Pneumatic Test Research Articles

Processing and evaluation of dissimilar Al-SS friction welding of pipe configuration: Nondestructive inspection, properties, and microstructure

In the present investigation, dissimilar friction welding between AA6063-T6 and SS 304L materials of pipe joint configuration with an outer diameter of 88.90 mm and a wall thickness of 5.4 mm was performed. Four different experimental conditions were varied based on visual inspection after each weld. The welded pipe joints were evaluated by vacuum leak detection, thermal shock test, pneumatic pressure test, tensile test, optical and scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffractions, X-ray elemental mapping, and hardness measurements. The results revealed that friction welded Al-SS bimetallic pipes sustained ultra-high vacuum pressure and cryogenic working environments without leak detection. Al-SS friction welded pipe resulted in high tensile strength with 72% of joint efficiency as compared to AA6063-T6 base material. Microstructure variations were observed significant towards AA6063-T6 material close to the Al-SS interface. The intermetallic compound of Fe3Al phase was identified with a reaction layer between Al-SS joints with varying thickness of 1.1 µm to 2.0 µm.

Design of ALB Tester for Heavy Vehicle Brake Systems

The brake system is used to keep the speed of the moving vehicle con-stant, slow down, stop it and fix it while parked. Heavy vehicles have an air braking system. (71/320/AT) It should be produced in accordance with the regulations of motor vehicle classes and brake systems. Periodic tests should be carried out in authorized institutions. In the brake systems of vehicles in Trucks, Trailers, Trailers, Semi Trailers, Buses, load adjusting valves called ALB are used, which increase or decrease the rear brake forces of the vehicle according to the load of the vehicle. ALB can be used mechanically or pneumatically in heavy vehicles. In this study, a test device was designed us-ing the microcontroller card, pressure sensor and LCD screen in order to ena-ble the operator, who performed the pneumatic ALB test, to perform the test alone without help and to increase the reliability of the test. As a result of the study, the operator was able to perform the Pneumatic ALB test alone, in-crease the reliability, and save time and labor.

Failure of an autotank repaired by welding

The aim of this work is to show that welded vessels, which have been coated by a polymer for overcoming the pneumatic test are susceptible to failure. This is so, because the cyclic load, which are applied in the vessel during its work. This aim was reached by applying different inspections and tests to a vessel manufactured with aluminium plates, which was used to freight. The vessel had to be repaired by welding, but it failed after few cycles of loading/unloading in the repaired weld. The specimen under study was inspected visually and by non-destructive tests. In this sense, the plate with fracture was tested by mechanical stress test, optical emission spectrometry, and metallographic analysis. The fracture surface was inspected by scanning electron microscopy. The results of all the techniques showed that the failure occurred due to coalesce of multiple cracks that grew by the mechanism of fatigue from welding defects. On the fracture surfaces was found evidence of sealing polymer used for the pneumatic pressure test. This work demonstrates that in welding repairing, the metallurgy and the welding engineering are critical to avoid premature failures of welded components.

Mathematical analysis and flux-based radius of influence for radon/VOC vapor intrusion mitigation systems

Volatile organic compounds (VOCs) and radon progeny pose potential health risks to occupants of certain buildings via subsurface vapor intrusion (VI) to indoor air. VI mitigation is usually performed using systems that extract gas from below the building, and the system performance is typically evaluated by measuring the distribution of applied vacuum below the floor. This article provides a new approach to assessing the radius of influence (ROI) for subslab venting systems based on mass flux instead of static vacuum distribution and includes an analyses of 121 pneumatic tests performed at 65 different suction points in 16 different buildings. The mathematical model represents a two-layer system with horizontal radial flow through transmissive material below the floor slab and vertical flow through discontinuities in the floor slab (which is simplified to approximate an equivalent porous medium). The analysis includes comparisons of the flux-based ROI to values calculated using the two-layer model for 1) vacuum, 2) velocity, and 3) travel time, which may be useful as alternative performance metrics for mitigation systems.

