NDT Weld inspection for Aero Components | NDT Inspection and Testing | Ultrasonic Weld Inspection

What is Non Destructive Testing

Non Destructive Testing (NDT) is a method of testing the material’s characteristics such as physical, chemical and structural components to perform their function in a cost effective way. In this, components are examined / evaluated without destroy / damage of the product. NDT tests conducted in the parts aren’t damage the raw materials as such happened in destructive methods and it guaranteeing the safe operation of the parts. NDT is no way alters the components in any type of inspection. NDT is carried out widely for the conditioning monitoring (industrial inspections) of the plants such as aerospace, automobile, manufacturing and construction.


Non Destructive Testing vs Destructive Testing

This process is done during the ‘production stage’ or ‘during the service life’ or ‘during the failure of the components’. Critical material properties are identified by testing under the different loads, where the components properties identified through the specimen failures. Some of the common destructive testing methods are Tensile and Compression Tests, Bending tests, Impact tests, Cupping tests, Hardness test etc. Defect are not identified in destructive testings. Destructive testing is a costliest process due to material loss. Hence it is not suitable for the service material testing.


Applications of NDT Weld inspection for Aeronautical Components

Production of Aero components are time consuming, complex designs and the components are very costly. Hence many components in aeronautical industries are keen to watch the parts.


List of NDT Inspections

  • Ultrasonic Testing

for Seamless tubes, Inspection, crack detection, materials characterization studies, Thickness measurement,

  • Infrared and Thermographic Testing
  • Visual Inspection

Corrosion damage in Built-up structure, Pitting on the exposed surface

  • Liquid Penetrant Testing
  • Magnetic Particle Testing
  • Eddy current theory

Abrupt changes in the components geometry, Cracking,

  • Radiography Testing
  • Acoustic emission Testing





Types of Pneumatic Conveyor | Vacuum and Positive Pressure Pneumatic Conveying Systems | Dense Phase Pneumatic Conveying System

Classification of Pneumatic Conveying Systems

Pneumatic conveying systems can be classified on different basis of consideration. These basis are listed below:

  • On average particle concentration (modes)
  • On air pressure (Types of systems)
  • On air supply arrangement
  • On solid feeder type

Of these, the first two are very important and often influence the choice of the specific design for a given material, loading and delivery condition and the distance to be covered.

01-pneumatic-conveying system plant - Coffee conveyor plant

Classification based on Average Particle Concentration – Modes of Conveying:

01-dilute phase - dense phase - plug phase - conveying of particles

Depending on the mass flow ratio, defined as the ratio of mass of particles conveyed to the mass of fluid used to convey, pneumatic conveying system may be classified into two modes; namely

  1. Dilute phase
  2. Dense phase


If the mass flow ratio is low, the system is said to operate in dilute phase. Whereas, if the mass flow ratio is high, the system is said to operate in dense phase. If the mode of operation of a system is in dilute phase, the probable range of mass flow ratio is 0 – 15. The dense phase system operates at mass flow ratio over 15.

In a dilute phase system the material is carried through the pipeline by a large volume of air having high velocity but relatively low pressure. The stream of air or gas carries the material in suspension in the pipeline as discrete particles owing to lift and drag forces acting on each particles. The distribution of particles over the cross section of the pipe is fairly uniform. In order to keep the particles in suspension, the air must possess a minimum velocity, called the pick up velocity. The pick up velocity for a particular material depends on many factors, like, the shape, size, specific weight of material and inclination of the pipeline.

01-dilute phase pressure conveying system

If the velocity of air is gradually lowered down below what is required to keep the particles in suspension, the particles gradually settle down and form dunes at the bottom of the pipeline all along the length of the pipe. In this condition the material is about to choke the pipeline and if the pressure is increased these dunes and plugs of materials may move along the pipeline causing a dense phase flow. In a dense phase flow usually the velocity of fluid is much lower than the minimum velocity required for a dilute  phase flow. The distribution of particles over the cross section of the pipe is non uniform. At the lower part of the pipe there is slow moving dunes or plugs of material and the upper part of the cross section of the pipe is filled with certain proportion of finer particles in suspension in a state of dilute phase.

01-dilute phase pressure conveying system - Pneumatic conveying system

01-dense phase pneumatic conveying system

The maximum mass flow ratio achievable for a dense phase flow depends on many factors like the nature of materials and air velocity. It is usually greater than 30

Classification based on Air Pressure:

Based on air pressure, Pneumatic conveying systems may be classified as follows:

  • Low pressure systems, in which the operating air pressure is about 1 atmosphere (760 mm Hg). This type of systems may be further sub classified into
  • Positive pressure system
  • Negative pressure system
  • Combined positive – negative pressure system
  • Medium pressure system
  • High pressure system

01- pneumatic-conveyor-systems - positive conveying - negative conveying