Pipe Threads where Pressuretight Joints are made on the Threads - ISO 7-1
ISO 7-1:1994 Pipe threads where pressure-tight joints are made on the threads
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ISO 7-1 tapered threads are equivalent to DIN 2999, BS 21 (BS EN 10227-1), JIS B0203. Characteristics of ISO 7-1 tapered threads:
- tapered thread 1o47'
- truncation of roots and crests are rounded
- 55o thread angle
- pitch is measured in threads per inch
Note! Pipe sizes do not refer to any physical dimensions. The outside diameter of a pipe or fitting must be measured and compared to a table for size identification. A 3/4" ISO 7-1 pipe thread has an outside diameter - OD - of 1.060 inches. Each thread size has a defined number of threads per inch - TPI, or pitch. The 3/4" NPT pipe thread has 14 threads per inch. Both the TPI and OD of the thread are required for positive identification of thread size because more than one size have the same TPI.
| ISO 7-1 Tapered Threads | |||
| Pipe Size (inches) |
Threads per Inch TPI - pitch |
Outside Diameter OD (inches) |
Distance between threads (inches) |
| 1/16" | 28 | 0.312" | 0.036" |
| 1/8" | 28 | 0.402" | 0.036" |
| 1/4" | 19 | 0.532" | 0.053" |
| 3/8" | 19 | 0.677" | 0.053" |
| 1/2" | 14 | 0.838" | 0.071" |
| 3/4" | 14 | 1.060" | 0.071" |
| 1" | 11 | 1.327" | 0.091" |
| 1-1/4" | 11 | 1.669" | 0.091" |
| 1-1/2" | 11 | 1.902" | 0.091" |
| 2" | 11 | 2.374" | 0.091" |
ISO 7-1 threads are not interchangeable with ISO 228/1 Parallel Pipe Threads. NPT threads may look similar to ISO 7/1 threads. However, ISO and NPT threads should not be mixed. ISO threads have 55o taper angle versus 60o for NPT. The NPT root and crest configurations are also different from ISO. For ISO threads pitch is usually measured in millimeters ( may be expressed in Inch). The pitch are different.
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Related Topics
- Dimensions - Sizes and dimensions of pipes and tubes, and their fittings - inside and outside diameter, weight and more
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Related Documents
- Briggs Standard Pipe Taps - Drill Sizes - Drill sizes for Briggs Standard Pipe taps
- NPT- National Pipe Thread Taper- ANSI B1.20.1 - NPT pipe threads - dimensions according ANSI/ASME B1.20.1
- Pipe Taps - Drill Sizes - Drill sizes for British Whitworth Standard and Briggs American Standard pipe taps
- Pipe Threads for Tubes and Fittings where Pressuretight joints are made on the Threads - BS 21 - BSPT - British Standard Pipe Taper threads & BSP or BSPF - British Standard Pipe Parallel (Straight) threads
- Thread Standards - Piping - Piping thread standards
- Threads - Metric ISO 724 - M Thread (metric ISO 724 thread) Standard in Europe
