Internal Surface Of Pipe Research Articles

A strain-based J-integral formulation for an internal circumferential surface crack of pipeline under inner pressure and large axial deformation

The presence of cracks on pipelines poses a potential threat to their operational status, and it is critical to assess the permissibility of pipelines containing cracks. The dimensional analysis combined with the finite element method is applied to investigate the fracture behavior of circumferential crack on the internal surface of pipe under internal pressure and large axial deformation. Dimensionless parameters are determined to represent the effects of crack size, pipe geometry, pipe material, and external load on the crack front driving force, and a strain-based J-integral formulation is obtained by a stepwise coefficient fitting approach rather than a polynomial fitting method. This J-integral formula can be used to quickly assess the crack front driving force of a pipe in service condition and subjected to axial displacement. The diameter-to-thickness ratio of the pipe and the dimensionless pressure of the pipe are found to act together in a combined form on the crack front driving force. Increases in dimensionless crack depth, dimensionless crack length, the ratio of circumferential stress to yield strength of the pipe, and strain hardening exponent cause an increase in the crack front driving force. The effect of dimensionless crack depth on crack front driving force is more significant than other dimensionless parameters. Changes in the other dimensionless parameters do not significantly change the crack front driving force when the dimensionless crack depth is small. Other dimensionless parameters have a progressively greater influence on the crack front driving force as the crack dimensionless crack depth increases. Large deformations in the ligament zone and increasing axial stress are the main reasons for the high crack front driving force. The J-integral formula has a similar form to that of the J-integral in the Electric Power Research Institute (EPRI) method when the effect of internal pressure is not considered. It can be reduced to predict the crack front driving force of a surface cracked plate subjected to uniaxial tensile loading. For the interaction between an internal surface crack and an embedded crack, re-characterizing the crack size using BS 7910 will overestimate the equivalent crack depth, and a more accurate equivalent crack size can be obtained using the J-integral formula proposed.

Magnetorheological Polishing Based on Honing Vertical Mechanism for Inner Surface of Titanium Alloy Pipes

Recently, high internal surfaces for titanium alloy pipes have been required due to the increment of various applications such as aerospace components. In this work, vertical magnetorheological polishing (VMRP) is carried out to achieve high polishing performance on the internal surface of the titanium alloy pipe. A series of comparative experiments were conducted to investigate the polishing mechanism of magnetorheological polishing (MRP) fluid and enhance the polishing performance. It is shown from the experimental results that the VMRP method under the opposite polarity arrangement improves the surface roughness from 47.85% to 83.34% by reducing unwanted vibration and noise during operation. This provides nanoscale surface polishing quality, while such a precision cannot be achieved from the previous horizontal MR polishing apparatus method. It is found that under a 2700 cycle polishing time, a polishing process combining a rough and fine polishing approach with a combination of different particle diameters results in an axial surface roughness of 0.05 μm and circumferential surface roughness of 0.038 μm, respectively. It is also identified that the axial surface roughness of 0.04 μm–0.041 μm is achieved through the combination of high- and low-speed polishing process after 1602 cycles.

A simple parameter configuration scheme for a simplified dynamic model of pipe-embedded wall

A pipe-embedded wall (PE-wall) can effectively reduce the building load through the water circulation in the embedding pipes. Using renewable energy as an alternative, the water may be produced by solar water heater, or by cooling tower etc. This PE-wall may be used to reduce the building energy consumption, which is beneficial to achieve nearly zero energy building (nZEB) target. In this study, a simple parameter configuration scheme is proposed for the RC simplified dynamic model of the PE-wall. Based on the wall geometry and thermal properties, the scheme can directly determine thermal resistance (R) values and thermal capacitance (C) values for a 5R3C simplified dynamic model. The finite element frequency domain (FEFD) models and time-domain CFD models of three typical (i.e., light-weight, medium-weight and heavy-weight) PE-walls are established as reference. The simplified 5R3C model with parameters determined by the configuration scheme is validated in terms of their thermal responses both in frequency domain and time domain. Under specified dynamic boundaries, mean relative errors of heat flow on the internal wall surface and internal pipe surface are less than 5 %. The comparison results indicate the good accuracy and reliability of the parameter configuration scheme for the RC simplified dynamic model.