Comparative Risks of Hydrostatic and Pneumatic Pipeline Testing

Abstract An important step in a pipeline-construction project is confirming that the piping and facilities are adequate for the expected operating pressures via static strength tests. All fluids have mass and internal energy. Fluids under pressure have significantly elevated internal energy. All fluids are compressible to some greater or lesser extent, and the fluid added to raise the pressure of the fluid in the bulk volume adds significant energy. The raw mass of a fluid must be considered when evaluating terrain elements and support elements (i.e., pipe stands and pipe racks). The selection process for a test fluid should always endeavor to minimize the total risk of the entire process. Code-guidance has historically not shown a clear preference for the selection of one particular test medium over another. Some jurisdictions have written regulations that step away from ASME guidance and do show a clear preference for hydrostatic testing over pneumatic testing. This preference manifests itself in several ways, but the primary representation is the requirement in statutes and regulations that a pneumatic test should have an “exclusion zone” around the test to reduce the risk of injury during the test. These documents tend to not have an exclusion-zone requirement for hydrostatic tests. This paper is undertaken to demonstrate the relative risks of liquid versus gaseous test media and presents a background of why pneumatic tests have been singled out by regulators as higher risk and shows why this regulatory preference can result in increasing risk rather than decreasing it.

Fuel pellet breakage in pneumatic transport and durability tests

Wood pellets for biofuel utilization are fragile and produce fines and dust when handled. Impact resistances of pellets were obtained by using tumbling box tester, ligno tester and rotary impact tester. The samples were sieved after each of the ten consecutive runs to generate a breakage vector of particle size classes: 0–1.00, 1.00–2.36, 2.36–3.15, 3.15–4.75 and > 4.75 mm. Similarly, a full-scale pneumatic blow wood pellets degradation experiment was conducted. The pellets were blown at different delivery pressures from 0.3 to 1 bars.The breakage patterns disclosed two independent mechanisms when analysed by multivariate modelling: surface breakage by the tumbling box and volume breakage by the rotary impact tester. The combination of these testers can describe the full outcome space for the pneumatic tests and it is possible to predict generation of fines and dust during pneumatic loading of wood pellets from a silo. The most severe damages corresponded to more than 10 times 500 revolutions in a tumbling box and 8 consecutive impacts at almost 20 m/s in the rotary tester. Furthermore, these results provided insights into pellet breakage mechanisms, evaluation of pneumatic pipe designs and construction of bench testing devices that purify the effect of surface vesus volume breakage.

A 350 °C piezoresistive n-type 4H-SiC pressure sensor for hydraulic and pneumatic pressure tests

It has been a challenge to develop pressure sensors that can work in harsh environments. In this work, a piezoresistive n-type 4H-SiC pressure sensor is demonstrated, capable of working at 350 °C under hydraulic and pneumatic pressure. The pressure measuring range of this sensor is 7 MPa and the chip dimension is 2.5 mm × 2.5 mm × 0.23 mm. A reliable Ti/TaSi2/Pt metal ohmic contact is used in the sensor and experimental results show that the metal combination can withstand a wide temperature range of 30 °C–350 °C. In order to avoid thermal stress induced by the mismatch of thermal expansion coefficients of different packaging materials when increasing temperature, a double-layer bonding scheme of cement glue and epoxy is proposed. The inner layer of the chip and the kovar alloy base are directly bonded with the epoxy, while the outer layer is wrapped with the high-temperature cement glue. Experiments confirm that this method can achieve reliable packaging with temperatures up to 350 °C for 5 h. Based on the above key technologies, the sensitivity of this sensor can reach 13.2 mV V−1 kPa−1 and the test data exhibit high linearity and repeatability. Static tests prove that the sensor has good media compatibility which can operate under a hydraulic pressure load at 220 °C and a barometric pressure load under 350 °C. The sensor in this work can provide a reference for pressure measurements at high temperature and in complex media environments.

