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  • 1.
    Bergström, Gunnar
    Göteborg (BMg).
    Fuktdiffusion i plaströrssystem2002Report (Refereed)
  • 2.
    Bergström, Gunnar
    Göteborg (BMg).
    Isocyanaterexponering vid svetsning av fjärrvärmerör2002Report (Refereed)
  • 3.
    Bergström, Gunnar
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Göteborg (BMg).
    Flansbjer, Mathias
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Karlsson, Linda
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Sällberg, Sven-Erik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Göteborg (BMg).
    Thörnblom, Kristian
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Göteborg (BMg).
    Acceptanskriterier för repor och intryck i plaströr2009Report (Other (popular science, discussion, etc.))
  • 4.
    Bergström, Gunnar
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Göteborg (BMg).
    Flansbjer, Mathias
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Karlsson, Linda
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Sällberg, Sven-Erik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Göteborg (BMg).
    Thörnblom, Kristian
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Göteborg (BMg).
    Acceptanskriterier för repor och intryck i plaströr Accpetance criteria for scratches and indentations in plastic pipes2009Report (Refereed)
    Abstract [sv]

    Development of materials and laying techniques have arisen the question how scratches and indentations in plastics pipes affect the strength and technical lifetime of pipelines. Scratches may occur both in the manufacturing of the pipes, in connection with the installation and subsequent maintenance. The problems in assessing the failure risk from scratches and indentations are similar for pipes used in gas and water distribution and in district heating applications. Therefore, a broad effort to identify the risks in relation to current pipe materials is technically and economically justified. The project has aimed to evaluate the effect of scratches and indentations on the technical lifetime of plastics pipes and to present criteria for maximum allowable depth of scratches and indentations. The study on pressure pipes focused on the conditions for scratched polyethylene pipes to achieve a lifetime of 50 years. It is noted that a scratch damage can not be judged solely on the basis of its depth and sharpness. To assess the impact of the scratch on the serviceability of the pipe, consideration must also be taken to the material from which the pipe was made and the safety factor used in the design. Extensive pressure tests show that pipes made of modern materials can withstand surface scratches to a higher degree than pipes of older materials. For pipes made of modern bimodal PE80 and PE100 materials, scratches up to 10% depth may be accepted without reduction of rated pressure. However, for pipes of older material, a reduction in pressure may be required already at smaller scratches. The study also indicates that for the same relative scratch depth, a greater reduction in pressure is required with increasing pipe dimension. The study on the non pressure pipes shows that the studied polypropylene pipes resist both deep scratches combined with ovalization and large indentations without any cracks penetrating the pipe wall. However, the extent and development of crazing and surface cracking vary with scratch depth, deformation level and material. The test pipes were subjected to extreme conditions very rarely or never occurring in practice. This suggests that small scratches at moderate ovalization and realistic indentations in temperatures around room temperature do not affect the lifetime of the pipes. One objective of the project was to develop a method for the evaluation of the scratch resistance of a pipe. In the proposed test method the force needed to produce a specified scratch is measured. This force is used as a relative measure of the scratch resistance of a pipe material when compared to other materials. In order to assess to what extent a scratch affects the lifetime of the pipe, the depth of the scratch must be estimated with reasonable accuracy. Since the scratch in many cases is found on existing pipelines the method must be suited for field use. To achieve that a simple instrument for scratch depth measurements was made and evaluated.

  • 5.
    Bergström, Gunnar
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Göteborg (BMg).
    Flansbjer, Mathias
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Karlsson, Linda
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Sällberg, Sven-Erik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Göteborg (BMg).
    Thörnblom, Kristian
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Göteborg (BMg).
    Accpetance criteria for scratches and indentations in plastic pipes2009Report (Refereed)
    Abstract [sv]

