Motorsport Plumbing Systems: Threaded Fittings & Adapters
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Threaded Fittings & Adapters
10.14
| 00:00 | The threaded connection points between the lines and other plumbing or components in a system are one of the most critical areas of knowledge when it comes to motorsport plumbing. |
| 00:10 | Simply, because there's so much variety and understanding the differences is key to a properly functioning system. |
| 00:17 | In this module we'll be primarily discussing the threaded connection side of the fitting, not the hose side. |
| 00:24 | But we'll also discuss the middle section between the threaded end and the hose end. |
| 00:29 | Before we start there's some base level understanding about threads that we need to cover. |
| 00:35 | Threads are named for two attributes, the external thread major diameter and the thread pitch. |
| 00:42 | For example a metric thread such as a M10 by 1.5 has a 10mm external diameter and a 1.5mm thread pitch. |
| 00:52 | For clarity's sake, the pitch is defined as the distance between adjacent threads or essentially the spacing of each thread. |
| 01:01 | An imperial example would be a 5/8-11, meaning 5.8 of an inch for the external diameter and in this case 11 threads per inch, commonly expressed as TPI. |
| 01:14 | It's also common to hear the words fine, coarse and standard used to explain the thread pitch. |
| 01:20 | An example of this is UNC and UNF, which are used after the external diameter is stated and stand for Unified National Coarse and Fine, the most common thread standards used in the USA. |
| 01:34 | While this gives a very simple view of threaded fittings, there's a lot more to thread design than this. |
| 01:41 | The angle of the flanks and the size of the crest and root of the threads can also vary significantly between different standards, meaning that they're not compatible with each other. |
| 01:52 | Introducing tapers, flares and other seals like o-rings into the mix further complicated what initially seems like a simple topic. |
| 02:00 | To help clarify, let's dive in with the first and maybe the most commonly used fitting type in motorsport applications ,and possibly a term that's most misunderstood, AN fittings. |
| 02:12 | We mentioned earlier in the course that AN stands for Army Navy and this describes the specification of the fitting. |
| 02:20 | An AN hose end, which we'll discuss in more detail in the following modules could use a female fitting, essentially forming a port or alternatively a male hose end is also available, but less common. |
| 02:33 | Besides the fine details of the thread design, one of the key features is the 37 degree flare which the female and male sides use to create a seal. |
| 02:43 | The advantage here is that the flare is all that's needed to create the seal and thread tape or sealant of any type is unnecessary and in fact should be avoided. |
| 02:53 | AN fittings range in size from dash 2 to dash 32 which corresponds to the hard lines or hoses that they're designed to work with. |
| 03:02 | The thread itself isn't based on the same number of sixteenth of an inch rule as the plumbing line, but it is a standardised system so as long as you're matching the same dash sizing for male and female AN fittings, there won't be a problem. |
| 03:17 | We've attached a sheet to this module with the corresponding thread size for AN fittings should you ever need it. |
| 03:24 | JIC fittings are very similar to AN. |
| 03:27 | They're often referred to as the industrial version and tend to come with a lower price tag. |
| 03:32 | The key difference being the lower thread class, which put simply means that the tolerance allowance isn't as tight resulting in a lower quality and fit. |
| 03:42 | These are often interchangeable with AN if you are budget conscious, but can come with the risk of a shorter service life and more potential for leaks or damage to the threads. |
| 03:53 | Another closely related fitting type is ORB or O-ring boss fittings. |
| 03:58 | I say this because it's possible to get an AN fitting, which is also ORB. |
| 04:04 | AN or not, the male ORB fittings use an O-ring just bigger than the thread size which creates a tight seal able to hold high pressures against the chamfer of the leading edge of the female port. |
| 04:17 | Some examples of common uses of ORB fittings are on fuel pressure regulators, fuel rails, hose ends and dry sump fittings. |
| 04:26 | While we'll be discussing the different types of hose ends in their own modules, hardline fittings can integrate the hardline itself into the fitting to form the seal, so we'll discuss them now. |
| 04:37 | Brake lines are an example of this, where the male tube nut, be it metric or imperial, is slid over the end of the line which is then flared. |
| 04:45 | When the tube nut is tightened into the corresponding female fitting or port at the connection point, the flared end is held against the corresponding flare on the part to form a seal. |
| 04:56 | We discussed the shape of the flare in the earlier brake line plumbing section, but for modern vehicles, performance and motorsport use, there's really two options. |
