Pipe Maintenance Research Articles

Wireless In-Piping Actuator Capable of High-Speed Locomotion by a New Motion Principle

Finding damage inside pipes is important for the inspection of pipes used in nuclear power plants and chemical plants. A number of studies have investigated the mechanisms of an actuator with an electric cable to provide locomotion through various devices in pipes. A wireless actuator capable of movement in narrow pipes of several millimeters in diameter has not yet been developed. This paper proposes a novel wireless magnetic actuator with a new propulsion module that exhibits a very high thrusting force and is capable of locomotion in a thin pipe by a new motion principle. Including this principle, we completely established the motion principles of three types due to the change of a supporting force of the wireless magnetic actuator by a theory and an experiment. The application of a rubber leg having optimal flexural rigidity demonstrates that a reciprocating motion caused by vibration can be efficiently converted into movement in one direction. This actuator contains an electrical inverter that directly transforms dc from button batteries into ac. The actuator is moved by the synergy of the vibration amplitude and elastic energy of the mass-spring system due to mechanical resonance energy. Experimental results indicate that the proposed actuator is able to move upward at a speed of 68.5 mm/s by the power provided by ten button batteries when pulling a 10-g load mass. This wireless magnetic actuator has several possible applications, including small pipe inspection and maintenance.

Bathtub curves and pipe prioritization based on failure rate

PurposeThe purpose of this paper is to analyze conditional failure rates, and prioritize water pipelines for replacement based on their expected failure rate where pipes are grouped based on age and pipe type. Thus, predictions can be made on the expected number of breaks in future years.Design/methodology/approachThe time to failure of a pipe can be characterized by the stochastic properties of the population as a whole, from which the likelihood of component failure is derived. When the corresponding failure rate is plotted against time, a bathtub‐shaped curve results. The bathtub curve assists in determining maintenance schedules depending on the age of the pipe. Failure rates help determine whether the rates are more than an acceptable best practice threshold to signal replacement.FindingsDuctile iron pipes had the highest failure rates, followed by asbestos cement pipes; PVC and concrete cylinder pipes had the lowest failure rates, but because concrete cylinder pipes are very time‐consuming to repair and very expensive to install, only PVC pipes are recommended on the basis of this study. Cast iron pipes fit the bathtub shape; ductile iron and asbestos concrete were somewhat bathtub shaped, though the early phase period was not apparent; the bathtub curve for concrete cylinder was fully inverted; while PVC pipes showed zero probability of failure during the middle period. The shapes of bathtub curves drawn on conditional failure rates were similar to those for the failure rates. The bathtub curves indicate that the general failure performance of pipe materials is somewhat contrary to general principles in manufacturing.Practical implicationsAnalysis of failure serves a practical purpose for water utilities to allocate funds for pipe maintenance and prepare a schedule for pipe replacement, so as to provide the best quality services and safe drinking water to users of the utility.Social implicationsThe proper prioritization of water supply pipes for repair and replacement is of great social importance to the public at large, which expends considerable funds to maintain their drinking water supply.Originality/valueThe study of bathtub curves has not been seen before in the analysis of water supply pipes. A unique discovery is that the traditional shape of the bathtub curve is not always applicable for water supply pipes.

Optimal pipe replacement strategy based on break rate prediction through genetic programming for water distribution network

Pipe breaks often occur in water distribution networks and result in large water loss and social-economic damage. To reduce the water loss and maintain the conveyance capability of a pipe network, pipes that experienced a severe break history are often necessary to be replaced. However, when to replace a pipe is a difficult problem to the management of water distribution system. This study took part of the water distribution network of Beijing as a case and collected the pipe properties and the pipe breaks data in recent years (2008–2011). A prediction model of pipe beak rate was first developed using genetic programming. Then, an economically optimal pipe replacement model was set up. Finally, the optimal pipe replacement time was determined by the model. The results could help the utility managers to make cost-effective pipe maintenance plans.

증기발생기전열관의 검사정비로봇용 엔드이펙터의 범용 제어시스템 개발

여러 종류의 증기발생기 검사정비 로봇의 엔드이펙터 모션 구동에 전부 사용할 수 있도록 ARM Cotex M3-107 MCU 기반의 제어기와 엔드이펙터 모션 프로그램 생성 응용소프트웨어로 구성된 범용 엔드이펙터 모션구동 제어시스템을 개발하였다. 범용 제어시스템을 적용하여 엔드이펙터의 직선이송 및 회전이송의 위치 결정의 오차는 무시할만한 수준이며, 재현성은 0.04% 오차를 보여줌으로써 실제로 사용 가능한 범용 엔드이펙터 모션구동 제어시스템을 개발하였다. The general purposed control system for driving a motion of many different typed robot end-effector, which consists of a controller based on ARM Cotex M3-11017 MCU and an application software for generating a motion of end-effector, was developed. Experimental results show that a positioning error is nearly negligible and a repeatability error is 0.04%. Accordingly the developed control system can be applied practically to actuate a robot end-effector for inspection and maintenance of steam generator heat pipe in nuclear power plant.