    Development of materials and laying techniques have arisen the question how scratches and indentations in plastics pipes affect the strength and technical lifetime of pipelines. Scratches may occur both in the manufacturing of the pipes, in connection with the installation and subsequent maintenance. The problems in assessing the failure risk from scratches and indentations are similar for pipes used in gas and water distribution and in district heating applications. Therefore, a broad effort to identify the risks in relation to current pipe materials is technically and economically justified. The project has aimed to evaluate the effect of scratches and indentations on the technical lifetime of plastics pipes and to present criteria for maximum allowable depth of scratches and indentations. The study on pressure pipes focused on the conditions for scratched polyethylene pipes to achieve a lifetime of 50 years. It is noted that a scratch damage can not be judged solely on the basis of its depth and sharpness. To assess the impact of the scratch on the serviceability of the pipe, consideration must also be taken to the material from which the pipe was made and the safety factor used in the design. Extensive pressure tests show that pipes made of modern materials can withstand surface scratches to a higher degree than pipes of older materials. For pipes made of modern bimodal PE80 and PE100 materials, scratches up to 10% depth may be accepted without reduction of rated pressure. However, for pipes of older material, a reduction in pressure may be required already at smaller scratches. The study also indicates that for the same relative scratch depth, a greater reduction in pressure is required with increasing pipe dimension. The study on the non pressure pipes shows that the studied polypropylene pipes resist both deep scratches combined with ovalization and large indentations without any cracks penetrating the pipe wall. However, the extent and development of crazing and surface cracking vary with scratch depth, deformation level and material. The test pipes were subjected to extreme conditions very rarely or never occurring in practice. This suggests that small scratches at moderate ovalization and realistic indentations in temperatures around room temperature do not affect the lifetime of the pipes. One objective of the project was to develop a method for the evaluation of the scratch resistance of a pipe. In the proposed test method the force needed to produce a specified scratch is measured. This force is used as a relative measure of the scratch resistance of a pipe material when compared to other materials. In order to assess to what extent a scratch affects the lifetime of the pipe, the depth of the scratch must be estimated with reasonable accuracy. Since the scratch in many cases is found on existing pipelines the method must be suited for field use. To achieve that a simple instrument for scratch depth measurements was made and evaluated.

  • 6.
    Bergström, Gunnar
    et al.
    Göteborg (BMg).
    Forsaeus Nilsson, Stefan
    Göteborg (BMg).
    Direktförlagda böjar i fjärrvärmeledningar - Påkänningar och skadegränser2001Report (Refereed)
  • 7.
    Bergström, Gunnar
    et al.
    Göteborg (BMg).
    Forsaeus Nilsson, Stefan
    Göteborg (BMg).
    Groundwater leakage in pipe joints due to temperature variations2002In: Euroheat & Power, ISSN 0949-166X, Vol. 31, no 1, p. 54-58Article in journal (Other academic)
  • 8.
    Bergström, Gunnar
    et al.
    Göteborg (BMg).
    Forsaeus Nilsson, Stefan
    Göteborg (BMg).
    Sällberg, Sven-Erik
    Göteborg (BMg).
    Fukttransport i skarvskum2002Report (Refereed)
  • 9.
    Bergström, Gunnar
    et al.
    Göteborg (BMg).
    Forsaeus Nilsson, Stefan
    Göteborg (BMg).
    Sällberg, Sven-Erik
    Göteborg (BMg).
    Tightness of joints in coarse grained backfill material2002Conference paper (Other academic)
  • 10.
    Bergström, Gunnar
    et al.
    Göteborg (BMg).
    Forsaeus Nilsson, Stefan
    Göteborg (BMg).
    Sällberg, Sven-Erik
    Göteborg (BMg).
    Utvändigt skydd hos fjärrvärmerörsskarvar2002Report (Refereed)
  • 11.
    Bergström, Gunnar
    et al.
    Göteborg (BMg).
    Forsaeus Nilsson, Stefan
    Göteborg (BMg).
    Sällberg, Sven-Erik
    Göteborg (BMg).
    Vattenläckage genom otät mantelrörsskarv2001Report (Refereed)
  • 12.
    Forsaeus Nilsson, Stefan
    Göteborg (BMg).
    Sparse district heating in Sweden2008In: Applied Energy, Vol. 85, no 7, p. 555-65Article in journal (Refereed)
  • 13.
    Forsaeus Nilsson, Stefan
    Göteborg (BMg).
    Spröda brott i mantelrör2005Report (Refereed)
  • 14.
    Forsaeus Nilsson, Stefan
    et al.
    Göteborg (BMg).
    Bergström, Gunnar
    Göteborg (BMg).
    Moisture transfer in joints in pre-insulated district heating pipes2002Conference paper (Other academic)
  • 15.
    Forsaeus Nilsson, Stefan
    et al.
    Göteborg (BMg).
    Bergström, Gunnar
    Göteborg (BMg).
    Sällberg, Sven-Erik
    Göteborg (BMg).
    Grund förläggning av fjärrvärmeledningar2006Report (Refereed)
  • 16.
    Forsaeus Nilsson, Stefan
    et al.
    Göteborg (BMg).
    Sällberg, Sven-Erik
    Göteborg (BMg).
    Air-gaps in pipe joints insulated with PUR half-shells.2004In: PROCEEDINGS OF THE 9TH INTERNATIONAL SYMPOSIUM, 2004Conference paper (Other academic)
  • 17.
    Forsaeus Nilsson, Stefan
    et al.
    Göteborg (BMg).
    Sällberg, Sven-Erik
    Göteborg (BMg).
    Repor och intryckningar i trycksatta plaströr - Kunskapsläge2006Report (Refereed)
  • 18.
    Forsaeus Nilsson, Stefan
    et al.
    Göteborg (BMg).
    Sällberg, Sven-Erik
    Göteborg (BMg).
    Bergström, Gunnar
    Göteborg (BMg).
    Fuktmätning med pulsekometer2005Report (Refereed)
  • 19.
    Forsaeus Nilsson, Stefan
    et al.
    Göteborg (BMg).
    Sällberg, Sven-Erik
    Göteborg (BMg).
    Bergström, Gunnar
    Göteborg (BMg).
    Läckagevägar för markvatten i skarvisolering2005Report (Refereed)
  • 20.
    Forsaeus Nilsson, Stefan
    et al.
    Göteborg (BMg).
    Thörnblom, Kristian
    Göteborg (BMg).
    Damage to coated plastics pipes from trenchless laying techniques2006Report (Refereed)
    Abstract [en]