Review of experimental techniques for impact property of adhesive bonds

Assessing the impact property of the adhesives and the joints requires specific suitable experimental methods. Especially the most of the adhesives are sensitive to the strain rate that they must have to meet when a load is applied abruptly on the adhesive and adhesively bonded joints. In general, the impact tests of adhesive joints are usually divided into three ranges including low, medium and high velocity. Sometimes a body in hypervelocity collides with another one is faster than the sound velocity. This document aims to review the experimental methods that have been previously undertaken in this field. Discussed research topics include the impact test methods for the adhesive joints under low, medium, high and hypervelocity. The standard impact tests for adhesive joints (involving both bonded blocks and strips) are typically test methods with low-velocity and they are discussed. In the medium-velocity range, the applications of drop weight, inertia wheel, wedge falling, servohydraulic and pneumatic test methods are presented. In the high-velocity range, the advance of Split-Hopkinson bar as a special apparatus conceived to test materials is reported. The final section describes two practical applications of adhesive joints impacted under hypervelocity.

Fracture characterization studies of concrete structures through experiments on reinforced concrete cylindrical shell specimens

BARC Containment (BARCOM) test model located within the experimental facility at Tarapur, India built for the ultimate load capacity evaluation and leakage assessment of nuclear containment, was subjected to pressurization experiments with air. Pneumatic experiments up to over-pressurization level of 1.77 times the design pressure (Pd) were carried out. With the limited air compressor capacity, further diminished by significant leakage due to the development of through thickness cracks localized around the discontinuity locations and parallel vertical cracks throughout the full circumference in the free field at certain elevations of BARCOM, it could not be pressurized beyond 1.77 Pd. For further pneumatic testing, requisite leak tightness needs to be ensured. Therefore, it was recommended to apply a polymer liner inside the surface of the nuclear containment test model, which are commonly deployed in various containment structures for improved leak-tightness characteristics.In addition to the qualification of synthetic liner coating material for the intended repair application, the fracture characterization studies conducted through Digital Image Correlation (DIC) and a novel Optical Crack Profiling (OCP) scheme developed by the present authors on cylindrical specimens enabled verification of various fracture parameters as observed during the standard material characterization studies. The size of the fracture process zone of concrete is evaluated and a correlation is evolved to estimate concrete fracture energy which is applicable for safety evaluation of important structures.

Acoustic Emission and Fractographic Analysis of Seamless Steel Pressure Cylinders with Artificial Flaws Under Hydrostatic Burst Testing

Eight 34CrMo4 high-pressure seamless steel cylinders (HPSC) with a nominal water-containing capacity of 80 l for a working pressure of 300 bar and an artificially manufactured flaw in each cylinder were subjected to a hydrostatic burst test with an additional monitoring of the acoustic emissions throughout the pressurization process. The use of water as a pressurizing medium makes the post-processing of acoustic emission data more difficult compared to pneumatic burst tests. Therefore, an artificial flaw has been utilized as a stress concentration element with the intent to situate the material damage process with the associated activity of the acoustic emission into a specific part of the geometry. With regards to the cylinder dimensions and the acquisition of an acoustic emission (AE) signal, the artificial flaw was, in all cases, milled in the middle of the cylindrical section and the remaining wall thickness under the flaw was equal to 1 mm. The presented results show the existence of three regions within the material damage process, namely void nucleation by cavitation, including the initiation of micro cracks, the stabilization of the cracks and the region with a further propagation of the previously stabilized cracks resulting in the final rupture of the cylinder wall under the notch. A complex analysis of the AE data, recorded at two different distances from the center of the flaw, in conjunction with the results from fractographic examination, enables the authors to perform a complex study of the material damage process evolution.

