Liquid penetrant

Nondestructive testing techniques for welded joints usually include visual, radiographic, magnetic particle, liquid penetrant, and ultrasonic testing methods. Of interest in this paper is the radiographic testing (RT) technique. 

Development of Theory and Practice of Liquid Penetrant Testing. 

General hydrodynamic theory for liquid penetrant testing (PT) has been worked out in [1], Basic principles of the theory were described in details in [2,3], This theory enables, for example, to calculate the minimum crack s width that can be detected by prescribed product family (penetrant, excess penetrant remover and developer), when dry powder is used as the developer. One needs for that such characteristics as surface tension of penetrant a and some characteristics of developer s layer, thickness h, effective radius of pores and porosity TI. One more characteristic is the residual depth of defect s filling with penetrant before the application of a developer. The methods for experimental determination of these characteristics were worked out in [4]. 

But there are two physical phenomena that were not taken into account in the frame of the theory [1-3], although our last researches demonstrate its principal significance for liquid penetrant testing. The aim of this study is to investigate these phenomena and to determine the restrictions on theory applicability. 

Another phenomenon is so called two-side filling of one-side closed conical capillaries with liquid [5]. On the one hand the more penetrant is trapped by the defect the wider indication will appear. Contrariwise it is almost impossible to extract a penetrant from the completely filled surface defects by dry developer [6]. In this study we propose the theory of the phenomenon. Besides experimental results of the investigation of two-side filling with various penetrants of conical capillaries are presented. Practical recommendations to optimize liquid penetrant testing process are proposed. 

Fig. 4 illustrates the time-dependence of the length of top s water column in conical capillary of the dimensions R = 15 pm and lo =310 pm at temperature T = 22°C. Experimental data for the top s column are approximated by the formula (11). The value of A is selected under the requirement to ensure optimum correlation between experimental and theoretical data. It gives Ae =3,810 J. One can see that there is satisfactory correlation between experimental and theoretical dependencies. Moreover, the value Ae has the same order of magnitude as Hamaker constant Ah. But just Ah describes one of the main components of disjoining pressure IT [13]. It confirms the rightness of our physical arguments, described above, to explain the mechanism of two-side liquid penetration into dead-end capillaries. 

Prokhorenko P.P., Migoun N.P. Introduction To Liquid Penetrant Testing Theory,... 

The Difficult Choice of Liquid Penetrant Range of Products. 

This study has been launched in order to provide quantified data about the compared performances of liquid penetrant product family and, finally, to introduce an acceptance criteria on performance of liquid penetrant range of products in RCC-M code which had no requirement on that point. 

Due to the well known human shortcomings the probability of finding flaws using Magnetic Particle Inspection (MPI) or Liquid Penetrant Inspection (LPI) can be restricted to only 60-85% and the inspection reproducablity is difficult. 

Magnetic Particle inspection Liquid Penetrant Inspection... 

With the objective determination of the visibilitity of magnetic particle indications quantitative researches on the influence of the inspection parameters will be possible. The first part deals with the type testing of detection media which is as well on the course of adoption for type testing of liquid penetrant systems (prEN 751-2). 

R. C. McMaster, ed., "Liquid Penetrant Inspection," Nondestructive Testing Handbook, Vol. 2, 2nd ed., American Society for Nondestmctive Testing, Columbus, Ohio, and the American Society for Metals, Cleveland, Ohio, 1982. 

Liquid-Penetrant Examination This examination shall be performed in accordance with Art. 6, Sec. V of the ASME Code. 

Visual Liquid-penetrant or magnetic-particle Ultrasonic or radiographic ... 

Liquid-penetrant examination involves wetting the surface with a fluid which penetrates open cracks. After the excess liquid has been wiped off, the surface is coated with a material which vidll reveal any liquid that has penetrated the cracks. In some systems a colored dye will seep out oi cracks and stain whitewash. Another system uses a penetrant that becomes fluorescent under ultraviolet hght. 

Identification. If the notch left by incomplete penetration emerges at a visually accessible surface, visual examination, perhaps aided by magnetic-particle or liquid-penetrant techniques, may reveal the defect. Otherwise, ultrasonics, radiography, or eddy-current techniques may have to be used. 

