Differences Between SCH 40 and SCH 40S Pipes

SCH 40 and 40S pipes play an integral role in sustaining our world. Almost every industry uses them for different purposes. From water supply lines to gas transportation, they are of utmost value. However, there are many differences between SCH 40 and SCH 40S pipes. Some people favor SCH 40, while others prefer SCH 40S.

Let’s, for a few seconds, keep their comparison aside. Do you know what SCH 40 and 40S mean? Many people don’t understand their specifications and consider them the same. Remember, these pipe categories are entirely different from each other.  In this article, you’ll know all the distinctions between these two. So, let’s get started!

What is SCH (Schedule)?

Both pipe categories have one thing in common: ‘SCH.’ But what does it mean? Let’s find out first.

SCH stands for ‘Schedule,’ which indicates the wall thickness of pipes. It is followed by a number, e.g., SCH 40 and SCH 10. These numbers indicate how thick or thin each pipe is. Pipes with a more significant schedule number will be thicker, and vice versa. This SCH is an international measurement standard.

Generally, inches or centimeters are measurement units used for thickness. However, their usage for measuring pipe size can create confusion in some regions of the world. So, the American Society of Mechanical Engineers (ASME) developed a standard. This standard is known as ‘Schedule,’ which is dedicated to the wall thickness of pipes.

This introduction of the schedule eliminated the confusion. Now, manufacturers refer to schedule numbers when choosing any pipe for their projects. These SCH 40 and 40S are pipe categories with the same wall thickness. How do I know? The reason is that 40 follows the SCH in both categories, indicating the wall thickness level.

What Do SCH 40 and SCH 40S Mean?

I’ve given you enough understanding of SCH in the above part. Let’s figure out the meaning of these two SCH 40 and 40S in more detail.

Both pipe categories, SCH 40 and SCH 40S, have the same wall thickness. Technically, the SCH followed by 40 in both categories indicates the same schedule. However, the S in SCH 40S indicates this pipe is made of stainless steel. The pipe with SCH 40 is non-stainless steel of any other material.

In simple words, the SCH 40 is the main category of pipe. It can be made of any material, such as rubber, plastics, carbon steel, or metal. There is no restriction on its material unless it has a schedule of 40 (wall thickness). However, the SCH 40S pipes are a subtype of SCH 40 and must be made of stainless steel. 

Stainless steel is a premium material and offers many unique perks. Therefore, the SCH 40S pipes are more expensive and perform better than SCH 40. The major differentiating factor between these two pipe categories is the stainless steel. Otherwise, both of these pipes are almost the same in thickness. 

SCH 40 vs SCH 40S: Discussing the Key Differences

I’m pretty sure you’ve got a grip on the specifications of these two pipes. Right? Let’s dig deeper and discuss the differences between SCH 40 and SCH 40S. After overviewing those differences, you’ll know their actual value. 

1- Materials and Formation

As I mentioned, SCH 40 pipes can be made of any material. For example, they can be carbon steel, PVC, or metal. However, the SCH 40S are very specific, and their making includes using stainless steel. This material enhances the overall value of the SCH 40S pipes.

2- Rust Protection & Durability

In all previous articles, I’ve always praised stainless steel material due to its number of properties. Among those, corrosion resistance ranks at the top. Remember, stainless steel consists of 10.5% of chromium. This chromium makes a chromium oxide layer when it comes in contact with oxygen.

This chromium oxide layer protects the surface of stainless from further corrosion. So, the pipes made with stainless steel are rust-resistant. They won’t get rusty even in worse moist conditions. On the other hand, the SCH 40 pipes also come with some zinc coating for rust resistance. However, these coatings are weaker and deteriorate after some time.

Quick Highlight: The SCH 40 pipes made with plastics or PVC are even more fragile. They have compromised strength and crack if they face stress. So, I rank SCH 40S pipes at the top in terms of both corrosion resistance and durability. It is a common-sense pipe that is corrosion-resistant and will be long-lasting and durable. 

3- Pressure Ratings & Flow Capacity

The flow and pressure ratings depend on the thickness of the pipes. However, both SCH 40 and 40S have the same wall thickness. So, they offer almost the same level of flow capacity. However, stainless steel is a strong material. It can bear more pressure flow with ease. Moreover, it is generally thinner and offers excellent strength. 

So, it can provide slightly better flow capacity. Additionally, the size of the pipe also impacts the pressure rating. If you compare SCH 40s pipe with SCH 40 with higher diameters, the latter will have low flow capacity. The higher diameters reduce the internal thickness. This influences the flow capacity, and you’ll see the power pressure rating in SCH 40  pipes with high diameters. 

4- Heat Resistance & Weight

Stainless steel is very stable thermally. It can bear extreme temperatures of around 1200°F. Such heat resistance makes SCH 40S pipes perform well in hot conditions. Manufacturers use them in heat exchangers and other steam lines. On the other hand, SCH 40 pipes are generally compromised in heat resistance.

Generally, SCH 40 pipes consist of PVC, plastics, or carbon steel. All these materials are not very good at bearing the higher temperatures. So, SCH 40 pipes are an inferior option to SCH 40S in terms of heat resistance. Let’s talk about weight and ease of handling. The stainless material is heavyweight, which is a big drawback.

Generally, weight depends on the wall thickness. However, SCH 40 and 40s pipes have the same wall thickness. However, these pipes will be heavier due to the higher weight of SCH 40S. Their installation and handling can be tedious and require labor as well. SCH 40 pipes are generally lightweight and easy to install. 

5- Age & Lifespan

In the above portion, I mentioned that SCH 40S pipes are rust-resistant. That’s due to the presence of chromium in stainless steel. This rust resistance makes SCH 40S pipes very durable and long-lasting. Generally, SCH 40S pipes can last around 40 to 50 years. Their life can even be extended by taking care. 

On the flip side, SCH 40 pipes are generally weaker. They are more prone to corrosion, and their overall strength is questionable. So, their life is shorter than that of SCH 40S pipes. For example, SCH 40 pipes are made of carbon steel, and PVC can last around 30 and 25 years, respectively. 

6- Price Affordability & Applications

The SCH 40S pipes are more expensive than the SCH 40 pipes. The reason behind this price difference is stainless steel. This premium material is very popular in the manufacturing industry, and its demand is very high. Its popularity is mainly because it contains 10.5% of chromium. 

This chromium makes it rust-proof. So, the SCH 40S pipes are more costly, but they offer better performance. If you use them in water supply lines, you won’t have to worry about their rusting issues. They will remain in good shape for more than 40 years. Although the SCH 40 pipes are inexpensive, they will require regular maintenance. 

In the long run, they will get rusty, creating leakage issues. Are you curious to learn about their applications? The table compares the application of SCH 40 vs SCH 40S.

Conclusion

Both SCH 40 and 40S have their unique value proposition. They have many differences, and SCH 40S pipes look premium. However, the higher price of SCH 40S can be a curtain for someone with a very tight budget. The SCH 40 pipes are inexpensive. But there is a downside.

Their rust-proofing and durability are compromised. Do you want my opinion? 

Well, I recommend SCH 40S despite its higher price. You’ll get better performance, durability, pressure rating, and heat resistance. However, SCH 40 pipes are ideal if you have a tight budget. They will perform well in gentle applications such as sprinkling or irrigation systems.