Latest Standards for Hydraulic Hose Crimping

Latest Standards for Hydraulic Hose Crimping Current standards for hydraulic hose crimping are categorized into prevailing domestic National Standards (latest versions published or implemented in 2024–2025) and major international standards. These standards center on four key dimensions: crimping processes, dimensional accuracy, quality acceptance, and safety regulations. They explicitly define both mandatory requirements and recommended practices for crimping operations. The following is a summary of the latest and most widely used standards, designed to be both practical and authoritative, and applicable to a diverse range of hydraulic hose crimping scenarios.

Domestic standards focus primarily on versions published or implemented between 2024 and 2025, under the centralized administration of the National Technical Committee for Standardization of Hydraulics and Pneumatics. Among these, GB/Z 44071-2024, GB/T 44072.1-2024, and GB/T 9065.2-2025 serve as the core foundational documents for crimping operations; they supersede previous versions and are tailored to meet the hydraulic hose crimping requirements of various industrial sectors and engineering machinery applications.

This standard adopts the international standard ISO/TS 17165-2:2018 as its equivalent and serves as the core guiding document for hydraulic hose crimping operations. It explicitly outlines the procedural requirements for the entire crimping process, with key highlights as follows:

1. Pre-Crimping Preparation: The standard clearly defines the requirements for selecting and matching hoses with fittings. It mandates the selection of hoses that comply with standards such as GB/T 15908 and GB/T 3683, as well as fittings that comply with the GB/T 9065 series standards. The mixing of components with different specifications or materials is strictly prohibited. Prior to crimping, the surface of the hose must be cleaned to remove any oxide layers, oil residues, or impurities; additionally, the inner bore of the fitting must be free of burrs and damage to ensure a tight, secure fit.
2. Crimping Process Specifications: It is stipulated that the crimping tool must be a specialized hydraulic crimping machine selected to match the specific specifications of the hose and fitting. Prior to crimping, the tool's pressure must be calibrated to ensure precise crimping force. During the crimping process, the insertion depth of the hose into the fitting must be carefully controlled; once inserted, the hose end must sit firmly against the fitting's internal shoulder, exhibiting no looseness or misalignment. It is recommended that the crimping operation be performed in two stages (the first stage crimping to half-stroke, followed by a full-stroke crimp once the position is verified as correct) to prevent uneven localized stress caused by a single-stage crimp.
3. Crimping Quality Control: Following crimping, the interface between the fitting and the hose must be free of gaps and burrs. The crimp marks should appear uniform and well-formed, with no localized depressions, protrusions, or indications of incomplete crimping. The axial tensile strength must meet the requirements specified for the corresponding hose type, thereby ensuring a secure connection between the fitting and the hose and eliminating any risk of detachment. Finally, the crimped surface must be cleaned after the process to prevent residual contaminants from compromising sealing performance.
4. Scope of Application: This applies to hose assemblies comprising hoses that comply with international standards—such as ISO 1436 and ISO 3862—and hose fittings that comply with the ISO 12151 series of standards. The scope covers various hydraulic systems across sectors including general industry, construction machinery, and mining.

This standard adopts, with modifications, the international standard ISO 17165-1:2007. It focuses on specifying dimensional requirements related to crimping—serving as the core basis for crimping precision—and supplements the detailed requirements outlined in GB/Z 44071-2024. Its core contents are as follows:

1. Crimping Dimensional Tolerances: It clearly defines the crimping dimensional requirements for hoses with different nominal inside diameters. For instance, for a hose with a nominal inside diameter of 6.3 mm, the outer diameter tolerance of the fitting after crimping must be controlled within ±0.1 mm. Furthermore, the length tolerance of the hose assembly must comply with standard specifications to prevent crimping position misalignment caused by length deviations.
2. Fitting-to-Hose Matching Dimensions: It stipulates that the hose skiving length must be precisely controlled, with a tolerance not exceeding ±2 mm. After skiving, the hose's reinforcement layer (steel wire braid) must remain intact—free from damage or looseness. Additionally, the inner bore dimensions of the fitting must precisely match the outer diameter of the hose, with a clearance not exceeding 0.2 mm, to ensure effective gripping of the hose during the crimping process.
3. Post-Crimping Appearance and Dimensions: The crimped surface must be smooth and flat, free from obvious scratches or deformation; the fitting port must be free of burrs and excessive chamfering. The diameter of the crimped section must be uniform, with a diameter deviation within any single cross-section not exceeding 0.15 mm, to prevent sealing failure caused by dimensional irregularities.

This standard sets forth specific requirements for the crimping of hose fittings featuring a 24° cone seal, applicable to hoses with a nominal inner diameter ranging from 5 mm to 38 mm. The core crimping requirements are as follows:

1. Cone Surface Crimping Requirements: During crimping, it must be ensured that the cone surface of the fitting fits tightly against the sealing surface of the hose. The crimping force must be applied uniformly across the cone surface to prevent localized stress that could deform the cone and compromise sealing performance. After crimping, the cone surface must be free of scratches and dents, and the contact fit of the sealing surface must exceed 95%.
2. Nut Tightening Torque: Upon completion of crimping, the tightening torque applied to the fitting nut must be controlled within the range of 35 to 45 N·m. The specific value should be adjusted according to the hose specifications; overtightening (which damages the cone surface) or insufficient tightening (which leads to leakage) is strictly prohibited.

