Aspects of the connection and restoration of polymeric pipelines for gas transport with the use of coupling and glue technologies based on heat-shrink couplings and glue compositions formed from epoxy polymers are analyzed. The effectiveness of epoxy glue compositions and the method for their ultrasonic modification is substantiated. It is noted that effective ultrasonic treatment makes it possible to enhance deformationstrength and adhesion characteristics of the polymeric composites obtained, which can be used for the repair and restoration of polymeric pipelines, and to reduce the level of residual stress in these pipelines, and lengthen their service life.Effective hardware components for the connection and repair of polyethylene (PE) pipelines using ultrasonic (US) modification and heat shrinkage are examined in a round of papers consisting of five parts.Among other things, characteristic features of the molding of epoxy repair couplings, which have a heat-shrinkage effect, are examined using low-frequency US-modification (Part 1), the effectiveness of production bases and equipment developed for repair of PE pipelines using US is investigated (Parts 2 and 3), characteristics of the connection of PE pipes with heat-shrinking epoxy-polymer (EP)-based couplings and with glass-cloth strips are brought to light (Part 4), and characteristics of the use of temperature-sensitive-resistor couplings for repair of PE pipes are analyzed (Part 5). The results presented are based on those of referenced investigations [1, 2] and on familiar technical solutions [3]. Problems of the Connection and Restoration of Polymeric Pipelines Used for Gas TransportIn addition to gas lines, polymeric, and, to wit, small-diameter (to 220 mm) PE gas lines are currently coming into ever-increasing use owing to their longevity (up to 50 years), and corrosion resistance.Restoration of damaged sections is one of the most important problems concerning pipeline operation [4]. Coupling and glue technologies, which offer a number of advantages over welding, are widely used for this purpose. Their implementation for polymeric, especially PE pipelines, is a complex technical problem [4].Thus, a number of pipelines, which have been assembled using polymeric glues, are operating successfully in Russia and other countries [5,6]. Analysis of the properties of familiar glues for the gluing of metals indicates that epoxy glue compositions (EGC) are being called upon all the more for these purposes [7,8].

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Production bases developed for the molding of epoxy repair couplings with shape memory are described. It is established that maximum deformation of tubular blanks of the epoxy polymers under investigation, which had not been exposed to ultrasonic vibrations, did not lead to their failure and amounted to no less than 15-17%. Variation in the strength of heat-shrinking couplings based on epoxy compositions is studied as a function of the parameters of their ultrasonic treatment. Effective regime parameters for the ultrasonic treatment, which contribute to maximum strain hardening of the couplings with retention of an acceptable degree of their deformation, are presented.The production bases developed by Kolosov et al. [1,2] and examined below are a refinement of the familiar technology based on the method of producing heat-shrinking articles [3]. This method includes preparation of an initial blank by casting liquid, anhydride-hardened, epoxy polymers (EP) in appropriate molds, heating of the blank to the point of its transformation to a highly elastic state, and its deformation in a highly elastic state with subsequent cooling and retention of its stress state [4].The familiar technology based on the method outlined in [3] does not provide a sufficient safety factor for heatshrinking articles formed from EP in connection with incomplete realization of the strength and engineering properties of epoxy oligomers (EO). When the method described in [3] is used, therefore, additional operations involving banding (underwinding) of the glued-coupling connection obtained with a fiberglass tape is often required as a result of inadequate strength of the couplings so formed.Let us examine production bases for the formation of epoxy repair couplings with shape memory. Useable MaterialsAs in the method outlined in [3], a mixture of liquid and elastic components was used as the basic epoxy composition (EC) in the production bases that we have developed. As a rigid component, we used a complex aromatic diglycidyl ether in the form of a Grade UP-640 resin, which is produced in accordance with regulations established by the Ukrainian Research Institute of Plastics (UkrNIIPM in Donetsk). A block oligomer (BO) formed from aliphatic EO and an acid oligomer in the form of a modified Grade UP-599 EO (Technical Specification TU 6-05-1869-79) was employed as the elastic component. The ratio of the weight of the rigid to the elastic component was 3:2, respectively [5].

