Alloy Pipe Joints Research Articles

Effect of Hot Working Technology on Shape Memory Effect of Fe-24Mn-3Si-7Cr-3Ni Alloy Pipe Joints

Effect of Hot Working Technology on Shape Memory Effect of Fe-24Mn-3Si-7Cr-3Ni Alloy Pipe Joints

Study on the Physical Properties of Split-type Iron Base Shape Memory Alloy Pipe Joint

Aiming at the leakage phenomenon of pipeline system due to corrosion and other reasons, a split type iron-based shape memory alloy pipe joint based on the button bond connection was designed for repair. This split-type pipe joint can be used for quick in-situ maintenance of pipelines without cutting off pipelines or stopping transmission without pressure relief. It is especially suitable for intensive pipeline maintenance and online emergency maintenance. In order to study the connection performance of the split iron-based shape memory alloy pipe joint, this paper took the Fe17Mn4Si10Cr4Ni alloy pipe joint as the research object, and carried out pressure sealing and pull-out experiments respectively on the integral pipe joint and the split pipe joint which had not been carried out and had been subjected to one heat and mechanical training. The results showed that, compared with the integral pipe joint, the pressure seal value of the split pipe joint decreased by 40% to 20MPa and the pulling force decreased by 48.9% without heat-mechanical training. However, after 1 time of thermal-mechanical training, the pressure sealing value of the split-type pipe joint decreased by 12.5% to 32MPa and the pulling force decreased by 21.2% compared with the integral pipe joint. It can be seen that thermal-mechanical training can significantly improve the joint performance of split pipe joints, and the split pipe joint can meet the requirements of medium and low pressure pipeline connection and maintenance.

Finite Element Simulation of NiTiNb Shape Memory Alloy Pipe‐Joint Subjected to Coupled Transformation and Plastic Deformation

The assembling process of Ni47Ti44Nb9 alloy pipe joints considering the phase transformation and plasticity was numerically simulated for the first time with a developed constitutive model. The simulated process was based on the experimental material parameters, which were determined with the experimental tensile results of Ni47Ti44Nb9 shape memory alloy (SMA) and steel bars. The results showed that, after assembly, the Mises stress distributed uniformly along the longitudinal direction of the NiTiNb joint, but nonuniformly along the radial direction. The maximum σeq does not appear at the inner wall of the joints due to the coupling effect of the plastic deformation and the recoverable transformation. The contact pressure distributed uniformly along the circumferential direction, but nonuniformly along the longitudinal direction. The sizes of the SMA joint and the pipe should be properly matched to ensure contact during the stage of the rapid reverse phase transformation to obtain stable connection performance. The pull‐out force was also computed, and the results were in good agreement with the experimental results. The results obtained can provide available information for the optimization of the design parameters of the high‐performance SMA pipe‐joint, such as inner diameter and assembly clearance.

Numerical Simulation of the Shape Memory Alloy Pipe Joint

Based on the existing constitutive model of shape memory alloys (SMA), as well as on the state of stress distribution between the pipe and pipe joint, a simplified constitutive model for SMA can indeed fit the SMA pipe coupling structure. Using this constitutive model to simulate the stress distribution during the process of heating up, we can use the system to discuss the relationship between the radial compressive stress and various influencing factors. KeywordsShape Memory Alloys; Constitutive Model; Radial Compressive Stress; Pipe Joint; Wall Thickness

Finite Element Analysis of Removable Shape Memory Alloy Pipe Joint’s Cone Sealing Performance

According to the behavior of shape memory alloys, a structure of removable shape memory alloy pipe joint was designed. The contact manner of two parts of this structure is cone-globe. Cone-globe sealing is the key point of this structure’s sealing. Therefore the finite element analysis software ANSYS was used to simulate and calculate the sealing. The result shows that the width of the sealing surface and the contact stress altered with the change of structural parameters, which affected the sealing most. According to the value of the sealing surface’s width and the contact stress, the structural parameters including cone angle can be definitely settled.

Research of Pipe Made of Cu-Zn-Si Shape Memory Alloy to Internally Sprayed Pipe Connection in Connected Technology

The copper-based shape memory alloy pipe joint was applied in the field of oil pipelines jointing as well as installing. It has many advantages than anything. In the paper, the basic principle and connection influence factors of copper-based shape memory alloy pipe joint were described. Experimental results shows the copper-based shape memory alloy pipe joints can be used in oilfield oil pipeline connection and it can solve the inner pipe joint corrosion damage problem by welding.

Methods of Improving Shape Memory Effect of FeMnSiCr Alloy Pipe Joint

The influence of different broaching rate, the training of thermo-mechanical cycle and Electro-pulse Modification (EPM) on the shape memory effect of the FeMnSiCr alloy was investigated. The recovery pulling force can be realized as high as 22850N after EPM treatment. The Fe-based shape memory alloy (SMA) pipe joint can meet the requirement of engineering application.

Simulation on Pipe Joints Expansion Technology of NiTiNb Shape Memory Alloy

In order to study the low-temperature expansion process of NiTiNb shape memory alloy, this paper makes use of numerical simulation method to complete the simulations and analysis. The shape memory effect of NiTiNb alloy pipe joints under different expansion temperatures and expansion strains have been compared and evaluated. Through simulations of low-temperature expansion and elevated temperature shape recovery of NiTiNb alloy pipe joints, the relationships between elastic deformation, phase transformation deformation and recovery ratio under different expansion temperatures and expansion strains have been acquired. The results show that the highest expansion strain should below 11%, in consideration of recovery ratio and recovery temperature, the optimal expansion temperature range is -60~-50°C .

Shape Memory Alloy Pipe-Joint with Copper Coating

In order to improve the performance of pipe couplings, a technique has been developed to electroplate copper on the inner surface of Ni-Ti-Nb pipe-joints after pre-deformation. Gas leak tightness and tensile tests were conducted to evaluate the performance of the couplings both with and without copper coating. It was found that electroplating a thin copper layer on the inner surface of the pipe-joint effectively solved the problem of leakage and greatly enhanced the pull-out force of the couplings. Furthermore, the pipe-joints without ribs can be demounted easily after being cooled to the liquid nitrogen temperature and benefit the maintenance of the pipeline.

DSC study of the reverse martensitic transformation behavior in a shape memory alloy pipe-joint

The reverse martensitic transformation behavior of a Ni–Ti–Nb shape memory alloy pipe-joint was investigated systematically by means of differential scanning calorimetry. It was found that the reverse transformation start temperature ( A′ s) of the pre-deformed pipe-joint increased while the transformation temperature interval decreased when the wall thickness declined. The reverse transformation temperature interval was widened by inserting a connecting pipe into the hole of the pipe-joint, demonstrating that the connecting pipes impeded the reverse transformation of the pre-deformed pipe-joints. On the basis of the kinetics of thermoelastic martensitic transformation, the specific characteristics of the reverse martensitic transformation behavior of shape memory alloy pipe-joints were explained.

A Study of NiTiNb Shape-Memory Alloy Pipe-Joint with Improved Properties

A Study of NiTiNb Shape-Memory Alloy Pipe-Joint with Improved Properties

Behavior Analysis and Design of FeMnSi Alloy Pipe-Joints

Behavior Analysis and Design of FeMnSi Alloy Pipe-Joints