P38 38kg/m Steel Rail in 12m and 12.5m Lengths: Specifications and Applications
Sep 22, 2025
Introduction to P38 38kg/m rail
The P38 rail, commonly called 38kg/m steel rail or 38kg heavy rail, is a hot-rolled steel rail profile defined in the Chinese railway standards, with its dimensions and weight aligned to GB 2585 (railway hot-rolled rails) and related series. The designation P38 refers to a nominal weight of 38 kg per metre. The profile is a standard flat-bottom rail with a rail head, a web and a rail base, rolled in one piece so that it provides a smooth running surface for the wheel and transfers the wheel load evenly to the sleepers below.
The rail performs two basic duties in track: it guides the train wheels forward while withstanding the enormous stress of the wheel at each pass, and it transfers that load to the sleepers. The running surface is kept smooth and continuous so that rolling resistance stays low. On electrified railways or automatic block sections, the rail additionally serves as the track circuit conductor.
Dimensions and theoretical weight
| Type | Rail height (mm) | Bottom width (mm) | Head width (mm) | Web thickness (mm) | Weight (kg/m) |
|---|---|---|---|---|---|
| 38kg (P38) | 134 | 114 | 68 | 13 | 38.733 |
| 43kg | 140 | 114 | 70 | 14.5 | 44.653 |
| 50kg | 152 | 132 | 70 | 15.5 | 51.514 |
| 60kg | 176 | 150 | 73 | 16.5 | 60.8 |
| 75kg | 192 | 150 | 75 | 20 | 74.64 |
The P38 profile has a rail height of 134 mm, a bottom width of 114 mm, a head width of 68 mm and a web thickness of 13 mm, with a theoretical weight of 38.733 kg/m. It is generally supplied in 12 m or 12.5 m lengths, and can also be cut to customer lengths with drilling and end finishing as required.
Steel grades
| Parameter | Value |
|---|---|
| Type | 38kg (P38) |
| Theoretical weight | 38.733 kg/m |
| Material | 50Mn / U71Mn |
| Length | 12 m / 12.5 m |
| Rail height | 134 mm |
| Bottom width | 114 mm |
| Head width | 68 mm |
| Web thickness | 13 mm |
The rail is commonly rolled in 50Mn or U71Mn steel. These grades give the head sufficient hardness and the web sufficient toughness for industrial service, and their chemical composition is controlled to meet the standard requirements for carbon, manganese and residual elements. For special projects, the rail can be supplied with anti-corrosion coating or with head hardening if the application requires extra wear resistance.
Typical applications
The P38 rail is a workhorse of industrial track. It is used on larger mine roadways, inside factory workshops, for crane hoisting equipment runways, and for the laying of special railway lines where loads are heavier than light rail can carry but the full heavy-rail sections of a main line are unnecessary. Typical projects include underground mining haulage roads, surface stockyard tracks, foundry and steel plant lines, and temporary industrial railways. Because it can be supplied with matching fishplates, fish bolts, rail clips and other fasteners, the P38 rail is normally installed as part of a complete track system rather than as a bare rail.
Rail processing services
Rail for industrial projects is rarely used exactly as rolled. Common processing includes 45-degree mitre cutting for rail ends, drilling of fishplate bolt holes, end hardening or grinding, welding preparation for long welded strings, and profile machining for special applications. Engineering support can extend to laying out the rail line geometry, designing the track layout for mining or crane movement lines, and specifying the fastening system for the sleeper type in use.
Frequently Asked Questions
What does P38 mean in the rail designation?
P38 refers to a rail with a nominal weight of 38 kg per metre. The actual theoretical weight of the standard profile is 38.733 kg/m.
What are the exact dimensions of the P38 rail?
The standard P38 profile has a rail height of 134 mm, a bottom width of 114 mm, a head width of 68 mm and a web thickness of 13 mm.
What lengths are available for 38kg rail?
The rail is normally supplied in 12 m or 12.5 m lengths. Other lengths can be produced or cut to order depending on the rolling schedule and the project requirement.
Which steel grades are used for P38 rail?
Common grades are 50Mn and U71Mn. The choice depends on the line duty; U71Mn offers higher strength and is preferred where axle loads or traffic frequency are higher.
Can P38 rail be used for crane runways?
Yes. The 38kg section is used on crane hoisting equipment and light crane runways in workshops and industrial plants, where its load capacity matches the crane wheel loads of medium lifting equipment.
What fasteners match the P38 rail?
Matching components include fishplates and fish bolts for joints, rail clips or spikes for fixing to sleepers, rail pads under the rail foot, and rail anchors where longitudinal movement must be controlled. They should be selected to match the 134 mm rail height and 114 mm base width.