    This project aims at evaluating an external coating on plastics pipes; and its protective function against scratches and scoring damage from trenchless laying techniques. PE100 pressure pipes with four different coatings were tested in horizontal drilling and pipe bursting field trials. During the tests, the lengthwise and cross-sectional deformations of the pipe were measured along with the traction force. The pipes’ surfaces were examined with respect to scratches, and the depth of the most prominent ones were determined. Of the two laying techniques, pipe bursting was the one that caused the deepest scratches. Horizontal drilling was not significantly worse than ordinary handling during transport and preparation with respect to scratch depth. Dragging of the pipe above ground on asphalt surfaces caused severe damage to the pipe wall. The deepest scratches were seen on two pipe selections with soft coatings. Due to their thickness, however, these coatings were not penetrated and thus successfully protected the main pipe wall. The hardest coating tested, made of polypropylene, was also the thinnest one, and it was penetrated at one location during the pipe bursting test. The traction force on the pipe was significantly higher during horizontal drilling than during pipe bursting. On the other hand, ovalisation of the pipe’s cross-section was greater during pipe bursting.

  • 21.
    Forsaeus Nilsson, Stefan
    et al.
    Göteborg (BMg).
    Thörnblom, Kristian
    Göteborg (BMg).
    Skador på skyddsmantlade plaströr vid grävningsfri förläggning2005Report (Refereed)
    Abstract [sv]

    Damage to coated plastics pipes from trenchless laying techniques This project aims at evaluating an external coating on plastics pipes, and its protective function against scratches and scoring damage from trenchless laying techniques. PE100 pressure pipes with four different coatings were tested in horizontal drilling and pipe bursting field-trials. During the tests, the lengthwise and cross-sectional deformations of the pipe were measured along with the traction force. The pipes’ surfaces were examined with respect to scratches, and the depth of the most prominent ones were determined. Of the two laying techniques, pipe bursting was the one causing the deepest scratches. Horizontal drilling was not significantly worse than ordinary handling during transport and preparation with respect to scratch depth. Dragging of the pipe above ground on asphalt surfaces caused severe damage to the pipe wall. The deepest scratches were seen on two pipe alternatives with soft coatings. Due to thic kness, however, these coatings were not penetrated and thus successfully protected the main pipe wall. The hardest coating tested, a polypropylene alternative, were also the thinnest one, and was penetrated at one location during the pipe bursting test. The traction force on the pipe was significantly higher during horizontal drilling than during pipe bursting. On the other hand, ovalisation of the pipe’s cross-section was greater during pipe bursting. Keywords: Horizontal drilling, pipe bursting, polyethylene, coated pipes, scratches

  • 22.
    Forsaeus Nilsson, Stefan
    et al.
    Göteborg (BMg).
    Thörnblom, Kristian
    Göteborg (BMg).
    Sällberg, Sven-Erik
    Göteborg (BMg).
    Bergström, Gunnar
    Göteborg (BMg).
    Durability of Non-Pressure Polypropylene Pipe Materials2007Report (Refereed)
    Abstract [sv]

