The sizing chart for JIC fittings (Joint Industry Council, or Joint Industry Council Fittings) covers several parameters, including thread diameter, teeth per inch, nominal inside diameter, and other relevant dimensions.
Because specific dimensions for JIC fittings vary by model, specification, and manufacturer, the following is an overview based on general information and references publicly released data to provide some examples of specific model dimensions.
JIC Fitting Size Overview
JIC fittings are commonly used in hydraulic systems, mechanical transmission parts, etc. The thread form is mostly a fine thread with a 74° internal taper. The fitting dimensions table will detail various parameters for different fitting types, including but not limited to:
Thread diameter: in inches, such as 3/8 inch, 1/2 inch, etc., converted to millimeters need to be multiplied by 25.4.
Number of teeth per inch: indicates the number of threads in 1 inch length, used to distinguish between coarse and fine threads.
Nominal inside diameter: the internal diameter of the joint, used to determine the flow rate and scope of application of the joint.
Other dimensions: such as the length of the fitting, outside diameter, thread depth, etc. These dimensions are equally important for the installation and use of the fitting.
JIC specific model size table:
| Size Designation | Taper width, “A”, inches | Thread width, “B”, inches | Thread Spec. “C” | Shoulder width, “D” inches | Shoulder Diameter, “E”, inches | Fitting Length, “F”, inches | Bore Diameter, “H”, inches | Tip Diameter, “I”, inches |
|---|---|---|---|---|---|---|---|---|
| 2 | 0.111 | 0.208 | 5/16” – 24 UNF | 0.067 | 0.250 | 0.448 | 0.062 | 0.083 |
| 3 | 0.11 | 0.239 | 3/8” – 24 UNF | 0.067 | 0.312 | 0.479 | 0.125 | 0.146 |
| 4 | 0.114 | 0.282 | 7/16” – 20 UNF | 0.080 | 0.364 | 0.550 | 0.172 | 0.193 |
| 5 | 0.114 | 0.282 | 1/2” – 20 UNF | 0.080 | 0.426 | 0.550 | 0.234 | 0.255 |
| 6 | 0.108 | 0.275 | 9/16″ – 18 UNF | 0.090 | 0.481 | 0.556 | 0.281 | 0.318 |
| 7 | — | — | — | — | — | — | — | — |
| 8 | 0.155 | 0.310 | 3/4” – 16 UNF | 0.098 | 0.659 | 0.657 | 0.406 | 0.426 |
| 9 | — | — | — | — | — | — | — | — |
| 10 | 0.155 | 0.385 | 7/8” – 14 UNF | 0.111 | 0.772 | 0.758 | 0.531 | 0.539 |
| 11 | — | — | — | — | — | — | — | — |
| 12 | 0.185 | 0.424 | 1-1/16” – 12 UN | 0.130 | 0.943 | 0.943 | 0.609 | 0.664 |
| 13 | — | — | — | — | — | — | — | — |
| 14 | 0.186 | 0.450 | 1-3/16″ – 12 UN | 0.129 | 1.068 | 0.890 | 0.719 | 0.788 |
| 15 | — | — | — | — | — | — | — | — |
| 16 | 0.186 | 0.471 | 1-5/16″ – 12 UN | 0.129 | 1.193 | 0.911 | 0.844 | 0.913 |
| 17 | — | — | — | — | — | — | — | — |
| 18 | — | — | — | — | — | — | — | — |
| 19 | — | — | — | — | — | — | — | — |
| 20 | — | — | 1-5/8” – 12 UN | — | — | 0.96 | 1.078 | — |
How to Identify JIC Fitting Sizes:
Understanding the Basic Characteristics of JIC Fittings
Thread Form: JIC fittings are typically straight threaded with a specific taper seating angle (e.g., 37° or 74°), which helps form a seal.
Measurement and identification of key parameters
Thread OD
Use calipers or thread gauge to measure the outer diameter of the threads of the fitting.The outer diameter of the threads of JIC fittings is usually expressed in inches, such as 3/8 inch, 1/2 inch, etc. Note that when converting the unit of inches to millimeters, the threads of JIC fittings will be converted to millimeters.
Note that when converting from inch units to millimeters, multiply by 25.4 (i.e. 1 inch = 25.4 mm).
Teeth per inch (TPI)
Measure and count the number of threaded teeth per inch. This is one of the most important parameters for identifying the size of a JIC fitting.
Common JIC fittings include 16, 20, 24, etc. teeth per inch, depending on the type of fitting and application.
Taper Seat Angle
Checking the taper seating angle of the fitting helps in identifying whether it is a JIC fitting or not and its specific type.
Common cone seating angles for JIC fittings include 37° and 74°, which are critical for forming a seal.
Other Dimensional Parameters
Dimensional parameters such as length, inside diameter, wall thickness, etc. can also be measured as needed.
These parameters may vary depending on the specific model and application of the fitting.
Reference standards and technical data
Checking standards: Refer to the relevant JIC standards or industry standards to understand the detailed specifications and dimensional requirements of the fittings.
Technical manuals: Consult the technical manuals or catalogs provided by the manufacturer, which usually contain detailed dimensional drawings and installation instructions for the fittings.
Example
Take a certain type of JIC fitting as an example, its dimensions may be labeled as “3/8-16 UNF”, where “3/8” means that the outside diameter of the threads is 3/8 inch, “16” means that the number of teeth per inch is 16, and “16” means that the number of teeth per inch is 16. 16” means 16 teeth per inch, and ‘UNF’ means fine thread series. This way of labeling helps to quickly identify the size and type of fittings.
Note
When measuring and identifying the dimensions of JIC fittings, make sure the tools are accurate and the measurement method is correct to avoid errors.
JIC fittings from different manufacturers may have slight differences, so the relevant parameters should be carefully checked when selecting and using them.
Conclusion:
The dimension table of JIC fittings is a complex table containing several parameters and detailed data, and the specific dimensions need to be determined according to the model, specification and manufacturer. In practical applications, it is recommended to consult the official information provided by the relevant manufacturer to obtain accurate information.
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