How to evaluate the trustworthiness of flange fittings suppliers

Raw material quality
Chemical composition analysis: Through professional testing equipment, the raw materials of flange fittings are subjected to chemical composition testing to ensure that the content of their main and trace elements meets the corresponding standards and design requirements. For example, for stainless steel flange fittings, the content of elements such as chromium, nickel, molybdenum, 等. needs to be tested to ensure that they have good corrosion resistance and mechanical properties. Marine pipe fittings, flange pipe fittings manufacturers, forged parts
Material certification documents: Check whether the manufacturer can provide quality certification documents for raw materials, such as material test reports, quality assurance certificates, 等. These documents are important basis for the quality of raw materials and can trace the source and quality status of raw materials.

Production process and equipment
Rationality of production process: Understand whether the manufacturer’s production process is advanced and reasonable, and whether it complies with relevant national standards and industry norms. For example, a reasonable forging ratio and forging temperature should be used for forging flanges to ensure a dense internal structure and improve their strength and toughness; The welding process for welding flanges should ensure the quality of the weld seam and avoid defects such as porosity and cracks.
Accuracy and stability of production equipment: Advanced production equipment is an important foundation for ensuring product quality. Check whether the manufacturer’s processing equipment, testing equipment, 等. have high precision and stable performance. For example, high-precision CNC lathes, milling machines and other processing equipment can ensure the dimensional accuracy and surface quality of flanges; Advanced non-destructive testing equipment such as ultrasonic flaw detectors and magnetic particle flaw detectors can promptly detect internal defects in products
dimensional accuracy
Measurement tools and methods: Use precise measuring tools such as calipers, micrometers, coordinate measuring instruments, 等. to measure the outer diameter, inner diameter, thickness, bolt hole diameter, and spacing of flange fittings, and check whether they meet the design drawings and standard requirements. Measurement should be carried out according to the prescribed measurement method and location to ensure the accuracy of the measurement results
Dimensional tolerance control: Evaluate the manufacturer’s ability to control dimensional tolerances. Good manufacturers can control dimensional tolerances within a small range. Generally speaking, the critical dimensional tolerance of flange fittings should be controlled within ± 0.5mm, or even higher precision, to ensure good matching and connection sealing between flanges and other fittings.
surface quality
Appearance inspection: Directly observe the surface of the flange fittings to check for defects such as cracks, pores, inclusions, sand holes, burrs, scratches, 等. The surface should be smooth and flat, without obvious unevenness or deformation. For flange fittings with anti-corrosion coating or galvanizing treatment, the quality of the coating or galvanizing layer should also be checked for uniformity, firmness, and no peeling or detachment
Roughness detection: The roughness of the flange surface is detected using equipment such as a roughness meter, and the roughness value should meet the corresponding standards and usage requirements. Generally speaking, the roughness requirement of the flange sealing surface is relatively high, reaching around Ra0.8-Ra1.6 μ m to ensure good sealing performancemechanical property
Tensile test: The mechanical performance indicators such as tensile strength, yield strength, and elongation of flange fittings are tested through tensile tests to evaluate their strength and plastic deformation ability under tension, ensuring that they can meet the mechanical requirements in engineering applications
硬さ試験: Measuring the hardness of flanges to evaluate their wear resistance and load-bearing capacity. Flange fittings of different materials and usage requirements have corresponding hardness ranges. For example, the hardness of stainless steel flanges is generally between HB187-229
Impact test: For some flange fittings used under low temperature or impact load conditions, impact tests are required to verify their impact resistance and ensure that brittle fracture does not occur under harsh working conditions.
Non destructive testing
Ultrasonic testing: Using ultrasonic flaw detectors to detect defects inside flanges, such as cracks, pores, inclusions, 等。, can detect smaller internal defects with high detection accuracy
Magnetic Particle Testing: Suitable for flange fittings made of ferromagnetic materials, it detects surface and near surface defects such as cracks by applying magnetic particles to the surface of the workpiece and observing the distribution of the magnetic particles
Radiographic testing: It can detect defects inside the flange, such as pores, slag inclusions, cracks, 等。, and provide intuitive defect images. It has a better detection effect for thicker flange fittings, but the detection cost is relatively high and there is a certain radiation hazard to the human body. Therefore, attention should be paid to protection
Sealing performance
Hydrostatic test: Connect the flange fittings into a test component, fill it with water at a certain pressure, maintain it for a period of time, and check for any leakage to verify the sealing performance of the flange. The test pressure is generally about 1.5 times the design pressure, but not less than 0.6 MPa
Air pressure test: For some situations where water pressure test is not suitable, air pressure test can be used. Fill a certain pressure of gas and use soap water or other leak detection methods to check for leaks. The pressure of air pressure test is generally the same as the design pressure, but corresponding safety measures need to be taken to prevent explosion and other hazards
Quality Certification and Management System
Quality certification: Check whether the manufacturer has passed relevant quality certifications, such as ISO9001 quality management system certification, ISO14001 environmental management system certification, OHSAS18001 occupational health and safety management system certification, 等. These certifications are important manifestations of the manufacturer’s quality management level, indicating that it has certain guarantee capabilities in product quality, environmental protection, occupational health and safety, 等.
Quality Management System: Understand whether the manufacturer’s quality management system is complete, whether a quality control system has been established throughout the entire process from raw material procurement, production and processing, inspection and testing to product sales, whether there are strict quality inspection standards and processes, as well as mechanisms for tracing and handling quality issues

After sales service and reputation
After sales service: Good after-sales service is an important supplement to product quality. It is necessary to examine whether the manufacturer can provide timely and effective after-sales service, including product installation guidance, debugging, maintenance, replacement, 等。, as well as whether there is a professional after-sales service team and a complete after-sales service network.
User word-of-mouth: learn about the manufacturer’s product word-of-mouth and reputation through the Internet, industry forums, customer evaluation and other channels. User feedback is an important reference for evaluating product quality. If the manufacturer’s product quality is good, it usually has good user word-of-mouth and market reputation.