    For plastics pipes used for underground drainage and sewerage as well as for other nonpressure pipe applications there are at present no internationally accepted methods for the evaluation of the durability of the material. In practice pipe material selection is based upon comparative operational experience of the different materials over a number of years. This means that there are no objective means of assessing new pipe designs and new pipe materials coming onto the market. Reasonably there will be a spread in material qualities with some materials having good properties and some being of lower quality (e.g.recycled materials or materials with very high filler content). Without a recognised testing method it is not possible to rank these alternatives or restrict their use to specific application areas without awaiting the outcome from their use in the field. It is today an established fact that plastics pipes are well suited for underground water and sewer systems due primarily to their flexibility to soil movement and their corrosion resistance. Pipe deflections of up to 10% of the diameter has been shown to be no problem for plastics pipes according to extensive field studies performed by the Teppfa organisation. However, it is also a fact, not so well known, that the stresses in the pipe wall can still be at a relatively high level after 10 or 50 years of use under such conditions. With new pipe structures and possibly lower quality pipe materials, the stresses and strains in the pipe may well exceed the limiting properties of the material and thereby put the reliable function of the pipe system at risk. One main objective of this study has been to look for limiting values of strain for the different materials, above which excessive deformation or failure can occur. The evaluation method presented is based on the use of a range of durability test methods on mainly polypropylene but also on one polyethylene material. The important characteristics studied include the stress relaxation/strainability properties, slow crack growth / notch resistance, thermo-oxidative degradation and environmental stress cracking. The basic properties of the materials are developed by tests on solid wall pipes. The relaxation behaviour of the materials was also modelled and compared using CAED methodology.

  • 23.
    Jacobsson, Lars
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Andersson, Hans
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Sällberg, Sven-Erik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Göteborg (BMg).
    Tightness of flange joints for large polyethylene pipes – Part 2 Full scale experimental investigations2011Report (Refereed)
    Abstract [en]

    Tightness of flange joints for large polyethylene pipes – Part 2 Full scale experimental investigations Leakage that sometimes occurs in flange joints in large size plastic pipelines for water supply is a serious problem. Research was undertaken in order to improve the knowledge about the function of such flange joints. The objectives were partly to find out the degree of sensitivity of the design, i e if small deviations from recommended practise is critical, partly to be able to suggest improved design and mounting procedures. One part of the investigation was a numerical (FEM) study of several geometries, which was reported in [2]. Use of a time-dependent material model made it possible to follow the development of deformations and flange surface pressures for long times. Although several important principal findings were made, the tightening procedure and exact material behaviour could not be modelled. Therefore a series of full-scale experiments were made on 630 mm pipes, for a number of combinations of flange dimension and gasket type. This second part of the research is reported here. Since four of the twenty bolts were instrumented, the bolt forces could be monitored and be related to the torque and to the pressure in the pipe over time. This resulted in novel, important information about the functioning of plastic flange joints. In short, the experiments were performed in the following way. First, the bolts were tightened in the recommended criss-cross fashion to pre-determined torque levels. Then the pressure in the pipe was increased until leakage occurred. For combinations of flanges, gaskets and torques where the joint was tight for pressures above 13 bars, the 13 bar pressure level was maintained for up to one week. The relationship between bolt force and torque does not agree at all with the frequently used rule of thumb formula, for the galvanized bolts used here. The bolt force was typically less than half the value obtained by the formula. Hence it is critical to verify the friction for the used combination of bolt material, surface treatment, and lubrication. The bolt forces also appear to be unevenly distributed, which is partly due to successive creep during the tightening procedure. For the high stresses in the flange creep is significant already for so short times as a few minutes, and the effect is increased by the fact that the bolts and backing rings are much stiffer than the plastic flange. For both the wide and the narrow (ISO) flange type used it appears that rubber gaskets perform better, in the sense that the joint is tight for lower applied torques. The hyper- elastic material properties help to smooth unevenness in the flange surface and to compensate for creep in the plastic. Use of SDR 17 pipes at pressure levels of 13 bars means considerable creep expansion of the pipe, although it is possible to obtain a tight joint. The expansion gives a wringing effect at the flange, also observed in [2], which contributes to concentrate the flange pressure to the outer parts of the flange surface. In summary, flange joints are possible to mount so that they are tight, also for 630 mm pipes. Since the design is a sensitive one it is vital to follow recommendations for 4 mounting of different combinations of flanges and gaskets. In particular, knowledge about the relationship between torque and bolt force is important.

