FLARES FOR TUBING
1Key Takeaways
This SAE standard specifies specifications and performance requirements for 37 and 45 degree single and double flares for use with SAE J512, SAE J513, SAE J514, and ISO 8434-2 connectors. The flares described in this document are suitable for use with SAE metal tubing materials. Selection of wall thickness for specific…
2Expert Interpretation
This in-depth analysis of the SAE J533-2020 pipe end flaring technical standard covers the specification requirements for 37-degree and 45-degree single and double flares, wall thickness optimization and adjustment, global standardization strategies, and compatibility analysis with ISO 8434-2, providing professional technical guidance for hydraulic system pipe connections.
SAE J533-2020 Standard Revision Background and Technical Evolution
SAE J533™, a key technical standard for pipe end flaring in the fluid power industry, has undergone numerous revisions since its initial publication in 1947. The latest version, released in May 2020, incorporates significant technical adjustments tailored to global manufacturing needs, particularly addressing long-standing thread engagement issues in stainless steel pipe applications.
Standard Scope and Global Standardization Strategy
This standard specifies the technical requirements for 37-degree and 45-degree single and double flares, applicable to pipe end preparation for use with fittings specified in SAE J512, SAE J513, SAE J514, and ISO 8434-2. The standard explicitly promotes global standardization of metric pipe and fitting sizes, aiming to: establish a global unified system, guide users to adopt the preferred system, reduce complexity, and eliminate inventory duplication.
Detailed explanation of the revision of key technical parameters
| Pipe Outer Diameter | Original Wall Thickness (mm) | Reason for Revision | Application Impact | |
|---|---|---|---|---|
| 10mm OD | 1.25 | 1.00 | Solve the forming difficulties | Improve the processability of stainless steel pipe |
| 9.52mm OD | 1.24 | 0.89 | Prevent thread stripping | Enhance assembly reliability |
Comparison of Flare Types and Technical Specifications
The standard specifies in detail the dimensional requirements of 45-degree flare (applicable to imperial pipes) and 37-degree flare (applicable to metric pipes), including single flare and double flare:
Key parameters of 45-degree flare
| Nominal pipe diameter (mm) | SAE specification number | Single flare diameter range (mm) | Maximum wall thickness (mm) | Total runout tolerance (mm) |
|---|---|---|---|---|
| 6.35 | -4 | 8.0-8.3 | 1.24 | |
| 12.7 | -8 | 15.4-15.8 | 2.11 | 0.35 |
37 degree flare key parameters
| Nominal pipe diameter (mm) | Flare diameter range (mm) | Maximum wall thickness of single flare (mm) | Maximum wall thickness of double flare (mm) | Recommended chamfer size |
|---|---|---|---|---|
| 10 | 11.7-12.7 | 1.5 | 1.0 | L≥0.2mm |
| 16 | 19.3-20.2 | 2.5 | 1.5 | L≥0.35mm |
Quality Control and Testing Requirements
The standard stipulates strict testing specifications. Total runout must be measured using a dedicated gauge. The sealing surface roughness requirement is ≤2.5μm. The testing method uses a V-block to simulate the datum and a dial indicator with angle positioning for rotational measurement to ensure that the entire sealing surface is within the tolerance zone.
Compatibility Analysis with ISO Standards
SAE J533-2020 is fully compatible with ISO 8434-2, reflecting the trend of global technical standard convergence. Performance testing requires hydraulic connector testing in accordance with ISO 19879, with operating pressures referenced to SAE J1065 and ISO 10763 standards.
Implementation Recommendations and Best Practices
1. Material Selection: For stainless steel pipe applications, it is recommended to adopt the revised wall thickness parameters to ensure processing quality.
2. Chamfering: For thick-walled pipes, it is recommended to adopt the chamfer dimensions specified in Table 4 to enhance sealing.
3. Deburring Requirements: Deburring must be performed before flaring to eliminate the risk of leakage caused by cutting burrs.
4. Thread Engagement: When the wall thickness exceeds the standard, an extended tube nut must be used to ensure sufficient thread engagement.
5. Automotive Braking System: The SAE J2879 standard is recommended for hydraulic brake pipes.
Technology Development Trends and Future Outlook
With the acceleration of global manufacturing integration, the integration of SAE and ISO standards will become mainstream. This revision of the wall thickness parameters reflects the technical pain points in actual applications. Future standard development will pay more attention to the balance between manufacturability and reliability, and promote the development of hydraulic connection technology towards higher performance and easier processing.