Carbon Steel Pipe Pressure Rating Chart​

Choosing the correct carbon steel pipe pressure rating is critical for pipeline safety, reliability, and compliance with ASME and ASTM standards. Carbon steel pipes are widely used in oil & gas, petrochemical, power generation, water treatment, and industrial processing systems, where pressure ratings directly affect safe operating performance.

Pipe pressure rating depends on more than pipe schedule alone. Factors such as material grade, wall thickness, operating temperature, corrosion allowance, and design code all influence the maximum allowable working pressure. This guide covers pressure rating calculations, pressure charts, flow rate tables, water hammer effects, burst pressure, and comparisons of Schedule 40, Schedule 80, Schedule 160, and XXS pipes to help you select the right pipe for your application.

What Is Carbon Steel Pipe Pressure Rating?

A carbon steel pipe pressure rating refers to the maximum allowable internal pressure that a pipe can safely withstand during continuous service under specified operating conditions. It is one of the most important parameters in piping system design because it directly affects safety, service life, and regulatory compliance.
Factors Affecting Pipe Pressure Rating
The maximum working pressure of a carbon steel pipe is determined by the following factors:
Pipe material (ASTM A53 Grade B, ASTM A106 Grade B, API 5L Grade B, etc.)
Outside diameter (OD)
Wall thickness (Schedule 40, Schedule 80, Schedule 160, XXS)
Operating temperature
Allowable stress specified by ASME codes
Manufacturing process (Seamless or ERW)
Corrosion or erosion allowance
Weld joint efficiency
As operating temperature increases, the allowable stress of carbon steel decreases. Consequently, the allowable pressure rating also decreases, even if the pipe dimensions remain unchanged.

What Does Pipe Schedule Mean?

The term Schedule (SCH) describes the wall thickness series of a steel pipe rather than its pressure rating. Pipes with the same nominal pipe size (NPS) have the same outside diameter, but different schedules have different wall thicknesses and inside diameters.

A thicker wall generally provides greater pressure resistance because more material is available to withstand internal stress. However, pressure rating is not determined by wall thickness alone. Material strength, operating temperature, corrosion allowance, and design code requirements must also be considered.

The most common carbon steel pipe schedules include:

Pipe Schedule	Wall Thickness	Typical Pressure Capacity	Common Applications
SCH 40	Standard	Medium	Water supply, HVAC, general industrial piping
SCH 80	Thick	High	Steam, oil & gas, compressed air
SCH 160	Extra Thick	Very High	High-pressure process systems
XXS (Double Extra Strong)	Thickest	Maximum	Critical high-pressure service

Working Pressure vs Design Pressure vs Burst Pressure

These three terms are frequently confused but have very different meanings.

Term	Definition	Typical Use
Working Pressure	The maximum pressure for continuous and safe operation.	Daily plant operation
Design Pressure	The pressure selected by engineers for system design, including safety margins.	ASME piping design
Burst Pressure	The pressure at which the pipe will rupture during destructive testing.	Laboratory testing only

Working pressure should never be confused with burst pressure. Burst pressure is only used to evaluate the structural limit of a pipe and should never be considered an acceptable operating pressure.

How Is Carbon Steel Pipe Pressure Rating Calculated?

A carbon steel pipe's pressure rating is not determined solely by its schedule number. Instead, engineers calculate the Maximum Allowable Working Pressure (MAWP) according to design codes such as ASME B31.3, ASME B31.1, and ASME Section II using the pipe dimensions, material properties, and service conditions.
A simplified pressure calculation formula 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.

Carbon Steel Pipe Pressure Rating Reference Chart

The following chart summarizes the approximate working pressure, burst pressure, and water hammer factors for ASTM A53 Grade B and ASTM A106 Grade B carbon steel pipes. These values are commonly used as a quick engineering reference under ambient temperature conditions.

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.

Quick Reference Pressure Comparison

Pipe Schedule	Relative Working Pressure	Relative Burst Pressure	Typical Applications
SCH 40	Standard	Medium	Water supply, HVAC, low-pressure process piping
SCH 80	High	High	Steam, oil & gas, compressed air
SCH 160	Very High	Very High	High-pressure process systems
XXS	Maximum	Maximum	Critical high-pressure service

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.

A more detailed table can be found here; the content is for reference only.

Carbon Steel Pipe Pressure Rating & Flow Rate Charts Guide (SCH40, SCH80, SCH160 & XXS)