Chinese standard heavy rails are designated by their nominal weight per metre, from P38 to P75. The profiles follow the dimensions in GB/T 2585 for hot-rolled rails and the railway industry standard TB/T 2344, and they are used on mainline railway, mine and factory track around the world. This article lists the sizes, steel grades and applications of P38, P43, P50, P60 and P75 rails.
What Are P38 to P75 Heavy Rails
Heavy rail is defined as rail with a linear mass of 38 kg/m or more. The Chinese standard series includes nominal 38, 43, 50, 60 and 75 kg/m sections. The letter P in the designation stands for the profile or rail section, and the number is the nominal weight; the actual mass per metre is slightly different because it is calculated from the rolled section area. Below 38 kg/m, rails such as 8 to 30 kg/m are classified as light rail.
Dimensions and Weights of Chinese Heavy Rails
| Section | Height mm | Head width mm | Foot width mm | Web thickness mm | Actual mass kg/m |
|---|---|---|---|---|---|
| P38 | 134 | 68 | 114 | 13 | 38.733 |
| P43 | 140 | 70 | 114 | 14.5 | 44.653 |
| P50 | 152 | 70 | 132 | 15.5 | 51.514 |
| P60 | 176 | 73 | 150 | 16.5 | 60.64 |
| P75 | 192 | 75 | 150 | 20 | 74.414 |
Standard supply lengths for Chinese heavy rails are 12.5 m and 25 m. The dimensions above follow the published profile tables and should be verified against the mill certificate for each rolling batch, because the actual section area determines the true linear mass.
Steel Grades for Heavy Rail
Chinese heavy rails are made of medium-manganese rail steel. U71Mn contains 0.65 to 0.76 percent carbon, 0.15 to 0.35 percent silicon and 1.10 to 1.40 percent manganese, with a minimum tensile strength of 880 MPa, and is the standard grade for general mainline use. U75V adds vanadium and reaches a minimum tensile strength of 980 MPa in the hot-rolled condition, with higher values after head hardening, making it the preferred grade for heavy-haul and high-speed lines. Plain carbon-manganese steel 50Mn, with a minimum yield strength of 390 MPa and a minimum tensile strength of 645 MPa, is typically used for fishplates and other connecting parts rather than for the rail itself.
| Grade | Min tensile strength | Typical use |
|---|---|---|
| U71Mn | 880 MPa | Standard mainline rail |
| U75V | 980 MPa | Heavy-haul and high-speed rail |
| 50Mn | 645 MPa | Fishplates and connecting parts |
Typical Applications of Each Section
P38 rail is used for larger mine roadways, factory workshops, crane runways and special industrial lines where space is limited. P43 suits branch lines, sidings and light traffic routes. P50 is a common choice for secondary lines, marshalling yards and lighter mainline traffic. P60 is the standard section for Chinese mainline railway, high-speed corridors and metro systems. P75 is reserved for heavy-haul corridors carrying the highest axle loads, where the extra mass reduces bending stress and extends service life.
Ordering and Quality Verification
When ordering Chinese heavy rail, confirm the section designation, the steel grade, the length, and the governing standard, and require a mill certificate with the chemical composition and mechanical test results of the delivered heats. Third-party inspection can verify dimensions, straightness, surface quality and ultrasonic soundness before shipment. Because P60 and P75 rails are heavy, check the loading plan and the number of layers per wagon against the logistics requirements for the destination.
FAQ
Q: What does P60 mean in rail designation? A: P60 is a Chinese standard heavy rail with a nominal weight of 60 kg/m, with an actual linear mass of 60.64 kg/m and a profile height of 176 mm.
Q: What is the difference between heavy rail and light rail? A: Heavy rail is 38 kg/m and above, used for mainline and industrial railway; light rail ranges from 8 to 30 kg/m and is used for mines, workshops and light tramways.
Q: Which steel grade is used for high-speed rail in China? A: U75V is the standard grade for Chinese high-speed and heavy-haul lines, with a minimum tensile strength of 980 MPa and higher after head hardening.
Q: What lengths are Chinese heavy rails supplied in? A: The standard supply lengths are 12.5 m and 25 m, and rails can be flash-butt welded into longer continuous strings on site.
Q: How much does P75 rail weigh? A: P75 rail has an actual linear mass of 74.414 kg/m, with a profile height of 192 mm and a foot width of 150 mm.