Multifunctional testing system design for varicose vein therapy apparatus

Varicose veins of lower extremity can be treated effectively with varicose vein therapy apparatus. In order to ensure its therapy effect, it is necessary to test the air tightness of pneumatic circuit and other related performance parameters. The traditional manual testing method has some problems, such as large error, low efficiency and so on. This paper developed a multifunctional testing system based on LabVIEW software to overcome these shortcomings. The system is a combination of software and hardware, which can realise key components calibration, pneumatic circuit air tightness testing, gasbag pressure-resistance performance testing, pressure sensor performance testing and air pump performance testing. The multifunctional testing system realises the goal of automated human-computer interaction testing, which has a bright future in the aspects of application prospect.

Evaluation of moisture susceptibility of asphalt-aggregate constituents subjected to direct tensile test using imaging technique

The bond strength of asphalt binder and aggregate is an important parameter to evaluate the mixture ability to resist moisture damage. An innovative approach was utilized where adhesive failures of asphalt-aggregate constituents were computed in direct tension using the Pneumatic Adhesion Tensile Testing Instrument (PATTI). Hydrated Lime (HL) and Pavement Modifier (PMD) were used as anti-stripping fillers in asphalt mastics, while Evotherm (EV) was incorporated as the Warm Mix Asphalt (WMA) additive. Three long-term conditioning levels were performed namely; unconditioned, conditioned long-term aged (LTA) + 1 freeze-thaw (F-T) cycle and LTA + 3F-T cycles prior to testing. The Accelerated Laboratory Vacuum Saturator (ALVS) was integrated to subject asphalt constituents to the combined effects of pore pressure and high temperature. The conventional moisture conditioning and aging procedures were also modified to better mimic the actual field condition. An interesting observation pertaining to the moisture-damage mechanism was made in this study where moisture penetrated into the asphalt-aggregate interface via holes on the asphalt film. Compared to asphalt mastics, more holes were observed to develop on the binder specimens. The percentage adhesive failure of asphalt constituent test specimens was quantified using 2-D imaging technique. The percentage adhesive failure of asphalt specimens increased with LTA and F-T cycle, while tensile strength reduced with moisture conditioning. Asphalt mastics specimens exhibited relatively lower percentage adhesive failure than binder specimens attributed to the addition of fillers that stiffened and reduced binder moisture susceptibility. The image analysis results showed that the percentage adhesive failure for specimens prepared with polymer modified binders was lower than unmodified binder specimens. Samples using PMD exhibited slightly lower percentage adhesive failure than HL specimens. The percentage of failure reduced further with the incorporation of EV, regardless of aggregate type. Specimens using limestone also showed superior moisture resistance than granite specimens in moist condition.

Laparoscopic Reverse Technique for Posterior Rectovaginal Deep Endometriosis Nodule Step by Step

To demonstrate the application of the so-called reverse technique to approach deep infiltrating endometriosis nodules affecting the retrocervical area, the posterior vaginal fornix, and the anterior rectal wall. In Video 1, the authors describe the complete procedure in 10 steps in order to standardize it and facilitate the comprehension and the reproduction of such a procedure in a simple and safe way. A case report. A private hospital in Curitiba, Paraná, Brazil. A 32-year-old woman was referred to our service complaining about cyclic dysmenorrhea, dyspareunia, chronic pelvic pain, and cyclic dyschezia. Transvaginal ultrasound with bowel preparation showed a 2.4-cm endometriotic nodule at the retrocervical area, uterosacral ligaments, posterior vaginal fornix, and anterior rectal wall, infiltrating up to the muscularis 10 cm far from the anal verge. Not applicable. Under general anesthesia, the patient was placed in the dorsal decubitus position with her arms alongside her body and her lower limbs in abduction. Pneumoperitoneum was achieved using a Veress needle placed at the umbilicus. Four trocars were placed according to the French technique as follows: a 10-mm trocar at the umbilicus for the 0 degree laparoscope; a 5-mm trocar at the right anterosuperior iliac spine; a 5-mm trocar in the midline between the umbilicus and the pubic symphysis, approximately 8 to 10 cm inferior to the umbilical trocar; and a 5-mm trocar at the left anterosuperior iliac spine. The entire pelvis was inspected for endometriotic lesions (step 1). The implants located at the ovarian fossae were completely removed (step 2). The ureters were identified bilaterally, and both pararectal fossae were dissected, preserving the hypogastric nerves (step 3). The lesion was separated from the retrocervical area, and the posterior vaginal fornix was resected (reverse technique), leaving the disease attached to the anterior surface of the rectum (step 4). The lesion was shaved off the anterior rectal wall using a harmonic scalpel (step 5). The anterior rectal wall was closed using X-shaped stitches of 3-0 polydioxanone suture in 2 layers (step 6). The specimen was extracted through the vagina (step 7). The posterior vaginal fornix was reattached to the retrocervical area using X-shaped sutures of 0 poliglecaprone 25 (step 8). A pneumatic test was performed to check the integrity of the suture (step 9). At the end of the procedure, hemostasis was controlled, and the abdominal cavity was irrigated using Lactate ringer solution (step10). The laparoscopic reverse technique is an alternative approach to face retrocervical or rectovaginal nodules infiltrating the anterior rectal wall.In this technique, the separation of the nodule from the rectal wall is performed at the end of the surgery and not at the beginning as performed within the traditional technique. This enables the surgeon to perform a more precise dissection of the endometriotic nodule from the rectal wall because of the increased mobility of the bowel. The wider range of movements serves as an ergonomic advantage for the subsequent dissection of the lesion from the rectum, allowing the surgeon to decide the best technique to apply for the treatment of the bowel disease (rectal shaving or discoid or segmental resection).