Parametric analysis for genetic algorithms handling parameters

In the present paper, Evolutionary Algorithms (EAs) computing techniques have been used for economical studies that concern water distribution networks, such as, economical design of pipe network, parallel expansion, and pipe rehabilitation and maintenance. EAs are used because of capability of searching vast and complex search space and locating near global optimal solutions rapidly. A model created under the name “EAnet” combines GA models with ELGTnet as hydraulic analysis models to obtain optimal design of water pipe networks. Finally, summary of key findings and recommended parameters to be used is presented.

Numerical Simulation for Erosion Thinning of Pipes in Petrochemical Plant

Numerical simulation of pipeline flow field was performed with CFD method and the factors of erosion thinning were analyzed. According to result of calculation, exact location of pipe thinning was predicted. The result shows that the prediction is in agreement with the actual instances, which provides reference for the inspection and maintenance of pipes along with the optimal design of pipeline system.

Pipe Maintenance: Strategies Enhance Reliability, Longevity

This is the second of two articles on best practices for concrete pressure pipe. This article details long‐term maintenance strategies and reviews whether pipe assessment is a worthwhile investment. The first article ‐ Concrete Pipe: Installation Strategies Ensure Longevity and Performance, Opflow, October 2012 ‐ explored practices to ensure pipe longevity and optimal performance.

Combined use of geocell reinforcement and rubber–soil mixtures to improve performance of buried pipes

Service trench provision and maintenance of buried pipes represent major cost items in the utilities industry. Using recycled material in order to optimize the design of the buried pipe system can lead to significant cost reductions, but only if performance is not degraded. The main purpose of the paper is to investigate the mitigation of strain in buried flexible service pipes and of the settlement of backfill over such pipes by the use of geocell reinforcement (as 3D-inclusion reinforcement) with rubber–soil mixtures under repeated loading conditions. Two rubber sizes (namely chipped and shredded rubbers), three different percentages of rubber content in the mixture, two positions for soil–rubber mixture inside the trench, four levels of repeated loading and the addition of geocell reinforcement over the pipe are the variables considered. Soil surface settlement, vertical diametral strain of the pipe (as an indication of pipe wall deflection) and stress distribution in the trench, especially on pipe’s crown, are assessed and evaluated. Both cumulative and resilient strains are considered. Using a material with high resilience, like the rubber–soil mixture, could lead to some critical issues that should be considered. These include the larger settlement of the soil surface, transfer of a larger pressure onto the pipe and, consequentially, greater pipe wall strain. For the chipped rubber and soil mixture, the pipe has the highest strains under the cyclic loading irrespective of the amount of rubber in the soil. However, the shredded rubber and soil mixture, dependent on the amount of rubber content, is able to reduce the soil settlement and plastic pipe’s diametral strain, attenuating the pipe’s accumulating strains and, finally, protecting the buried pipe from fatigue under repeated loadings. This benefit is enhanced by the combined action of geocell reinforcement over rubber-modified soil. According to the results, the minimum soil surface settlement and vertical diametral strain are provided by 5% of shredded rubber–soil mixture placed over the pipe with a geocell, giving values of, respectively, 0.30 and 0.53 times those obtained in the unreinforced and untreated soil.

Design of a Bidirectional Telescopic In-Pipe Robot

Millions of miles of pipeline are carrying fluent energy for our daily life, including water, natural gas, crude oil and nuclear materials. Micro in-pipe robot offers an effective technical method for pipe inspection and maintenance. A new bidirectional telescopic in-pipe robot was presented in this paper. In the first place, the whole structure of the in-pipe robot was described, illustrating its functions of motion principle and telescopic mechanisms, respectively. Then the inverting discipline and the driving force of mechanisms were analyzed in detail. The supporting lead screw nut was selected according to robots characteristic requirements, and its structural stability requirements were met after a series of verification. In the end, the buffer spring that satisfied with the restriction analysis was successfully designed.

Analysis and Design of One Degree of Freedom Worm Robots for Locomotion on Rigid and Compliant Terrain

Worm-like robots for applications including maintenance of small pipes and medical procedures in biological vessels such as the intestines, urethra, and blood vessels, have been the focus of many studies in the last few decades. The robots must be small, reliable, energy efficient, and capable of carrying cargos such as cameras, biosensors, and drugs. In this study, worm locomotion along rigid and compliant terrain is analyzed, and a novel design of worm-like multicell robots actuated by a single motor is presented. The robots employ a screw-like axis for sequencing and coordination of the cells and clamps. This design allows for significant miniaturization and reduces complexity and cost. The design of the robots and analysis of their dynamics and power efficiency are described. Two earthworm and two inchworm prototypes were built to demonstrate their performance. The robots are capable of moving forward, backward, and vertically and consume low power, which allow them to climb for hundreds of meters using onboard batteries.

