RJT Stainless Steel Fittings Dimensions
RJT (Ring Joint Type) is the most widely used hygienic pipe fitting standard in the UK, found throughout dairy, brewing, food, and pharmaceutical processing wherever pipework needs to be dismantled regularly for cleaning or inspection. An RJT union consists of four parts: a male part and weld liner (both welded to the pipe ends), a captive nut that draws the two liners together, and a seal (typically an elastomer ring) compressed between the liner faces to form the seal. Because the seal sits in a shallow recess between two flat, easily cleaned faces, RJT unions avoid the crevices that can harbour bacteria in less hygienic fitting designs — the main reason they're specified so heavily in food and pharmaceutical applications.
The charts below give dimensional information for RJT standard male, nut, weld liner, blank, and seal parts. Dimensions shown are in mm; if you wish to convert to inches, please use our universal converter.
Dimensional Charts relating to RJT Standard Male, Nut, Weld Liner, Blank and Seal Parts.
RJT fittings (Ring Joint Type) are used in many of the Hygienic industries and are a popular fitting for frequently dismantled sections of pipework.
Dimensions shown are in mm, if you wish to convert to Inches, please use our universal converter.
RJT WELDING MALE - BS4825:5 1991
| Nominal Size | A | B | C | D | E | F | G | |
|---|---|---|---|---|---|---|---|---|
| inch | mm | mm | mm | mm | mm | mm | mm | mm |
| 1 | 25.4 | 25.65 | 22.2 | 25.4 | 33.3 | 14.3 | 21.5 | 4.8 |
| 1 1/2 | 38.1 | 38.35 | 34.9 | 38.1 | 46.0 | 14.3 | 21.5 | 4.8 |
| 2 | 50.8 | 51.05 | 47.6 | 50.8 | 58.7 | 14.3 | 21.5 | 4.8 |
| 2 1/2 | 63.5 | 63.75 | 60.3 | 63.5 | 71.4 | 14.3 | 21.5 | 4.8 |
| 3 | 76.2 | 76.45 | 73.0 | 76.2 | 84.1 | 14.3 | 21.5 | 4.8 |
| 4 | 101.6 | 101.85 | 97.6 | 101.6 | 109.5 | 14.3 | 21.5 | 4.8 |
RJT HEXAGON NUT - BS4825:5 1991
| Nominal Size | A | B | C | D | E | F | |
|---|---|---|---|---|---|---|---|
| inch | mm | mm | mm | mm | mm | mm | mm |
| 1 | 25.4 | 33.3 | 46.6 | 22.2 | 15.1 | 4.0 | 50.8 |
| 1 1/2 | 38.1 | 46.0 | 59.3 | 22.2 | 15.1 | 4.0 | 65.0 |
| 2 | 50.8 | 58.7 | 73.6 | 22.2 | 15.1 | 4.0 | 79.4 |
| 2 1/2 | 63.5 | 71.4 | 86.3 | 22.2 | 15.1 | 4.0 | 92.1 |
| 3 | 76.2 | 84.1 | 99.0 | 22.2 | 15.1 | 4.0 | 104.8 |
| 4 | 101.6 | 109.5 | 124.4 | 22.2 | 15.1 | 4.0 | 130.2 |
RJT WELD LINER - BS4825:5 1991
| Nominal Size | A | B | C | D | E | F | G | |
|---|---|---|---|---|---|---|---|---|
| inch | mm | mm | mm | mm | mm | mm | mm | mm |
| 1 | 25.4 | 32.5 | 25.65 | 22.2 | 26.2 | 27.8 | 41.3 | 10 or 12.7 |
| 1 1/2 | 38.1 | 45.2 | 38.35 | 34.9 | 38.9 | 40.5 | 54.0 | 10 or 12.7 |
| 2 | 50.8 | 57.9 | 51.05 | 47.6 | 51.6 | 53.2 | 66.7 | 10 or 12.7 |
| 2 1/2 | 63.5 | 70.6 | 63.75 | 60.3 | 64.3 | 65.9 | 79.4 | 10 or 12.7 |
| 3 | 76.2 | 83.3 | 76.45 | 73.0 | 77.0 | 78.6 | 92.1 | 10 or 12.7 |
| 4 | 101.6 | 108.5 | 101.85 | 97.6 | 102.4 | 104 | 117.5 | 12.7 or 25.4 |
RJT PRESSED BLANK - BS4825:5 1991
| Nominal Size | A | B | |
|---|---|---|---|
| inch | mm | mm | mm |
| 1 | 25.4 | 41.0 | 8.0 |
| 1 1/2 | 38.1 | 54.0 | 8.0 |
| 2 | 50.8 | 67.0 | 9.0 |
| 2 1/2 | 63.5 | 79.0 | 9.0 |
| 3 | 76.2 | 92.0 | 9.0 |
| 4 | 101.6 | 118.0 | 9.0 |
RJT SEAL - BS4825:5 1991
| Nominal Size | A | B | |
|---|---|---|---|
| inch | mm | mm | mm |
| 1 | 25.4 | 33.3 | 6.6 |
| 1 1/2 | 38.1 | 46.0 | 6.6 |
| 2 | 50.8 | 58.7 | 6.6 |
| 2 1/2 | 63.5 | 71.4 | 6.6 |
| 3 | 76.2 | 84.1 | 6.6 |
| 4 | 101.6 | 109.5 | 6.6 |
RELATED PAGES
- IDF Stainless Steel Fittings Dimensions
- SMS Stainless Steel Fittings Dimensions
- DIN Stainless Steel Fittings Dimensions
FREQUENTLY ASKED QUESTIONS
How does RJT differ from IDF or SMS fittings?
All three are hygienic union designs serving the same basic purpose, but they aren't interchangeable — each has its own thread form, sealing face geometry, and nut design, so a male part from one standard won't mate with a nut or liner from another. RJT is the standard most commonly specified in the UK; IDF is common across mainland Europe and internationally; SMS originates from Sweden and is also widely used across Europe. See our IDF and SMS fitting charts for comparison.
What seal material should I use in an RJT union?
This depends on the process fluid, temperature, and any regulatory requirements (such as FDA or EHEDG compliance for food contact) — common choices include nitrile, EPDM, and silicone, each with different chemical and temperature resistance. Always check the seal manufacturer's compatibility data for your specific application.
Can an RJT nut be over-tightened?
Yes — over-tightening can distort or damage the seal and, over time, the sealing faces themselves. Hand-tight plus a controlled amount of additional torque (or tightening until a consistent, repeatable feel is reached) is the usual approach; excessive force is rarely necessary for a proper seal.
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