Condition of the Substrate

A proper survey requires dividing the structure or facility into easily defined parts, zones, or sections before proceeding in a methodical fashion to establish exactly what has happened to the structures and the coating systems since its last painting program. 

Determining the condition of the substrate is a critical part of any condition survey. Coatings can mask some rather severe corrosion for a period of time. Corrosion under insulation (CUI) is a particular example of the development of a very severe environment that may go unnoticed until a catastrophic leak occurs. Contaminants from process or environmental upsets can be difficult to find from a purely visual standpoint. The underl5dng substrate must be accessed in some way. If it is under insulation, strategically placed inspection windows may need to be cut into the insulation or its cladding so proper inspection or monitoring can be performed on the substrate to determine its true state. 

If it is under an old protective coating system, strategically located sections of the coating system may need to be removed to provide access to the substrate for the same types of tests. Adhesion may need to be verified by following either ASTM D3359 [15] or ASTM D4541 [16]. If it is visually rusty, the extent of the rust and the depth of the 

Blisters should be identified using the ASTM D714 [18] in which blisters are categorized by size, shape, location, and density. The standard has a set of photographs depicting blister sizes from No. 2, which is the largest size to No. 8, which is the smallest. The photographs also depict the density of the blisters as few, medium, medium dense, and dense. 

It is often critical to determine how much of the original wall thickness of the metal has been lost on visually rusty surfaces. This can be done with a number of instruments. A portable A-scan ultrasonic thickness gauge may be quite useful to determine and store in memory the remaining wall thickness at any given point of a structure. B-scan-type ultrasonic thickness gauges can measure and plot wall thickness on complete structures or sections of structures from which isolated corrosion pits, vessel corrosion rate, general wall thickness, and visual presentation of the section being measured can be produced. 

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Mirzamaani et al. [74, 75] point out that the earlier studies of the interrelationships between structure and magnetics have examined films substantially thicker than those now being used in thin-film disks. These authors have examined very thin CoP films and have studied the relative roles of shape anisotropy, stress anisotropy, and crystal anisotropy in determining the magnetic properties. For their CoP-deposition system, shape anisotropy dominated the other factors in determining the film magnetic properties. The shape anisotropy of a particular deposit was determined by the surface condition of the substrate on which the CoP was deposited. 

Thermal Inhibition, Heat treatment of milk is the most important practical means of inactivating its lipases. The temperature-time relationship necessary for partial or complete inactivation has been extensively studied, but a number of discrepancies have been apparent. These are probably due to several factors, including the sensitivity of the assay procedure, the length of the incubation period following heating, the presence and concentration of fat and solids-not-fat in the milk at the time of heating, and the type and condition of the substrate. In view of these variables, references to a number of early studies on heat inactivation have been omitted. 

Usually, there is a small oxygen burst due to greater oxygen solubility in methanol, followed by a short lag in oxygen uptake. Depending on the condition of the substrate and the amount of enzyme, a lag may not be observed. Next, a rapid linear portion is observed, usually followed by an eventual decrease as oxygen and substrate are depleted. 

These are only two examples of the vast number of methods available to the practitioner for the characterization of surfaces. In general, though, it should be stated that, even at the shop floor, one should put more emphasis on the condition of the substrate than the degree of dirt (soil) removal. 

Often the OEM coatings depend on the nature and condition of the substrate to which paint is applied application methods and conditions drying time required and decorative and protective requirements. The substrate most commonly coated with industrial coatings are iron and steel, but also include other metals such as aluminum and its alloys, zinc-coated steel, brass, bronze, copper, and lead. Nonmetalhc substrates include timber and timber products, concrete, cement, glass, ceramics, fabric, paper, leather, and a wide range of different plastic materials. Consequently, industrial coatings are usually formulated for use on either a specific substrate or a group of substrates. 

The chemical behaviour of IPs is determined not only by the chemical properties of the imidazole and pyridine rings separately, but also by intramolecular interaction effects (electronic and steric) that arise between the rings in the fused systems. These effects strongly depend both on the electronic condition of the substrate (neutral molecule, cation or anion) and on the geometrical orientation of the rings. IP s behaviour in various reactions will be considered below. We will also examine the behaviour of related heterocycles (for example, pyridine, isoquinoline or triazolo [4,5-c]pyridine, etc.) to illustrate the general or particular character of the IP s properties. 

Varies with ambient temperature and condition of the substrate. 

Which pre-treatment is possible, and what will the condition of the substrate be... 

Adhesion values are also influenced by the method of coating. Aqueous, extruded melt, and solvent coatings all wet substrate surfaces differently. The condition of the substrate (cleanliness, degree of oxidation, etc.) also has a marked influence on the adhesion values attained. ... 

We say The possibility for a connection [between the body and a soul] is insufficient for [the soulj s [coming into] existence, unless its existence is already possible in itself For a substrate can only become prepared for a thing that is possible in itself to become connected to it, to the exclusion of what is not possible [in itself]. So [the soul] s possibility in itself is different from the possibility of it becoming connected to a substrate. A thing s being possible or impossible in itself may be known before consideration of the condition of the substrate, [specifically,] whether or not preparedness to receive it has obtained in [the substrate], as we have already established. 

One of the most important factors in adhesive bonding is the surface condition of the substrate, i.e. the surfaces of the materials to be joined. Since adhesion takes place only at the interface between the component and the adhesive, it is evident that surface preparation or chemical pretreatment has a crucial bearing on the quality of the adhesive bond. 

Similarly because these surface insensitive cyanoacrylates are good general purpose bonders, they are particularly suited to the maintenance sector where the condition of the substrate is not well defined. 

Production limitations. AH adhesives require clean surfaces to attain optimal results. Depending on the type and condition of the substrate and the bond strength desired, surface preparations ranging from a simple solvent wipe to chemical etching are necessary. 

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