Schedule 20 Steel Pipe: Weight, Wall Thickness & Material Guide

1.What is Schedule 20 Steel Pipe

Schedule 20 steel pipe (SCH 20 pipe) is a standardized pipe wall thickness classification defined by ASME B36.10M and ASME B36.19M. Compared with Schedule 40 and Schedule 80 pipes, Schedule 20 pipe features a thinner wall thickness, lighter weight, and lower pressure rating.Due to its cost-effectiveness and adequate mechanical strength, Schedule 20 steel pipe is widely used in low-pressure fluid transportation systems, drainage networks, HVAC piping, chemical processing systems, and general industrial applications.

It is crucial to understand that "Schedule" itself is not a physical measurement but a wall thickness designator. The actual thickness varies significantly depending on the Nominal Pipe Size (NPS).

According to ASME B36.10M (Welded and Seamless Wrought Steel Pipe), the dimensions are standardized:

NPS 2 (DN50): Wall thickness is 0.109" (2.77 mm)
NPS 4 (DN100): Wall thickness is 0.120" (3.05 mm)
NPS 8 (DN200): Wall thickness is 0.148" (3.76 mm)
NPS 12 (DN300): Wall thickness is 0.180" (4.57 mm)

2. Characteristics of Schedule 20 Steel Pipe

2.1 Thin Wall Construction
The primary characteristic of Schedule 20 steel pipe is its relatively thin wall thickness.
Compared with heavier schedules such as Sch 40 and Sch 80, Schedule 20 pipe offers:
Reduced weight
Easier installation
Lower transportation costs
Improved material efficiency
These advantages make it suitable for large piping systems where pressure requirements are moderate.

2.2 Good Corrosion Resistance
When manufactured from stainless steel or protected with coatings such as galvanizing or epoxy lining, Schedule 20 pipe provides excellent corrosion resistance.
Typical applications include:
Water distribution systems
Wastewater treatment facilities
Chemical process piping
Rainwater collection systems

2.3 Chemical Compatibility
Schedule 20 stainless steel pipe demonstrates excellent compatibility with a wide range of chemicals and industrial fluids.
Depending on the material grade, it can be used for transporting:
Process water
Mild chemicals
Food-grade liquids
Pharmaceutical products

2.4 Cost Efficiency
Because less steel is required during manufacturing, Schedule 20 pipe is generally more economical than Schedule 40 or Schedule 80 pipe.
This lower material consumption helps reduce:
Project costs
Installation expenses
Transportation costs

3. Schedule 20 Steel Pipe Standards

Schedule 20 steel pipe dimensions and manufacturing requirements are governed by several international standards.

Standard	Description
ASME B36.10M	Welded and Seamless Carbon Steel Pipe
ASME B36.19M	Stainless Steel Pipe
ASTM A53	Welded and Seamless Carbon Steel Pipe
ASTM A106	Seamless Carbon Steel Pipe
ASTM A312	Stainless Steel Pipe
ASTM A790	Duplex Stainless Steel Pipe

These standards specify pipe dimensions, wall thickness, manufacturing tolerances, testing requirements, and material properties.

4.Schedule 20 Pipe Materials Analysis

4.1Alloy steel
Used for higher temperature or more demanding environments, offering better strength and heat resistance. However, because Schedule 20 has a relatively thin wall, it is still not suitable for very high-pressure applications.
Grades include ASTM A335 P11, P22, and P91.

4.2Carbon steel
The most commonly used option for Schedule 20 pipes. It performs well in normal to medium temperature conditions where corrosion is minimal or not a concern.
Typical grades include ASTM A106 Gr. B, ASTM A53 Gr. B, and API 5L Gr. B / X42 / X52.

4.3Stainless steel
Preferred when corrosion resistance and cleanliness are important, such as in food processing, medical systems, or chemical service.
Common grades: AISI 304 / 304L, 316 / 316L, 321.

4.4Galvanized Steel
Galvanized steel pipe features a protective zinc coating that improves corrosion resistance. It is commonly used in outdoor piping systems, water distribution networks, and construction projects where moderate corrosion protection is required.

5.Schedule 20 Steel Pipe Dimensions Chart

Schedule 20 pipe dimensions are standardized according to ASME B36.10M.The following chart lists common Schedule 20 pipe sizes, outside diameters, wall thicknesses, and approximate weights.

NPS	1/2	3/4	1	1¼	1½	2	2½	3	3½	4
DN	15	20	25	32	40	50	65	80	90	100

6.Schedule 20 Pipe Weight Calculation

Pipe weight is an important factor in transportation, structural design, and installation planning.
The theoretical weight can be calculated using the following formula:

Weight (kg/m) = (OD − WT) × WT × 0.02466
Where:
OD = Outside Diameter (mm)
WT = Wall Thickness (mm)
For example, a 4-inch Schedule 20 pipe with an OD of 114.3 mm and wall thickness of 3.05 mm has an approximate weight of 8.36 kg/m.
Because Schedule 20 pipe has thinner walls, it weighs significantly less than Schedule 40 pipe of the same diameter.

7.ASME B36.10M Schedule 20 Wall Thickness Chart

Schedule 20 is a lightweight, thick-walled steel pipe specification. Its wall thickness is slightly thicker than Schedule 10 but significantly less than Schedule 40, making it a commonly used and economical pipe type for low-pressure systems. It is widely used in HVAC, water supply and drainage, and general industrial transmission systems. Its advantages include light weight and low cost, but its pressure-bearing capacity is limited.

In the ASME B36.10M standard, the wall thickness of Schedule 20 varies with pipe diameter; therefore, it cannot be represented by a single numerical value and must be looked up using NPS (nominal size).

Diameter Nominal	Nominal Pipe Size	Outside Diameter (mm)	Wall Thickness (mm)	Weight (kg/m)
DN 200	8 inch	219.1	635	33.32
DN 250	10 inch	273	635	41.76
DN 300	12 inch	323.8	635	49.71
DN 350	14 inch	355.6	792	67.91
DN 400	16 inch	406.4	792	77.83
DN 450	18 inch	457	792	87.71
DN 500	20 inch	508	9.53	117.15
DN 550	22 inch	559	9.53	129.14
DN 600	24 inch	610	9.53	141.12
DN 650	26 inch	660	12.7	202.74
DN 700	28 inch	711	12.7	218.71
DN 750	30 inch	762	12.7	234.68
DN 800	32 inch	813	12.7	250.65
DN 850	34 inch	864	12.7	26663
DN 900	36 inch	914	12.7	282.29

8.Applications of Schedule 20 Steel Pipe

Water Supply and Drainage Systems
Fire Protection Systems
Low-Pressure Industrial Fluid Transport
HVAC (Heating, Ventilation, and Air Conditioning) Systems
Agricultural Irrigation Systems
Building Utility and Auxiliary Piping Systems

Light Industrial Equipment Piping Systems

9.Frequently Asked Questions

Q1: What does Schedule 20 mean?
Schedule 20 refers to a standardized pipe wall thickness classification defined by ASME standards.

Q2: Is Schedule 20 pipe suitable for high-pressure applications?
No. Schedule 20 pipe is generally intended for low-pressure and moderate-duty applications.

Q3: What is the difference between Schedule 20 and Schedule 40 pipe?
Schedule 40 pipe has a thicker wall, higher pressure rating, and greater weight than Schedule 20 pipe.

Q4: Is Schedule 20 available in stainless steel?
Yes. Schedule 20 dimensions are available in stainless steel grades such as 304, 304L, 316, and 316L.