Motorsport Plumbing Systems: Hardlines
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Hardlines
06.56
| 00:00 | In this section of the course we're going to be diving deeper into the specific components used in automotive plumbing systems. |
| 00:07 | Some of these components we've touched on already, but we'll be approaching this from a different angle in this section of the course, giving you a clear view of how and where each component can be used and any specific considerations we need to keep in mind to ensure good results. |
| 00:23 | The first topic and something we've discussed previously is hard lines. |
| 00:27 | More specifically, referring to the smaller diameter plumbing that's used for the transfer of liquids as opposed to our intake and charge air plumbing that's also rigid. |
| 00:38 | Hard lines are ideal for plumbing fluids where no movement of the plumbing is required. |
| 00:43 | Generally speaking, hard lines are the strongest, most abrasion resistant form of plumbing and also the most resistant to damage from chemicals and heat, as well as compliance issues caused by swelling with high pressure applications like brake lines. |
| 00:58 | They're also significantly cheaper when considering the long length from the front to the rear of the car for components like dry sump or fuel cell plumbing. |
| 01:07 | For this reason, where possible, it's most often best to use hard lines and saying that, for cases that require flexibility, we'll need to use flexible hose. |
| 01:18 | And it can be best to only use flexible hose to cut down on the need for fittings and connections that can be potential failure points. |
| 01:26 | Regardless, both flexible hose and hard lines will be required in some areas of our plumbing so let's push forward. |
| 01:33 | The sizing of the hard lines we use can vary significantly depending on the application. |
| 01:39 | For example, the brake lines that act to transfer relatively high pressures and displace relatively small volumes are therefore fairly small, most often 3/16th inch size. |
| 01:51 | On the upper end, hard lines for coolant in situations where we have the radiator mounted at the other end of the vehicle to the engine might be up to 1/4 inch. |
| 02:02 | These measurements by the way are of the outer diameter of the hard lines which is the standard way of expressing their size. |
| 02:09 | And to be clear, I'm talking in imperial here, because that's how the lines are generally sized and sold no matter where you are in the world. |
| 02:17 | Dash sizes are also commonly used to express hose, tube or hard line and fitting sizes in automotive plumbing. |
| 02:24 | The dash size for hard lines refers to the number of 16ths of an inch of the outer diameter. |
| 02:31 | For example, dash six is 6/16 or 3⁄8 inch hard line. |
| 02:36 | The other dimension of interest here is the wall thickness of which there's usually multiple options for the same outer diameter. |
| 02:44 | While steel hard lines are commonly used from factory due to their relatively low cost, the lack of corrosion resistance, even when zinc plated, means their service life is relatively short, especially if we value the aesthetics of our plumbing. |
| 02:59 | The three main hard line materials we see in aftermarket and motorsport use are aluminium, stainless steel and copper nickel. |
| 03:07 | The key advantages of aluminium are its lightweight and easy formability, meaning we can bend and flare for routing and fittings relatively easily. |
| 03:17 | While aluminium will oxidise, it doesn't rust like steel and it tends to last longer and retain a tidy appearance. |
| 03:25 | The main downside of aluminium is its strength when compared to the other hard line options. |
| 03:30 | For example, the most common brake line sizing, 3⁄16 of an inch outer diameter with a 0.028 inch wall thickness, has a burst pressure of less than 4000 psi. |
| 03:43 | It's not uncommon to see brake pressures around 2000 psi in motorsport so this leaves us with a safety factor of less than two, which is simply not enough for such a critical function, especially for a line that'll often be run outside the vehicle and be subject to damage. |
| 04:01 | For these reasons, aluminium hard lines are more suited for the use with oil, coolant and air plumbing, and shouldn't be used for high pressure applications like brake lines and power steering, at least not without a much greater wall thickness. |
| 04:16 | Copper nickel is much heavier than aluminium, but still very easy to work with. |
| 04:21 | It also has great corrosion resistance and is significantly stronger than aluminium, making it suitable for higher pressure applications. |
| 04:30 | The key distinction that needs to be made here is that 100% copper tubing is not suitable. |
| 04:36 | Copper nickel 9010 alloy is as the name suggests, 90% copper and 10% nickel, albeit with common variations containing small amounts of other metals. |
| 04:48 | When purchasing copper nickel tubing for brake lines, it's best to ensure it was designed for that specific application, and of course is legal for local road use or with your motorsport governing body. |
| 05:02 | Moving on, stainless steel hard lines are a similar weight to copper nickel, but much stronger, they also offer the best corrosion resistance and therefore service life, and stay looking nice for the longest. |
| 05:15 | The downside is that they're a lot more difficult to form, so bending and flaring them can be a pain to say the least. |
| 05:22 | Whether that's a deal breaker for you or not is on a case by case basis, but stainless steel hard lines can be used for plumbing any system on our vehicle where flexibility isn't required. |
| 05:34 | On the topic of material, the final consideration is around the contact of dissimilar metals. |
| 05:40 | More specifically, metals that have a big difference in their electrode potential such as steel, aluminium and copper. |
| 05:48 | Simply put, this results in accelerated corrosion of one of the materials. |
| 05:52 | This is something we should be aware of in all areas of our racecars and as a general rule of thumb, we want to avoid direct contact of dissimilar metals when possible. |
| 06:02 | Of course, in some cases this won't be practical and if this is the situation, we ideally need to use a non conductive barrier between the metals such as an epoxy paint. |
| 06:14 | Hard lines can be connected to each other or plumbing lines through various fittings, often involving the use of flares, but we'll cover that in more detail in the coming modules. |
| 06:24 | In summary, hard lines are ideal for high integrity plumbing when no flexibility is required. |
| 06:31 | Aluminium, copper, nickel and stainless steel all have their advantages and drawbacks, mostly around weight, formability, strength and service life. |
| 06:40 | It's important to remember that aluminium hard lines aren't suitable for high pressure applications without significant increases in wall thickness, and we should avoid physical contact of dissimilar metals wherever possible. |
