Issues in Manufacture and Qualification of Specialty Brazed Joints for Nuclear Applications

2016 ◽  
Vol 1138 ◽  
pp. 37-42 ◽  
Author(s):  
Calin Truta ◽  
Marin Ciocanescu ◽  
Adrian Amzoi
Keyword(s):  
Base Material ◽  
Pressure Vessels ◽  
The Body ◽  
National Standards ◽  
French Experience ◽  
Asme Code ◽  
Material Erosion ◽  
Brazed Joints ◽  
Thin Walled ◽  
French Design

Nuclear experimental instrumentation frequently includes the usage of thin-walled (metallic sheathed) thermocouples passing through the boundaries of pressure vessels. This is accomplished by sealing the thermocouples by brazing through special design fittings (passages) which are later sealed / welded to the body of the vessel.Two are the challenges to face : (a) the manufacture of the instrumented passage (b) its mandatory qualification, according to relevant standards. Even the brazing qualification standards are more flexible than for welding, the peculiar situation of nuclear instrumentation still needs special consideration and it is not properly covered by the regular standards.The paper describes the experience of the authors in manufacture of the instrumented passages with steel or Inconel sheathed thermocouples, along with some other known projects, in conjunction with applicability of relevant standards: ASME code, AWS standards, national standards. Since it is about pressure vessels, ASME prescriptions are mandatory in Romania; other standards may serve as valuable sources for the “engineering judgment” allowed and recommended by ASME code.The main problem in such specialty brazing qualification is that for some combinations of base metals and filler (imposed by application), one cannot avoid the significant fragilization due to a tremendous increase of hardness in the brazing area. Base material erosion is added and the effect is catastrophic : sectioning the thermocouples at the slightest movement. For example, brazing Inconel thin-walled tubes with BNi-7 is very hard to control – experimental data and images are included in the paper to illustrate this.Therefore, special means must be applied both in fabrication and in qualification, in order to ensure the product is functional and safe, even being fragile. This approach can be found in French design of irradiation devices, being also considered in the French code for design and construction of experimental reactors and irradiation devices. Being known that French experience in this field is vast, their approach makes us confident that our brazing technique is not wrong but the problem is to be solved through ‘smart’ design and specific procedures. Consequently a tentative set of domestic rules for work and qualification is proposed for discussion and further improvement.

Influence of Elevated Temperature on the Acoustic Emission Evaluation of FRP Vessels Through Internal Fluid Pressure Tests

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
Guillermo Ramirez ◽  
Paul H. Ziehl ◽  
Timothy J. Fowler
Keyword(s):  
Acoustic Emission ◽  
Elevated Temperature ◽  
Operating Temperature ◽  
Fluid Pressure ◽  
Pressure Vessels ◽  
The Body ◽  
Emission Testing ◽  
Internal Fluid ◽  
Asme Code ◽  
Acoustic Emission Testing

A research program evaluating the effect of elevated temperature in the acoustic emission testing of fiberglass vessels was completed recently. The program aimed at evaluating the current ASME provisions that require acoustic emission testing for Class II vessels be carried out at operating temperature in the event that the operating temperature exceeds 49°C (120°F). Lack of data from fiber reinforced polymer vessels and/or components that have been subjected to acoustic emission evaluation at elevated temperature has resulted in speculation regarding the appropriateness of conducting the acoustic emission evaluation at elevated temperature. To address these issues, an experimental investigation was conducted on representative coupon specimens and pressurized cylindrical specimens at differing temperatures. The results from the coupon tests were presented in a previous publication. This paper will present the results of the cylindrical specimens and compare them to the coupon specimens drawing the final conclusions from the overall results of the program. The results from this study resulted in changes in the body of the ASME code for testing pressure vessels with acoustic emission at temperature.

Design Formulas of Blind End Closures for High Pressure Vessels

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
R. D. Dixon ◽  
E. H. Perez
Keyword(s):  
High Pressure ◽  
Fatigue Life ◽  
Maximum Stress ◽  
Accurate Determination ◽  
Pressure Vessels ◽  
Stress Distributions ◽  
Fatigue And Fracture ◽  
Asme Code ◽  
Section Viii

The available design formulas for flat heads and blind end closures in the ASME Code, Section VIII, Divisions 1 and 2 are based on bending theory and do not apply to the design of thick flat heads used in the design of high pressure vessels. This paper presents new design formulas for thickness requirements and determination of peak stresses and stress distributions for fatigue and fracture mechanics analyses in thick blind ends. The use of these proposed design formulas provide a more accurate determination of the required thickness and fatigue life of blind ends. The proposed design formulas are given in terms of the yield strength of the material and address the fatigue strength at the location of the maximum stress concentration factor. Introduction of these new formulas in a nonmandatory appendix of Section VIII, Division 3 is recommended after committee approval.

