Schedule 40 carbon steel pipe

What is a Pipe Schedule?
A pipe schedule (SCH) is a measure of a steel pipe’s nominal wall thickness.

In the past, metal fabricators used three pipe dimensions — standard, extra strong, and double extra strong. Just having these three undetermined dimensions wasn’t helpful, though. So today, steel pipes come in 14 different schedules.
The most commonly used one is schedule 40.

Schedule 40 Carbon Steel Pipe is one of the medium schedule pipes. There are different schedules in all pipes. The schedule indicates the dimensions and the pressure capacities of the pipes. Hunan Standard Steel Co., Ltd is a leading supplier and manufacturer of the Sch 40 Carbon Pipe products. There are various grades of carbon with various chemical compositions. But the pressure containment capacities are measured and classified. The Carbon Steel Pipe Schedule 40 is a medium range pressure capacity pipe with diameters ranging up to 24 inches and the wall thicknesses ranging up to 46mm.

The diameter to wall thickness ration in addition to the strength of the material decides if it is a Pipe Sch 40 or some other schedule. The schedule is determined in relation to the outer diameter, wall thickness and the pressure capacity of the material. The Schedule 40 Carbon Steel Pipe Weight varies depending on the material it is made. The more carbon is added onto the steel, the less the weight of the pipe is. But the wall thickness and the diameter also play a role. Since schedule 40 is a medium pressure class, the pipes are of medium size wall Schedule 40 Pipe Thickness and the weight is also in the medium range. Please contact us for more information.

Chemical Composition of Schedule 40 Carbon Steel Pipe

Schedule 40 pipe refers to the nominal wall thickness, not the grade. Therefore, the chemical composition of a pipe schedule is not necessarily uniform.

However, schedule 40 pipe is made from low-carbon steel, usually grade A53 steel pipe. Its chemical composition also varies across types and welds, but as a point of reference, type S seamless weld A53 steel looks something like this:

Carbon – 0.25% (max)
Manganese – 0.95% (max)
Phosphorous – 0.05% (max)
Sulfur – 0.045% (max)
Copper – 0.4% (max)
Nickel – 0.4% (max)
Chromium – 0.4% (max)
Molybdenum – 0.15% (max)
Vanadium – 0.08% (max)

Common uses of Schedule 40 steel pipes:

1. Low-pressure fluid transportation
Tap water, gas (ASTM A53 Sch 40 galvanized pipe).
Chemical media (such as ASTM A106 Sch 40 seamless pipe).

2. Buildings and structures
Scaffolding (but must comply with structural standards, such as EN 39).
Air conditioning and ventilation ducts (thin-wall Sch 5/10 is more commonly used).

3. Machinery and equipment
Low-pressure pipelines in hydraulic systems (high pressure requires Sch 80 or above).
Food industry (stainless steel 304 Sch 40).

How to identify Schedule 40 steel pipes?

1.Marking method
Pipe body spray code or label marking (such as "ASTM A106 Sch 40").
Color marking at the end of some steel pipes (such as Sch 40 carbon steel pipes have no special color, but stainless steel pipes may be marked green).

2. Measurement verification
Use a caliper to measure the outer diameter and wall thickness, and compare with the standard size table (such as the wall thickness of NPS 1" Sch 40 should be 3.38mm).

Notes on the selection of Sch 40 steel pipe:

1. Pressure matching
Calculate the design pressure to ensure that the pressure bearing capacity of Sch 40 is sufficient (safety factor needs to be considered).

2. Material selection
Corrosive environment → Select stainless steel Sch 40 (ASTM A312) or galvanized carbon steel (ASTM A53).
High temperature environment → Select ASTM A106 Sch 40 (temperature resistance ≤350℃).

3. Economic efficiency
Sch 40 is the most cost-effective general choice, but Sch 80/160 is required for ultra-high pressure scenarios.

Frequently Asked Questions:

Q1: Is Sch 40 a seamless pipe or a welded pipe?
Both!
Seamless pipe: ASTM A106 Sch 40
Welded pipe: ASTM A53 Sch 40

Q2: Sch 40 Can it be used for natural gas pipelines?
Yes, but it must comply with local specifications (e.g. ASTM A53 Sch 40 galvanized pipe in the United States, GB/T 8163 in China).

Q3: Are Sch 40 and "STD" (standard wall thickness) the same?
They are the same when NPS≤10", but the "STD" wall thickness is slightly thinner than Sch 40 when NPS≥12".

Read more: Schedule 80 Carbon Steel Pipe Thickness