What are the requirements for NDT? What are the characteristics?

Date：2021-08-16 16:29:00 Views：1966

In many industries around the world, nondestructive testing is required by law. Nondestructive testing is a testing technology for defects, chemical and physical parameters of materials, parts and equipment by using principles and technical instruments such as ray, ultrasonic, infrared, electromagnetic and terahertz nondestructive testing without affecting the future use function or current operation state of the tested object. Common methods include ultrasonic testing of cracks in welds.

NDT features

The biggest feature of nondestructive testing is that it can be tested without damaging the material and structure of the test piece. Therefore, after the implementation of nondestructive testing, the inspection rate of products can reach 100%.However, not all items and indicators that need to be tested can be subject to nondestructive testing, and nondestructive testing technology also has its own limitations. Some tests can only use destructive tests. Therefore, nondestructive testing can not replace destructive testing at present. In other words, for the evaluation of a workpiece, material, machinery and equipment, the results of nondestructive testing and destructive test must be compared and matched with each other in order to make an accurate evaluation.

NDT requirements

The law sets minimum standards for certain non-destructive tests. Different countries or institutions follow different standards, so companies operating in multiple countries may have to meet different testing or reporting requirements for the same application. Companies subject to overlapping restrictions must comply with the strictest of these regulations. Airlines, oil and gas companies and manufacturers are most vulnerable to complex and overlapping regulatory requirements. NDT plans shall be developed in consultation with appropriate experts or professional legal counsel to ensure full compliance.

Most government standards for NDT are based on the recommendations of independent international organizations, including ISO and ASTM. The standards of these organizations are based in part on the research of manufacturers and several national and international trade associations. These industry associations include the international nondestructive testing Commission, the American Nondestructive Testing Association and the Nondestructive Testing Management Association.

Non destructive testing regulations can specify the parts to be tested, the method to be used, the test cycle, the minimum acceptable value and the record retention standard. NDT manufacturers use these standards as a reference when developing inspection equipment and solutions. With the development of standards and equipment, more and more effective solutions came into being to meet increasingly stringent requirements. Manufacturers should be able to demonstrate how their products meet the regulatory requirements for any application on the market.

NDT scope:

1. Weld surface defect inspection: check the welding quality such as weld surface crack, incomplete penetration and weld leakage.

2. Inspection of inner cavity: check surface cracks, peeling, pull wires, scratches, pits, bulges, spots, corrosion and other defects.

3. Status inspection: when some products (such as worm gear pump, engine, etc.) work, endoscopic inspection shall be carried out according to the items specified in the technical requirements.

4. Assembly inspection: when required and required, use Yatai Optoelectronic Industrial video endoscope to check the assembly quality; After assembly or a process is completed, check whether the assembly position of all parts and components meets the requirements of drawings or technical conditions; Whether there are assembly defects.

5. Surplus inspection: check the residual internal debris, foreign objects and other surplus in the inner cavity of the product.

In China, nondestructive testing technology has been integrated into the overall national economic development goal, and is serving to solve the safety of large-scale engineering projects and major projects related to safety and people's livelihood. With the research and development of some major nondestructive testing instruments included in the national development special plan, China's nondestructive testing technology has developed on a much higher platform than ever before.