Carbon Steel Pipe Pressure Rating Chart​

In the four major pipeline projects of petrochemicals, heating, municipal water supply and drainage, and long-distance oil and gas transmission, carbon steel pipes are the most widely used basic pipe material. Commonly referred to as Carbon Steel Pipes in the industry, their pressure rating tables are the core basis for pipeline layout, strength verification, pipe procurement, and hydrostatic testing. Numerous on-site safety accidents have revealed that over 70% of carbon steel pipe leaks and ruptures stem from personnel misusing ambient temperature pressure parameters, ignoring temperature derating, and confusing SCH wall thickness ratings with nominal pressure. This article, combining three major domestic and international standards—ASME B36.10M, ASTM A106, and GB/T 8163—systematically interprets the logic of the pressure rating tables, parameter differences, and on-site usage specifications.

What exactly is Schedule wall thickness?

In the US standard system, Schedule (Sch) is a "wall thickness series", not directly equivalent to "can only be used up to 10 bar / 16 bar / 25 bar". At the same nominal diameter (NPS), Sch 80 is thicker and has a smaller inner diameter than Sch 40; therefore, it allows for higher pressure resistance, but the specific allowable working pressure (MAWP/maximum working pressure) still depends on:

Material and allowable stress S(T) (different for A53 Gr.B/A106 Gr.B/low-temperature steel A333, etc.)
Manufacturing method: Seamless pipe (usually with a weld coefficient E≈1.0) and ERW welded pipe (commonly E≈0.85) will have significant differences
Design temperature: Increased temperature → decreased material strength → temperature derating is necessary
Effective wall thickness "eaten up" by corrosion allowance/wear allowance, thread thinning (if using threaded connections), etc.

System bottlenecks: Valve, fitting, flange, and joint types often determine the "usable pressure" of the entire pipe section, not just the pipe itself.

Actual Pressure Rating of Sch 80 Carbon Steel Pipe at Room Temperature

At room temperature (20℃) (room environment, water flow, ambient temperature oil, compressed air), no complex formula calculations are needed. Directly record the actual measured safe working pressure on site. Note: This is the long-term stable operating pressure, not the instantaneous burst pressure. Burst pressure is a safety margin and should never be used as a standard for use.
- Small diameter DN15-DN40: Sch80 carbon steel pipes have a safe pressure resistance of up to 16MPa. This specification is commonly used in high-pressure air compressors and high-pressure hydraulic oil pipes in workshops, and can easily operate continuously at pressures up to 10MPa.
- Medium diameter DN50-DN100: Sch80 carbon steel pipes have a safe pressure resistance of 8-12MPa. The larger the diameter, the larger the stress area of the pipe wall, and the lower the pressure resistance automatically. This is why even thick-walled large pipes cannot withstand high pressure.
- Large diameter DN125-DN200: Sch80 carbon steel pipes have a safe pressure resistance of only 4-6MPa. This is the mainstream use for high-pressure circulating cooling water in factories. For pressures exceeding 6MPa, alloy pipes must be used.
In short: the thinner the pipe, the higher its pressure resistance; the thicker the pipe, the lower its pressure resistance. At the same diameter, Sch80 has twice the pressure resistance of Sch40. For example, a DN50 Sch40 pipe can only withstand 5MPa, while a Sch80 pipe of the same diameter can withstand 10MPa.

How Is Carbon Steel Pipe Pipe Pressure Rating Determined?

Pressure ratings do not come directly from the schedule number.
Instead, engineers calculate allowable pressure using ASME B31.3 and ASME B31.1 formulas.
The simplified equation is:

P=2St/D

Where:
P = Allowable pressure
S = Allowable stress of material
t = Wall thickness
D = Outside diameter
Several variables influence the final result.

