Quality Control of Drying Process The temperature used to dry parts after the application of an aqueous wet developer or prior to the application of a dry powder or a nonaqueous wet developer, must be controlled to prevent "cooking" of the penetrant in the defect. High drying temperature can affect penetrants in a couple of ways.
Full Answer
What happens to the penetrant during the drying process?
Excessive heat or too long a drying time tends to bake the penetrant out of discontinuities. When the drying process is complete, the specimen is ready for the application of either dry or non-aqueous wet developer.
What is the principle of liquid penetrant testing?
The basic principle of liquid penetrant testing (PT) is capillary action, which allows the penetrant to enter in the opening of the defect, remain there when the liquid is removed from the material surface, and then re-emerge on the surface on application of a developer, which has a capillary action similar to blotting paper.
When should wet developer be applied after penetrant removal?
If water-based wet developer is used, it is applied to still damp specimen immediately after the penetrant removal wash. Excessive heat or too long a drying time tends to bake the penetrant out of discontinuities. When the drying process is complete, the specimen is ready for the application of either dry or non-aqueous wet developer.
Is there an example Dye penetrant inspection procedure?
This article provides you with a example dye penetrant inspection procedure. This procedure contains water washable process with both visible and fluorescent systems.
Which of the following is purpose of the drying process used in penetrant testing?
Which of the following is a purpose of the drying process used in penetrant testing? -After the application of a wet developer, the drying process aids in securing a uniform developer coating.
What is the process for dye penetrant test process?
In dye penetrant testing, inspectors generally follow these six steps:Clean the surface. ... Apply the dye penetrant. ... Remove extra penetrant and apply remover. ... Apply developer. ... Inspection. ... Clean the surface.
What is the purpose of penetrant in liquid penetrant inspection?
Liquid or dye penetrant testing (PT) is a non-destructive material testing method which uses capillary forces to find surface cracks or pores and make them visible. It can detect surface-breaking flaws such as cracks, laps, porosity.
What are the 4 methods of penetrant systems?
The four methods are listed below:Method A - Water Washable.Method B - Post-Emulsifiable, Lipophilic.Method C - Solvent Removable.Method D - Post-Emulsifiable, Hydrophilic.
What are the two most important properties in determining the penetrating ability of a penetrant?
Q.What are the two most important properties in determining the penetrating ability of a penetrant?B.Viscosity and contact angleC.Surface tension and wetting abilityD.None of the aboveAnswer» c. Surface tension and wetting ability1 more row
What is the difference between liquid penetrant and dye penetrant?
Dyes Vs. With dye penetrant, the liquid penetrant itself is the indicating material. The subject material in magnetic testing must be magnetized, whereas liquid penetrant techniques may be used on a wider variety of materials.
Should the penetrant be allowed to dry on the part?
Generally, there is no harm in using a longer penetrant dwell time as long as the penetrant is not allowed to dry. The ideal dwell time is often determined by experimentation and may be very specific to a particular application.
Why penetrant testing is most widely used?
Liquid penetrant testing is one of the most widely used NDT methods. Its popularity can be attributed to two main factors: its relative ease of use and its flexibility. It can be used to inspect almost any material provided that its surface is not extremely rough or porous.
Which penetrant process is the most sensitive to detect fine discontinuities?
Q.Which penetrant process is the most sensitive to detect fine discontinuities?B.Water washableC.Post emulsifiable fluorescentD.Water washable fluorescentAnswer» c. Post emulsifiable fluorescent1 more row
Which penetrant method is the easiest to use?
Since visible dye penetrants do not require a darkened area for the use of an ultraviolet light, visible systems are more easy to use in the field.
Which method of penetrant removal is water washable?
Water washable penetrants are removed by manual or automated water spray, manual wipe or air agitated immersion wash. If a manual spray is used the water pressure should not exceed 40 psi; the temperature should be between 50–100°F / 10–38°C using a coarse spray at a minimum distance of 12 in / 30 cm from the part.
Which type of penetrant is most sensitive?
Fluorescent penetrantFluorescent penetrant is inherently more sensitive than colour contrast. Post-emulsifiable is more sensitive than water washable since there is less danger of over-washing of the penetrant. Non-aqueous developer is the most sensitive.
What is DPT method?