International standards are primarily centered around the European EN series and the ISO series. Notably, the EN 853 standard is the 2025 revised edition (the latest version), while the ISO series standards are updated in parallel with domestic Chinese national standards, thereby meeting the crimping requirements for both imported and exported hydraulic equipment. The core contents are as follows:

This standard serves as the predominant standard within the European region. Following its revision in 2025, the requirements regarding crimping quality have been enhanced. The core contents related to crimping are as follows:

1. Crimping Process Requirements: The standard explicitly defines the crimping parameters for different types of hoses. For Type 1SN (single-layer wire braid) hoses, the tolerance for the crimping diameter reduction must be within ±0.1 mm. For Type 2SN (double-layer wire braid) hoses, the specified skiving length (rubber removal length) must be accurate to within ±2 mm, and following crimping, the axial tensile strength between the fitting and the hose must be ≥ 25 kN.
2. Crimp Quality Acceptance: Following crimping, a static pressure test must be conducted. The assembly is pressurized to 1.5 times the working pressure and held for 60 seconds; it is deemed acceptable if no leakage or deformation occurs. The number of cycles for the impulse test has been increased to 200,000 (up from 150,000 in the previous edition) to simulate actual operating conditions and ensure the long-term stability of the crimped joint.
3. Special Requirements: A new test for resistance to biodiesel corrosion has been introduced. The crimped joint must be capable of withstanding prolonged exposure to biodiesel media without seal failure or joint detachment. Furthermore, after crimping, the hose's bending radius must meet a minimum requirement of 8 to 10 times its outer diameter to prevent stress-induced fracture at the crimped joint caused by bending.

This standard is a globally recognized international standard; the domestic standard GB/Z 44071-2024 adopts it as an equivalent standard. The core crimping requirements align with domestic national standards, with particular emphasis placed on the following points: Crimping operators must undergo professional training and be proficient in the proper use of crimping tools. Comprehensive records of the crimping process—including crimping parameters, hose specifications, and fitting models—must be maintained to facilitate future traceability.

Regardless of whether domestic national standards or international standards are applied, hydraulic hose crimping operations must adhere to the following general specifications to ensure crimp quality and safety—points that are strongly emphasized in the latest standards:

1. Component Compatibility Requirements: The hose, fitting, and ferrule (sleeve) must be of the same specification and material; intermixing of components is strictly prohibited (e.g., pairing a stainless steel hose with a carbon steel ferrule, or a φ16 hose with a φ14 fitting). The ferrule model selected must be compatible with the reinforcement layer of the hose to prevent crimping failure caused by component mismatch.
2. Crimping Tool Requirements: Crimping pliers must be calibrated periodically (at least once annually) to ensure precise pressure application. The crimping jaws must be flat and free of wear to prevent uneven crimp marks caused by tool defects. The use of standard manual wrenches as substitutes for specialized crimping pliers is strictly prohibited to prevent insufficient crimping force.
3. Crimping Environment Requirements: The work environment must be clean, dry, and free of dust and oil contamination to prevent impurities from entering the crimping interface. In low-temperature environments (below -10°C), the hose and fittings must be preheated to room temperature prior to crimping to prevent hose embrittlement or damage to the sealing surfaces.
4. Quality Acceptance Requirements: Following crimping, a visual inspection must be performed (checking for burrs, deformation, or gaps), along with a tensile test (verifying that axial tensile strength meets specifications) and a pressure test (checking for leaks). For high-pressure hydraulic systems (operating pressure ≥ 31.5 MPa), non-destructive testing must be conducted after crimping to ensure the absence of internal defects.
5. Prohibitions: Crimping operations performed while the system remains under pressure are strictly prohibited. Forcibly twisting or stretching the hose after crimping is strictly prohibited. The use of damaged or aged hoses or fittings for crimping is strictly prohibited. The application of standard sealants to the crimping interface is strictly prohibited (only specialized high-pressure sealants may be used).

1. Standard Currency: Domestically, GB/Z 44071-2024 and GB/T 9065.2-2025 represent the currently implemented standards. GB/T 44072.1-2024 officially takes effect on January 1, 2025, superseding previous versions; in practical operations, priority must be given to adhering to the latest versions of these standards.
2. Contextual Applicability: For domestic industrial hydraulic systems, adherence to national standards (GB series) takes precedence. For export equipment or imported components, reference may be made to standards such as EN 853:2025 and ISO 17165-2:2018 to ensure that crimping quality meets the specific requirements of the corresponding regions or equipment.
3. Personnel Requirements: Crimping operators must possess the requisite qualifications and be familiar with the latest standard requirements; unauthorized operation is strictly prohibited. Regular training shall be conducted to ensure mastery of the latest specifications and operational techniques for the crimping process.
4. By following the latest hydraulic crimping standards, manufacturers and maintenance providers can significantly improve system safety, extend hose service life, and ensure compliance with international regulations.