Material Strength
Higher-grade steel provides higher pressure capability.
Common materials include:
ASTM A53 Grade B
ASTM A106 Grade B
ASTM A333 Grade 6
API 5L Grade B

Schedule 80 Carbon Steel Pipe Pressure Rating Chart

SCH 80 Steel Pipe Pressure Rating(psig)
Pipe Size	Pipe Schedule	Temperature(oF)
(inches)		100	200	300	400	500	600	650	700	750
1"	40	3048	2629	2362	2171	2019	1924	1867	1824	1810
	80	4213	3634	3265	3002	2791	2659	2580	2528	2501
	160	6140	5296	4759	4375	4068	3876	3761	3684	3646
1 1/2"	40	2257	1947	1750	1608	1496	1425	1383	1354	1340
	80	3182	2744	2466	2267	2108	2009	1949	1909	1889
	160	4619	3984	3580	3291	3060	2916	2829	2772	2743
2"	40	1902	1640	1474	1355	1260	1201	1165	1141	1129
	80	2747	2369	2129	1957	1820	1734	1682	1648	1631
	160	4499	3880	3486	3205	2980	2840	2755	2699	2671
3"	40	1806	1558	1400	1287	1196	1140	1106	1084	1072
	80	2553	2202	1979	1819	1691	1612	1564	1532	1516
	160	3840	3312	2976	2736	2544	2424	2352	2304	2280
4"	40	1531	1321	1187	1091	1014	967	938	919	909
	80	2213	1909	1715	1577	1466	1397	1355	1328	1314
	160	3601	3106	2791	2566	2386	2273	2206	2161	2138
5"	40	1342	1158	1040	956	889	847	822	805	797
	80	1981	1709	1535	1411	1312	1250	1213	1189	1176
	160	3414	2945	2646	2433	2262	2155	2091	2049	2027
6"	40	1219	1052	945	869	808	770	747	732	724
	80	1913	1650	1483	1363	1267	1208	1172	1148	1136
	160	3289	2836	2549	2343	2179	2076	2014	1973	1953
8"	40	1073	926	832	765	711	678	657	644	637
	80	1692	1459	1311	1205	1121	1068	1036	1015	1005
	160	3175	2738	2460	2262	2103	2004	1944	1905	1885
10"	40	974	840	755	694	645	615	596	584	578
	80	1609	1388	1247	1147	1066	1016	986	966	956
	160	3147	2714	2439	2242	2085	1986	1927	1880	1868

To view the Schedule 40 chart, please click: Schedule 40 Pipes Pressure Rating Chart

For international EPC projects, exported equipment, and overseas oil and gas stations: Strict adherence to the original English version of the ASME B36.10M Carbon Steel Pipe Pressure Rating Reference Chart, using SCH+Class dual labeling to meet the acceptance standards of various countries.

Simplified Reference Chart for Pressure Rating of Carbon Steel Pipes at Normal Temperature (Field-Use Version) This chart is based on seamless ASTM A106 Gr.B pipes at 20℃ normal temperature, in non-corrosive clean water media. It is a simplified version of the industry-standard Carbon Steel Pipe Pressure Rating Reference Chart and can be used directly for quick on-site selection, replacing the original lengthy standard chart.

SCH 40 vs SCH 80 Pressure Rating Comparison

Feature	SCH 40	SCH 80
Wall Thickness	Lower	Higher
Pressure Capacity	Lower	Higher
Weight	Lighter	Heavier
Cost	Lower	Higher
Typical Use	Water, HVAC	Oil & Gas, Steam

In short, the carbon steel pipe pressure reference table cannot be used directly; it is only a reference for normal temperature, clean water, and seamless pipes. When selecting pipes, one cannot simply look at the pressure values in the table. It is also necessary to consider the steel pipe material, wall thickness, processing method, operating temperature, and the medium being transported. If only harmless media such as normal temperature clean water or ordinary compressed air are being transported, the table in this article is perfectly adequate for selection. However, in the event of high-temperature steam, corrosive wastewater, or flammable and explosive oils and gases, one must not rely solely on the simplified table. Instead, one must consult the original industry standards and calculate the pressure-bearing capacity based on the actual site conditions to prevent pipe cracking and leakage, and to avoid safety hazards.