P24 & P38 Crane Rails: Naming Rules, National Standards & Selection for Overhead & Gantry Cranes

1. Why 24kg/m, 38kg/m Rails Are Also Named P24, P38 for Crane Projects

For small and medium tonnage overhead bridge cranes and gantry cranes, 24 kg/m and 38 kg/m steel rails are the most widely adopted types, commonly shortened as P24 rail and P38 rail in the machinery industry. Two naming formats refer to the identical rail product without essential differences, following independent definition logics:
  1. 24kg/m, 38kg/m: International standard weight marking

    The kg/m label is a globally recognized physical dimension identification adopted in national standards. It directly indicates the theoretical weight of steel rail per meter length, the official specification naming method in GB standards.

  2. P24, P38: Industry conventional model code

    The “P+number” naming system originates from railway track classification and is widely recorded in professional crane design textbooks such as Crane Design Handbook edited by Wang Jinnuo and Zhang Zhiwen. The letter “P” stands for railway light rail series, while the digit matches the per-meter weight of the rail.

The unified P-series rail mapping list covers full rail grades:

P18=18kg/m, P24=24kg/m, P30=30kg/m, P38=38kg/m, P43=43kg/m, P50=50kg/m, P60=60kg/m.

Table 1 (Source: Page 913, Crane Design Handbook) provides rail selection reference matching rail type with crane wheel diameter, which engineers use to pick P light rails, QU special crane rails or solid steel bars for different load capacities.

2. Light Rail vs Heavy Rail Classification: GB/T 11264-2025 & GB/T 2585-2021

China national standards divide hot rolled rails into light rail and heavy rail with a clear boundary: rails ≥38 kg/m are heavy rails, while rails below 38 kg/m belong to light rails. Two independent mandatory standards apply to corresponding rail grades:

2.1 Heavy Rail Standard: GB/T 2585-2021 Hot Rolled Rails for Railway

  • Effective Date: Oct 1, 2021
  • Covered rail models: 38kg/m, 43kg/m, 50kg/m, 60kg/m, 75kg/m (P38 ~ P75)
  • Industrial Application: Apart from railway transportation, P43, P50 and P60 heavy rails are extensively applied as travel tracks for large tonnage gantry crane trolley and main carriage.

2.2 Light Rail Standard: GB/T 11264-2025 Hot Rolled Light Rail

  • Released Date: Aug 29, 2025 | Implementation Date: Mar 1, 2026
  • Covered rail models: 9kg/m, 12kg/m, 15kg/m, 18kg/m, 22kg/m, 24kg/m, 30kg/m (P9 ~ P30)
  • Application Scope: Mining track, forestry track, small-medium overhead & gantry crane running tracks, including matched hot rolled light rail tie plates and joint fishplates.

3. Key Revisions of New Standard GB/T 11264-2025 vs GB/T 11264-2012

The latest GB/T 11264-2025 integrated three outdated separate standards to unify technical requirements for light rails and supporting accessories:
  1. Standard consolidation and replacement
    • Merged GB/T 11264-2012 Hot Rolled Light Rail, GB/T 11265-1989 Fishplates for Light Rail Joints, GB/T 11266-1989 Tie Plates for Light Rail
    • Fully replaced the obsolete GB/T 11264-1989 edition
  2. Mandatory technical items in purchase contracts

    Any light rail order contract must contain complete information as below:

    a) National standard document number

    b) Product name (light rail, tie plate, joint fishplate)

    c) Steel grade

    d) Rail model

    e) Delivery length

    f) Total weight

    g) Other customized technical requirements

  3. Standard steel grades for light rail production

    Qualified light rail steel marks: 50Q, 55Q, 45SiMnP, 50SiMnP

  4. Standard delivery length range

    Standard factory lengths range from 5m to 12m, fixed standard sizes: 5.0m, 5.5m, 6.0m, 6.5m, 7.0m, 7.5m, 8.0m, 8.5m, 9.0m, 9.5m, 10.0m, 10.5m, 11.0m, 11.5m, 12.0m. Non-standard custom lengths are available with mutual agreement recorded in purchase contracts.

4. Cross-Section Dimension Differences Between P Light Rail (P15-P30) & P Heavy Rail (P38-P60)

From official form drawings of P-series rails, obvious structural distinctions exist between light rail and heavy rail series:
  1. Light Rail P15 ~ P30 (Compliant with GB/T 11264-2025)

    Three core dimensions change simultaneously with each model: rail head tread width, overall rail height and base width. Each light rail grade carries a unique cross-section design for low-load small crane operation.

  2. Heavy Rail P38 ~ P60 (Compliant with GB/T 2585-2021)

    All heavy rail types feature an identical rail head tread width of around 70mm. Load capacity classification only relies on adjusted rail height and rail base width. The unified 70mm tread surface guarantees stable contact and low wear for heavy-duty frequent crane travel.

5. Practical Rail Selection Guide for Bridge & Gantry Cranes

  1. Small & medium tonnage overhead/gantry cranes: P24 (24kg/m) and P38 (38kg/m) are the mainstream track options
  2. Large tonnage gantry crane main/trolley tracks: Select P43, P50 or P60 heavy rails
  3. Standard compliance rule: Light rails under 30kg/m follow GB/T 11264-2025; rails ≥38kg/m adopt GB/T 2585-2021
  4. Design reference: Match P rail specification with crane wheel diameter per the rail selection table from Crane Design Handbook to balance bearing capacity, wheel abrasion and overall project cost.
    。。。。。。。。。。。。。。。。。。。。。。。。P24 P38 Crane Rails