An approach to determination of geometric parameters of corrugated tubular articles, which makes it possible to relate structurally assigned parameters of the corrugation layout to the thickness of the product being extruded with the geometric profile dimensions of the corrugation being shaped, is proposed. Cases of free shaping of the arch of the corrugation, shaping of high-profile corrugations with inclined walls, and shaping of a low-profile corrugation are examined. Generalization is offered for any types of corrugated tubular articles.Various aspects of the profile shaping of two-layer corrugated tubular articles (CTA) are discussed in a series of papers issued in three parts.Part 1 describes results of modeling of the parameters of various corrugation profiles, and the equipment used to shape them by establishing the interrelation between the parameters of various corrugation profiles by the method of pneumatic-vacuum shaping, and the structural dimensions of the forming recess of the corrugation machine and the geometric dimensions of the blank being extruded.Part 2 examines characteristic features of the modeling of the extrusion fusing of CTA layers by defining a physical and mathematical model of the production process of the extrusion fusing of layers of a corrugate tubular article, and also the cooling of its various sections.Part 3 analyzes certain aspects of the extrusion shaping of polymeric blanks for the production of CTA. Production of the first CTA dates back to the late 1950s. As compared with smooth tubes, their design makes it possible to attain the radial stiffness and excellent longitudinal flexibility required. Initially, CTA were developed for electrical-engineering demands; they have, however, also become useful in other spheres of application.Use of CTA as draining articles has permitted a significant expansion of their range of application. CTA are used in the chemical and petroleum-gas fields, machine building, agriculture, and communal farming, and also in everyday life [1][2][3][4].Owing to refinement of the fabrication process and expansion of the list of articles produced, polymeric CTA are coming into use where steel and reinforced had previously been employed. Today, approximately one-fourth of the total number of tubes produced in the world are polymeric tubes, and of them, approximately 50% are CTA [2].

Problem situations are analyzed for the basic production cycle of preparing reinforced objects of composite epoxy polymers. The expedience of using ultrasonic modification in order to achieve energy saving and improve object quality is substantiated.In industrial countries of the CIS there is manufacture of cast and impregnated epoxy oligomers (EO) and epoxy resins, classified as a class thermosetting plastics (more than 40 grades). Most widespread are epoxydiane resins, whose proportion within the overall volume of thermosetting plastics is more than 90%. New types of epoxypolymers (EP) and hardeners for them [1][2][3] are being rapidly worked out, for which more than one hundred grades have been developed.EO and epoxy binders (EB) based on them are used extensively in the production of thermosetting polymer composite materials PCM), they are used successfully in chemical, and oil and gas engineering, during building reconstruction and repair, restoration and reinforcement of building structures, installation of joints for assembly elements, and in structure protection from action of the environment [1].The main tendency in the PCM industry now involves not so much development of new polymers, but modification of known materials used for their manufacture [1]. Modifications regulating the structure, and connected with this polymer properties at different levels of a production process for improving production and operating properties of epoxy composite materials, i.e., in order to improve life, reduce viscosity, improve deformation and strength properties, heat-, bio-, and chemical-resistance, increase dielectric properties, reduce combustibility, and improve economic indices (reduce EO consumption, reduce their cost, and utilize production waste).Therefore, it is important to study effective modification methods (both chemical, physical, and physicochemical) within a basic production cycle for preparation of reinforced fiber fillers (FF) for objects of composite EP in order to improve their production and operating properties.The aim of this study is analysis of the expediency of using physical modification (contact ultrasonic action) within the basic production cycle for preparing reinforced objects based on FF and composite epoxy polymers (EP) in order to improve the properties of objects obtained with simultaneous achievement of saving energy during their preparation.Features of Liquid Epoxy Composite Physical Modification. Physical methods for modifying EP are heat treatment, beam methods, vacuum-compressor finishing, periodic deformation, and treatment of polymers in electric and magnetic fields, etc.[1].