After sueeessful eompletion of all testing, eaeh rotating assembly must be disassembled for visual inspeetion of the rotor, bearings, and seals. Oversped wheels should be examined by the liquid penetrant method. 

All circumferential and longitudinal butt welds of pressure containing casings shall be 100% radiographed, if possible. All other welds shall be magnetic-particle or liquid-penetrant examined. 

Toxicity. This factor is becoming an increasingly important consideration in the design of mechanical seals. Since the rubbing seal faces require liquid penetration to cool and lubricate them, it is reasonable to expect that there will be some vapor passing across the faces. This is in fact the case. A normal seal can be expected to leak from a few ppm to 10 cc/min. It is also generally accepted that the seal leakage rate will increase with speed. 

Styrene 32 (Vinyl benzene) C6H5CH CH2 490 1.1-6.1 0.9 3.6 145 Colourless/oily yellow liquid Penetrating odour Polymerizes slowly in air or light, accelerated by heat or catalysts Ignition/explosion possible Usually inhibited Store <21 °C... 

Liquid Penetrant Examination. All accessible surfaces of the main load carrying components of the equipment shall be examined by a liquid penetrant examination or technique conforming to the requirements of ASTM E165 Recommended Practice for the Liquid Penetrant Examination Method. Acceptance limits shall be as agreed upon by the manufacturer and the purchaser. 

Aqueous standard solutions are a source of certain difficulties In electrothermal atomic absorption spectrometry of trace metals In biological fluids The viscosities and surface tensions of aqueous standard solutions are substantially less than the viscosities and surface tensions of serum, blood and other proteln-contalnlng fluids These factors Introduce volumetric disparities In pipetting of standard solutions and body fluids, and also cause differences In penetration of these liquids Into porous graphite tubes or rods Preliminary treatment of porous graphite with xylene may help to minimize the differences of liquid penetration (53,67) A more satisfactory solution of this problem Is preparation of standards In aqueous solutions of metal-free dextran (50-60 g/llter), as first proposed by Pekarek et al ( ) for the standardization of serum chromium analyses This practice has been used successfully by the present author for standardization of analyses of serum nickel The standard solutions which are prepared In aqueous dextran resemble serum In regard to viscosity and surface tension Introduction of dextran-contalnlng standard solutions Is an Important contribution to electrothermal atomic absorption analysis of trace metals In body fluids. 

Eyes Very high toxicity much greater through eyes than skin. Very low concentration of vapor causes pupil of eyes to constrict, resulting in difficulty in seeing in dim light. Skin Very toxic. Decontamination of smallest drop of liquid agent is essential. Liquid penetrates skin readily. 

The rate at which selected liquids penetrate into tablets can be used to study their pore structure. A knowledge of the rate of liquid penetration should also provide information on the disintegration/dissolution behavior of a tablet on administration. Such investigations are capable of forming a valuable link between physico-mechanical characteristics and in vivo performance. 

Under the conditions for deepest liquid penetration, Eq. (2-16) becomes... 

LS Wang, PW Heng. Liquid penetration into tablets containing surfactants. Chem Pharm Bull 33(6) 2569-2574, 1985. 

The achievements in optical detection techniques and the interest in the sol-gel process for creation of new materials, are leading to developing of various sensors. The majority of reported sensors developments have concentrated on the use of thin films. There are many reasons for this. The important one is the susceptibility of monoliths to cracking due to internal stresses, particularly when exposed to liquid penetration. More attractive are... 

Studies have shown that the pore size distribution can influence liquid penetration into tablets [28,29,52]. The accessibility of water vapor to tablet components has been related to chemical stability, especially in the case of hydrolyzable drugs [28]. Solvent penetration, which can affect tablet disintegration and dissolution, has been related to pore size [52]. 

Pale-yellow to dark-brown liquid with a faint odor like garlic. Odor becomes more pronounced during storage. This material is hazardous through inhalation, skin absorption (liquid), penetration through broken skin, and ingestion, and produces local skin/eye impacts. 

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