ASME B16.51:2021 pdf download

ASME B16.51:2021 pdf download Copper and Copper Alloy Press-Connect Pressure Fittings
Table 9.1-1.Examples of various tube stop configurationsare shown in Figure 8-1.
9 DESIGN
9.1 General
As a minimum, the fitting shall be designed to withstandthe tests specified in section 14 without leakage. Thepress-connect ends shall be assembled in accordancewith the fitting manufacturer’s installation instructions.
The dimensions and tolerances of the press-connectends shall be as shown in Table 9.1-1.
9.2 Out-of-Roundness of Fitting End (P or FTG)Maximum out-of-roundness ofthe press-connect fittingends,dimensions A and F, shall not exceed 1% ofthe maximum corresponding diameters shown inTable 9.1-1. The average of the maximum andminimum diameters shall be within the dimensionsshown in Table 9.1-1.
9.3 Inside Diameter of Fitting
The minimum cross-sectional area of the insidediameter through the fitting body shall not be lessthan the theoretical minimum area defined by diameter0in Table 9.1-1.The out-of-roundness condition of thecross-sectional area shall not exceed 10%of theminimum diameter shown in Table 9.1-1.
For reducer or adapter fittings,the smallest enddiameter shall apply. provided that this diameter doesnot restrict the other outlets.
9.4 wall Thickness
The minimum wall thickness taken at any location of thefitting shall not be less than shown in Table 9.1-1.
10 THREADED ENDS
The threaded ends shall have right-hand nominal pipetaper (NPT) threads conforming to ASME B1.20.1.
10.1 Countersink or Chamfer
All internal threads shall be countersunk a distance noless than one-half the pitch of the thread, at an angle ofapproximately 45 deg with the axis of the thread. Allexternal threads shall be chamfered at an angle of 30deg to 45 deg from the axis. Countersinking and cham-fering shall be concentric with the threads. The lengthof threads shall be measured to include the countersinkor chamfer.
10.2 Threading Tolerances
NPT threads shall be checked by use of a plug or ringgage in either standard or limit types. When gaginginternal taper threads, the plug gage shall be screwedhand-tight into the fitting. The reference point forgaging internal product-threads depends on thechamfer diameter. When the internal chamfer diameterexceeds the major diameter of the internal thread, thereference point shall be the last thread scratch on thechamfer cone.Otherwise, when the internal chamferdiameter does not exceed the major diameter of theinternal thread, the reference point shall be the end ofthe fitting. In gaging external taper threads, the ringgage shall be screwed hand-tight on the externalthread. On the external thread, the ring gage shall beflush with the end of the thread.
Tolerance for an internal threaded end having aninternal shoulder shall be from the gage referencepoint (notch) to one turn small. Tolerance for an internallythreaded end without a shoulder and for an externallythreaded end shall be from one turn small to one turnlarge.
10.3 Design of Threaded Ends
The wrenching section of internally threaded ends shallbe polygonal, and the wrenching section of externallythreaded ends shall be furnished with either polygonor flats, at the manufacturer’s option.
11 ALIGNMENT
The maximum allowable deviation in the angular align-ment of any end from the specified axis position shall be1hdeg (1 deg total). See Figure 11-1.
12 GAGING
12.1 Preferred Gaging Method of Press-Joint EndsThe preferred method of gaging the diameter tolerancesfor external and internal ends shall be by the use of plainplug and ring gages designed to hold the product withinthe limits established in Table 9.1-1.Gage tolerances shallbe Class ZM, as defined in ANSI B4.4M.
12.2 Optional Gaging Method of Press-Connect
Pressure Fittings
For gaging the diameter tolerance of external andinternal ends, the use of direct-reading instrumentsinstead of ring and plug gages as specified in para.12.1 shall be permitted. When gaging the diameters ofexternal and internal ends using direct-reading instru-ments,refer to para.9.2.