Mechanical Properties and Leak-Tightness of Polymeric Pipe Adhesive Joints

This paper presents issues related to the determination of the selected mechanical properties of adhesive joints made of polymeric pipes and the evaluation of the leak-tightness of the adhesive joints. The article attempts to demonstrate that the type of adhesive may affect the quality of adhesive joints in terms of both tightness and strength of joints. Five types of the polymer pipes differing in a polypropylene and a polyvinyl chloride, diameter and a wall thickness were used in the experiments. Two types of the adhesives were used to make the adhesive joints: Loctite 3430 A&B Hysol, a two-component epoxy adhesive, and Loctite 406, a one-component cyanoacrylate adhesive. Based on the leak-tightness tests results, it was possible to determine the quality of their adhesive joints without damaging the samples, while their tensile strength was determined through the strength tests. The tests performed allowed for the conclusion that the use of the polyvinyl chloride pipes and Loctite 406 one-component adhesive is recommended for this type of adhesive joints.

A study on the effect of process parameters on the joint strength and leak tightness in electromagnetically assisted adhesive Cu-SS tube-to-tube joining through statistical analysis

This work studies an improved hybrid joining technique combining electromagnetic forming and adhesive joining to create a leak-tight Cu-SS tube-to-tube joint named as electromagnetically assisted adhesive joining (EAAJ). An experimental investigation is performed considering three discharge energy (3.9 kJ, 4.4 kJ and 5.0 kJ), four adhesive application lengths (20 mm, 15 mm, 10 mm and 5 mm), three adhesives (Loctite 638, Loctite 567, and Loctite SI 596) and four curing times (24 hours, 48 hours, 96 hours and 120 hours) as process parameters. The mechanical properties of the joints are investigated using testing techniques like pull-out, compression, and micro-hardness tests. An increase in joint strength is observed with the decrease in adhesive application length and increase in curing time. Maximum joint strength, 90% of the base copper tube strength, is obtained in the case of Loctite 638, with 5 mm of adhesive application length, 5.0 kJ of discharge energy and 96 hours of curing time. Furthermore, a three-way analysis (3-way ANOVA) of variance technique is implemented to calculate the contribution of the three factors (discharge energy, adhesive application length, type of adhesives) on the joint strength. A cohesive and adhesive failure mode combination leading to sliding failure mode is observed as a joint failure mechanism during pull-out and compression testing. A leak testing setup has been developed to investigate the joint’s leak tightness by an air pressure decay test. An increment in leak tightness by 1000 times is observed in 638 EAAJ samples compared to samples joined without adhesives. A 3-way ANOVA analysis is also performed to calculate the contribution of different factors on leak tightness of the joint. Micro-hardness is observed to be increased near the joint interface compared to the base metal. Deformation analysis has highlighted the impact of field shaper slit causing a non-uniformity in radial deformation in the circumferential direction and leading to non-uniform circumferential accumulation of adhesive.

Laboratory investigations on the quality of leak tests and visual inspections of wastewater connection pipes carried out by specialist contractors

In addition to stability and operational safety, leak tightness is the permanent functional objective of wastewater pipes. Tests to determine the tightness of wastewater pipes can in some cases produce results that are worthy of discussion. Therefore, laboratory tests were carried out by 29 specialist contractors to obtain results on the quality of leak tests and visual inspections of connection pipes. The results showed that different test errors can be observed for leak test methods (air overpressure, air underpressure and water pressure). However, only in the case of the water pressure tests did the observed test errors occasionally lead to incorrect test results, i.e. the ‘leaking pipe’ was tested as ‘test passed (tight)’. The investigations into the accuracy (trueness and precision) of the test methods showed that all test methods examined were sufficiently accurate to determine the tightness of the connection pipes. In general, correct test results were achieved if the expert testers did not make any serious test errors and the test equipment used functioned properly. In contrast, the investigations on the quality of visual inspection showed that the procedure is not sufficiently reliable to fulfil all normative requirements regarding damage detection and naming as well as damage classification.

A normalized method for determining the influence on the fixed joints tightness using the technology of the sealing surface job

The existing approaches for determining and evaluating the sealing properties of seals for fixed sealants, as well as methods of leakage monitoring are considered. The description of a normalized method for leak-tightness assessment is given, which allows solving a sufficiently large number of evaluation tasks, for example, technological task: assessment of the influence of the technology sealing surfaced job; design: assessment of the influence of the seals surface layer quality of sealants and geometric parameters of them on sealing capacity (service property).

Study of the Long Term Acid Gas Sequestration Process in the Borzęcin Structure: Measurements Insight

Geological sequestration of acid gases, including CO2, is now a growing solution to prevent progressive Earth climate change. Disposal of environmentally harmful greenhouse gases must be performed safely and securely to minimise leakage risk and possible uncontrolled emissions of injected gases outside the sequestration structure. The paper describes a series of research activities at the Borzęcin sequestration site located in western Poland, which were designed to study the migration paths of injected acid gases (mainly mixture of CO2 and H2S) into the water-bearing layers underlying natural gas reservoir. Along with understanding the nature and dynamics of acid gases migration within the sequestration structure, the research was also addressed to assess its leak-tightness and the long-term safety of the entire reinjection facility. As a part of the research works, two downhole sampling campaigns were completed in 2018–2019, where samples of water underlying the Borzęcin reservoir were taken and subsequently studied to determine their physicochemical parameters that were never before examined. Compositions of gas dissolved in downhole brine samples were compared with produced and injected gas. Relevant studies of reservoir water from selected wells were performed, including isotopic analyses. Finally, four series of soil gas analyses were performed on the area surrounding the selected well, which are important for the hazardous gas sequestration safety analysis in the Borzęcin facility. All the above mentioned research activities aimed to acquire additional knowledge, which is valuable for risk assessment of the acid gas sequestration process taking place on the specific example of the Borzęcin site operating continuously since 1996.

