LOW VISCOSITY SEALANT TO PREVENT CORROSION UNDER INSULATION

Abstract

A cellular glass system for the exterior surface of a pipe or vessel. The insulation system has an outer and an inner surface and is composed of cellular glass segments. A sealant is provided at the interface between the individual cellular glass segments and is configured to limit water intrusion and prevent corrosion.

Description

LOW VISCOSITY SEALANT TO PREVENT CORROSION UNDER INSULATION Cross-reference to related applications This application claims priority and the benefit of U.S. Provisional Application Number 62 / 893,882, filed on August 30, 2019, the full content of which is incorporated herein by reference. Field of invention The present invention relates to insulation systems for pipes and vessels, and more particularly to systems that prevent problems associated with corrosion occurring between the insulation and the underlying metal surfaces. Background of the invention Conventional pipe insulation can be made from a variety of materials ranging from flexible materials such as plastics and foam rubber to those that are more rigid such as thermoset plastics and cellular glass. Cellular glass can be manufactured in sections to insulate industrial and commercial pipes or vessels. Cellular glass is a preferred choice for certain insulation applications due to its ability to maintain its shape under strenuous conditions and its closed-cell composition, which makes it vapor-impermeable. While insulation in these applications provides the necessary purpose of energy conservation or process control, other problems can arise. For example, corrosion under insulation (CUI) can occur under insulation where moisture has become trapped or has been allowed to migrate between the insulation and the pipe or vessel, which is typically made of metal. The temperature range for CUI generally occurs between 0°C and 204.44°C (32°F and 400°F). This includes liquid water that becomes trapped under the insulation and has not been allowed to evaporate or be removed from the system. Therefore, there is a need for an insulation system that can provide adequate insulation to the pipes and vessels but also prevent corrosion along the insulation and the metal interface. Brief description of the invention The general inventive concepts are based, in part, on the discovery that conventional, higher-viscosity sealants, combined with the sealant's application area, can allow unwanted water infiltration between the pipe and cellular glass insulation systems. During conventional installation, higher-viscosity sealants may not be installed correctly, and the sealant does not compress sufficiently to efficiently reduce or eliminate the gap between the pipe or vessel and the insulation. Lower-viscosity sealants, on the other hand, can be compressed to a greater extent, creating a larger surface area coverage. The lower-viscosity sealant allows for both a better seal against moisture ingress and a tighter insulation joint, limiting thermal break.Furthermore, by initially applying the sealant to the inner portion of a side joint section (at the interface between the tube bore and the side joint section), the lower viscosity sealant is forced into the tube bore interface, creating an additional seal between the tube and the cellular glass insulation. Applying the sealant to the interface between the insulation and the tube or the vessel interface creates a compartmentalized insulation system that greatly inhibits water and moisture migration should the system be compromised. In certain exemplary embodiments, the general inventive concepts include a cellular glass insulation system. The cellular glass insulation system comprises a plurality of cellular glass insulation segments and a low-viscosity sealant. The cellular glass insulation segments comprise a length, side joint sections, an inner tube bore, and end joint sections. The low-viscosity sealant is applied along the length of the cellular glass insulation segment at an interface between the side joint section and the inner tube bore. In the case of a vessel or tank, the sealant is applied in the same manner. In certain exemplary embodiments, the general inventive concepts contemplate a method for insulating a tube. The method comprises providing a cellular glass insulation segment and a low-viscosity sealant, the cellular glass insulation segment comprising a length, an inner tube orifice or vessel surface, side-seal sections extending along the cellular glass insulation segment between the inner tube orifice and an exterior of the cellular glass insulation segment, and end-seal sections; applying the low-viscosity sealant along an interface between the inner tube orifice and at least one side-seal section; and positioning the cellular glass insulation system around the exterior of a tube. Other aspects and features of general inventive concepts will become more evident to those skilled in the art after reviewing the following description of several exemplary forms together with the accompanying figures. Brief description of the drawings The general inventive concepts, as well as their modalities and advantages, are described in more detail below, by way of example, with reference to the drawings in which: Figure 1 shows an illustration of a segment of conventional cellular glass insulation. Figure 2 shows an example of a conventional cellular glass insulation placed around a tube. Figure 3 shows a modality of a cellular glass insulation system placed cr Lznn / zznz / B / Yi around a tube according to the general inventive concepts. Figure 4 shows a modality of a cellular glass insulation segment with low viscosity sealant applied thereto according to a modality of the general inventive concepts. Detailed description of the invention Several illustrative embodiments will be described in detail, with the understanding that this disclosure merely exemplifies the general inventive concepts. The embodiments encompassed by the general inventive concepts can take various forms, and the general inventive concepts are not intended to be limited to the specific embodiments described herein. Although various exemplary embodiments are described or suggested in this document, other exemplary embodiments that use a variety of methods and materials similar or equivalent to those described or suggested herein are encompassed by the general concepts of the invention. