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Comparison of pressure ratings for SCH 40 and SCH 80 steel pipes

Date:2025-11-27View:1918Tags:sch 40 pipe, sch 80 pipe, pipe pressure ratings

Steel pipes of different wall thickness grades (SCH) are widely used in various piping systems, with SCH 40 and SCH 80 being two of the most common choices. Both conform to ASME/ANSI B36.10 standards, but their wall thickness and load-bearing capacity differ significantly.

SCH 40 steel pipe

Nominal pipe size (NPS) is a standard size designation used in the United States for steel and iron pipes. It's important to note that NPS only represents the approximate inner diameter of the pipe, not its actual inner diameter (ID) or outer diameter (OD). At the same nominal pipe size, the outer diameter remains constant, while the wall thickness varies depending on the pipe's wall thickness grade (Schedule Number).

Different wall thickness grades directly affect the pipe's inner diameter: a higher wall thickness grade means a thicker wall, a smaller inner diameter, and a higher pressure-bearing capacity.

For example, in 1-inch NPS pipe, SCH 40 has a thinner wall and a larger inner diameter than SCH 80, making it more suitable for medium-to-low pressure and cryogenic systems.

Among common wall thickness standards: SCH 40 is usually referred to as standard wall thickness (STD, Standard Weight); SCH 80 corresponds to extra strong wall thickness (XS, Extra Strong), which can withstand higher pressure.

SCH 40 vs SCH 80 Steel Pipe Pressure Rating

Carbon Steel Pipe - SCH 40 vs SCH 80

Size (in)	Outside Diameter (in)	Wall Thickness (in)	Inside Diameter (in)	Schedule	Temperature (^oF)
					100	200	300	400	500	600	650	700
					Allowable Stress (psi)
					20000	20000	20000	20000	18900	17300	17000	16500
1/2	0.840	0.109	0.622	40	4995	4995	4995	4995	4721	4321	4246	4121
	0.840	0.147	0.546	80	6980	6980	6980	6980	6596	6038	5933	5759
3/4	1.050	0.113	0.824	40	4074	4074	4074	4074	3849	3524	3463	3361
	1.050	0.154	0.742	80	5721	5721	5721	5721	5406	4948	4863	4720
1	1.315	0.133	1.049	40	3810	3810	3810	3810	3600	3295	3238	3143
	1.315	0.179	0.957	80	5266	5266	5266	5266	4976	4555	4476	4344
1 1/4	1.660	0.14	1.38	40	3137	3137	3137	3137	2964	2714	2666	2588
	1.660	0.191	1.278	80	4380	4380	4380	4380	4139	3789	3723	3613
1 1/2	1.900	0.145	1.61	40	2822	2822	2822	2822	2667	2441	2399	2328
	1.900	0.2	1.5	80	3977	3977	3977	3977	3759	3440	3381	3281
2	2.375	0.154	2.067	40	2377	2377	2377	2377	2247	2056	2021	1961
	2.375	0.218	1.939	80	3433	3433	3433	3433	3244	2970	2918	2832
2 1/2	2.875	0.203	2.469	40	2600	2600	2600	2600	2457	2249	2210	2145
	2.875	0.276	2.323	80	3602	3602	3602	3602	3404	3116	3062	2972
3	3.500	0.216	3.068	40	2258	2258	2258	2258	2133	1953	1919	1862
	3.500	0.3	2.9	80	3191	3191	3191	3191	3016	2761	2713	2633
3 1/2	4.000	0.226	3.548	40	2059	2059	2059	2059	1946	1781	1750	1699
	4.000	0.318	3.364	80	2946	2946	2946	2946	2784	2549	2505	2431
4	4.500	0.237	4.026	40	1914	1914	1914	1914	1809	1656	1627	1579
	4.500	0.337	3.826	80	2766	2766	2766	2766	2614	2393	2351	2282
5	5.563	0.258	5.047	40	1678	1678	1678	1678	1585	1451	1426	1384
	5.563	0.375	4.813	80	2476	2476	2476	2476	2340	2142	2105	2043
6	6.625	0.28	6.065	40	1524	1524	1524	1524	1441	1319	1296	1258
	6.625	0.432	5.761	80	2391	2391	2391	2391	2260	2069	2033	1973
8	8.625	0.322	7.981	40	1342	1342	1342	1342	1268	1161	1140	1107
	8.625	0.5	7.625	80	2115	2115	2115	2115	1998	1829	1798	1745
10	10.75	0.365	10.02	40	1217	1217	1217	1217	1150	1053	1035	1004
	10.75	0.594	9.562	80	2012	2012	2012	2012	1901	1740	1710	1660
12	12.75	0.406	11.938	40	1140	1140	1140	1140	1077	986	969	940
	12.75	0.688	11.374	80	1963	1963	1963	1963	1855	1698	1668	1619
14	14.00	0.438	13.124	40	1120	1120	1120	1120	1058	968	952	924
	14.00	0.75	12.5	80	1948	1948	1948	1948	1841	1685	1656	1607
16	16.00	0.5	15	40	1118	1118	1118	1118	1057	967	950	923
	16.00	0.812	14.376	80	1842	1842	1842	1842	1740	1593	1565	1519
18	18.00	0.562	16.876	40	1117	1117	1117	1117	1056	966	950	922
	18.00	0.938	16.124	80	1893	1893	1893	1893	1789	1637	1609	1562

