pipe threads, general - American Society of Mechanical Engineers

pipe threads, general - American Society of Mechanical Engineers

A AN M E R I C A NN A T I O N A SL T A N D A R D
PIPE THREADS, GENERAL
PURPOSE (INCH)
ANSI/ASME B1.20.1 - 1983
( R E V I S I O N A N D R E D E S I G N A T I O NOF ANSI 82.1-1968)
REAFFIRMED 1992
FOR CURRENT COMMITTEE PERSONNEL
PLEASE SEE ASME MANUAL AS-1
1
S P O N S O R E DA N DP U B L I S H E D
T H EA M E R I C A NS O C I E T Y
United Engineering Center
OF
MECHANICAL
3 4 5 E a s t 47th
Street
BY
E N G I N E E R S
N e w York, N. Y. 10017
CONTENTS
Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
StandardsCommitteeRoster
.........................................
iii
iv
.................................................
1.1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2 Thread
Designations
........................................
1.3 Sealing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.4 Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
1
1
1
1
..........................
4
4
4
4
1
Introduction
1.5
1.6
2
Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Related
Standard
..........................................
AmericanNationalStandard
2.1
2.72.3
Pipe ThreadForm
Thread
Form . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Angle of Thread . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TruncationandThreadHeight
..................................
1
1
3 Specification for GeneralPurpose Taper Pipe Threads, NPT . . . . . . . . . . . . . . . . . .
3.1 TaperPipeThreads
.........................................
3.2 Tolerances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4
4
9
4
Specifications for Internal Straight Threads in Pipe Couplings, NPSC . . . . . . . . . . . .
4.1 Straight Pipe Threads in PipeCouplings . . . . . . . . . . . . . . . . . . . . . . . . . . .
9
9
5
Specifications for Railing Joint TaperPipe Threads, NPTR
............................................
..................
9
9
6
Specifications for Straight Pipe Threads for Mechanical Joints;
NPSM,NPSL, NPSH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13
5.1
Railing
Joints
6.1 StraightPipeThreads
.......................................
6.2 Free-FittingMechanicalJointsforFixtures,
NPSM . . . . . . . . . . . . . . . . . . . .
6.3 Loose-FittingMechanicalJoints With Locknuts.NPSL . . . . . . . . . . . . . . . . .
6.4 Loose-FittingMechanicalJointsforHoseCoupling,
NPSH . . . . . . . . . . . . . . .
7
Gages and Gage Tolerances for American National Standard
7.1
7.2
7.3
7.4
PipeThreads
1;
16
. . . . . . . . 16
Design o f Gages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Classes of Gages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gage Tolerances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Relation of Lead and Angle Deviations t o Pitch Diameter
Tolerances of Gages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
vii
13
13
16
16
18
18
8
9
Gaging of TaperPipeThreads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.1 Gaging External Taper Threads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.2 Gaging InternalTaperThreads
.................................
8.3 Gaging Practice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.4 Gaging Chamfered,Countersunk, or Recessed Threads . . . . . . . . . . . . . . . . .
Gaging of Straight PipeThreads
9:1
9.2
....................................
Types ofGages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gage Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18
18
18
18
18
22
12
22
Figures
I Basic Form of AmericanNational Standard Taper Pipe Thread . . . . . . . . . . . . . . . .
2 AmericanNational StandardTaper Pipe Threads for Pressure-Tight Joints. NPT . . . .
3 AmericanNational StandardTaper Pipe Thread Notation . . . . . . . . . . . . . . . . . . . .
4 NPT Standard Taper Pipe Thread Plug and Ring Cages . . . . . . . . . . . . . . . . . . . . . .
5 Suggested Form of Gage Thread . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6 Gaging External Taper Threads With Ring Gage . . . . . . . . . . . . . . . . . . . . . . . . . .
7 Gaging Internal Taper Threads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8 Gaging of ChamferedThreads
.....................................
2
4
5
14
14
14
14
15
Tables
Limits on Crest and Root Truncation of American National Standard External
and InternalTaper Pipe Threads. NPT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Basic Dimensions of American National Standard Taper Pipe Thread. NPT . . . . . . . .
Tolerances on Taper. Lead. and Angle of Pipe Threads. NPT . . . . . . . . . . . . . . . . .
Dimensions. Internal StraightThreads in Pipe Coupling. NPSC . . . . . . . . . . . . . . . .
Dimensions of External and Internal Taper Pipe Threads for Railing Joints. NPTR . . .
Dimensions of External and Internal Straight Pipe Threads for Fixtures. NPSM . . . . .
Dimensions. External and Internal Straight Pipe Thread for
LocknutConnections. NPSL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8 Basic Dimensions of Threaded Plug and Ring Gages for National American National
Standard Taper PipeThreads. NPT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9 Tolerances for American National Standard Working Taper Pipe Thread Plug and
RingGages. NPT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10 Diameter Equivalent of Deviation in Half Included Angle of Thread for
Tools and Gages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1 1 Diameter Equivalent of Deviation in Lead for Tools and Gages . . . . . . . . . . . . . . . .
1
Appendix
......................................................
Viii
3
6
8
8
10
11
12
17
19
20
21
23