Schedule 40 stainless steel pipe

Schedule 40 (also known as SCH 40S) is one of the most commonly used nominal wall thickness series for stainless steel pipes. It features moderate wall thickness, balanced rigidity and cost, and is widely used in commercial and industrial fields. Schedule 40 stainless steel pipes offer a good strength-to-weight ratio among numerous pipe specifications, can withstand medium pressure conditions, and have excellent corrosion resistance.

Common standards and norms

ASTM A312 / ASME SA312
Schedule 40 stainless steel pipes are often produced in accordance with ASTM A312/A312M (seamless or butt-welded stainless steel pipes) and ASME SA312 standards. This standard specifies requirements for chemical composition, mechanical properties and dimensional tolerances, etc., to ensure that the pipes are suitable for harsh environments such as chemical engineering, petroleum and Marine.

ANSI B36.19
In terms of size and wall thickness, ANSI B36.19M provides standards for the outer diameter and wall thickness of welded and seamless austenitic stainless steel pipes, including Schedule 5S, 10S, 40S, 80S, etc. The wall thickness corresponding to Schedule 40S is clearly defined in this standard.

Materials and Grades

Common material grades:

304/304L: General-purpose austenitic stainless steel, resistant to oxidizing media and most chemical media.
316/316L: Molybdenum-containing austenitic stainless steel, with better resistance to chloride corrosion, suitable for Marine and chemical processing environments.

Dimensions and wall thickness

Nominal size [inches]	Outside diameter [inches]	Outside diameter [mm]	Wall thickness [inches]	Wall thickness [mm]	Weight [lb/ft]	Weight [kg/m]
1/2	0.840	21.3	0.083	2.11	0.68	1.00
3/4	1.050	26.7	0.083	2.11	0.87	1.29
1	1.315	33.4	0.109	2.77	1.41	2.11
1 1/4	1.660	42.2	0.109	2.77	1.82	2.71
1 1/2	1.900	48.3	0.109	2.77	2.1	3.13
2	2.375	60.3	0.109	2.77	2.66	3.96
2 1/2	2.875	73.0	0.120	3.05	3.56	5.29
3	3.500	88.9	0.120	3.05	4.37	6.50
3 1/2	4.000	101.6	0.120	3.05	5.01	7.46
4	4.500	114.3	0.120	3.05	5.66	8.42
5	5.563	141.3	0.134	3.40	7.82	11.64
6	6.625	168.3	0.134	3.40	9.35	13.91
8	8.625	219.1	0.148	3.76	13.50	20.10
10	10.750	273.1	0.165	4.19	18.79	27.96
12	12.750	323.9	0.180	4.57	24.34	36.22
14	14.000	355.6	0.188	4.78	27.97	41.62
16	16.000	406.4	0.188	4.78	32.02	47.65
18	18.000	457.0	0.188	4.78	36.05	53.65
20	20.000	508.0	0.218	5.54	46.42	69.09
22	22.000	559.0	0.218	5.54	51.14	76.10
24	24.000	610.0	0.250	6.35	63.93	95.13
30	30.000	762.0	0.312	7.92	99.60	148.22

Rated pressure
The allowable working pressure is affected by the pipe diameter, wall thickness, temperature and the allowable stress of the material. Take 4 "Schedule 40S (t=4.85 mm) as an example. At 100 °F (approximately 38 °C), according to the ASME B31.3 formula, the allowable pressure can reach approximately 1102 psi (≈ 75.9 bar).

Typical applications

Petroleum and natural gas: high-pressure transmission pipelines, high-temperature steam pipes.
Chemical engineering and chemical processing: Transportation of acid and alkali corrosive media.
Food and beverage: Sanitary piping system, easy to clean and does not contaminate the medium.
HVAC and construction: Condensate and compressed air piping.
Pharmaceuticals and Biotechnology: High-purity fluid delivery.