Difference Between SCH 40 and SCH 40S


From construction to plumbing, selecting the correct pipe makes a big difference. Different pipes with varying sizes and thicknesses are available. However, SCH 40 vs SCH 40S has been the talk of the town. Due to their inclusion of numerical values, they are least understood. Often, people will also compare SCH20 with SCH40, SCH40 vs SCH80.

Both of these pipes have equal dimensions and thickness. However, they vary in terms of their manufacturing materials. SCH 40S is considered superior to the SCH 40. Wondering why? Read this article till the end to get a detailed answer.

What is a Pipe Schedule?

It is necessary to comprehend the pipe schedule to understand the differences between SCH 40 and SCH 40S. The SCH used before numbers represents the pipe schedule. Let’s simplify the term for better understanding.

The pipe schedule represented as SCH is the standard used to indicate the wall thickness. ASTM (American Society for Testing and Materials) and ASME (American Society of Mechanical) set it. It indicates that SCH 40 and SCH 40S have the same thickness and dimension.

So, pipe schedules measure how thick or thin a wall of pipe is. A higher schedule means that the pipe wall is thicker and vice versa. In our present case, these pipe types have the same wall thickness. So, the question arises: what does S mean when written with SCH 40S? Let’s go down and understand the meaning of S.

What Does the S Stand for in the Pipe Schedule?

The S written after 40 in SCH 40S represents the stainless steel. So, this pipe is made from stainless steel. In other words, it indicates the material used to manufacture the pipe. So, these pipes have the same dimension and thickness but differ in material. 

The counterpart SCH 40 can be made up of any material. Those include carbon steel and PVC. The characteristics of these types of pipes differ due to the material used in manufacturing them. As stainless steel is a premium material, SCH 40S is a superior option to its counterpart.

Sch 40 vs sch 40S 

You understood the basic definition of these two types in the section above. In summary, they both have the same wall thickness and dimension. However, they are different in terms of the materials they consist of. Let’s dive deeper and understand the key differences that influence their performance.

1- Rust Protection

In the above section, I mentioned that SCH 40S is made of stainless steel. This material is solid and does not get rusty. Even if you use this material in harsh conditions, it won’t get corrosive. Due to this, SCH 40S pipes are resistant to corrosion.

Let’s understand the logic behind its rust-proofing. Stainless steel consists of 10.5% of chromium. So, when this material comes in contact with oxygen, it makes a thin protective layer. This layer, known as chromium oxide, prevents oxygen and moisture from reaching the surface of stainless steel. 

So, when no moisture reaches the surface, no corrosion happens. The SCH 40 pipes are also protected from corrosion through zinc coating. However, this coating starts to deteriorate after some time. So, these pipes get rusty when the coating gets depleted. Therefore, SCH 40s is a better option.

2- Pressure Ratings

The SCH 40s pipes made with stainless steel are more robust. Even though their thickness is the same as SCH 40, the material quality is much better. Therefore, they can easily bear the highest pressure. 

On the flip side, the SCH 40 pipes are relatively thinner. They cannot bear the extreme pressure. Therefore, the pressure rating of SCH 40S is a better option. If you need a pipe with better pressure-bearing capacity, I recommend using SCH 40S.

3- Ease of Installation

The stainless steel is heavy, and its usage in SCH 40S makes it heavyweight. On the flip side, the SCH40 pipes are lightweight and easy to hold and carry. Therefore, it would be easier to install SCH 40 than SCH 40S. However, the heavyweight SCH 40S will give you better performance than its counterpart.

4- Age & Lifespan

Rust and corrosion are the big enemies of the pipes. As these pipes carry water and other fluids, their continuous contact with moisture makes them susceptible to rust. So, the pipe that is more rust-resistant will have more age. The SCH 40s are rust-resistant. So it won’t get damaged.

However, the SCH 40 pipes will get rusty once the zinc coating is depleted. However, you can expect 40 to 50 years of life from this pipe. SCH 40S pipes, being more robust and rust-proof, can go up to 70 to 80 years. This makes SCH 40S an ideal investment for the long run.

5- Price & Affordability

This is one of the most crucial factors to consider. Due to the usage of premium material, SCH 40S is more expensive. You’ll need a handsome budget to buy these pipes. On the flip side, the SCH 40 pipes are less expensive. However, due to better performance, the higher price of SCH 40S is worth every penny.

Frequently Asked Questions

Q1: What does SCH 40 stand for?

SCH 40 stands for the pipes having 40 SCH wall thickness. They are made up of materials other than stainless steel. Those can be either carbon steel or PVC plastics.

Q2: What is the schedule for a 40 stainless steel pipe?

Schedule 40 stainless steel pipe means that they have 40 schedule thickness. Their making material is stainless steel. They are rust-proof, strong, and durable. 

Q3: Are these two pipes different dimensions from every unit or just in SCH?

These two pipes, SCH 40 and SCH 40S have the same wall thickness. They have the exact measurements even in nominal pipe size (NP) outer diameter.


Both SCH 40 and 40s are excellent options. You can choose either of them and get a decent performance.

However, it is vital to understand their differences. SCH 40S is a superior option due to its ideal rust-proofing.

You’ll get more age from these. It would be a wise investment if you prefer SCH 40s. We specialize in providing steel pipes in different thicknesses and grades. Contact us for an instant quote.