A connection name alone does not prove that a fitting is suitable for a stainless-steel fogging line. Approval should be based on the exact tube, fitting, seal, assembly method, and intended operating conditions tested as one assembly.
Push-in, compression, and YUCHENG Top-Pressure connections use different retention and sealing structures. They should be compared as separate connection families, not treated as interchangeable terms.
Identify the connection structure correctly
| Connection family | How it is identified | What must be confirmed |
|---|---|---|
| Push-in | The tube is retained and sealed after insertion by internal gripping and sealing parts. | Approved tube material, insertion depth, release method, seal material, and retention. |
| Compression or ferrule | A nut and ferrule or compression element mechanically tighten around the tube. | Ferrule orientation, tightening procedure, tube tolerance, and whether reassembly is permitted. |
| Top-Pressure | A YUCHENG product-series label for a screw-pressure locking structure, not a universal fitting standard. | Exact model, drawing, mating tube, seal arrangement, and installation instruction. |
None of these names is a universal guarantee of performance. Suitability depends on the complete, correctly assembled combination.
Freeze the sample specification before testing
- Tube material, outside diameter, wall thickness, dimensional tolerance, roundness, hardness, and surface condition
- Fitting model, material, drawing, thread or outlet form, gripping parts, and seal material
- Tube cutting, deburring, insertion, tightening, and inspection method
- Design pressure, test pressure, operating cycle, temperature, humidity, vibration, and chemical exposure where relevant
- The supplier and production lot represented by each sample
If any of these inputs changes after testing, the earlier result may no longer represent the production assembly.
Run a representative qualification sequence
- Inspect and measure the tube and fitting samples against the approved description.
- Assemble samples using the proposed production tools and written installation method.
- Check insertion or tightening, alignment, visible seal damage, and installation consistency.
- Perform a pressure-hold and leak check under agreed test conditions.
- Perform a retention or pull test using an agreed method and acceptance criterion.
- Add pressure cycling, vibration, temperature, or humid-environment checks when the application requires them.
- Inspect the assemblies after testing and record the result against the exact sample identity.
Use project-specific acceptance criteria
A sample test should state the pressure, duration, medium, fixture, number of assemblies, and pass or fail criteria. A statement such as tested successfully is not enough for purchasing control.
The test program should be proportionate to the consequence of failure and the installation environment. The project engineer or buyer should approve the final criteria; this guide does not replace the applicable design code or safety review.
Control production and installation after approval
Keep the approved tube and fitting family together in the BOM. Record the fitting model, tube dimensions, seal specification, installation instruction, and approved sample or test report so that purchasing and installation teams use the same interface.
Requalification should be considered if the tube supplier, fitting structure, seal material, dimensions, surface finish, installation method, or operating condition changes. First-article checks and installer training help prevent a qualified design from being assembled incorrectly on site.
Information to send for a supplier review
- Tube drawing or measured outside diameter, wall thickness, material, and tolerance
- Connection points, fitting photographs or drawings, and required outlet configuration
- Operating pressure, zoning logic, installation environment, and maintenance expectations
- Required quantity, sample quantity, and the acceptance tests expected before bulk production
This information allows the proposed connection to be reviewed and sampled without assuming that similarly named or similarly sized parts are interchangeable.