ASME Y14.00 pdf download SCREW THREAD REPRESENTATION
Definitions of terms are in accordance with ASMEB1.7M and the applicablc standard.
2.1 Straight Threads
Straight 60 deg screw thread designations for draw-ings are based on ASME B1.1，ASME B1.15，ASMEB1.13M，ASME B1.21M,and ASME B1.10M. Straightpipe thread standards are covered in thc documentscited in para.2.2.
2.2 Taper Threads
Taper pipe thread designations for drawings are basedon AsME B1.20.1 (General Purposc) and ASMEB1.20.3 (Dryseal).
NOTE: Pipe threads are designated in established trade sizes,whichsignify a nominal diameter only.
2.2.1 Taper Pipe Thread Features. General pur-pose pipc thread forms allow crest and root interferenceor clearance when the flanks contact. When a clearanceoccurs,unless filled with a lute or sealer，a spiralpassage will exist through which leakage can occur.The dryseal pipe thread form does not allow suchclearance，but rather has crest and root metal-to-metalcontact or interference when the flanks contact. It isthis feature that eliminates the need for a lute or sealerto provide for leak-proof assemblies.
2.2.2 General Purpose Taper Pipe Thread Se-ries. General purpose taper pipe thread requirementsare specified in ASME B1.20.1. Included are taperthreads designated as NPT and NPTR. See Table 1for designations and definitions.
a)Straight pipe threads NPSC, NPSL, and NPSM are also includedin ASME B1.20.1.
(b) Acronautical taper pipe threads specified in MIL-P-7105 weredesignated ANPT. MIL-P-7105 is no longer active，but SAE AS71051replaces it.
2.2.3 Dryseal Pipe Thread Series. Dryseal pipethrcads are specified in ASME B1.20.3. Included aretaper dryseal pipe threads designated NPTF-1，NPTF-2, and PTF-SAE Short Series. See Table 1 for designa-tions and definitions.
NOTE: Intermal straight dryseal pipe threads NPSF and NPSI arealso included in ASME B1.20.3.
2.3 Acme Threads
Acme screw thread drawing practices are based onASME B1.5. Included are general purpose threads,where there is clearance on flanks and at major/minordiameters,and centralizing threads，where clearance atthe major diameter is limited. See Table 1.
2.4 Stub Acme Threads
Stub Acme screw thread drawing practices are basedon ASME B1.8.See Table 1.
2.5 Buttress Threads
Buttress screw thread drawing practices are basedon ASME B1.9. The Buttress thread is designated“BUTT”for external thread pulls or “PUSH-BUTTfor external thread pushes. See Table 1.
Representation，specification，and dimensioning ofthreads shall be in accordance with the following para-graphs.
3.1 Thread Representation
Three methods in general use for represcnting screwthrcads on drawings are as follows: simplified in Fig.1，schematic in Fig. 2, and dctailed in Fig. 3.Onemethod is generally used within any one drawing. Whenrequired,all three methods may be used. See Figs. 4and 5.
3.1.1 Simplified Representation. Thc simplifieddrawing mcthod is recommended for straight and tapered60 deg form,Acme，Stub Acme，Buttress，helical coilinsert,and other thread forms exeept where detailedrepresentations are required. Sce para. 3.1.3 and Figs.1，6,7,and 8.