Ruber hoses and hose assemblies - Rubber-covered spiral wire reinforced hydraulic type - Specification; German version EN 856:2015
1Key Takeaways
This European Standard specifies the requirements for four types of hoses and hose assemblies with a steel wire spiral reinforcement layer, with an inner diameter of 6 to 51 mm (4SP and 4SH types are suitable for temperatures from -40°C to +100°C, and R12 and R13 types are suitable for temperatures from -40°C to +120°C…
2Expert Interpretation
This article provides an in-depth interpretation of the EN 856:2015 standard for wire-spiral hydraulic rubber hoses, covering key requirements such as technical specifications, pressure ratings, dimensional tolerances, and impulse testing for four hose types. It also provides guidance and implementation recommendations for selecting high-pressure hoses that comply with ISO 6743-4 for hydraulic fluids.
EN 856:2015 Standard Overview and Technical Evolution
EN 856:2015, "Rubber hoses and hose assemblies — Wire-spiked reinforced hydraulic types — Specification," is a key technical standard published by the European Committee for Standardization (CEN). It replaces the 1997 edition of DIN EN 856. This standard specifies the technical requirements for four types of wire-spiked hydraulic rubber hoses, applicable to hoses with nominal inside diameters of 6 to 51 mm.
Major Technical Changes and Updates
Compared to EN 856:1996, the 2015 edition incorporates several significant technical updates: comprehensive updates to the referenced documents, adjustments to inside diameter tolerance limits, and the addition of three new annexes (Appendixes A, B, and C). These changes reflect the latest developments in hydraulic technology and increased safety requirements.
| Technical parameters | EN 856:1996 | EN 856:2015 | Impact of changes |
|---|---|---|---|
| Inner diameter tolerance | Original range | Adjustment and optimization | Improve fit accuracy |
| Test method | Basic requirements | New Appendix AC | Improve quality system |
| Material requirements | General specifications | Specific indicators | Enhance reliability |
Hose Types and Structural Characteristics
The standard defines four hose types, each with unique structural design and performance characteristics:
1. 4SP Hose
4-layer spiral steel wire reinforcement, medium pressure range, operating temperature -40°C to +100°C, suitable for standard hydraulic applications.
2. 4SH Hose
4-layer spiral steel wire reinforcement, ultra-high pressure design, significantly improved pressure bearing capacity, suitable for heavy hydraulic equipment.
3. R12 Hose
4-layer spiral steel wire reinforcement, high-performance high-temperature hose, extended operating temperature -40°C to +120°C, medium pressure range.
4. R13 Hose
Multi-layer spiral steel wire reinforcement, high-performance high-temperature design, high pressure range application, suitable for extreme working conditions.
Material Composition and Construction Requirements
The hose must consist of an oil- and water-resistant synthetic rubber inner liner, a cross-threaded steel wire spiral reinforcement layer, and an oil- and weather-resistant rubber outer layer. Each steel wire reinforcement layer must be isolated from the adjacent layers by a synthetic rubber insulation layer to ensure interlayer adhesion.
According to the test requirements of EN ISO 8033:2006, the interlayer adhesion strength of hose types 4SP and 4SH must not be less than 2.5 kN/m, while that of hose types R12 and R13 must not be less than 1.4 kN/m.
Dimension and Tolerance Requirements
The standard specifies strict tolerances for hose dimensions to ensure compatibility with connectors and system sealing.
Inner Diameter Tolerance
The hose inner diameter, measured according to EN ISO 4671, must conform to the values specified in Table 1. Taking a nominal inner diameter of 16mm as an example, the allowable inner diameter range is 15.8-16.7mm.
Outer Diameter and Reinforcement Layer Diameter
The measurement of the reinforcement layer diameter and outer diameter must comply with the requirements of Table 2 to ensure the uniformity of the reinforcement layer layout and the consistency of the outer protective layer thickness.
Concentricity Requirements
The concentricity deviation of the hose is strictly controlled: ≤0.8mm for nominal inner diameter ≤6mm, ≤1.0mm for 6-19mm, and ≤1.3mm for >19mm.
