Destructive Testing: A Guide
Destructive testing is a testing method that analyzes the point at which a component, asset, or material fails.
Inspectors subject the material they are testing to different destructive test methods, which will deform or destroy the material completely, in order to gain insights about how the material performs under pressure.
Destructive testing methods can identify physical properties of a component, like toughness, hardness, flexibility, and strength.
- Destructive testing (DT) is also commonly called destructive physical analysis (DPA).
Metal samples for strength testing | Source: DedMityay, iStock
Destructive testing is an important testing method that identifies the limits of components in order to mandate accurate operating, maintenance, and replacement recommendations.
DT methods are commonly used for failure analysis, process validation, materials characterization, and can form a key part of engineering critical assessments, which also involves non-destructive testing (NDT) techniques, such as digital radiography.
In this guide, we will cover the different types of destructive testing methods and provide some examples of use cases.
If you would like to jump down to specific sections, here are the key topics we cover:
- Destructive Testing vs. Non-Destructive Testing
- Which Industries Use Destructive Testing?
- What are Some Types of Destructive Testing Methods?
- Destructive Testing Examples
Destructive Testing vs. Non-Destructive Testing
Destructive testing aims to deform or destroy a material to analyze its point of failure. On the other hand, non-destructive testing uses inspection methods that do not damage a material or asset in any way.
Inspectors use DT and NDT in different scenarios.
For example, DT is used before a component is mass produced or used in its actual application in order to understand what will happen when it’s placed under different kinds of stress.
NDT is used to test an asset that is already in operation for early detection of damage and to prevent operational failures. This test method is performed to keep records of assets, to inform maintenance schedules, and to identify defects before they become worse.
What Industries Use Destructive Testing?
Destructive testing is typically performed by in-house technicians or by a third party testing provider. Many of these tests are performed in a lab using specialized equipment.
Industries that use destructive testing include:
- Electrical Engineering
- Oil & Gas
- Power Generation
Destructive Testing Technicians
Occupations that conduct destructive tests include:
- Electrochemical process experts
- Failure analysis experts
- Material scientists
- Metallurgical and polymer engineers
- Quality control analysts
- Regulatory compliance experts
What Are the Primary Destructive Testing Methods?
There are several types of destructive testing that simulate the environmental factors that materials may actually be exposed to once they are in use, and that are designed to test the strength of a material under certain types of pressure.
Destructive testing methods include:
Aggressive environment testing
Aggressive environment testing is used to test fatigue and fracture points of a component when it is exposed to corrosive environments at different pressures and temperatures. Tests mimic the environment where components will be operating.
Examples of corrosive environments include those that contain:
- Hydrogen sulfide
- Carbon dioxide
- And other natural elements
Corrosion testing tests a component’s corrosion point when it is exposed to saltwater and freshwater.
Fracture and mechanical testing
Fracture and mechanical testing includes the following destructive tests:
- Bend test is a quality control test that bends materials either in a guided or free form test to expose embrittlement.
- Charpy impact test is a high strain DT method that determines the amount of energy absorbed by a material during a fracture.
- Crush test or compressive strength test is a test widely used to determine the strength of concrete bearing loads.
- Weld fracture test is a test designed to reveal imperfections such as cracking due to inadequate width to height ratio, incomplete penetration, lack of fusion, porosity, and slag inclusion.
- Peel and chisel test is a test that determines weld size and failure type.
- Pellini drop weight test is a test that determines the nil-ductility transition temperature (NDTT). NDTT is the test temperature in explosion bulge tests at which the plate remains flat after a fracture and crack propagation occurs in the presence of elastic strains only.
- Hydrostatic pressure test is primarily an NDT method, but recently hydrostatic pressure tests have shown to exert strain within a material's elasticity, which only occurs micro structurally when the material being strained is slightly proportional to the pressure applied.
Fatigue testing is conducted in salt water or open-air environments to determine the endurance of welded joints, base metals, and heat affected zones under variable- or constant-amplitude loading.
Hardness testing determines whether a component undergoes permanent deformation under stress using the Rockwell scale. How much a material resists indentation is what determines hardness. This test determines how well a component will perform over time and how long it can be in use.
Hardness testing | Source: Kimtaro, Dreamstime
Hydrogen testing exposes a component at risk of corrosion to hydrogen at different strain rates and temperatures.
Residual stress measurement
Residual stress measurement measures the internal stress of a component and its effect on the surface stress. These measurements allow engineers to analyze residual stress distribution. Here are three methods that can be used in residual stress measurement:
- Neutron diffraction
- Synchrotron diffraction
- X-ray diffraction
Software testing is performed by software engineers who investigate the quality of the software, find failures, and understand risks before the product is fit for use.
Tensile (elongation) testing
Tensile (elongation) testing is a type of stress testing performed by elongating or compressing a component to determine the strength of the material. Breaking strength, maximum elongation and compression, and tensile strength are all measured to calculate physical properties and to determine which materials can withstand a great amount of force.
Tensile (elongation) test
Torsion testing is a type of stress testing where twisting forces are applied to determine shearing of the material before it becomes deformed. Once the material succumbs to twisting, that is considered the failure point of the material.
Examples of Destructive Testing
Perhaps one of the most common examples of destructive testing is crash simulations.
Automakers and aerospace industries alike will use destructive testing to test the limits and ability of their safety equipment to function when other components fail.
In aerospace, high temperature and pressure are applied to the cabin to ensure that safety features—like the air respirator release—will still function under such conditions.
Destructive testing is also used to test the strength of safety glass. Sandbags can be dropped at specified heights to simulate impactful forces for failure analysis, and fire can also be applied to determine flame resistance.
Fire-related personal protective equipment (PPE)—like coveralls, earplugs or muffs, full body suits, gloves, hard hats, respirators, safety glasses, shoes, and vests—are exposed to destructive tests to comply with IEC and/or ASTM standards. These tests include exposing the safety equipment to an electrical arc simulation (arc rating) or an open flame (fire rating) to determine how much energy the material can be subjected to before failure.
DT is also used to determine which materials should be used in the construction of industrial boilers, which undergo extreme pressure and high temperatures, thus determining the pressure and temperature ratings of the boiler for safe operation.
Tensile testing is used to test weld-strength for construction materials. These tests ensure the structural integrity of a weld and of the building itself. For example, a skyscraper that is exposed to natural elements will use materials and components that are deemed safe to use by destructive testing methods to withstand conditions under expected limits.
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