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the invention pertains. In this respect, unless otherwise stated, the concentrations of ingredients given herein refer to the concentrations of these ingredients in the master batch or concentrate, in accordance with customary practice. The term "low viscosity," as used herein, refers to a sealant having a lower viscosity than those conventionally used in pipe and vessel insulation applications. The viscosities stated herein are measured with an RV-7 spindle at 10 revolutions per minute. Typically, sealants for pipe and vessel insulation have a viscosity above approximately 400,000 cPoise, which would be considered a higher viscosity sealant for the purposes of the general inventive concepts. In general, low viscosity sealants according to the general inventive concepts include those having a viscosity below approximately 300,000 cPoise, but this is highly dependent on the sealant composition. In certain exemplary embodiments, the sealant must be designed so that a 0.635 mm (1 / 4 inch) wide sealant bead permits less sag in the 0.508 mm (0.2 in) to 2.524 cm (1 in) when placed on a vertical surface. Thus, the sealant must have a very low viscosity but also a body suitable to allow the installer to apply the low-viscosity sealant to a surface and have adequate time to install the insulation without the sealant flaking off the application surface. Examples of suitable sealants include butyls, silicones, polyurethanes, polysulfides, and silane-modified polymers. The viscosity referenced herein is for newly manufactured sealants. Technicians in the art will recognize that the viscosity of a sealant, in accordance with general inventive concepts, will tend to vary over time and will generally increase. Thus, the preferred viscosity referenced herein may increase by 100,000 cPoise or more during the expected service life of the sealant.The terms "not stored" and "freshly manufactured products" with respect to low viscosity sealants refer to the manufacturer's viscosity measurement or a measurement taken after a short period of time after the original manufacture. General inventive concepts relate to systems and methods for insulating a pipe or similar structure. Moisture intrusion into an insulation system can cause significant complications for an industrial facility or building owner. In particular, water ingress can promote corrosion beneath the insulation and degrade the system's desired insulating properties. Corrosion under insulation (CUI) is a major problem in systems operating at temperatures where liquid water can exist. For example, even high-temperature equipment can exhibit CUI when liquid water circulates over the equipment's surface during system shutdowns or cycling. CUI is particularly aggressive in above-ambient systems (e.g., those operating above 65.556°C–76.667°C (150°F–170°F)). In the case of cellular glass, corrosion results from moisture penetrating the spaces between the cellular glass joints. To prevent corrosion under insulation and the degradation of thermal characteristics, an effective insulation system must prevent water intrusion into the system and also onto the surface of the pipe or vessel. If water infiltrates the sealed system (due to damage or other circumstances), the insulation system must still be able to contain / isolate the ingress of moisture to prevent further damage. Cellular glass is a non-porous, closed-cell foam material with a rigid structure and zero water permeability. This low permeability means that cellular glass will not allow water to enter a properly sealed system. Because cellular glass is inflexible, to create custom insulating products, it must be formed into manufactured sections (e.g., halves, quarter sections, or segments) that are placed around the outside of the pipe. For larger vessels, manufacturing may not be required for the larger diameter of the structures. Because it is a watertight, closed-cell foam, water does not penetrate the cellular glass structure.Therefore, any water at the interface between the pipe and the cellular glass is the result of infiltration through the joints between the cellular glass segments or into an opening between the pipe or vessel and the insulation, such as a termination. While general inventive concepts are applicable to a variety of insulation systems, cellular glass for use according to these concepts is characterized by stable thermal conductivity that does not change substantially when exposed to high humidity environments. Cellular glass insulation is uniquely characterized within the insulation market because the product uses an insulating cell gas composition that cannot escape from the glass structure. Thus, cellular glass is unique in that its thermal conductivity remains constant even when exposed to moisture. This constant thermal conductivity and impermeability can only be compromised by physically altering the product through mechanical means or a similar process. Figure 1 shows an exemplary segment of cellular glass tube insulation 100. Although the segment is illustrated herein as quarter-and-a-half segments, those skilled in the art will understand that a variety of segment combinations are contemplated and would be suitable for the general inventive concepts. Accordingly, the general