Picosecond pulsed 532nm laser system for roughening and secondary electron yield reduction of inner surfaces of up to 15m long tubes.

Laser-induced surface structuring is a promising method to suppress electron mulitpacting in the vacuum pipes of particle accelerators. Electrons are scattered inside the rough surface structure, resulting in a low Secondary Electron Yield (SEY) of the material. However, laser processing of internal pipe surfaces with a large aspect ratio is technologically challenging in terms of laser beam guidance and focusing. We present a 532nm ultrashort-pulse laser setup to process the inner parts of 15m long beam vacuum tubes of the Large Hadron Collider (LHC). Picosecond pulses at a repetition rate of 200kHz are guided through an optical fiber toward an inchworm robot traveling inside the beam pipe. The system was installed, characterized, and tested for reliability. First surface treatments achieved the required scan precision. Cu2O-dominated nano-features were observed when processing at high average laser power (5 W) and slow scanning speed (5mms-1) in nitrogen flow, and the maximum SEY of copper was decreased from 2.1 to 0.7.

Pipe internal grooving using closed magnetic field system: A novel method

AbstractThe present work proposes an innovative method to form microgrooves on a tube's internal surface through new machining based on the principle of the closed magnetic circuit. A newly designed machine with a magnetic grooving tool was fabricated. The tool consists of a pair of magnets positioned in the pipe to be pulled by another pairing magnet set at the pipe's external side, arranged in sequence of N−S−N−S direction so that it creates a closed magnetic field that has a greater pulling force. By controlling the magnet pair at the pipe's external side in the linear and rotational direction, the magnetic grooving tool is moved in both directions and simultaneously pulled towards the pipe surface to form the microgrooves. The experiment was carried out by adjusting the magnet's size combination and its distance to vary the magnetic strengths. The grooving dimension was examined by using an optical microscope and analysed using a 3‐dimensional laser profilometer surface analyser. With N52 class Nd2Fe12B neodymium (40×10×10 mm3), the maximum groove depth of 75.51 μm was recorded and the minimum depth of 2.33 μm was recorded by using magnet size 10×10×10 mm3. The method is capable to produce microgrooves on the copper pipe's internal surface.

An Inverse Perspective Mapping-Based Approach for Generating Panoramic Images of Pipe Inner Surfaces

We propose an algorithm for generating a panoramic image of a pipe’s inner surface based on inverse perspective mapping (IPM). The objective of this study is to generate a panoramic image of the entire inner surface of a pipe for efficient crack detection, without relying on high-performance capturing equipment. Frontal images taken while passing through the pipe were converted to images of the inner surface of the pipe using IPM. We derived a generalized IPM formula that considers the slope of the image plane to correct the image distortion caused by the tilt of the plane; this IPM formula was derived based on the vanishing point of the perspective image, which was detected using optical flow techniques. Finally, the multiple transformed images with overlapping areas were combined via image stitching to create a panoramic image of the inner pipe surface. To validate our proposed algorithm, we restored images of pipe inner surfaces using a 3D pipe model and used these images for crack detection. The resulting panoramic image of the internal pipe surface accurately demonstrated the positions and shapes of cracks, highlighting its potential utility for crack detection using visual inspection or image-processing techniques.