  • 24.
    Jacobsson, Lars
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Andersson, Hans
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Vennetti, Daniel
    Sällberg, Sven-Erik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Göteborg (BMg).
    The functioning of flange joints – findings from full scale experiments and FEM analyses2012In: Proceedings of PPXVI, 2012Conference paper (Refereed)
  • 25.
    Jacobsson, Lars
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Bygg och Mekanik, Strukturer och Komponenter.
    Bergström, Gunnar
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Göteborg (BMg).
    Sällberg, Sven-Erik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Göteborg (BMg).
    Tillfällig avstängning av plaströrsledningar genom sammanklämning - kunskapsläge2014Report (Refereed)
    Abstract [sv]

    Temporary closure of plastic pipes by squeeze-off - state of the art State of the art and present use of squeeze-off methods for temporary closure of polymer pipelines for water and gas was investigated by an enquiry and a literature study. A limited, supplementary series of tests was also performed. The aim was to find, if possible, general limitations for use in terms of temperature at squeezing, pipe dimensions and materials, and to identify important problems that have to be analysed before guidelines can be issued regarding the use of the method. Some producers, suppliers and users in Sweden, were interviewed by the aid of a questionnaire. Although the investigation was limited, the answers are so homogeneous that they are considered representative. The belief is that the technique is harmful. It is used mostly for PE 80 and PE 100 materials and when necessary, e. g. when no valves are available. Decisions and risk assessments are mostly made ad hoc. The performance is according to manuals from producers and suppliers. Design of equipment, geometry, and recommended squeeze rates varies among suppliers. The literature on pipes consists mainly of papers from the 80-ies and 90-ies and from some research groups in the USA. There is a heuristic knowledge about formation and appearance of damage, and to some extent about the influence on service life. Newer research on general damage and fracture in polymers is available that is not related to the specific conditions in squeezed pipes. Such models are lacking, which may be due to the complexity of the area and its hands-on character. The commonly used PE 80 and PE 100 materials are clearly damaged by squeezing, particularly so for high compression levels, but the pipes still fulfil the requirements for use. Stronger and more crystalline materials, and larger pipe sizes, seem to be more severely damaged. It is not known how the damages influence slow crack growth and life. Squeeze-off on PE pipes with external longitudinal scratches should strictly be avoided. Also squeeze-off on PE pipes with PP coating at low temperature should be conducted with precaution until the opposite have been proven as some damage cases were reported. Removing the PP coating is recommended by some in this case. The experiments, on one old PE 80 pipe and two new PE 100 pipes with dimensions from 315 to 355 mm confirm the picture of damage. Commercial equipment was used and according to the supplier’s manual. All the pipes show similar damage, with crack formation and unevenness. Those are less significant for thinner pipe walls than for thicker ones. There is no apparent difference between new and old pipes. A few pressure tests were carried out on the squeezed pipes as well as the untouched pipes. The results show that no significant reduction of the lifetime could be proven regardless when an interrelated comparison between a squeezes and not squeezed pipe was made or when the lifetimes were compared with those obtained in earlier available material classification tests for the actual materials.

  • 26.
    Lundh, Karin
    et al.
    Hållfasthet (BMh).
    Almström, Stefan
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Bergström, Gunnar
    Göteborg (BMg).
    Ageing and wear in polymeric child articles2008Report (Refereed)
    Abstract [sv]

