It can be hard jumping into a new career or new field and having to catch up to the level of understanding that you feel you should already have. This post should help you add one more wrinkle in your brain to let you feel more confident in your knowledge base. The topic we will be going over is the riveting language of SAE fluid connector (hydraulic fittings) part numbers.
It is a fairly common practice to have part numbers designed to help differentiate what a part is without needing the description, this is sometimes referred to as a “smart part number." Every fitting supplier will have their own unique numbering system. Since it is also common practice to quote multiple suppliers, engineering may have to validate 3, 4, or 5+ supplier part numbers for the same functional component. It’s easy to get lost in the weeds, not knowing if part x from supplier x is the same as part y from supplier y, or if you are trying to compare an apple to an orange.
SAE J846 - The universal language
The good news is that SAE (Society of Automotive Engineers) has a standard to help engineers differentiate which fluid connector is which from one brand to another. The goal of the standard is to give OEMs confidence that they are comparing apples to apples. This standard is SAE J846, “Coding Systems for Identification of Fluid Conductors and Connectors” (this post uses the version released in November 2015). SAE J846 uses the same concept that we mentioned above with “smart part numbers.” SAE J846 should be thought of as the universal language between suppliers of fluid conductors and connectors.
While SAE J846 is aimed at helping engineers, the numbers are quite long and intimidating, but, if you know what you’re looking at you can use the standard like a decoder ring. So, let’s start with an easy example, SAE J514 12 070101 SA. Looking at that part number, it may seem very daunting. However, this big part number can be broken down into four parts to make it easier to understand. Figure 1 shows the part number broken into the four sections so that you can see what we’re explaining.
Section 1: SAE Number
The SAE number at the beginning of the part number is a reference to the standard associated with the fitting identification. The SAE number will give you a hint at what type of fitting you are working with. Using the example in Figure 1, SAE J514 is a specific SAE standard that covers 37 degree flare and 24 degree flareless fittings, as well as pipe fittings and adapters. Another example of an SAE standard that could be used is SAE J1453, which is used for o-ring face seal fittings. A list of other applicable standards that would use this same nomenclature can be found in SAE J846 in the section titled “SAE Publications."
Section 2: Size
Now that we’ve decoded section 1, let’s move to section 2 in the SAE part number. Section 2 shown in Figure 1 is identifying the size of the fitting. It is standard practice that sizes are by sixteenth inch. As in, a size 8 is a size 8/16 inch or ½ inch which is the intended tube OD size that works with this fitting. The size shown in our example is a pretty cut and dry size (12), but fittings can be more complicated than that. For example, you could have a size 8 at the tube end and a size 10 at the port end, this would be shown as an 8-10. The tube end size is always listed before the port end size. You could also have a tee or a cross which only adds to what this number could look like. Similar to what is found in Figure 1B in SAE J846, Figure 2 shows you which order the sizes need to go in for a tee shaped fitting.
If there are other configurations that you need, SAE J846 also outlines what to do in scenarios that don’t fit perfectly into the tube and port nomenclature, this is outlined in section 3.1.1. in J846. For example, it states that with tube to tube fittings, the largest size tube comes first.
Section 3: Fitting Identification
This section is the most intimidating part of the SAE part number. In reality though, it is the most beneficial section when trying to define what a fitting is. So again, our part number is SAE J514 12 070101 SA. What is labeled as Section 3 in Figure 1 is “070101”, this number can be broken into another three groups of two, 07, 01, and 01 as you can see in Figure 3. The tables we’re going to be referencing are found in SAE J846.
What do these numbers mean?
- 07 in Table 6 means “37 degree flared, hydraulic per SAE J514”
- 01 in Table 7 means “straight”
- 01 in Table 8 means “tube, all ends”
Now that we’ve decoded these numbers, can you tell what the type of fitting? Let’s combine it with what we learned in the previous sections. The fitting is a size 12, 37 degree flared (JIC), straight, with tube ends on both sides, also known as a 37 degree straight union fitting.
Pro Tip: Be careful with Table 6, because Tables 6A and 6B are showing the exact same content, just arranged differently. These two arrangements can be very helpful though. Use table 6A when you are trying to find out what a number you already have is, and use table 6B when you are defining what a part number should be.
Section 4: Material Finish & Assembly
Finally, we have the last section of the part number. This section designates what the material is and if the fitting is a complete assembly (i.e. with a sleeve and nut). These are defined in Table 10 in section 3.1.4 of J846.
Here are some examples:
- BA to signify Brass Assembly
- CA to signify Carbon steel Assembly
- SA to signify Stainless steel Assembly
If it is not a complete assembly (i.e., without sleeve and nut) then we drop the A, so B means brass, C means carbon steel and S means stainless steel.
Pro Tip: Be careful with S and C, because many times S typically signifies steel (carbon steel) in most manufacturers’ nomenclature and C can designate stainless steel (CRES). SAE uses C to designate carbon steel, and S to designate stainless steel.
Pro Tip: Somewhat hidden in the Appendix of the SAE J846 standard is Table A1 which contains codes for additional material and finishes that are not included in Table 10.
The code has now been deciphered and we know what kind of fitting the part number shown in Figure 1 is. SAE J514 12 070101 SA is a size 12 stainless steel, 37 degree flare (JIC), straight fitting, with tube ends on both sides (union), that has a nut and sleeve for each tube end. An example of this fitting (without nut and sleeve) is shown in Figure 4.
Here is a quick recap of the unlocked sections of the SAE number:
Section 1: The SAE number (ex. SAE J514) is the standard with which the fitting is in accordance.
Section 2: Size (ex. 12 or 6-4).
Section 3: Fitting identification, a 6-digit descriptor (ex. 070101), the definitions of these digits can be found in SAE J846, specifically Tables 6, 7, and 8.
Section 4: Material Finish and Assembly (ex. BA or C) defined in Table 10 of SAE J846.
The nomenclature is quite helpful once you can decipher what it is saying. Now that you have a baseline, you should easily be able to go to J846 and grasp what it is outlining. When in doubt, get your decoder ring, SAE J846, and check your work. Eventually, the common aspects of the SAE part number that are being used in your arena will become another part of your vocabulary. Until then, use this newly unlocked knowledge in your tool belt to see a little more of the fittings picture and be confident in knowing you are getting the fitting you need.
If you have any questions or comments, please post them and we will respond if warranted. To talk to our techConnect engineer team directly, they can be reached at Parker Tube Fittings Division, 614.279.7070. See Parker Tube Fittings Division's SAE product line offering now.
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Contributed by Emily Alexander, senior design engineer at Parker Tube Fittings Division, and
Contributed by Burleigh Bailey, senior project engineer at Parker Tube Fittings Division
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