non destructive testing application

NDT(non destructive testing) is used in a variety of settings that covers a wide range of industrial activity.

• Automotive
• Powerplants
• Construction
• Structures
• Bridges
• Maintenance
• Bridges
• Manufacturing
• Machine parts
• Castings and Forgings
• Industrial plants such as Nuclear, Petrochemical, Power, Refineries, Fabrication shops, Mine processing and Risk Based Inspection programmes.
• Pressure vessels
• Storage tanks
• Welds
• Boilers
• Heat exchangers
• Turbine bores
• In-plant Piping
• Pipelines
• Pipeline integrity
• Leak Detection
• Railways
• Rail Inspection
• Wheel Inspection

Ultrasonic Testing

Ultrasonic Testing (UT) uses high frequency sound energy to conduct examinations and make measurements. Ultrasonic inspection can be used for flaw detection/evaluation, dimensional measurements, material characterization, and more.

Advantages

1. High penetrating power, so that detection of flaws deep in the part.
2. High sensitivity, permitting the detection of extremely small flaws.
3. Greater accuracy than other nondestructive methods in determining the depth of internal flaws and the thickness of parts with parallel surfaces.
4. Some capability of estimating the size, orientation, shape and nature of defects.
5. Nonhazardous to operations and has no effect on equipment and materials in the vicinity.
6. Capable of portable or highly automated operation.

Salt Spray Weathering

Salt spray testing under ASTM B117 conditions subjects the test samples to conditions that are actually more corrosive than usual “real world” exposure. This is because the test uses sodium chloride in de-ionized water and usually lacks the moderating effects of other dissolved salts such as those containing calcium and magnesium, which tend to be somewhat protective.

is the most popular form of testing for protective coatings. These tests have been used for more than 90 years as accelerated tests in order to determine the degree of protection afforded by both inorganic and organic coatings on a metallic substrate. The most widely used salt spray (fog) tests are described below.

The neutral salt spray (fog) test (ASTM B 117): is perhaps the most commonly used salt spray test in existence for testing inorganic and organic coatings, in particular where such tests are used for material or product specifications. The duration of the test can range from 8 to over 3000 hours, depending on the product. A 5% sodium chloride solution containing not more than 200 parts per million (ppm) total solids and with a pH range of 6.5 to 7.2 is used. The temperature of the salt spray chamber is controlled to maintain 35 + 1.1 or – 1.7Þ C (95 + 2 or -3Þ F) within the exposure zone of the closed chamber.

The acetic acid salt spray (fog) test (ASTM G 85, Annex A1): is also used for testing inorganic and organic coatings, but is particularly applicable to the study or testing of decorative chromium plating and cadmium plating on steel or zinc die castings, as well as for the evaluation of product quality. This test can be as short as 16 hours, although it normally ranges from 144 to 250 hours or more. Similar to the neutral salt spray test, a 5% sodium chloride solution is used, but the solution is adjusted to a pH range of 3.1 to 3.3 by the addition of acetic acid. The temperature of the salt spray chamber is controlled to the same temperature range as for neutral salt spray.

The copper accelerated acetic acid salt spray (fog), or CASS test (ASTM B 368): is primarily used for the rapid testing of chromium plating on steel and zinc die castings. It is also useful in the testing of anodized, chromated, or phosphated aluminum. The duration of this test ranges from 6 to 720 hours. A 5% sodium chloride solution is used, with one gram of copper (II) chloride dihydrate added to each 3.8 liters of salt solution. The solution is then adjusted to a pH range of 3.1 to 3.3 by adding acetic acid. The temperature of the salt spray chamber is controlled to the same temperature range as for neutral salt spray and for acetic acid salt spray.

Leak Testing

Leak testing equipment is used to measure the escape of liquids, vacuum or gases from sealed components or systems. Some configurations require a separate leak detector or sensor as an input. Such types of leak testing equipment are often equipped with various other components such as pumps, calibrators, gauges and cases. Output options include analog voltage, analog current, frequency or modulated frequency, and switch or alarm signal. Some leak testing equipment includes an analog front panel with potentiometers, dials, and switches. Other features a digital front panel that is set up with a keypad or menus. Leak testing equipment with a serial interface, a parallel interface, and/or integral application software is also available.

Leak test method is an important specification to consider when choosing leak testing equipment. Methods include bubble testing, colorimetric development, electronic gas detection, mass flow, mass spectrometry, and hydrogen leak detection. Bubble testing is used for applications which do not require high sensitivity. A pressurized test object is submerged in a water tank so that the emergence of bubbles indicates a leak. Colorimetric development uses a chemical developer which reacts with the leaking fluid, causing a visible color change to occur at the place of leakage. Leak testing equipment that uses electronic gas detection pressurizes the test object with a tracer gas so that a sniffer probe can be used to find the leak. Mass flow devices direct the leakage across a heating element. The temperature change produces an output voltage proportional to mass flow. Mass spectrometers are used with helium leak detection. Leak testing equipment that is designed to detect hydrogen leaks is also available.

Leak testing equipment may use test methods such as pressure differential (decay) and ultrasonic leak detection. A pressure decay test involves the initial inflation of the test object and the establishment of a reference pressure. After a designated amount of time, the pressure is measured again and the initial and final measurements are compared. The change in pressure can be used to calculate the leak rate given the internal volume of the device. Ultrasonic leak detection (sonic flow, choked flow) involves the turbulent flow of a fluid across a pressure boundary to create acoustic waves. These waves are transmitted through the medium of the fluid itself, through the containment structure, or through the air surrounding the containment structure. Leak testing equipment that uses other test methods is also available.