    Ageing and wear in polymeric child articles This report targets child use and care articles, toys and playground equipment. These products will in this report collectively be referred to as ‘child articles’. It is the authors’ experience that polymers are getting more and more frequent in child articles, probably since they are cheaper and in many ways easier to process than metals. This is not an unwanted development in itself, but the choice of material has to be carefully made since the material properties of polymers vary greatly depending on the type and amount of additives and this can not be assessed visually. In addition they degrade with time due to environmental influence. To verify the properties of a polymer the material has to be tested. One of the challenges with polymers is that they all have a limited lifetime. They degrade over time and might lose almost all their strength, leading to material failure and, in the worst case scenario, accidents. It is a fact that accidents happen due to material failure, although it is hard to trace the true cause in accident statistics. In this report the term ‘ageing’ will be used for chemical degradation of the material structure due to light and/or heat exposure and ‘wear’ refers to mechanical degradation as a result of mechanical stress and contact. The current regulation covers property changes in polymers during the lifetime of a product insufficiently, if at all. Ageing of materials is virtually non-existing in existing child article standards. During its life a product is subjected to all kinds of environmental factors which more or less lead to reduction of function of the product. All products get worn, in one way or another, when used and the surrounding environment affects the material of the product. These effects are greater or lesser depending on usage and the harshness of the surrounding environment, as well as material choice and other qualities of the product. Therefore the material and processing have to be chosen based on the knowledge of the environment in which the product will be used as well as the expected lifetime. This process is called environmental design or environmental engineering. In order to simplify the material selection process when a product is developed, it is recommended to compose a material qualification system for child articles. This system can preferably be based on existing systems from other industries. This study recommends that the requirements and test methods proposed in Chapter 5 are considered when new standards for child articles are being developed or when existing standards are being revised. It is also recommended to perform a risk analysis to identify the hazards of a product.

  • 27.
    Puig von Friesen, Marc
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Energi och Bioekonomi, Klimatisering och installationsteknik.
    Arinder, Pernilla
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience, Microbiology.
    Lundin, Maria
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Life Science.
    Yarahmadi, Nazdaneh
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Bygg och Mekanik, Rörcentrum.
    Kjellin, Mikael
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Life Science.
    Kurkinen, Eva-Lotta
    Byggnadsfysik och innemiljö (ETi ).
    Thörnblom, Kristian
    Göteborg (BMg).
    Säkerställa vattenkvalitet vid 45˚C med avseende på Legionella: En förstudie för innovationsupphandling2014Report (Refereed)
  • 28.
    Sällberg, Sven-Erik
    et al.
    Göteborg (BMg).
    Forsaeus Nilsson, Stefan
    Göteborg (BMg).
    Mantelfria fjärrvärmerör2005Report (Refereed)
  • 29.
    Sällberg, Sven-Erik
    et al.
    Göteborg (BMg).
    Forsaeus Nilsson, Stefan
    Göteborg (BMg).
    Bergström, Gunnar
    Göteborg (BMg).
    Thermal performance of water permeable EPS as pipe insulation.2004In: ON DISTRICT HEATING AND COOLING, 2004Conference paper (Other academic)
  • 30.
    Sällberg, Sven-Erik
    et al.
    SP - Sveriges Tekniska Forskningsinstitut / Göteborg (BMg).
    Karlsson, Linda
    SP - Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Hur djupa repor tål ett plaströr?2009In: Svenskt Vatten, no 6, p. 1-Article in journal (Other (popular science, discussion, etc.))
  • 31.
    Sällström, Jan Henrik
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Bygg och Mekanik, Rörcentrum.
    Sällberg, Sven-Erik
    SP - Sveriges Tekniska Forskningsinstitut / Göteborg (BMg).
    Ramnäs, O
    Status assessments of district heating pipes2012Conference paper (Refereed)
    Abstract [en]

    Large parts of the existing pre-fabricated district heating pipe networks are close to reaching their technical life. There is a need to assess the status of the district heating pipes in order to plan maintenance and replacements of pipes. A first step towards developing a simple and cheap method for technical status assessments of existing pipes without shutting the pipes down has been taken. The proposed mechanical field method is based on that the district heating pipes are uncovered and cylindrical samples still attached to the service pipes are created by removing material around them by use of hole drills. Laboratory equipment for pulling or turning the cylindrical samples off, while measuring load and deformation, has been developed.

  • 32.
    Sällström, Jan Henrik
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Bygg och Mekanik, Rörcentrum.
    Thörnblom, Kristian
    SP - Sveriges Tekniska Forskningsinstitut / Göteborg (BMg).
    Andersson, Hans
    SP - Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Bolin, Lisa
    SP - Sveriges Tekniska Forskningsinstitut / Energiteknik (ET).
    Minskning av risken för skador på gasledningar genom djupförläggning och användandet av grävskydd (Reducing the risks for gas pipe damages through deep digging and the use of protective plates)2013Report (Refereed)
    Abstract [sv]

