X-ray and gamma (RT) tests – Radiological tests

Radiological examination (RT) is one of  the most important non-destructive inspection (NDI)  techniques, as it uses X-rays and gamma rays to examine the internal structure of materials. This efficient technique enables the identification of internal defects in various industrial materials and components. In this comprehensive article, we will review the principles, equipment, standards, applications and safety precautions of this method.

Table of Contents

1. Introduction and history of the RT test

2. Scientific principles of industrial radiation detection

3. The difference between X-rays and gamma rays in RT test

4. Equipment for radiation testing

5. How to take an RT test

6. Industrial applications of radiation detection testing

7. Advantages and disadvantages of the hypnotherapy method

8. Safety and radiation protection tips

9. International RT Standards

10. Conclusion and future prospects

1. Introduction and history of the RT test

Radiological examination is one of the oldest methods of non-destructive screening, dating back to Wilhelm Roentgen’s discovery of X-rays in 1895. Today, this examination is widely used in various industries, including oil and gas, power plants, aerospace and medicine. According to statistics from the International Society for Non-Destructive Inspection (ASNT), about 23% of non-destructive inspections in heavy industry are performed using radiological screening.

2. Scientific principles of industrial radiation detection

The RT test works according to three physical principles:

• Differential absorption of radiation  : Materials of different densities and thicknesses absorb radiation to different degrees.

• X-ray  film effect: Special films can record differences in radiation intensity.

• Digital  imaging: In modern systems, digital detectors have replaced film.

The main equation governing this process is:
I = I₀e^(-μx)
Where:
I = output
beam intensity I₀ = input
beam intensity μ = linear attenuation coefficient of the material
x = material thickness

3. Difference between X-rays and gamma rays in RT test

4. Equipment for radiation testing

• Radiation  source: X-ray machine or gamma ray generator

• X-ray  films: different types according to sensitivity and contrast

• Cassette  : Protects the film from light and physical damage.

• Quality Measurement Indicators (QMIs):  such as panel cables and materials

• Film  processing device: traditional methods

• Digital  reagents: modern methods

• Dosimeter  : to measure radiation exposure.

5. RT test implementation method

1. Preparation of parts  : cleaning and coding

2. Setting parameters: determine the appropriate power based on the thickness and type of  material

3. Film/detector  location: on the other side of the radiation source

4. Radiation  therapy: maintaining a safe distance

5. Processing  Results: Film Development or Digital Image Processing

6. Interpretation of results  : by experienced Tier 2 and 3 operators

6. Industrial applications of radiation detection tests

• Oil and gas  industry: inspection of pipe welds and pressure vessels

• Power  :  Plant Industry Boiler and Turbine Analysis

• Aerospace and Aviation  : Quality Control of Castings

• Medical: Examination of  medical implants

• Automotive  : Checking Sensitive Engine Parts

7. Advantages and disadvantages of the hypnotherapy method

Advantages:

• The ability to identify internal defects with high accuracy

• Record a visual document of the results

• Possibility of use of different materials

• Ability to check multiple defects simultaneously

Restrictions:

• Radiation hazards to operators

• Relatively high cost in some cases

• It is necessary to reach both sides of the piece.

• Relatively long time by traditional methods

8. Safety and radiation protection tips

• Compliance   with the ALARA principle (as little   as reasonable)

• Use of bullet shields

• Installation of radiation warning signs

• Use of personal dosimeters

• Keep a safe distance from the source.

• Time limit for working with radiation sources

9. International RT Standards

• Section V  of ASME  : Welding Inspection Standard

• ISO 17636  : International Standard for Radiation Testing of Welds

• ASTM E94  : Radial Interpreting Guide

• EN 1435  : European Standard for Radiation Testing

10. Conclusion and future prospects

Radiological examination remains one of the most reliable non-destructive screening methods despite the emergence of new methods of non-destructive screening. The development of digital systems and artificial intelligence in the interpretation of radiographs bodes well for this technology. However, it is essential to consider operator safety and training when using this method.

Frequently Asked Questions:

• Are RT tests suitable for composite materials?
  Yes, but with appropriate settings to standards, and may require complementary methods.

• What is the maximum thickness that can be checked with X-rays?
  For X-rays, up to about 300 mm of steel, and for  gamma rays  , up to 500 mm, depending on the energy of the source.

• Can MRI detect small cracks?
  Yes, using special techniques, cracks as small as 1% of the thickness of the piece can be detected.