What does the designation sch20 mean? What are
SCH20-SCH40-SCH80-SCH160? Friends who do foreign trade often ask questions like, ‘ASTM A106 Gr.B, 12,
SCH40, 6m, SML, API 5L Gr.B, 12, SCH40, 6m, SML’ What do these mean? The steel pipe size given by the customer is in British system, how to convert it to metric MM? What are the outer diameter, inner diameter and thickness of the steel pipe? Let’s take a look at what SCH20 means today?
Definition of SCH20
The term SCH20 originates from the series of pipe wall thickness classifications, known as Schedule. Its full name is Schedule 20. This classification defines the wall thickness of pipes, a key factor in determining their structural strength and pressure-bearing capacity.
Difference Between SCH20 and SCH20s
It is important to note that SCH20s is used exclusively for stainless steel pipes, while SCH20 applies to carbon steel pipes.
Expression method of steel pipe wall thickness:
There are three ways to express the wall thickness of steel pipes: pipe schedule, steel pipe wall thickness size and pipe weight
(1) The wall thickness is expressed by the pipe schedule "Sch". The pipe schedule is the ratio of the pipe design pressure to the material allowable stress at the design temperature multiplied by 1000 and rounded. That is: Sch＝P/[σ]t×1000 ANSI B36.10 wall thickness grades: Sch10, Sch20, Sch30, Sch40, Sch60,
Sch80, Sch100, Sch120, Sch140, Sch160 ten grades; ANSI B36.19 wall thickness grades: Sch5s, Sch10s, Sch40s, Sch80s four grades;
(2) Expressed by steel pipe wall thickness size China, ISO, Japan part of the steel pipe standards adopted
(3) The pipe wall thickness is expressed by the pipe weight, it divides the pipe wall thickness into three types: a. Standard weight pipe, indicated by STD b. Thickened pipe, indicated by XS c. Extra thick pipe, indicated by XXS. For pipes with DN≤250mm, Sch40 is equivalent to STD, and for pipes with DN<200mm, Sch80 is equivalent to XS.
Converting Imperial to Metric Measurements
To convert dimensions from the imperial system to metric, the following is needed:
NPS (Nominal Pipe Size): Standard size in inches.
DN (Diameter Nominal): Metric equivalent in millimeters.
For example:
|
NPS
|
1/2
|
3/4
|
1
|
1¼
|
1½
|
2
|
|
DN
|
15
|
20
|
25
|
32
|
40
|
50
|
Additionally, the outer diameter (OD), inner diameter (ID), and wall thickness are calculated based on the Schedule.
The following is the sch20 size specification table
Schedule 20 Steel Pipe Dimensions :
|
Nominal size [inches]
|
Outside diameter [inches]
|
Outside diameter [mm]
|
Wall thickness [inches]
|
Wall thickness [mm]
|
Weight [lb/ft]
|
Weight [kg/m]
|
|
8 inches
|
8.625 inches
|
219.1 mm
|
0.250 inches
|
6.35 mm
|
22.36 lb/ft
|
33.31 kg/m
|
|
10 inches
|
10.750 inches
|
273.0 mm
|
0.250 inches
|
6.35 mm
|
28.04 lb/ft
|
41.77 kg/m
|
|
12 inches
|
12.750 inches
|
323.8 mm
|
0.250 inches
|
6.35 mm
|
33.38 lb/ft
|
49.73 kg/m
|
|
14 inches
|
14.000 inches
|
355.6 mm
|
0.312 inches
|
7.92 mm
|
45.61 lb/ft
|
67.90 kg/m
|
|
16 inches
|
16.000 inches
|
406.4 mm
|
0.312 inches
|
7.92 mm
|
52.27 lb/ft
|
77.83 kg/m
|
|
18 inches
|
18.000 inches
|
457.0 mm
|
0.312 inches
|
7.92 mm
|
58.94 lb/ft
|
87.71 kg/m
|
|
20 inches
|
20.000 inches
|
508.0 mm
|
0.375 inches
|
9.53 mm
|
78.60 lb/ft
|
117.15 kg/m
|
|
22 inches
|
22.000 inches
|
559.0 mm
|
0.375 inches
|
9.53 mm
|
86.61 lb/ft
|
129.13 kg/m
|
|
24 inches
|
24.000 inches
|
610.0 mm
|
0.375 inches
|
9.53 mm
|
94.62 lb/ft
|
141.12 kg/m
|
|
26 inches
|
26.000 inches
|
660.0 mm
|
0.500 inches
|
12.70 mm
|
136.17 lb/ft
|
202.72 kg/m
|
|
28 inches
|
28.000 inches
|
711.0 mm
|
0.500 inches
|
12.70 mm
|
146.85 lb/ft
|
218.69 kg/m
|
|
30 inches
|
30.000 inches
|
762.0 mm
|
0.500 inches
|
12.70 mm
|
157.53 lb/ft
|
234.67 kg/m
|
|
32 inches
|
32.000 inches
|
813.0 mm
|
0.500 inches
|
12.70 mm
|
168.21 lb/ft
|
250.64 kg/m
|
|
34 inches
|
34.000 inches
|
864.0 mm
|
0.500 inches
|
12.70 mm
|
178.89 lb/ft
|
266.61 kg/m
|
|
36 inches
|
36.000 inches
|
914.0 mm
|
0.500 inches
|
12.70 mm
|
189.57 lb/ft
|
282.27 kg/m
|
Schedule 20 Pipes Pressure Rating
|
Outer diameter, Inner diameter, & Wall Thickness Dimensions For Given Pipes Sizes
|
|
Pipes Size in inch
|
Schedule 20 Thickness
|
|
Outer diameter.
|
Inner diameter
|
Wall Thickness
|
|
3/4 inch
|
1.050 inch
|
0.920 inch
|
0.065 inch
|
|
1 inch
|
1.315 inch
|
1.185 inch
|
0.065 inch
|
|
1-1/4 inch
|
1.660 inch
|
1.530 inch
|
0.065 inch
|
|
1-1/2 inch
|
1.900 inch
|
1.770 inch
|
0.065 inch
|
|
2 inch
|
2.375 inch
|
2.245 inch
|
0.065 inch
|
|
2-1/2 inch
|
2.875 inch
|
2.709 inch
|
0.083 inch
|
|
3 inch
|
3.500 inch
|
3.334 inch
|
0.083 inch
|
|
3-1/2 inch
|
4.000 inch
|
3.834 inch
|
0.083 inch
|
|
4 inch
|
4.500 inch
|
4.334 inch
|
0.083 inch
|
|
6 inch
|
6.625 inch
|
6.407 inch
|
0.109 inch
|
|
8 inch
|
8.625 inch
|
8.407 inch
|
0.109 inch
|
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