Material Removal Characteristic of Laser Cladding Cobalt-Based Alloy in the Photochemical Process

Cobalt-based alloy materials, widely used for laser cladding, are difficult to process. To address this problem, and based on the analysis of the physicochemical properties of cobalt and its compounds, a method for removing cobalt-based alloy materials under photocatalytic conditions was proposed under the effect of ultraviolet photocatalysis and chemical corrosion. In this study, a material removal model under photocatalytic conditions was established, and the reaction principle of cobalt-based alloys under ultraviolet photocatalysis and chemical corrosion conditions was described. We designed a corrosion solution configuration test and established a cobalt-based alloy processing test based on a pneumatic wheel test platform. The processing test proved that the combination of ultraviolet (UV) photocatalysis and Basic Yellow 40 + TiO2 chemical corrosion pretreatment can significantly increase the mechanical material removal rate of cobalt-based alloy materials and effectively reduce surface roughness. At the same time, processing efficiency can be increased over 40%. This showed that the new method is capable of performing well in the field of mold cobalt-based alloy coating processing in the future.

Type tests of the ITER switching network unit components and protective make switches

In ITER, each circuit of the central solenoid as well as poloidal field coils PF1 and PF6 is provided with a system for plasma initiation, called the Switching Network Unit (SNU), able to supply voltage up to 8.5 kV for the coils. This will be obtained by inserting resistors in series with the pre-energized coils by means of a DC current commutation unit (CCU) composed of connected-in-parallel mechanical bypass switch and a thyristor circuit breaker.After a short description of the design, the paper focuses on the procedures and results of the type tests performed on the full-scale prototypes of CCU switching units, namely, the Bypass Open Switch (BPOS) and Bypass Make Switch (BPMS), which are able to perform commutation of direct current up to 55 kA at a voltage of 10 kV within 2–4 ms. In addition, Protective Make Switch (PMS) is considered, which is similar to BPMS in design. This device is intended to shunt the AC/DC converter supplying power to the coil in case of its failure or in case of a quench, when the energy stored in the magnet system is rerouted into fast discharge resistors (FDR) by a special fast discharge unit (FDU).Various types of electrical, hydraulic, pneumatic tests, performed in 2017–2018 are described as well as EMC tests and functional tests with control system.The successful results of the type tests confirmed the suitability of the design and compliance with the ITER requirements making it possible to start manufacturing of the switches for delivery to the ITER Site.

