9. LEGEND OF PIPE CONNECTIONS
UNI ISO 228/1
Pipe threads where pressure-tight joints are not made on the
threads - Designation, dimensions and tolerances
Used terminology:
G: Pipe threads where pressure-tight joints are not made on the
threads
A: Close tolerance class for external pipe threads where pres-
sure-tight joints are not made on the threads
B: Wider tolerance class for external pipe threads where pres-
sure-tight joints are not made on the threads
Internal threads: G letter followed by thread mark (only toler-
ance class)
External threads: G letter followed by thread mark and by A let-
ter for A class external threads or by B letter
for B class external threads.
UNI ISO 7/1
Pipe threads where pressure-tight joints are made on the
threads - Designation, dimensions and tolerances
Used terminology:
Rp: Internal cylindrical threads where pressure-tight joints are
made on the threads
Rc: Internal conical threads where pressure-tight joints are
made on the threads
R: External conical threads where pressure-tight joints are
made on the threads
Internal cylindrical threads: R letter followed by p letter
Internal conical threads:
R letter followed by c letter
External conical threads: R letter
Designation
Description
UNI ISO 7/1 - Rp 1 1/2
Internal cylindrical threads where pressure-tight joints are made on the threads, defined by stand-
ard UNI ISO 7/1
Conventional ø 1 1/2”
UNI ISO 7/1 - Rp 2 1/2
Internal cylindrical threads where pressure-tight joints are made on the threads, defined by stand-
ard UNI ISO 7/1
Conventional ø 2 1/2”
UNI ISO 7/1 - Rp 3
Internal cylindrical threads where pressure-tight joints are made on the threads, defined by stand-
ard UNI ISO 7/1
Conventional ø 3”
UNI ISO 7/1 - R 3
External conical threads where pressure-tight joints are made on the threads, defined by standard
UNI ISO 7/1
Conventional ø 3”
UNI ISO 228/1 - G 4 B
Internal cylindrical threads where pressure-tight joints are not made on the threads, defined by
standard UNI ISO 228/1
Tolerance class B for external thread
Conventional ø 4”
DN 80 PN 16
Flange Nominal Diameter: 80 mm
Nominal Pressure: 16 bar
Notes:
Conventional diameter value [in inches] identifies short thread
designation, based upon the relative standard.
All relative values are defined by standards.
As example, here below some values:
UNI ISO 7/1
UNI ISO 228/1
Conventional ø
1”
1”
Pitch
2.309 mm
2.309 mm
External ø
33.249 mm
33.249 mm
Core ø
30.291 mm
30.291 mm
Thread height
1.479 mm
1.479 mm
A6
NECS_ME_0152_1604_201004_GB
NECS-ME
HFC R410A
Summary of Contents for CLIMAVENETA NECS-ME 0152
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