    This report concerns part 2 of a project with the aim to propose protective measures for cables and pipelines for bio and natural gas. Part 1 was previously reported in SGC Rapport 2011:239. The wish is to be able to increase the pressure in the distribution networks from 4 to 10 bar without having to retain the safety distances valid for 80 bar pipelines. Polymer, concrete and steel protective plates, and deep digging are the physical measures considered. In part 1 a survey was made, in part by an enquiry, of the frequency, causes and consequences of incidents where pipelines were hit by excavators. Further, the rules and standards were investigated in countries where 7–10 bar pipelines are already in service. Here, in part 2 the perspective was widened to include, apart from gas pipelines, also all kinds of buried pipelines and cables. Now a visit to a supplier in France is reported, as well as an vestigation of costs and environmental impacts of the different protective measures, and an analysis of the strength of protective plates and of how they can best be positioned in the ground in relationship to the pipeline. The main result from the study visit to France was that new regulations mean that both new and existing pipelines have to be satisfactorily protected. For the physical point of view these plastic protective plates play an important part, and there are commercially available building systems of plates for which the strength and durability have been verified by tests. In the full scale experiments done in, e.g., France, it can be concluded that the plastic (HDPE) plates can wit stand high loads which are applied by use of a bucket with teeth mounted on an excavator. In some cases penetration of teeth occurs, but the plates will in that case either come up and alert the operator or stay in the ground and still protect the buried cable or pipeline. Concrete plate can also break, but the pieces are held together by the steel reinforcement. The analysis of costs and environmental impacts shows that plastic plates are preferred with regard to both aspects. In addition they have a very good signalling effect being produced in a bright yellow colour. Also deep digging can be effective taking into account costs and environmental aspects, but the risk reduction will according to literature be less than for the plates. Plastic plates are shown, in the literature surveyed, by full scale experiments to have at least as good, and sufficient, resistance to impact as concrete ones. This is verified by in-house numerical analyses. The finite element analyses show that the plastic plates deforms but do not break. The arching action of the backfill protects the buried pipe, and the stresses become only somewhat higher when using plastic plates instead of using stiff plates of steel or concrete. There may be unfavourable cases when the plastic plates cannot by themself stop forces and stresses passing down through soil layers acting on the buried pipe.

  • 33.
    Thörnblom, Kristian
    et al.
    Göteborg (BMg).
    Palmlöf, Magnus
    Hjertberg, Thomas
    The extractability of phenolic antioxidants into water and organic solvents from polyethylene pipe materials - Part 12011In: Polymer Degradation and Stability, Vol. 96, no 10, p. 1751-1760Article in journal (Refereed)
  • 34.
    Thörnblom, Kristian
    et al.
    Göteborg (BMg).
    Sällström, Jan Henrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Bygg och Mekanik, Rörcentrum.
    Grävskydd och djupförläggning som riskreducerande åtgärder vid förläggning av 10 bars PE-rörsystem: Del 22012Report (Refereed)
    Abstract [sv]

    This report concerns part 2 of a project with the aim to propose protective measures for cables and pipelines for bio and natural gas. The wish is to be able to increase the pressure in the distribution networks from 4 to 10 bars without having to retain the safety distances valid for 80 bar pipelines. Polymer, concrete and steel protective plates, and deep digging are the physical measures considered. In part 1 a survey was made, in part by an enquiry, of the frequency, causes and conse-quences of incidents where pipelines were hit by excavators. Further, the rules and standards were investigated in countries where 7-10 bar pipelines are already in service. Now a visit to a supplier in France is reported, as well as an investigation of costs and environmental impact of the different protective measures, and an analysis of the strength of protective plates and of how they can best be positioned in the ground in relationship to the pipeline. The main result from the study visit to France was that new regulations mean that both new and existing pipelines have to be satisfactorily protected. For the physical part of these plastic protective plates play an important part, and there are commercially available building systems of plates for which the strength and durability have been verified by tests. The analysis of costs and environmental impact shows that plastic plates are to prefer with regard to both aspects. In addition they have a very good signalling effect being produced in a bright yellow colour. Also deep digging can be effective taking into account environmental and costs aspects, but the risk reduction will according to literature be less than for the plates. Plastic plates are shown, in the literature surveyed, by full scale experiments to have at least as good, and sufficient, resistance to impact as concrete ones. This is verified by in-house numerical analyses. A discussion is presented of how well the geometric design of pipeline and protective plate protects the pipeline against some digging scenarios with excavators of different sizes. Since the regulations are differing between countries and comprise a mix of administra-tive and physical protective measures in a way that is not quite evident, it was also found worthwhile to make a note, for possible further use, on how risk analysis can, and has been, used in connection with the establishment of major pipelines for optimization of protective measures.

1 - 34 of 34
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