General Metal to Metal Static Seals Leak Tightness Overview - R&D Processes, FEA and Tests and Further Code Implementation

Latest development in oil and gas industry is focused on higher pressure and temperature. In addition, standard oil and gas components are more frequent adapted to the other applications like aerospace, food processing, renewable energy. For those conditions, tightness is even more critical than before. In the existing codes the requirements for different tightness classes can be find as well as detailed fugitive emission test descriptions. However, the complete design methodology for HPHT seal solution is still missing. There is no engineering procedure/methodology in the code which will link the design concept, R&D process to the prototype and real tests results. The method which will predict tightness for each size and each configuration/condition is not there. Therefore, there is an urgent need to understand the leakage phenomena and describe it by simplified and safe engineering method. Method, which will connect the design concept with real behavior and be in agreement (or conservative) with test results. By having such method, it will be possible to understand better the sealing mechanism in the existing solutions as well as designing new robust, simple, and cheap (optimized) solutions. There are some more or less accurate methods/rules which are already existing in the supplier companies. There is also more and more research about the continuum flow between two surfaces in contact. Based on those sources in this paper we will present the concept for metal to metal sealing solution designing methodology which can be implemented for future revision of the designing codes. The method which can be used simply and effectively and help to understand the current designs and further R&Ds. Presented here design concept, will be described based on example. The example will go through the process from design concept to the real component tightness test.

Proposed Alternative Rules for Establishing Pressure-Temperature Rating of Aluminum Alloy Flanges

Pressure-temperature ratings for aluminum alloy flanges made from ASTM B247 3003-H112 and 6061-T6 materials are covered in ASME B31.3 Appendix L since 1995. They were previously included in ANSI B16.5 between 1960 and 1968, and in ANSI B16.31 Non-ferrous Alloy Flanges from 1968 and until it was withdrawn in 1981. In 2018, Xu and Rana [PVP 2018-84076] used a modified version of the rules for establishing the pressure-temperature rating from ASME B16.5 Steel Flanges to re-assess the pressure-temperature rating of aluminum alloy currently listed in ASME B31.3 Appendix L. Based on their work, they recommended raising the pressure-temperature ratings for Classes 150, 300 and 600, as well as expanding rating to cover Classes 900 and 1500. In this paper, the author will revisit this topic, explain the background of why ANSI B16.31 was withdrawn and the drawbacks of higher pressure-temperature rating of aluminum alloy flanges. The author will also explain the concept of “ceiling pressure” used in B16 standards to cap the maximum pressure rating for flanges and valves, and significant difference in the modulus of elasticity between Carbon Steel and Aluminum alloys, and its impact on flange rigidity and leak tightness, and will propose alternative rules for establishing the pressure-temperature ratings for aluminum alloy flanges.

Valve for two-phase fluid loop

Improvement of heat transfer efficiency of the spacecraft thermal control subsystem constitutes a relevant problem for today space industry. Two phase thermal control system presents the most suitable solution for this problem. Implementation of reliable thermal control loop elements constitutes one the major prerequisites for reliability of thermal control systems featuring the operating pressure of 4.8 MPa and ammonia as heat fluid. This paper presents the design and test results of manual valve and fill and drain valve to be operated within the spacecraft two phase thermal control subsystem. The paper provides considerations and detailed description of the technical solutions adopted to ensure compliance with the specification requirements such as operating pressure and plug seat leak tightness under the operating pressure and 160 open/close cycles. Valve plug torque selection criteria are described. The employed design and technical solutions as well as qualification test results have proven that the units designed feature outstanding combination of performances such as leak tightness, life cycle with ammonia as heat fluid.

Mass spectrometric study of the leak tightness of products made of technical sintered beryllium

Beryllium products exhibiting a low level of absorption of the radiation energy are widely used in scientific instrumentation design (x-ray technology, radiation detectors, etc.). We present the results of studying the leak tightness of products (disks, plates) made of technical sintered beryllium of standard purity and foil obtained by «warm» rolling from high-purity beryllium. The relevant standards and requirements for testing are given. The leak tightness control was performed using mass spectrometric helium leak detectors with forevacuum backing pumps (oil and dry diaphragm pumps) and specialized vacuum equipment. The parameters of tightness of samples made of technical sintered beryllium were determined. The level of the helium signal during blowing was (0.6 – 7.4) × 10–11 Pa · m3/sec, which corresponds to the tightness standard of foreign analogues and matches the requirements of domestic manufacturers of x-ray equipment. The data spread tended to increase due to the growth of the background value. The obtained results can be used to improve high-tech equipment intended for flaw detection, medical devices, rapid analysis of ore raw materials, radiation safety equipment, etc.