하수도 시스템의 효율적인 운영 및 유지관리를 위한 시스템다이내믹스 모형의 개발

In this paper, the feedback loop mechanisms among the operational indices and exogenous variables of a sewerage system that are inherent in the operation and maintenance of a sewerage system were identified using the System Dynamics (SD) modeling methodology. The identified feedback loops were used to develop a SD computer simulation model that can be used to predict future operational conditions of a sewerage system and identified the efficient ways of operation. The data of Busan metropolitan city sewerage system was applied to verify the developed SD model and predict future operational conditions of the system. As a result, it was predicted that sewage treatment efficiency, volume of sewage treatment and cost recovery rate will be gradually increased, whereas service rate which was already very close to the target will remain almost the same as the current value. Furthermore, sensitivity analysis concerning some operational indices was performed in order to discover the policy leverage. As a result, it was found that the exogenous variables related to the pipe maintenance had a great effect on facility using rate, volume of sewage treatment as well as sewage treatment efficiency.

多層配管の非破壊評価へのレーザ超音波法の適用に関する検討

Recently, multilayer piping has been used widely. Multilayer piping has excellent durability and corrosion resistance. An effective means for quality maintenance of multilayer piping is the laser ultrasonic technique for checking the state of adhesion of the vinyl chloride layer and the steel layer of multilayer piping. The wave is refracted at the interface between the steel layer and the vinyl chloride layer based on the wave motion principle. The arrival time of the reflection wave was calculated and confirmed by measurements. If measurement of piping under high temperature becomes possible, the effectiveness of the non-destructive testing technology by the laser ultrasonic technique can be expected, enabling the production of higher reliability and quality of multilayer piping.

Cableless Magnetic Actuator Capable of High-Speed Movement in Pipe by New Type Propulsion Module

The present paper proposes a novel cableless magnetic actuator that exhibits a very high thrusting force and is capable of high speed locomotion in a thin pipe by using new type propulsion module. The magnetic actuator is moved according to the vibration amplitude and elastic energy of a mass-spring system due to mechanical resonance energy. The proposed actuator contains an electrical inverter that directly transforms DC from button batteries into AC. The electrical DC-AC inverter incorporates a mass-spring system, a reed switch and a curved permanent magnet that switches under an electromagnetic force. Experimental results indicate that the proposed actuator is able to move upward at a speed of 51 mm/s by the power provided by 8 button batteries when pulling a 10 g load mass. This cableless magnetic actuator has several possible applications, including small pipe inspection and maintenance.

SAFL Baffle retrofit for suspended sediment removal in storm sewer sumps

Standard sumps (manholes) provide a location for pipe junctions and maintenance access in stormwater drainage systems. Standard sumps can also remove sand and silt particles from stormwater, but have a high propensity for washout of the collected sediment. With appropriate maintenance these sumps may qualify as a stormwater best management practice (BMP) device for the removal of suspended sediment from stormwater runoff. To decrease the maintenance frequency and prevent standard sumps from becoming a source of suspended sediment under high flow conditions, a porous baffle, named the SAFL Baffle, has been designed and tested as a retrofit to the sump. Multiple configurations with varying percent open area and different angles of attack were evaluated in scale models. An optimum configuration was then constructed at the prototype scale and evaluated for both removal efficiency and washout. Results obtained with the retrofit indicate that with the right baffle dimensions and porosity, sediment washout from the sump at high flow rates can be almost eliminated, and removal efficiency can be significantly increased at low flow rates. Removal efficiency and washout functions have been developed for standard sumps retrofitted with the SAFL Baffle. The results of this research provide a new, versatile stormwater treatment device and implemented new washout and removal efficiency testing procedures that will improve research and development of stormwater treatment devices.

Simplified Procedure for Water Distribution Networks Reliability Assessment

This work describes a simple procedure for the analysis of water distribution system (WDS) performance. It is based on the reliability assessment of a WDS during failure states resulting from the unavailability of a pipe (maintenance or repair), taking into account the probability of the failure events. The procedure may consider changes in daily demand by using patterns defined to represent seasonal trends. Applying this method to a network with around 200 pipes demonstrates its usefulness, especially when the aim is to objectively compare different design solutions. The procedure takes also into account variations in design parameters such as an increase in water demand and/or a drop in hydraulic conductance resulting from pipe lining degradations (corrosion or deposits). DOI: 10.1061/(ASCE)WR.1943- 5452.0000184. © 2012 American Society of Civil Engineers. CE Database subject headings: Water distribution systems; Reliability; Water pipelines. Author keywords: Performance indicators; Water distribution network; Reliability assessment; Water systems.