Experimental rig for ice accretion and adhesion strength measurement for air cycle machine system

Air cycle machines (ACM) which are part of the air-conditioning pack in every aircraft, are one such turbomachinery device that can be affected by icing issues particularly at the turbine end. Current ice protection solutions for the air cycle machines use a heating system on the downstream pipe to heat the surface, using electric resistance heaters or hot air coming from the ACM compressor stage. Both solutions require high energy, hence the need to reduce energy consumption through the development of passive energy-saving solutions.Clean Sky 2 ERICE project aims at developing an eco-friendly and cost-effective hydrophobic / ice-phobic solution able to resist ice adhesion in the ACM turbine scroll and its downstream pipe. This paper discusses the implementation of an experimental rig to reproduce the ice formation and accretion conditions within the ACM and a new shear test method to measure the ice adhesion strength on existing and new solutions in the form of coatings. The flow through the ACM turbine exhaust has also been characterized for the first time in published literature. The results from the ice accretion and adhesion tests show that hydrophobic coatings developed for the purposes of ice protection perform better than the current industry baseline material for ACM turbine scroll pipe internal surface. While these coatings could not be used to prevent accretion, they do help in reducing adhesion of ice to the surface.

The effect of additional external cooling on the formation of the weld during pipe welding.

The paper presents an analytical description of real-time thermal field arising in industrial welding of a pipe wall taking account of possible accelerated cooling of the seam after welding. Considered was the case when the surface opposite to the welding bath is cooled with a spray of air or air-water mixture under certain pressure. A concept of characteristic cooling time is introduced depending on heat exchange coefficient at the cooled surface of the pipe. Calculations were performed for various heat exchange coefficient values ranging from 1•10–3 (no cooling) to 6•104 W/(m2•K) (cooling with air-water mixture under pressure). Results show that even cooling with an air spray results in sufficient increase of cooling rate, and in case of cooling with an air-water mixture it increases much greater. Namely, the time to finish crystallization becomes shorter, and cooling rate in the temperature range of austenite transformation increases. There are a number of factors favouring the greater impact toughness of the welded pipe under accelerated cooling of the internal pipe surface: accelerated crystallization resulting in grain size refinement; accelerated cooling of gamma phase resulting in more disperse ferrite-pearlite (or even bainite) structure, which may have also resulted in an increase of impact toughness; all these structure changes do nevertheless result in martensite formation

Stress corrosion cracking of 316LN stainless steel with orthogonal scratches

316LN stainless steel is used to produce the third generation primary circuit pipe of pressurized water reactor (PWR). Its internal and external pipe surfaces are generally introduced with scratches when manufactured, transported and installed processes, making their research and discovery on the stress corrosion cracking (SCC) sensitivity challenging. In the present study, multiple orthogonal scratches on 316LN stainless steel are prepared using the rotary cutting head. The effects of the orthogonal scratches on the SCC of 316LN stainless steel are investigated. The experimental results show that the force bearing point of this kind of rotary cutter head is near 60° on the side, which is different from the common cutter head. At the intersection of orthogonal scratches, larger strain concentration and more oxide particles can be formed comparing with single scratch. With increasing strain concentration, the more nucleation sites and the greater growth driving force for the oxide particles can be formed. Thus larger and more oxide particles in this case are generated, resulting in finally a greater SCC sensitivity.

Simultaneous deposition of DLC film on the internal surface of multiple pipes

Diamond-like carbon (DLC) film effectively prevent the corrosion and wear of the internal surface of the pipe. However, many related reports focus on the deposition of DLC film on internal surface of single pipe, ignoring the importance of mass production. In order to improve production efficiency and achieve single mass production in the industry, it is necessary to explore the deposition technology of multiple pipes. In this paper, multiple pipes were applied with the same negative bias voltage and the high-density plasma was generated through hollow cathode plasma enhanced chemical vapor deposition (HC-PECVD) technology. Multilayer Si-DLC films were deposited in each pipe under the same working pressure. The results show that when multiple pipes are deposited at the same time, the DLC films with high hardness (11–12 GPa), low friction coefficient (0.123–0.168), low wear rate (2.65 × 10−7–3.46 × 10−7 mm3 N−1 m−1) and low corrosion current density (more than an order of magnitude lower than SS304) are deposited in each pipe, and the DLC films on the internal surface of multiple pipes display good uniformity. The method mentioned in this study provides theoretical guidance for industrial production of DLC films on the internal surface of pipes.

