NON-DESTRUCTIVE TESTING

Technique varieties and inspection testing that do not affect subsequent use of materials and equipment submitted to them. Any techniques are capable of locating, quantifying and dimensioning indications found. Each testing type has its characteristics, advantages and limitations. Some of the methods provided to our clients are listed below:

Ultrasound Thickness measurement

Very simple and widely used technique by the industry; through portable devices, the thickness of plates and pipes may be measured from one of the sides, since the physics principle of emission and reflection of sonic waves is applied, produced by a head equipped with a piezoelectric crystal. A sonic wave with known speed is applied to the material. The thickness value may be calculated upon knowing the sending and return times.

Welding Ultrasound - A-scan

Widely used in the industry, particularly in welding quality control and inspections of deterioration control. In a similar way of the thickness measurement technique, a sonic wave is applied to he region near the weld. With angular heads, speed, known sending and reflection times, it is possible to locate and dimension the disruptions in the part being inspected.

Plate ultrasound - B-Scan

Often used to discover the corrosion profile on a plate. The technique enables viewing the remaining thicknesses throughout a certain cross section of the part. It employs the same principles of conventional ultrasound.

Phased-array ultrasound

Although it employs the same physical principles of conventional ultrasound, this technique uses devices with multiple channels and heads with multiple elements. This feature has as its advantages:

  • Electronic scan - severely reduces the movement of the head by the inspector
  • Inspection time reduction
  • Three-dimensional viewing of the disruptions, for easier assessment and dimensioning

ToFD ultrasound

Alternative method to the conventional ultrasound inspection, that employs two heads and is based on the transit time of ultrasound waves diffracted and reflected by the disruptions. Its advantages are:

  • Higher inspection speed
  • Covers entire volume between heads
  • Allows full dimensioning of detected disruptions (length, height and depth)

Penetrating Liquid

Liquids with low surface tensions are able to infiltrate small cavities or cracks at the surface of a material. Some powdered substances may absorb liquids due to the capillarity property.

Due to low surface tension and capillarity properties, detection of disruptions or defects that emerge to the surface of a certain material, the detection process takes place as follows: a colored fluid is applied with penetration time on the disruption; afterwards, the surface is cleaned to remove excess fluid, and a powder is applied in order to cause emergence of the fluid within. The result is the appearance of the disruption, if any, in the form of the contrast between the fluid and the powder, usually white.

Magnetic Particles

When a magnetic field is applied to a ferromagnetic material, such as steel, the force lines follow their standard trajectories throughout the surface and subsurface. In case of a disruption, the force lines will by pass its extremities, allowing for a concentration on said points, or leak points, creating new magnetic poles. By applying extremely fine particles of ferromagnetic material over this surface, it is possible to check the alignment of said surfaces in regions where the new magnetic poles were created, thus identifying the disruptions.

Magnetic flux leakage- MFL

This is an inspection technique also based in the principles of magnetism. A strong magnetic field is applied over a ferromagnetic surface, such as steel plates, on places where disruptions are present, thus the magnetic flow is disturbed, creating leak fields. The equipment captures said leak fields by visually indicating the disruptions on a screen. This technique is extremely useful to detect and locate cavities and thickness losses on the inner face of the bottom plates of storage tanks, therefore, undetectable by internal visual inspection.

Hardness Test

There are several definitions for hardness, however, in the petrochemical area, where the welding metallurgy of plates and pipes is of utmost importance, it may be said that hardness is the strength against plastic deformation. Depending on the material used, type of welding, thickness of the piece, etc., hardness control is very important. There is a relationship between hardness and tensile strength thresholds of the material. Devices used in the field are portable and easy to use. The testing is safe and accurate. Normally, a small indentation or deformation is made at the surface of the part or the welding region in order to assess the hardness value.

Acoustic pulse reflectometry - APR

Pipe bundles made from metallic or polymeric materials of interchanged res and up to 4” diameter pipelines.

The principle of this technique is the emission of a sound pulse that propagates through the air inside the pipes. While the pulse finds no change in the transverse section of the pipe, it maintains its path, with some dampening due to air friction at the pipe walls. If, however, any disruptions are found, reflected sound waves are created and propagate back. The more sudden the changes in the transverse section of the tube, the stronger are these reflections, which are recorded and analyzed by a software in order to determine what kind of disruptions caused them, which are: holes, corrosion cavities, loss of thickness, kneading and obstructions.

Another relevant application of this technique is the assessment of the cleanliness degree of pipe bundles and pipelines up to 4” diameter. The test has a very high productivity rate, saving considerable time and resources.

O ensaio possui uma produtividade muito elevada, economizando com isto tempo e recursos consideráveis.

Industrial thermography

All heated bodies, even those at relatively low temperatures, emit infrared radiation. Thermography devices deploy eco sensors or microbolometers which are able to capture this infrared radiation emitted by the bodies and transform it into images on a video screen, representing temperature gradients of the body being observed, and is able to record temperatures at any point in the image. This technique is widely used in the electric sector, as occurs in the inspection of an electric switchboard from a thermal image that identified hot spots that may indicate future faults. In the petro chemistry oil and gas sector, this method is often used in inspection of furnaces, heaters, pressure vessels, exchangers, etc.

Industrial Videoendoscopy

The use of endoscopes with image access though remote video screens are relatively common in the medical field, and also in the industrial field. For equipment with access restrictions, such as small diameter pipelines, furnace pipes and small-sized pressure vessels, internal inspection of said equipment is possible with this technique, including with recording and dimensioning of obstructed and/or corroded regions. The probes include their own light source and articulations with allow for a 360º view.

Eddy Current

The eddy current testing is an inspection method that applies to conductive materials, based on electromagnetic induction. The presence of disruptions on the material, or local changes of any electromagnetic property of the tested material may be detected and measured. The coils are the inducing elements of the eddy current on the material and sensors of the disturbances caused. This interaction between primary and secondary magnetic fields changes coil impedances, according to thickness changes, disruptions and metallurgical alterations. The disturbances of eddy currents are featured on a screen, such as changes in electric impedance of the coil-part assembly that are interpreted by a trained inspector in order to correctly identify the type of defect or disruption detected. This technique is widely used in the nuclear and petrochemical areas, particularly in inspections of heat exchanger pipes.

Alternating Current Field Measurement – ACFM

This is an electromagnetic technique used for detection and dimensioning of surface cracks, mainly caused by strain, in welds and metallic materials. It combines the advantages of the ACPD (Alternate Current Potential Drop) and Eddy Current techniques, mainly in ferromagnetic materials.

The presence of a crack disturbs electromagnetic fields and the information is displayed on a computer screen in graphic form. The edges of the crack are easily identified, as well as length and depth. No need to remove coating such as paint, or extended surface preparation.