PENETRANT LIQUIDS

PENETRANT LIQUIDS

Instructions

Dear costumer, thank you for using SAMA Tools penetrant liquids to control and maintain the quality in your company.

Our products

• SALP151 – red penetrating spray HD
  
• SALP152 – yellow-fluorescent high visibility penetrating spray
• SALP164 – white developer spray 
• SALP166 – white developer spray HD
• SALP153 – non-halogenated solvent & cleaner spray

ASME compliance

ASME (American Society of Mechanical Engineering) is an engineering company born in 1880 in America in order to solve problems related to steam plants, but then it began to formulate also standards for manufacture and to size properly several types of mechanical plants. ASME Boiler and Pressure Vessel Code (BPVC) is still now an international standard for design, manufacturing and inspection of steam and / or pressure plants, such as the gas section in the production of electricity (nuclear, fossil fuels, etc.).

Section V of the BPVCspeaks about inspection by Non-Destructive Testing, including Penetrant Liquids; in particular, this document looks for requirements of fluorides, chlorides and sulphates content, because these chemicals can trigger dangerous events of corrosion in ferrous materials and the like: for example nickel-based alloys, Austenitic stainless steels and Duplex (said austenitic-ferritic) and Titanium.

ASME compliance of penetrant liquids must be guaranteed by:

a)   Number of “batch”. Themixtures are prepared in large-capacity bins, and a number called “batch number” identifies each one. This number identifies uniquely a quantity of material produced in a single operation and having uniform properties (indicated in UNI EN ISO 3452-2). Then, this identification number is printed on each bottle or barrel that come from the mixture related. A sample of this mixture is preserved: this procedure ensures the traceability of the product for many years and it protects from possible objections.

b)   Chemical analysis. Every batch must be analysed by a certified laboratory and the test results become part of product and single batch’s documentation. ASME Compliance means ensuring a very low capacity to trigger corrosion (rust) in ferrous materials, high degree of product purity and traceability for long. Our products comply with ASME. The analysis certificates for each batch are available in our company. Please contact us directly or through your dealer to have them.

UNI EN ISO 3452-2:2006

The products purity is very important in the Non-Destructive Testing field. The new UNI EN ISO 3452-2:2006 section 6.12 also speaks about products low in sulphur and halogens. The requirement is quite restrictive and shows as absolute limit maximum 200 parts per million of sulphur and 200 parts per million of chlorides and fluorides. Batch Certificates of analysis carried out so far show that this requirement is satisfied.

Application fields of penetrant liquids

There are numerous application fields of penetrant liquids; our products can be used to detect discontinuities in any type of non-porous material. Concerning the metallurgy, two applications are particularly interesting: in the welding processes control, to detect any discontinuity defects during the process (crater cracks, shrinkage cracks, porosity, slag cracks, undercut), and in the control of elements subjected to fatigue to detect discontinuities, due to repeated and prolonged stresses.

Production process and chemical analysis

In accordance with ASME, internal production procedures ensure the quality of our products. The correct application is assured both by analysing all chemicals in entrance, and by a manager who personally certify the proper execution in the mixtures preparation. All chemical analysis takes place according to very accurate procedures in a laboratory that operates with certified quality management system ISO 9001:2000.

Application

1. Preliminary cleaning. Although it may seem marginal, this is the most important phase of an examination with penetrant liquids. From the correct execution of this procedure depends the possibility of the liquid to penetrate or less, so it’s important to use appropriate products: products offered by SAMA Tools are non-halogenated solvent & cleaner spray (SALP153) and different types of loose solvent: all the solvents comply with the ASME standard concerning the purity and the presence of contaminants.
2. Penetrant application. The examined surface has to be completely covered by the liquid: for example, in case of welds control, it must overhang for at least 2 cm beyond the welds’ edges. After the spraying step, the liquid should be quit to drain in order to penetrate by gravity or by capillary action. The penetration time is fixed by the tables ASME, but can be determined also experimentally: for example, for the contrasting liquid colour (red) is recommended a time of 5-10 minutes, while the fluorescent is appropriate to let it act for a longer period. In any case, the duration of this phase must be verified according to the discontinuities you have to detect, possibly establishing the acceptability criteria.  Do not allow the penetrant to dry: if necessary, reapply it. The tests should be performed in an appropriate temperature in order to have a good result.  The temperature for both the work piece and the environment in which the tests take place should stay in the range between 10°C and 40°C. If you do not comply with these limits, the penetrant may work incorrectly, so its use should be verified by test at different temperatures. Two are the products offered by SAMA Tools: red penetrating spray SALP155 and fluorescent penetrating spray SALP152 (visible by “Wood’s Light”). What is the “Wood’s light” or “black light”? It is a particular frequency of light that stay in the ultraviolet field (wavelength less than 400 nanometers, “nm” symbol). It is produced by mercury vapor lamps, equipped with special filters that must let pass an ultraviolet radiation between 320 nm and 400 nm, with a peak at about 370 nm. Frequencies below 320 nm can be dangerous for the operator. The fluorescent penetrating spray illuminated by the Wood’s light at the correct frequency is much more accentuated and receptive to cracks’ research in comparison with a standard spray penetrating color contrast (red). It can detect also cracks few hundredth of a millimeter’s wide.
3. Penetrant cleaning. The excessive penetrant must be removed from the product’s surface before the application of the developer. Our penetrants are washable both in water (max 200 kPa, the pressure of a normal tap, and not hot) and with solvent. In the case of cleaning with solvent, you have to utilize, dabbing lightly, a lint-free cloth soaked in solvent & cleaner SALP153; do not rub. Use the recommended solvent to ensure proper compliance with ASME.
4. Application of white developer spray SALP164/SALP166.  This step is necessary to ensure that all discontinuities will be visible in natural light (red SALP155) or under Wood’s lamp (fluorescent spray SALP152). Use white developer spray SALP164/SALP166, because it is in line with the others. This spray contains a mixture of very fine white powder (max 10 micron diameter); this feature permits to lead in surface the penetrant remained in cracks. It contains also additives that help to attract the penetrant, acting by capillarity. The product has to be completely dry and it must not have penetrant’s residuals. Now spread a thin and uniform layer of developer and wait for the solvent’s evaporation. The layer used on fluorescent should be as thin as possible. The development time is generally about 5/15 minutes and starts from the time when the developer is dried. The developer’s drying should not be too quick: excessive speed may affect the highlight of thinner cracks.
5. Inspection setting. The inspection setting should be very bright for the red penetrating spray, while it should be low-light (as dark as possible) for the fluorescent penetrating spray, because visible light, whether natural or artificial, impairs visibility of fluorescence and yield of the Wood's lamp.
6. Evaluation and acceptability criteria. It is very important to establish with the customer parameters for acceptability of identified defects (practically, according to written rules, some signs, cracks or defects are accepted and others not) in order to avoid useless disputes. Please note that penetrating liquids’ control has to ensure that none of the products that exceed the control contains the defects set out in the acceptability parameters. A Non-Destructive Testing (NDT) cannot guarantee the absolute perfection of the product.

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