Inspection of stainless steel metal hoses is a crucial step in ensuring their safe use and mitigating the risks of leakage and damage. It must strictly adhere to industry standards (such as GB/T 14525) and cover the entire process from pre-shipment to pre-installation and in-use. A scientific inspection procedure can accurately identify structural defects, substandard performance, and other issues. The following is a standardized inspection procedure based on industry practice.
I. Preliminary Preparation: Basic Verification and Environment Setup
First, verify the specifications, confirming that the hose's nominal diameter, pressure rating, length, material (e.g., 304/316L), and connector type match the design requirements. Verify the completeness of product certificates, performance test reports, and other documentation. Next, clean the inspection site to ensure it is free of obstructions. Set up a suitable environment according to the inspection items-for water pressure testing, prepare a pressure pump, pressure gauge, and sealing clamps; for air tightness testing, prepare an air compressor and air tightness tester. All instruments must be calibrated. Simultaneously, inspect the hose's appearance, removing surface contaminants to prepare for subsequent testing.
II. Core Inspection Steps: Implement each step according to the procedure
1. Visual Inspection: Inspect the bellows for dents, deformation, cracks, and corrosion spots with the naked eye or a magnifying glass. Check the joints for damage and rust, and ensure the seals (gaskets, O-rings) are intact and free from aging. Pay special attention to the bellows welds to ensure there are no defects such as incomplete welds or missing welds.
2. Dimensional Inspection: Use calipers, measuring tapes, etc., to measure the total length of the hose, nominal diameter, joint dimensions, and bellows wall thickness. Deviations must be controlled within the allowable range of industry standards.
3. Pressure Testing: Divided into water pressure and air pressure tests. Water pressure testing is suitable for liquid transportation scenarios. Pressurize to 1.5 times the rated working pressure. Holding the pressure for a specified time without leakage or abnormal deformation is considered合格 (qualified). Air pressure testing is suitable for gas transportation scenarios. The pressure is usually 1.2 times the rated working pressure. Use the soap solution application method to check for air bubbles and leaks at the joints and bellows.
4. Flexibility Test: Under no pressure, conduct repeated bending tests according to the minimum bending radius specified in the product manual. After completion, check for structural damage and perform a pressure test again to confirm no leakage.
5. Corrosion Resistance Test (Special Conditions): For hoses used in highly corrosive environments such as chemical plants, a salt spray test or chemical medium immersion test is required to test the surface corrosion resistance.
III. Post-Testing Process: Record Keeping and Disposal of Non-conforming Products
After testing, promptly drain any water or gas from the hose, clean any residual media from the surface, and properly label and archive testing records for qualified products (including testing time, items, results, and testing personnel). If non-conforming products are found (e.g., leaks, dimensional errors, structural damage), they must be stored separately with the reason for non-conformity clearly marked, and must not be allowed to enter the installation process; contact the manufacturer for repair or disposal. For hoses after installation and during use, regular visual inspections and pressure checks are required, and aged or damaged parts must be replaced promptly.
In summary, the testing of stainless steel metal hoses must follow a standardized process of "preliminary verification-core testing-post-testing," with a focus on controlling the pressure testing and visual inspection stages. Strictly implementing testing procedures ensures that hoses are suitable for actual working conditions and effectively extends their service life, which is a core principle in the industry for ensuring the safe operation of pipeline systems.