference point is the last thread scratch on the chamfer cone. When the internal chamfer diameter does not exceed the major diameter of the internal thread, the reference point is the end of the fitting (see Figure 8-1).
9 RIBS (a) Theadditionofribsorlugsispermittedonthreaded fittings. Where ribs are used, itis recommended thattheir thickness be the same as specified for metal thickness of the fitting. (b) Right-hand couplings shall have notmore than two ribs. (c) Right- and left-hand couplings shall have four or more ribs unless the left-hand opening is clearly marked, in which case the use of ribs is at the discretion of the manufacturer. 10 PLUGS, BUSHINGS, AND LOCKNUTS For dimensions of plugs, bushings, and locknuts to be used in connection with Classes 125 and 250 gray iron threaded fittings, see ASME B16.14. 11 FACE BEVEL A bevel notexceeding 5 deg is permitted on the faces of fitting openings. Center-to-end, end-to-end, and width-of- band dimensions may include or exclude the bevel. 12 COATINGS When grayironfittings are zinccoated, theyshall be hot dipped in accordance with ASTM A153/A153M orhave an electrodeposited zinc coating conforming to ASTM B633, TypeI,ServiceCondition4.Hot-dippedcoatingsshallhave a minimum thickness of0.0864 mm (0.0034 in.) and shall be applied before threading. Electrodeposited zinc shall have a minimum thickness of 0.025 mm (0.001 in.) and may be applied either before or after threading.