inventive concepts are not intended to be limited to the specific embodiments described herein. The cellular glass tube insulation is defined by a length L, side joint sections 110, an inner tube bore 120, and end joint sections 130. The inner tube bore defines the area in which the tube will be placed between the cellular glass tube insulation segments and is adapted to fit around an arc of the outside of the tube.The end joint sections are substantially flat and extend along the length of the cellular glass tube insulation segment between the inner tube bore and the outer cellular glass tube insulation segment. During installation, the individual insulation segments are placed around the tube, and sealant is applied along the end joint sections. Figure 2 shows a conventional cellular glass tube insulation system. In this configuration, the 300 tube is substantially surrounded by two 200 cellular glass insulation segments. The interface where the foam glass segments meet is with a sealant 400. The sealant is traditionally a higher viscosity sealant (e.g., above approximately 400,000 cPoise). A higher viscosity sealant is typically used because high body and non-sag properties are advantageous in other markets requiring sealing. For example, many applications require filling and sealing gaps, and therefore low viscosity / low sag sealants are essential.Because the purpose of sealant is to close the joint between adjacent foam glass segments, it is generally applied to the joint sections, which are then joined around the tube, compressing the sealant between the insulation segments. Furthermore, a lower viscosity sealant must penetrate the fine cell structure of the cellular glass surface to provide a watertight seal. The cell structure of the cellular glass is generally less than 2 mm per cell, and a lower viscosity sealant can more easily penetrate the surface of the cell structure. The purpose of the sealant is to bond the individual foam glass segments and form a barrier to prevent water ingress at the joints. However, the use of high viscosity sealants has been shown to cause unwanted thermal break separation between the cellular glass and the tube itself. Conversely, Figure 3 shows a pipe insulation system according to the general inventive concepts. As in the conventional process, the pipe is substantially surrounded by two segments of cellular glass insulation. These segments are placed around the pipe 300 with a sealant 410 positioned at the interfaces between the two segments. The inventive concepts involve providing the sealant on the inner portion of the side joint section 310, closest to the inner pipe opening 320. The sealant is then compressed during installation, forcing it into the dual interface between the pipe and the individual segments. As can be seen in the figure, applying the sealant to the inner area of ​​the joint section allows the sealant to be compressed in contact with the outer arc of the pipe, in addition to bringing the two insulation segments into contact.The additional compression of the joints shown in Figure 3 will allow for a very thin joint that has a very small separation or space between adjacent pieces of insulation and also has a superior filling of the insulation cells that are within the sealed joint. Figure 4 shows an exemplary embodiment of a cellular glass insulation segment according to the general inventive concepts prior to installation around a pipe. Low-viscosity sealant 410 is substantially applied along the interface between the side joint section and the inner pipe bore 320. The low-viscosity sealant is also applied to the end joint section 330. In this way, insulation segments placed approximately one pipe length apart are sealed together by applying and compressing the low-viscosity sealant, and adjacent lengths of pipe insulation are also sealed together to prevent CUI (Cellular Insulation Unit). The sealant in Figure 4 is shown applied in a bead, but it can also be further smoothed with a trowel or applied directly to the surface with a trowel or similar tool. While not limited to theory, it is believed that this increased contact between the sealant and the pipe provides a more effective seal (and watertightness) to the pipe insulation system. This has the dual benefit of increasing overall watertightness and isolating any corrosion that may develop. The improved seal also provides a strong mechanical bond between adjacent pieces of sealed insulation and the pipe or vessel substrate. Consequently, the general inventive concepts are based, in part, on the dual findings that higher viscosity sealants, combined with the sealant's application area, allowed unwanted water infiltration between the tube and the cellular glass. Despite the well-accepted consensus that higher viscosity sealants would perform better, they did not compress in a way that efficiently reduced or eliminated the gap between the tube and the insulation. Lower viscosity sealants, on the other hand, can be more easily compressed to a greater extent to create a larger surface area coverage for the sealant.In addition, by initially applying the sealant to the inner portion of the side joint section (at the interface between the tube hole and the side joint section), the lower viscosity sealant is forced into the tube hole, creating an additional seal between the tube and the cellular glass insulation, further preventing water intrusion. In certain exemplary embodiments, the cellular glass insulation system comprises a plurality of cellular glass insulation segments and a low-viscosity sealant. In certain exemplary embodiments, the low-viscosity sealant has a viscosity below approximately 300,000 cPoise but also exhibits low sag when applied to a vertical surface. In certain exemplary embodiments, the low-viscosity sealant has a viscosity below approximately 275,000 cPoise. In