{"id":11950,"date":"2023-02-22T16:10:00","date_gmt":"2023-02-22T15:10:00","guid":{"rendered":"http:\/\/pslsystemtechnik.com\/wax-appearance-temperature-wat\/"},"modified":"2025-09-18T12:31:45","modified_gmt":"2025-09-18T10:31:45","slug":"wax-appearance-temperature-wat","status":"publish","type":"post","link":"https:\/\/psl-systemtechnik.com\/en\/wax-appearance-temperature-wat\/","title":{"rendered":"Wax Appearance Temperature WAT"},"content":{"rendered":"\t\t
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Expert Knowledge<\/h4>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Wax appearance temperature WAT<\/h1>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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Definition of wax appearance temperature WAT<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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The Wax Appearance Temperature (WAT)<\/strong> is the temperature at which the first wax crystals form in a crude oil or oil product. The wax crystals initially remain finely dispersed in the liquid as a suspension. The WAT therefore indicates when the first wax crystals form, but it does not indicate at what temperature and in what quantity the wax crystals are deposited on cooler surfaces.<\/p>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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Determination of WAT & WDT<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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Determinaton of WAT of a crude oil, cooling rate 1 \u00b0C\/min, WAT = 23.1 \u00b0C<\/figcaption>\n\t\t\t\t\t\t\t\t\t\t<\/figure>\n\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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The determination of the wax appearance temperature WAT<\/strong> and the wax deposition temperature WDT<\/a> must be carried out as accurately as possible in order to assess the transport stability. The wax appearance temperature of a crude oil or an oil product is independent of the ambient conditions. Wax crystallization is a physical process. The wax deposition temperature, on the other hand, can vary greatly for a product, as it depends on several influencing factors, e.g. temperature difference between liquid and surface, surface properties, flow velocity, etc.<\/p>\n

When determining the wax appearance temperature, the tempering process must be as slow as possible so that the thermal equilibrium state is maintained and crystallization has sufficient time. Cooling too quickly leads to delayed crystallization. The WAT measurement result obtained is then too low and is therefore falsified. The wax deposition temperature, on the other hand, must be determined under realistic ambient conditions during transportation or storage. The different measurement methods therefore consider different parameters.<\/p>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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Measuring methods for detecting the Wax Appearance Temperature (WAT)<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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There are various measurement methods for determining the wax appearance temperature (WAT). The methods differ mainly in terms of accuracy and the time, personnel and equipment required. The required sample quantity is very small for all methods. The following overview is sorted in descending order of accuracy. It contains the Cross Polarization Microscopy CPM, the Cross Polarization Translucency CPT and the Differential Scanning Calorimetry DSC.<\/p>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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Cross Polarization Microscopy CPM<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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The CPM method is a microscopy with polarized light. It uses the effect that wax crystals that form change the plane of polarization of the light and can therefore be detected.<\/p>\n

Specifically, a melted sample is applied as a thin layer to a transmitted light microscope in a tempering cell. Polarization filters 3 are set below and above the sample so that no more light passes through the filter arrangement. This is the case when the polarization planes of the filters are at a 90\u00b0 angle to each other. The light, which would normally pass through the sample unhindered, is now first polarized at the first filter (primary filter), then passes through the sample and reaches the second filter (secondary filter, analyser), where it cannot pass due to the possible vertical plane of oscillation.<\/p>\n

The CPM makes use of the fact that crystals in solutions can rotate the plane of polarization of light, i.e. change it (optical anisotropy). If crystals are formed when the sample cools down, these crystals rotate the plane of oscillation of the polarized light. Points of light now appear in the previously dark secondary filter at the points where wax crystals are located. The first appearance of these points of light represents the wax appearance temperature. Due to the high magnification of the microscope, even the smallest crystals are clearly visible. This method is very accurate, but also time-consuming and labor-intensive, as it usually involves direct optical observation.<\/p>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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Advantages and disadvantages of the CPM method<\/h4>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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Advantages<\/h5>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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