Pressure Performance Index
Hose pressure performance is the core indicator, including three levels: working pressure, test pressure, and burst pressure.
| Nominal Inside Diameter (mm) | Maximum Working Pressure (bar) | Test Pressure (bar) | Burst Pressure (bar) |
|---|---|---|---|
| 6 | 450 | 900 | 1800 |
| 10 | 445 | 890 | 1780 |
| 51 | 165 | 330 | 660 |
Pressure testing is performed in accordance with EN ISO 1402. The length change at maximum working pressure for hoses 4SP and 4SH shall not exceed +2% to +4%. For hoses R12 and R13, the length change shall not exceed ±2%.
Impulse Test Requirements
Impulse testing is a key component in evaluating hose fatigue life and is performed in accordance with EN ISO 6803:
Hose types 4SP and 4SH are tested at a temperature of 100°C, an impulse pressure of 133% of the maximum working pressure, and a minimum requirement of 400,000 impulse cycles.
Hose types R12 are tested at a temperature of 120°C, an impulse pressure of 133% of the maximum working pressure, and a minimum requirement of 500,000 impulse cycles.
R13 hoses are tested at a temperature of 120°C and a pulse pressure of 120% of the maximum working pressure, with a minimum requirement of 500,000 pulse cycles.
Environmental Adaptability Test
The standard specifies several environmental adaptability tests to ensure the hose's reliability in various working conditions:
Low-Temperature Flexibility Test
Tested according to EN ISO 10619-2 Method B at -40°C, no cracks should appear on the inner or outer layers. After returning to room temperature, the hose must pass a test pressure test.
Fluid Compatibility Test
Inner and outer layer materials must be tested for compatibility with oil, glycol-water solution, and water. Volume expansion rates are strictly limited:
- 4SP/4SH inner layer expansion ≤60% in oil at 100°C
- R12/R13 inner layer expansion ≤100% in oil at 120°C
- Expansion in aqueous solution ≤25% (inner layer)
Marking and Traceability Requirements
Hoses must be marked continuously at 500mm intervals with the following information: manufacturer's name or logo, EN 856 standard number, type, nominal inside diameter, quarter and year of production. Example: XXX/EN 856/4SP/16/1Q15.
Hose assemblies are recommended to be marked on the fittings with the following information: manufacturer's logo, maximum working pressure (bar), and year and month of production. Example: XXX/350/1501.
Appendix Detailed Explanation and Test Methods
Appendix A: Abrasion Resistance Test
This is a normative appendix that specifies in detail the test method for the abrasion resistance of the outer layer of the hose. Using special test equipment, perform 2000 cycle tests with a vertical force of (50±0.5)N. The average mass loss shall not exceed 1g.
Appendix B: Type Test and Routine Test
Specifies the items and frequency of type tests (every 5 years or when the product is changed) and routine tests (for each batch of products), including dimensional measurement, pressure testing, pulse testing, etc.
Appendix C: Production Acceptance Test
This is an informative appendix that provides test requirements for every 3000 meters and every year during the production process to ensure continuous compliance with the standard requirements.
Implementation Recommendations and Application Guide
Selection Recommendations
Select the appropriate hose type based on the hydraulic system's operating pressure, temperature range, and media characteristics:
- Standard pressure applications: Select type 4SP for economical efficiency
- High-pressure systems: Select type 4SH for increased pressure resistance
- High-temperature environments: Select type R12 or R13 for excellent temperature resistance
Installation and Usage Precautions
Install in strict accordance with the minimum bend radius requirements to avoid damage to the reinforcement layer due to excessive bending. Note the variable length characteristics of the hose and allow for appropriate margins in the system design.
Maintenance and Replacement Cycles
Establish a regular inspection system, paying attention to signs of outer wear, joint leakage, and other signs. Develop a preventative replacement plan based on operating conditions and equipment manufacturer recommendations.
Declaration of Conformity and Market Surveillance
Manufacturers should establish a comprehensive quality control system in accordance with the requirements of Appendices B and C and keep test records for inspection. End users should choose products that comply with EN 856:2015 and require suppliers to provide a declaration of conformity.
It is worth noting that this standard does not apply to castor oil or ester-based fluids, nor does it apply to underground mining hydraulic hoses (for which there are separate standards). Be sure to confirm fluid compatibility and applicable temperature range before use.