Акустико-эмиссионный контроль качества сварных швов объектов морской техники

This paper discusses the potential of acoustic emission-based methods in technical condition assessment of marine technology, including methodology and results of marine pipeline checks during pneumatic tests and welding quality control of hull structures directly in the process of their manufacturing.

Nonlinear Model Establishment and Experimental Verification of a Pneumatic Rotary Actuator Position Servo System

In order to accurately reflect the characteristics and motion states of a pneumatic rotary actuator position servo system, an accurate non-linear model of the valve-controlled actuator system is proposed, and its parameter identification and experimental verification are carried out. Firstly, in the modeling of this system, the mass flow rate of the gas flowing through each port of the proportional directional control valve is derived by taking into account the clearance between the valve spool and the sleeve, the heat transfer formula is used to the derivation of the energy equation, and the Stribeck model is applied to the friction model of the pneumatic rotary actuator. Then, the flow coefficient, the heat transfer coefficient and the friction parameters are identified by the model and pneumatic test circuits. After the verification experiment of the mass flow rate equations, the charging and discharging experiment reveals that the model can clearly show the effect of clearances on gas pressure changes and describe the effect of heat transfer on gas temperature changes. Finally, the results of model verification indicate that the simulation curves of rotation angle and two-chamber pressures are consistent with their experimental values, and the non-linear model shows high accuracy.

Intrinsic adhesive and cohesive assessment of the moisture sensitivity of bio-rejuvenated recycled asphalt binders

Alternative binders not derived from fossil fuels, known as biobinders, are opening new paths for multiple applications in road infrastructure. Biobinders, usually produced from bio-oils obtained from the processing of biomass and industry by-products, are tuneable materials whose properties can be adjusted to meet specific targets. For this reason, an interesting approach is to couple biobinders with Reclaimed Asphalt (RA) by taking advantage of their rejuvenating properties to design bio-asphalt mixtures with high-content RA and no additional virgin bitumen. Recent research has proven the feasibility of this approach through validation at full-scale (BioRePavation project). However certain aspects related to the durability of bio-asphalt mixtures still require further research, one of these being their resistance to moisture damage. This study aims at filling some of these current gaps by conducting an initial investigation of the moisture sensitivity of selected biobinders and bio-rejuvenated asphalt binders. In order to do this, the intrinsic adhesion and cohesion properties of an extracted RA binder, two biobinders, their blends and two types of aggregates were characterised by means of Surface Free Energy (SFE), individually and as a system. The binders/blends-aggregate systems were further tested by means of the Pneumatic Adhesion Tensile Test Instrument (PATTI) to determine their pull-off tensile strength (POTS). The results show that the bio-rejuvenated asphalt binders present equivalent cohesive and adhesive properties to a conventional bitumen and superior performance when compared to the RA binder. Hence, the combination of biobinders and RA has great potential to guarantee resistance to moisture damage of bio-recycled asphalt mixtures with high-content RA and no additional bitumen.

Comparison of the moisture damage of bituminous binder coupled with glass and limestone substrate using pull-off test

In this paper, the moisture susceptibility of different bituminous binders with two substrates (glass and limestone) was investigated. To that end, the tensile strength of different combinations of bituminous binder–substrate bond was measured using a pull-off test. This test was adapted from the pneumatic adhesion tensile testing instrument (PATTI) test to improve repeatability. Samples were tested in dry condition and after a 7-day conditioning in hot water bath (60 °C). An analysis of variance (ANOVA) was performed on the test results. Overall, the results show that in dry condition, the pull-off strength is a function of the bituminous binder type rather than of the substrate type. After water conditioning, an increase in the pull-off strength was observed for the bituminous binder without polymers and coupled with glass substrate. This was associated with an increase in binder stiffness. For the limestone substrate, the effect of water conditioning was significant only for one type of binder.

Ensuring LNG Liquefaction Facility's System Integrity: Pipe Pneumatic Testing as a "Build it Tight" Attribute

Ensuring LNG Liquefaction Facility's System Integrity: Pipe Pneumatic Testing as a "Build it Tight" Attribute