SYNERGETIC EFFECT OF A DRAG REDUCER AND PIPELINE INTERNAL COATING ON CAPACITY ENHANCEMENT IN OIL AND GAS PIPELINES: A LITERATURE REVIEW

This article presents a review of investigations on the effect of drag-reducing agents and internal coatings to increase gas and liquid pipeline system capacity, and the correlation between the pipe internal surface roughness, pressure drop, and the maximum flow rate of gas through the pipeline. The enhancements in pipeline hydraulics are identified and used to estimate increase in pipeline capacity and subsequent savings in operating cost over a wide range of fluid and pipeline parameters. The economic benefits are presented as payback periods using discount cash flow techniques. Moreover, the aim of this study was to review published information on drag reducers and pipeline internal coating relevant to pipeline capacity enhancement.

Reliability-Based Criterion for Evaluating Explicit Approximations of Colebrook Equation

Numerous explicit approximations of the Colebrook equation have been developed and evaluated based on two criteria: prediction accuracy and computational efficiency. This paper introduces a new evaluation criterion based on the reliability of each equation. The reliability is defined by the coefficient of variation (CV) of the explicit friction factor that is a function of the variabilities of component random variables (roughness height of the internal pipe surface and kinematic viscosity of the fluid). The coefficient of variation of the friction factor depends on its first derivative for roughness height of the inner pipe surface and kinematic viscosity of the fluid and their correlation. Seven explicit approximations were evaluated using the new reliability-based criterion. The results show that all explicit approximations are very reliable, but variations exist regarding the reliability level. The reliabilities of the seven approximations is very close for the rough-flow regime and when the CV of the viscosity is minimal. However, for the smooth-flow regime, and when the CV of the roughness is minimal, various approximations showed substantially different reliabilities. The novelty of the proposed criterion is that it addresses an evaluation dimension that complements the accuracy and efficiency criteria.

Simultaneously Improving the Corrosion Resistance and Wear Resistance of Internal Surface of Aluminum Pipe by Using Multilayer Diamond-Like Carbon-Si Coatings

Simultaneously Improving the Corrosion Resistance and Wear Resistance of Internal Surface of Aluminum Pipe by Using Multilayer Diamond-Like Carbon-Si Coatings

Use of bench and portable rugosimeters in evaluating the internal roughness of PVC pipes of different diameters

For the dimensioning of hydraulic systems used for water distribution, it is necessary to quantify the continuous head loss along the pipes. For this, one of the variables that influences this process is the surface roughness of these pipes, which, many times, does not have updated information and exact values ??for a correct dimensioning of the systems. An alternative to this is the measurement of these roughnesses through specialized instruments that determine various parameters of amplitude of irregularities. This work aims to analyze and compare the internal surface roughness, represented by the Ra parameter, through two measuring equipment (bench rugosimeter and portable rugosimeter), measured in PVC tubes used for water distribution, in addition to verifying the possibility of use of portable and easy-to-handle equipment. It was verified that the portable rugosimeter proved to be satisfactory for determinations of the roughness of the inner surface of PVC pipes, with smaller deviations than the bench rugosimeter, regarding the calculation off, and, in addition, it will serve the manufacturers to supply information related to the quality of the internal surface of your pipes.