certain exemplary embodiments, the low-viscosity sealant has a viscosity below approximately 250,000 cPoise. In certain exemplary embodiments, the low-viscosity sealant has a viscosity below approximately 225,000 cPoise. In certain exemplary embodiments, the low-viscosity sealant has a viscosity below approximately 200,000 cPoise.In certain exemplary formulations, the low-viscosity sealant has a viscosity of approximately 80,000 to approximately 200,000 cPoise. In certain exemplary formulations, the low-viscosity sealant has a viscosity of approximately 80,000 to approximately 225,000 cPoise. In certain exemplary formulations, the low-viscosity sealant has a viscosity of approximately 80,000 to approximately 250,000 cPoise. In certain exemplary formulations, the low-viscosity sealant has a viscosity of approximately 80,000 to approximately 275,000 cPoise. In certain exemplary formulations, the low-viscosity sealant has a viscosity of approximately 80,000 to approximately 300,000 cPoise. However, the lower limit of the sealant is highly variable depending on the sealant fillers and other modifiers such as plasticizers. As mentioned, the general inventive concepts contemplate a method for insulating a tube. The method comprises providing a cellular glass insulation segment and a low-viscosity sealant. The cellular glass insulation segment comprises a length and an inner tube bore, and side joint sections extending the length of the cellular glass insulation segment between the inner tube bore and the outside of the cellular glass insulation segment. The sealant is applied along an interface between the inner tube bore and at least one section of the side joint. The cellular glass insulation system is placed on the outside of a tube. In certain exemplary embodiments, the low-viscosity sealant is also applied to a section of the end joint of the cellular glass insulation segment. All references to singular features or limitations in this disclosure cr Lznn / zznz / B / Yi shall include the corresponding plural feature or limitation, and vice versa, unless otherwise specified or clearly implied by the context in which the reference is made. All combinations of method or process steps as used herein may be performed in any order, unless otherwise specified or clearly implied by the context in which the referenced combination is performed. It is understood that all intervals and parameters, including but not limited to percentages, parts, and proportions, disclosed herein encompass each and every subinterval assumed and subsumed herein, and every number between the endpoints. For example, a given interval of 1 to 10 is to be considered to include each and every subinterval between (and inclusive of) the minimum value of 1 and the maximum value of 10; that is, all subintervals that begin with a minimum value of 1 or more (e.g., 1 to 6.1) and end with a maximum value of 10 or less (e.g., 2.3 to 9.4, 3 to 8, 4 to 7), and finally every number 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 contained within the interval. The cellular glass compositions and related methods of this disclosure may comprise, consist of, or essentially consist of the essential elements and limitations of the disclosure as described herein, as well as any additional or optional ingredients, components, or limitations described herein or otherwise useful in foam glass composition applications. The cellular glass compositions in this disclosure may also be substantially free of any optional or selected ingredient or feature described herein, provided that the remaining composition still contains all the required elements or features as described herein. In this context, and unless otherwise specified, the term substantially free means that the selected composition contains less than a functional amount of the optional ingredient, typically less than 0.1% by weight, and also includes zero percent by weight of such optional ingredient or selected essential ingredient. To the extent the terms include, encompasses, or that encompasses are used in the specification or the claims, they are intended to be inclusive in a manner similar to the term comprising as defined when used as a transitional word in a claim. Furthermore, to the extent the term or (e.g., A or B) is used, it is intended to mean A or B or both A and B. Where the applicant intends to indicate only A or B but not both, then the term A or B but not both shall be used. Therefore, the use of the term or herein is the inclusive, not exclusive, use. In this disclosure, the words a or one are to be taken to include both the singular and the plural. Conversely, any reference to plural items shall include, where applicable, the singular. In some embodiments, it may be possible to use the various inventive concepts in combination with each other. Furthermore, any particular element described in connection with a particular disclosed embodiment should be interpreted as available for use with all five disclosed embodiments, unless the incorporation of the particular element contradicts the express terms of the embodiment. The additional advantages and modifications will be readily apparent to those skilled in the art. Therefore, the disclosure, in its broadest sense, is not limited to the specific details presented herein, the representative apparatus, or the illustrative examples shown and described. Consequently, deviations from such details may be made without departing from the essence or scope of the general inventive concepts. Although the invention has been illustrated and described in detail in the drawings and description above, this should be considered illustrative and not restrictive. It should be understood that only exemplary embodiments have been shown and described, and that it is intended to protect all changes and modifications that are essential to the invention.