| 05:06 | The bubble flare, also known as ISO or DIN, or more ideally the double flare or SAE. |
| 05:14 | This flare has a 45 degree angle and is very robust, creating a tight seal, as it's formed with two operations, hence the name double flare. |
| 05:24 | Naturally the fitting it makes with also needs to have a 45 degree surface. |
| 05:29 | Using a single flare with brake lines is not recommended as the risk of cracking the hardline around the flare is much higher, especially with the harder to form stainless steel lines. |
| 05:41 | Larger diameter hardlines for oil and power steering can use a 37 degree single flare for use with AN fittings. |
| 05:48 | The double flare isn't required, as it is with brake lines due to the different impact on safety. |
| 05:55 | However, in this case a tube sleeve is used in the inside of the tube nut, which applies pressure to the flare when tightened. |
| 06:03 | The alternative is a compression hardline fitting which uses an olive or ferrule rather than an inner sleeve and flare. |
| 06:10 | This is slid over the hardline after the tube nut which can be tightened to an adapter piece, converting the end of the hardline to an AN fitting. |
| 06:19 | Tightening the nut compresses the olive, forming a seal against the fitting body and hardline to prevent leaks. |
| 06:27 | Moving on and back to the threaded end of the fitting, next we'll discuss tapered fittings, which is where the thread reduces in diameter as it gets deeper. |
| 06:37 | When used with thread sealing tape or liquid thread sealant, this forms a seal as the fitting tightens against the tapered port. |
| 06:44 | The angle of the taper is generally around two degrees, but can vary between standards, of which the most common would be BSPT, standing for British Standard Pipe Tapered, and NPT for National Pipe Taper, which definitely aren't compatible with one another despite looking very similar, the pitch and the shape of the threads are very different. |
| 07:08 | Using a pitch gauge, tap or die is a good way to check threads if you are unsure. |
| 07:13 | With all of these different threads that won't fit together, adapters are often required when we're trying to connect to existing parts or what we need just isn't available in the right thread. |
| 07:24 | In most cases we'll be adapting AN to whatever thread type the component has, so what's important is to understand specifically what we need. |
| 07:34 | For example, a male NPT to male AN or potentially female AN. |
| 07:40 | Almost anything we need will be available, it might just take a bit of hunting to find the supplier. |
| 07:46 | Past this there are some other forms of fittings that also function as adapters. |
| 07:51 | For example: angled AN fittings as opposed to the straight variety can help us with routing our plumbing to avoid big loops of hose and extra bends in our hard lines, keeping things tidy. |
| 08:03 | These are available in a myriad of different angles from 30 or 45 degrees through to 180 and feature a swivel allowing them to be rotated when the fitting is tight, so we can get the lines pointed wherever we want them to go. |
| 08:18 | Banjo fittings should also be mentioned here as they're used all over vehicles for plumbing pressurised fluids. |
| 08:24 | These use a banjo bolt which is hollow down the centre that fits into the port on a component. |
| 08:30 | The internal passage allows the fluid to be transferred between the port and small holes in the upper non threaded section of the bolt, which is housed inside another piece called the banjo union. |
| 08:42 | The union is sealed to the bolt and the component surface using crush washers and can have almost any different fitting allowing the attachment of flexible hose or even hard lines. |
| 08:54 | Naturally, banjo fittings lend themselves to creating nice tight low profile 90 degree angles in our plumbings straight out of the port, although they tend not to flow as well as a smoothbore 90 degree hose end. |
| 09:07 | This hasn't been an exhaustive list of every type of thread and fitting, as we'd be here all week but we have covered those that are most commonly used in performance and motorsport applications. |
| 09:19 | In addition to this, we've already discussed clamshell fittings like Wiggins clamps, so be sure to check back if you need a refresher. |
| 09:27 | We'll also cover some additional fittings in the following modules, but again the focus here was mainly on the threaded connections so let's summarise the key points. |
| 09:38 | Having a sound understanding of the different specifications, sizes and pitches for threads and fittings is critical for a successful plumbing job. |
| 09:47 | AN, JIC and a range of other specification fittings use flares of various angles to form seals. |
| 09:55 | O-rings and tapers can also be used in fittings to create seals and might require some additional thread tape or sealant to get the job done. |
| 10:03 | Adapters, angled swivels and banjo fittings are also available to join any plumbing to a component to complete the system. |