Design of a novel superhydrophobic F&Si-DLC film on the internal surface of 304SS pipes

Superhydrophobic surfaces are an effective measure to achieve drag reduction in the process of water transmission. A novel superhydrophobic F and Si incorporated DLC (F&Si-DLC) film with a micro/nanoscale structure was deposited on the internal surface of 304SS pipe by reducing the pumping speed (increasing the pressure), which combined hollow cathode discharge and plasma immersion implantation. The results indicate that the water contact angle and rolling angle of the as-deposited F&Si-DLC film are 151.6° and 9.4°, respectively. The water flow shed through the superhydrophobic F&Si-DLC film surface without adhesion and no sign of wetting was observed on the surface of the F&Si-DLC film, exhibiting a good and stable superhydrophobicity. Besides, the superhydrophobic F&Si-DLC film presents better mechanical properties (hardness ~ 7.1 GPa) than traditional organic superhydrophobic film. Compared with the pure DLC film, the DLC film containing only F atoms (F-DLC), and the DLC film containing only Si atoms (Si-DLC) deposited on the inner surface of the pipe under the same conditions, it is found that the incorporation of F or Si element is an effective way to reduce the surface energy of DLC films and improve their hydrophobicity. However, the F&Si-DLC film deposition a constant pressure (F&Si-DLC (one)) does not exhibit superhydrophobic properties (the water contact angle of 90°). Therefore, an important reason for obtaining superhydrophobic F&Si-DLC films by reducing the pressure is to generate more micro/nanoscale clusters, in other words, to obtain a rough surface with micro/nanoscale. The as-deposited superhydrophobic F&Si-DLC film offers the possibility of reducing drag in water transmission.

Evaluation Method of Pipe Corrosion Based on the Natural Frequency II: Corrosion of internal surface of pipe

Corrosion of internal surface of pipe is serious because it is difficult to observe. So it is very important to put forward a new method to evaluate the average corrosion rate of pipe which corrosion occurred in internal surface of pipe. Based on the damage of corrosion to the mechanical properties of materials, the mass loss factor of corroded pipe is defined, and the elastic modulus of pipe materials is equivalent. According to the modal analysis theory of elastic materials, a modal analysis model of corroded pipe was established, and the relationship between the modal of the corroded pipe and the mass loss factor was analyzed. The results indicate that it is effective and feasible to equivalence the elastic modulus of corroded pipe, and external surface corrosion is more destructive to the pipe than internal surface in the case of the same corrosion rate. At the same time, the model can be used to evaluate the corrosion rate of corroded pipe by monitoring and analyzing the modal..

Study of diffusion bonded flat plate closed loop pulsating heat pipes with alternating porous media

This work aims to discuss the application of diffusion bonding process in the fabrication of flat plate pulsating heat pipes and to analyze the thermal performance effect of porous media structures applied to alternating channels in the evaporator section and compare it with a smooth conventional flat plate pulsating heat pipe. For that, two different copper flat plate pulsating heat pipes with five turns and 1.5 mm of inner diameter channels were fabricated, using diffusion bonding. Samples were made with two different diffusion process to evaluate the ability of the resulting device to keep the vacuum, avoiding the use of filler material during the welding process, which could result in contamination and, therefore, undesirable corrosion on both internal and external heat pipe surfaces. The results allowed to assess the quality of the bonded interface of two different configurations of the diffusion process. Microscopic results obtained on controllable pressure furnace and non-pressure control were analyzed, where the diffusion process with controlled pressure presented best results of continuity, alignment, and tightness. A comparison of the heat transfer characteristics between the two devices was performed under the same experimental conditions; for both devices, the thermal resistance in horizontal position showed to be like heat transfer of pure conductive copper plate. However, pulsating heat pipe containing smooth channels showed the lower thermal resistance in vertical position and filling ratio of 50%.