Claims

1. A cellular glass insulation system comprising a plurality of cellular glass insulation segments and a low-viscosity sealant, wherein the cellular glass insulation segments have a length, side joint sections, an inner tube hole, and end joint sections, wherein the low-viscosity sealant is positioned along the cellular glass insulation segment at an interface between the side joint section and the inner tube hole.

2. The cellular glass insulation system according to claim 1, wherein the low viscosity sealant has a viscosity of less than 300,000 cPoise of the freshly manufactured, unstored product.

3. The cellular glass insulation system according to claim 1, wherein the low viscosity sealant has a viscosity of less than 200,000 cPoise of the freshly manufactured, unstored product.

4. The cellular glass insulation system according to claim 1, wherein the low viscosity sealant has a viscosity of 300,000 cPoise to 80,000 cPoise of the freshly manufactured, unstored product.

5. The cellular glass insulation system according to claim 1, wherein the low viscosity sealant has a viscosity of 200,000 cPoise to 80,000 cPoise of the freshly manufactured, unstored product.

6. The cellular glass insulation system according to claim 1, wherein the low viscosity sealant is compressed into an interface between the tube and the inner tube orifice.

7. The cellular glass insulation system according to claim 1, wherein the cellular glass has a thermal conductivity that, due to the enclosed insulating gases, does not degrade over time or exposure to ambient humidity.

8. A method for insulating a tube, the method comprising providing a first cellular glass insulation segment, a second cellular glass segment, and a low-viscosity sealant, each of the cellular glass insulation segments having a length, an inner tube hole, side joint sections extending along the cellular glass insulation segment between the inner tube hole and an outer surface of the cellular glass insulation segment of at least one of the glass insulation segments; applying the low-viscosity sealant along an interface between the inner tube hole or container and at least one side joint section; placing the cellular glass insulation segments on the outside of a tube or container.

9. The method according to claim 8, further comprising applying the low viscosity sealant to an end joint section of at least one of the cellular glass insulation segments.

10. The method according to claim 8, further comprising pressing the cellular glass insulation segments to compress the sealant at an interface between the tube and the inner tube orifice.

11. The method according to claim 8, wherein the low viscosity sealant is applied along the entire length of at least one side joint section of at least one of the cellular glass segments.

12. The method according to claim 8, wherein low viscosity sealant is applied along each side joint section.

13. The method according to claim 8, wherein the low viscosity sealant has a viscosity of less than 300,000 cPoise.

14. The method according to claim 8, wherein the low viscosity sealant has a viscosity of less than 200,000 cPoise.

15. The method according to claim 8, wherein the low viscosity sealant has a viscosity of 300,000 cPoise to 80,000 cPoise.

16. The method according to claim 8, wherein the low viscosity sealant has a viscosity of 200,000 cPoise to 80,000 cPoise.

17. The method according to claim 8, wherein the cellular glass has a non-storable thermal conductivity ranging from 0.2 to 0.5 BTU cm (in) / h m2 (ft2)F measured at 24C.

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