Dye Penetrant Test (DPT) is one of the most inexpensive non-destructive test (NDT) methods, used to check the surface irregularities of any component. This test method is popular by many names, which are as follows; Liquid Penetrant Inspection (LPI) Liquid Penetrant testing or Liquid Penetrant test (LPT)
What is dye penetrant made of?
Abstract The dye penetrant composition may include an extender, preferably an isoparaffinic solvent consisting essentially of a mixture of isoparaffins having a chain length of about 10 to about 17 carbon atoms, and an average chain length of about 13 to about 14 carbon atoms.
What order is liquid penetrant test?
Which is the correct order for the liquid penetrant test? Explanation: Firstly surface is cleaned. Penetrant is applied and surface flow is made visible. Finally, surface is inspected.
What is liquid penetrant testing?
For surface examination, liquid penetrant testing (PT) is the traditional method and, in practice, the main method employed. Improved detection sensitivity is normally achieved with magnetic particle inspection (MPI), but this method can only be applied on magnetic materials. Duplex steels contain about 50% of magnetic ferrite, although this can vary significantly in welds. This means that duplex steels are less magnetic than ferritic steels, but more magnetic than austenitic steel on which MPI is ineffective. Although MPI is theoretically feasible for duplex steels, in practice, it has a much reduced capability.
What is the dimensional effect of penetrant viscosity?
In penetrant testing the dimensional effect of penetrant viscosity manifests itself both at the stage of filling microdefects and, to a substantially greater extent, during absorption of penetrant by a layer of fine-disperse developer at the development stage . The physical meaning of the suggested interpretation of the dimensional viscosity effect is as follows. The effect is found in polar liquids whose molecules Not only shear but also moment stresses act between the components of such a micropolar liquid. As a result, the liquid associates not only perform translational motion, but also have proper angular velocities. Thus, energy spent on liquid absorption to a certain depth is spent on overcoming both shear and moment stresses between the associates, i.e. at a given pressure drop the liquid consumption decreases and effective viscosity rises. Particularly, we obtained the expression for calculating the displacement of the penetrant meniscus in a dead-end cylindrical capillary, l o in length and R in radius, from the mouth to the depth [ 1, 2 ]°:
How to test for cracks in a surface?
Dye penetrant testing is an effective method of testing for surface-breaking defects such as cracks or porosity. The process involves spraying the surface to be tested with a penetrating liquid, often with a colored or fluorescent dye. After allowing the penetrant to work for a few minutes, the surface is washed and then either left or coated with a dye-absorbing material. After a time the liquid in any crack seeps out and either can be seen as a discoloration of the dye-absorbing coating, or can be seen under ultraviolet light. The technique can be used on as-cast or machined surfaces. An example of the type of results obtained is shown in Figure 119.
What type of light is used to detect fluorescent penetrants?
With fluorescent penetrants, the process is essentially the same as for colour contrast, but the examination is performed using an ultraviolet light, sometimes called black light. This is performed as follows:
What material can PT detect?
PT can detect discontinuities open to the surface in all materials except porous ones. It is commonly used on nonmagnetic materials such as austenitic stainless steel where MT is not possible. A typical colour contrast technique would be carried out as follows:
What temperature is required for a PT?
For a standard PT technique, the temperature of the penetrant and the surface of the part to be processed must be between 50 °F (10 °C) and 125 °F (52 °C) throughout the examina tion period. Local heating or cooling is permitted to maintain this temperature range.
Why is it important to remove excess surface penetrant?
Because the emulsifier is “built-in” to the water-washable penetrant, it is extremely important to exercise proper process control in removal of excess surface penetrant to ensure against overwashing. Water-washable penetrants can be washed out of discontinuities if the rinsing step is too long or too vigorous.
What temperature should an aerosol can be kept out of?
10.4 Aerosol cans of penetrant materials should be kept out of direct sunlight or areas in excess of 130 °F. Excessive heat may cause aerosol cans to explode. 10.5 Avoid looking directly into black light source, since the eyeball contains a fluid that fluoresces if black light shines directly into the eye. 11.
Can water washable penetrants be washed out?
Water-washable penetrants can be washed out of discontinuities if the rinsing step is too long or too vigorous. Some penetrants are less resistant to overwashing than others. 4.5 Post-Emulsifiable penetrants with lipophilic and hydrophilic emulsifiers are not included in this procedure.