Study of deformation conditions at longitudinal pipes rolling from austenite steel grades

Stainless steels of austenite class 08–12Х18Н10Т have a high corrosion resistance, which stipulates for their wide application in various areas of industry. Technology of pipes production of the steels is rather specific and requires observation of some conditions. It was shown that temperature of a work-piece heating before deformation is an important parameter of the technology. It was noted that for the piercing of a steel work-piece with various chrome content, there is a rational temperature interval. Nonobservation of the temperature can lead to defects formation on internal pipe surface because of earlier destruction and opening of metal cavity during piercing. The choice of the rolling-out scheme has a direct effect on the work-piece forming in cross-sections. Results of hot rolling of Ø37×2,5 tube samples, manufactured of 08–12Х18Н10Т steel and carbon steel of grade 40 presented. The rolling was done at a laboratory mill. As a result of the experiment the lower limit of ovality of rolls grooves was specified for conditions of rolling of pipes from 08–12Х18Н10Т steels by 2-roll scheme. At the rolling with ovality B/H ≤1,07, defects appeared on the internal tube surface in the form of scratches caused by the mandrel. The rational range of ovality of grooves at multi-stand rolling can be from 1.08 to 1.15. According to criterion of groove overfilling by metal for steels 08–12Х18Н10Т, requirements were formed towards the groove width of the first stand of longitudinal rolling mill. The groove width must be larger than the sleeve diameter: for 3-roll scheme – at least by 2–3%, for 2-roll scheme – at least by 7.0–7.5%. Potential advantages of 3-roll scheme comparing with 2-roll scheme for rolling of 08–12Х18Н10Т steels were established as follows: lower probability of grooves overfilling by metal of the work-piece, absence of defects (scratches caused by mandrel), on the tube internal surface at minimal ovality level of 1.07, lower level of transverse pipe wall non-uniform thickness.

Pipeline durability and integrity issues at hydrogen transport via natural gas distribution network

Hydrogen will play a significant role in a decarbonised energy system in the coming decades. Extensive infrastructure exists for distribution of natural gas and it is an obvious step to assess it to be used for supply hydrogen or mixtures with natural gas. The durability and integrity issues in existing natural gas distribution steel pipelines associated with hydrogen embrittlement of steel at transporting hydrogen or mixtures natural gas with hydrogen are considered. Two mechanisms of steel hydrogenation from pipe internal surface are taken into account, namely, as a result of electrochemical corrosion due to presence of moisture in transported gas, and molecular hydrogen dissociation. Dissipated microdamaging in the bulk of the pipe wall is distinguished as the main factor of manifestation of hydrogen embrittlement of steel and its durability loss, increasing a risk of structural integrity violation. A sensitivity of some physico-mechanical properties of pipeline steels to hydrogen degradation is analysed. Some technological solutions are considered which should accompany experimental research on the assessment of the pipe serviceability at supply hydrogen or mixtures natural gas with hydrogen, including long-term exposing of pre-loaded specimens in hydrogen or hydrogen-natural gas mixture.

Magneto-rheological abrasive finishing (MAF) of soft material using abrasives

Magnetorheological finishing is highly developed unconventional machining process used for nanometer range surface finishing with the help of magnetic abrasive particles. The cutting forces are generated and controlled by the magnetic field in this process, which is developed between the electromagnetic poles and magnetic abrasives. Excellent process capabilities were attained by this technology. But one of the major limitation or drawbacks is in the wide utilization of the process in industries. This is due to the huge cost of magnetic abrasives, which act as cutting tool in these processes. Very few studies have been performed in the direction of development of new or alternative magnetic abrasives. The present research mainly focuses on the development of magnetic abrasives and performance of these magnetic abrasives. This investigation aims to develop magnetic abrasives by different techniques i.e. Simple Mixing, Adhesive bonding, Microwave sintering and Mechanical alloying, then investigating the performance on brass work piece with SiC abrasives and to find the best technique. The surface topography was done through the x-ray diffraction (XRD) and scanning electron microscope (SEM) to analyze the surface obtained after finishing. The Mechanical Alloying is the best technique concluded through this work to prepare the magnetic abrasives, which further gives the best results in terms of Material removal rate (MRR) and percentage improvement in surface finish (PISF) upon the internal surface of hollow cylindrical brass pipes.