Stainless Steel Pipes - SCH 40 vs SCH 80

Pipe Size (inches)	Pipe Schedule	Outside Diameter (in)	Wall Thickness (in)	Pressure Rating (psig)
				Temperature (^oF)
				100	200	300	400	500	600	650	700	750
				Allowable Stress (psi)
				16700	16700	16700	15500	14400	13500	13200	12900	12600
1"	40	1.315	0.133	2205	2205	2205	2047	1902	1783	1743	1703	1664
1"	80	1.315	0.179	3061	3061	3061	2841	2640	2475	2420	2365	2310
1 1/2"	40	1.900	0.145	1629	1629	1629	1512	1404	1317	1287	1258	1229
1 1/2"	80	1.900	0.200	2303	2303	2303	2138	1986	1862	1821	1779	1738
2"	40	2.375	0.154	1371	1371	1371	1272	1182	1108	1083	1059	1034
2"	80	2.375	0.218	1985	1985	1985	1843	1712	1605	1569	1534	1498
3"	40	3.500	0.216	1301	1301	1301	1208	1122	1052	1028	1005	982
3"	80	3.500	0.300	1844	1844	1844	1712	1590	1491	1458	1425	1391
4"	40	4.500	0.237	1102	1102	1102	1023	950	891	871	851	831
4"	80	4.500	0.337	1596	1596	1596	1482	1377	1291	1262	1233	1204
5"	40	5.563	0.258	965	965	965	896	832	780	763	746	728
5"	80	5.563	0.375	1428	1428	1428	1325	1231	1154	1129	1103	1077
6"	40	6.625	0.280	877	877	877	814	756	709	693	677	661
6"	80	6.625	0.432	1379	1379	1379	1280	1189	1115	1090	1065	1040
8"	40	8.625	0.322	771	771	771	716	665	623	610	596	582
8"	80	8.625	0.500	1218	1218	1218	1131	1050	985	963	941	919
10"	40	10.750	0.365	699	699	699	649	603	565	553	540	528
10"	80	10.750	0.594	1159	1159	1159	1075	999	937	916	895	874

What factors determine the rated pressure of a pipeline?

The rated pressure of a pipeline refers to the highest internal pressure that a pipeline can fully withstand at a specific temperature. Many factors influence pipeline pressure; the following are some of the most critical determining factors in engineering design:

1. Wall Thickness (Direct Factor)

The thicker the pipeline wall, the stronger its pressure-bearing capacity. Different grades such as SCH 40, SCH 80, SCH 160, and XXS correspond to different wall thicknesses. Thicker walls are less prone to deformation or rupture under pressure.

2. Pipe Material

Different materials have different strengths and allowable stresses. For example:
Carbon steel (ASTM A53, A106) → Commonly used for medium and high pressure
Alloy steel (ASTM A335) → High temperature and high pressure environments
Stainless steel (ASTM A312) → Corrosion resistant and temperature difference resistant
Duplex stainless steel, nickel-based alloys → Used in extreme conditions

The yield strength and tensile strength of the material directly affect the pressure rating.

3. Temperature
As temperature increases, the allowable stress of a material decreases. Engineering standards typically specify allowable stress values at different temperatures. Proper temperature control can significantly improve the material's compressive strength.

4. Manufacturing Method
Steel pipes are manufactured in two ways: seamless manufacturing and welded manufacturing.

Seamless steel pipes: Without weld seams, they have higher overall strength and are suitable for high-pressure applications.
Welded pipes: Have weld seams, resulting in lower overall strength. The weld seams are significant weak points, making them unsuitable for high-temperature and high-pressure applications.

The rated pressure of a pipeline is not determined by a single factor but by a combination of factors, including wall thickness, material, temperature, outer diameter, manufacturing process, design standards, and corrosion allowance.

Summary

SCH 40 and SCH 80 pipes have the same outer diameter but differ in wall thickness, weight, and pressure rating. SCH 80 offers higher pressure resistance and is ideal for harsh industrial environments, while SCH 40 is suitable for general applications.

Read more : Steel Pipe Pressure Ratings Guide

【Prev】 : Schedule 80 steel pipe pressure rating
【Next】 : Schedule 40 Pipe Elbow

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