Methodology for determining life-cycle environmental impacts due to material and energy flows in wastewater pipeline networks: A case study of Oslo (Norway)

Any saturated urban wastewater pipeline network has an ageing mix of pipelines of different lengths, diameters and materials of construction. Each of these pipe-lengths has its own life-cycle which encompasses the material production and pipe fabrication, installation, operation and maintenance during the use phase, rehabilitation and repair and finally retirement from service. An analysis of the inflows of materials and energy into the network and the corresponding outflows, facilitates the determination of the environmental impacts associated with the life-cycle stages of the pipeline network, and an examination of how the contributions of each of these phases to the whole, changes as the network ages and progresses towards saturation. The forecast of the future flows of materials which again, is highly interlinked with the historic flows provides insight into the likely future environmental impacts. The authors, in this paper, present a general methodology which can be applied with some tailor-making, to the analysis of any wastewater pipeline network in general. The methodology is then applied to the pipeline network in the city of Oslo, and the results thereof presented towards the end of the paper.

The research of the accurate measure of static transfer function for the TDI CCD camera

In the test course of static transfer function of TDI CCD camera, because of the influence that gets environmental and artificial etc. factor, the value of static transfer function measured at any time is between unceasing fluctuation, so, make accuracy reduce. To solve this problem, a kind of accurate measurement technique of static transfer function is put forward. First, before carrying out the measure of static quiet of transfer function, the best test point of transfer function of the TDI CCD camera must be determined, it is parallel to guarantee the rectangle target surface of parallel optical pipe and camera focal plane maintenance parallel, and again guarantee target strip in rectangle target and TDI CCD in camera focal plane maintenance vertical. TDI CCD catches rectangle target image, per 1000 lines of target mark image as a measures sample of static transfer function, exclude because of atmosphere tremble twisted, vague rectangle target mark image, retain 500 distinct and steady target mark image as measure sample set. Then, calculate the static transfer function of each measure sample respectively, take the average of all static quiet transfer function in measure sample set as the static transfer function of camera. Finally, the measure of the static transfer function for TDI CCD camera makes error analysis. Experimental results indicate that the value of the static transfer function of TDI CCD camera measured with this kind of method is 0.2923, with before measurement technique comparison, the value of static transfer function has raised 0.02, makes the accuracy of the measure of static transfer function have gotten raising.

Novel Globular Magnetic Actuator Group Capable of Free Movement in a Complex Pipe

Finding damage inside pipes is important for the inspection of complex pipes used in nuclear power plants and chemical plants. A number of studies have investigated the mechanisms of an actuator with an electric cable to provide locomotion through various devices in complex pipes. An in-pipe robot capable of movement in narrow complex pipes has not yet been developed. In the present paper, we propose a globular magnetic actuator group that exhibits a very high thrust force and is capable of free reversible motion in complex pipes. Two actuators of the same size and characteristics are coupled by the magnetic connection method, which generates almost no mechanical loss. The globular magnetic actuator group capable of reversible motion through elongation and contraction of eight shape-memory-alloy (SMA) coils was fabricated. Experimental results indicate that the prototype actuator group is able to climb at a rate of 29 mm/s in a straight pipe while pulling a load mass of 48 g. In addition, the average speeds for two patterns of movement in a complex pipe with several curved sections and step sections were measured. The prototype actuator group is able to move in a complex pipe at an average speed of over 30 mm/s. This actuator group has several possible applications, including inspection using a micro-camera and pipe maintenance.

2A1-L13 ウェーブレット変換を用いた下水道管のひび割れ検出(ロボットビジョン)

Sewer pipe exists close to our living environment and is one of the most important infrastructures, however, the inspection and maintenance of sewer pipes are not automated and is a risk for direct human operations. We have been working on automation of sewer pipe inspection using mobile robots. This paper describes a method of crack detection of sewage pipe using wavelet transform and categorizing the crack level.

Performance of Cableless Magnetic In-Piping Actuator Capable of High-Speed Movement by Means of Inertial Force

The present paper proposes a novel cableless magnetic actuator with a new propulsion module that exhibits a very high thrusting force. This actuator contains an electrical inverter that directly transforms DC from button batteries into AC. The electrical DC-AC inverter incorporates a mass-spring system, a reed switch, and a curved permanent magnet that switches under an electromagnetic force. The actuator is moved by the inertial force of the mass-spring system due to mechanical resonance energy. The experimental results show that the actuator is able to move upward at a speed of 19.7 mm/s when using 10 button batteries when pulling a 20 g load mass. This cableless magnetic actuator has several possible applications, including narrow pipe inspection and maintenance.