New Lightweight Construction Material: Cellular Mat Using Recycled Plastic

2013 ◽  
Vol 594-595 ◽  
pp. 503-510
Author(s):  
T.I.T. Noor Hasanah ◽  
D.C. Wijeyesekera ◽  
Ismail bin Bakar ◽  
Wahab Saidin
Keyword(s):  
Cellular Structure ◽  
Construction Material ◽  
Construction Materials ◽  
Base Material ◽  
Social Benefit ◽  
The Body ◽  
Lightweight Construction ◽  
Ground Condition ◽  
Application Specific ◽  
Design And Construction

Applications of lightweight construction materials enable the design and construction in challenging, difficult and demanding scenarios. Construction materials with enhanced stiffness as in sandwich panels, large portable structures and floating foundations are examples of such materials. The advent of cellular structure technology has actively introduced innovation and enabled design and construction, meeting engineering requirements such as in the construction of the body of air crafts. Cellular mat structures present in the minimum, triple benefits in being lightweight, load sharing and minimising non-uniform deformation. This paper further explores the use of recycled plastic waste as the base material for an innovative geomaterial. The combination of cellular structure, mat structure and use of recycled waste material is a desirable development in manufacturing. Paper also outlines the techno social benefit of adopting such material in construction. Other application-specific benefits related to cellular mats are those like noise reduction, energy absorption, thermal insulation, mechanical damping. This paper specifically presents the development of a new multifunctional lightweight material is been proposed as an invective innovation for highway construction on challenging ground condition.

Limit Loads of Bolted Flange Connections

2021 ◽  
Author(s):  
Finn Kirkemo ◽  
Przemyslaw Lutkiewicz
Keyword(s):  
Calculation Method ◽  
Production Systems ◽  
Pressure Vessels ◽  
Finite Element Analyses ◽  
Limit Loads ◽  
Face To Face ◽  
Structural Capacity ◽  
Process Piping ◽  
Asme Code ◽  
Bolted Flange

Abstract High-pressure applications such as process piping, pressure vessels, risers, pipelines, and subsea production systems use bolted flange connections. Design of flanged joints may be done by design by rules and design by analysis. This paper presents a design by rules method applicable for flanges designed for face-to-face make-up. Limit loads are used to calculate the structural capacity (resistance) of the flanges, bolts, and metallic seal rings. Designers can use the calculation method to size bolted flange connections and calculate the structural capacity of existing bolted flange connections. Finite element analyses have been performed to verify the analytically based calculation method. The intention is to prepare for an ASME code case based on the calculation method presented in this paper.

Novel Elastomer Materials for Extreme Temperature Operation in Subsea Thermal Insulation Applications at Unlimited Water Depth

2021 ◽  
Author(s):  
Adam Jackson ◽  
Rodrigo Diaz ◽  
Heidi Svalund ◽  
Raymond Hansen ◽  
Grethe Hartviksen
Keyword(s):  
High Temperature ◽  
Thermal Insulation ◽  
Water Depth ◽  
Extreme Temperature ◽  
Base Material ◽  
Development Project ◽  
Pressure Vessels ◽  
Hand Tools ◽  
Gentle Pressure ◽  
Cost Efficient

Abstract Rubber based systems have been used in subsea thermal insulation for many years and have proven themselves to be reliable and cost efficient. Formulations have been changed over the years, pressing the maximum usage temperature upwards and into the realm of 160 to180°C in a hot-wet environment. Until recently there was a need for high temperature along with pressure vessels (autoclaves) for vulcanisation. This has limited the widespread use of such systems. Recent changes have eliminated the need for autoclaves, however the high temperature vulcanisation hasstill been required. A novel formulation has been developed to address these shortcomings, so that this class of materials could have wider use. This new material employs freely available materials in a unique blend. The material contains no hydrolysable groups and can operate from −40°C to 180°C continuously in air and in a hot-wet environment and retains its resilience and flexibility; and thus opening for use in both high and low temperature systems. The formulation does not include the use of hollow glass microspheres and is, correspondingly, without water depth limitations. A new, highly reliable vulcanisation chemistry allows for a stable latency time for application, with vulcanisation temperatures reduced to 50°C. This allows for rapid hand application and simultaneous vulcanisation on subsea trees, valves, manifolds, etc. The material is self-agglomerating, merging under gentle pressure, and can be applied at high thickness. As the base material has an intrinsically low thermal conductivity, glass-based fillers are not needed. The material adheres well to painted or primed surfaces and to many other materials typically used in the offshore thermal insulation industry. The 2-component material is conveniently combined on site, reducing the need for refrigeration during transport and easing mobilisation logistics and is applied using simple hand tools. Extruded profiles can be used directly on complex structures or combined into sheets for ease of application on more regular shapes in order to optimise application rates. Moulds are not required for application, reducing engineering and fabrication cost, while also shortening mobilisation time. The system has been extensively qualified according to ISO 12736 for continuous use at 180°C. This paper will detail important aspects of the development project along with the results of the qualification testing.

Assessment Procedure for Multiple Volumetric Flaws in p-M Diagram

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Shinji Konosu
Keyword(s):  
Body Force ◽  
Pressure Vessels ◽  
The Body ◽  
Assessment Procedure ◽  
Force Method ◽  
Reference Stress ◽  
Body Force Method ◽  
Common Problems ◽  
Shielding Effects

Assessment of multiple volumetric flaws is one of the most common problems relating to pressure vessels and piping components. Under the current fitness for service rules, such as ASME, BS, and so on, multiple volumetric flaws are usually recharacterized as an enveloping volumetric flaw (defined as a single larger volumetric flaw) as well as multiple cracklike flaws, following their assessment rules. However, the rules proposed in their codes will not often agree and their justification is unknown. Furthermore, they can provide unrealistic assessment in some cases. In this paper, the interaction between two differently sized nonaligned volumetric flaws such as local thin areas is clarified by applying the body force method. Unlike multiple cracklike flaws, the effect of biaxial stresses on the interaction is evident. Based on the interaction that indicates the magnification and shielding effects and reference stress solutions, a new procedure for multiple volumetric flaws is proposed for assessing the flaws in the p-M (pressure-moment) diagram, which is a simple assessment procedure for vessels with volumetric flaws.

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