RETRACTED ARTICLE: Dynamic boundary of floating platform and its influence on the deepwater testing tube

Statement of Retraction We, the Editor and Publisher of the journal European Journal of Remote Sensing, have retracted the following articles that were published in the Special Issue titled “Remote Sensing in Water Management and Hydrology”: Marimuthu Karuppiah, Xiong Li & Shehzad Ashraf Chaudhry (2021) Guest editorial of the special issue “remote sensing in water management and hydrology”, European Journal of Remote Sensing, 54:sup2, 1-5, DOI: 10.1080/22797254.2021.1892335 Jian Sheng, Shiyi Jiang, Cunzhu Li, Quanfeng Liu & Hongyan Zhang (2021) Fluid-induced high seismicity in Songliao Basin of China, European Journal of Remote Sensing, 54:sup2, 6-10, DOI: 10.1080/22797254.2020.1720525 Guohua Wang, Jun Tan & Lingui Wang (2021) Numerical simulation of temperature field and temperature stress of thermal jet for water measurement, European Journal of Remote Sensing, 54:sup2, 11-20, DOI: 10.1080/22797254.2020.1743956 Le Wang, Guancheng Jiang & Xianmin Zhang (2021) Modeling and molecular simulation of natural gas hydrate stabilizers, European Journal of Remote Sensing, 54:sup2, 21-32, DOI: 10.1080/22797254.2020.1738901 Tianyi Chen, Lu Bao, Liu Bao Zhu, Yu Tian, Qing Xu & Yuandong Hu (2021) The diversity of birds in typical urban lake-wetlands and its response to the landscape heterogeneity in the buffer zone based on GIS and field investigation in Daqing, China, European Journal of Remote Sensing, 54:sup2, 33-41, DOI: 10.1080/22797254.2020.1738902 Zhiyong Wang (2021) Research on desert water management and desert control, European Journal of Remote Sensing, 54:sup2, 42-54, DOI: 10.1080/22797254.2020.1736953 Ji-Tao Li & Yong-Quan Liang (2021) Research on mesoscale eddy-tracking algorithm of Kalman filtering under density clustering on time scale, European Journal of Remote Sensing, 54:sup2, 55-64, DOI: 10.1080/22797254.2020.1740894 Wei Wang, R. Dinesh Jackson Samuel & Ching-Hsien Hsu (2021) Prediction architecture of deep learning assisted short long term neural network for advanced traffic critical prediction system using remote sensing data, European Journal of Remote Sensing, 54:sup2, 65-76, DOI: 10.1080/22797254.2020.1755998 Yan Chen, Ming Tan, Jiahua Wan, Thomas Weise & Zhize Wu (2021) Effectiveness evaluation of the coupled LIDs from the watershed scale based on remote sensing image processing and SWMM simulation, European Journal of Remote Sensing, 54:sup2, 77-91, DOI: 10.1080/22797254.2020.1758962 Ke Deng & Ming Chen (2021) Blasting excavation and stability control technology for ultra-high steep rock slope of hydropower engineering in China: a review, European Journal of Remote Sensing, 54:sup2, 92-106, DOI: 10.1080/22797254.2020.1752811 Yufa He, Xiaoqiang Guo, Jun Liu, Hongliang Zhao, Guorong Wang & Zhao Shu (2021) Dynamic boundary of floating platform and its influence on the deepwater testing tube, European Journal of Remote Sensing, 54:sup2, 107-116, DOI: 10.1080/22797254.2020.1762246 Kai Peng, Yunfeng Zhang, Wenfeng Gao & Zhen Lu (2021) Evaluation of human activity intensity in geological environment problems of Ji’nan City, European Journal of Remote Sensing, 54:sup2, 117-121, DOI: 10.1080/22797254.2020.1771214 Wei Zhu, XiaoSi Su & Qiang Liu (2021) Analysis of the relationships between the thermophysical properties of rocks in the Dandong Area of China, European Journal of Remote Sensing, 54:sup2, 122-131, DOI: 10.1080/22797254.2020.1763205 Yu Liu, Wen Hu, Shanwei Wang & Lingyun Sun (2021) Eco-environmental effects of urban expansion in Xinjiang and the corresponding mechanisms, European Journal of Remote Sensing, 54:sup2, 132-144, DOI: 10.1080/22797254.2020.1803768 Peng Qin & Zhihui Zhang (2021) Evolution of wetland landscape disturbance in Jiaozhou Gulf between 1973 and 2018 based on remote sensing, European Journal of Remote Sensing, 54:sup2, 145-154, DOI: 10.1080/22797254.2020.1758963 Mingyi Jin & Hongyan Zhang (2021) Investigating urban land dynamic change and its spatial determinants in Harbin city, China, European Journal of Remote Sensing, 54:sup2, 155-166, DOI: 10.1080/22797254.2020.1758964 Balaji L. & Muthukannan M. (2021) Investigation into valuation of land using remote sensing and GIS in Madurai, Tamilnadu, India, European Journal of Remote Sensing, 54:sup2, 167-175, DOI: 10.1080/22797254.2020.1772118 Xiaoyan Shi, Jianghui Song, Haijiang Wang & Xin Lv (2021) Monitoring soil salinization in Manas River Basin, Northwestern China based on multi-spectral index group, European Journal of Remote Sensing, 54:sup2, 176-188, DOI: 10.1080/22797254.2020.1762247 GN Vivekananda, R Swathi & AVLN Sujith (2021) Multi-temporal image analysis for LULC classification and change detection, European Journal of Remote Sensing, 54:sup2, 189-199, DOI: 10.1080/22797254.2020.1771215 Yiting Wang, Xianghui Liu & Weijie Hu (2021) The research on landscape restoration design of watercourse in mountainous city based on comprehensive management of water environment, European Journal of Remote Sensing, 54:sup2, 200-210, DOI: 10.1080/22797254.2020.1763206 Bao Qian, Cong Tang, Yu Yang & Xiao Xiao (2021) Pollution characteristics and risk assessment of heavy metals in the surface sediments of Dongting Lake water system during normal water period, European Journal of Remote Sensing, 54:sup2, 211-221, DOI: 10.1080/22797254.2020.1763207 Jin Zuo, Lei Meng, Chen Li, Heng Zhang, Yun Zeng & Jing Dong (2021) Construction of community life circle database based on high-resolution remote sensing technology and multi-source data fusion, European Journal of Remote Sensing, 54:sup2, 222-237, DOI: 10.1080/22797254.2020.1763208 Zilong Wang, Lu Yang, Ping Cheng, Youyi Yu, Zhigang Zhang & Hong Li (2021) Adsorption, degradation and leaching migration characteristics of chlorothalonil in different soils, European Journal of Remote Sensing, 54:sup2, 238-247, DOI: 10.1080/22797254.2020.1771216 R. Vijaya Geetha & S. Kalaivani (2021) A feature based change detection approach using multi-scale orientation for multi-temporal SAR images, European Journal of Remote Sensing, 54:sup2, 248-264, DOI: 10.1080/22797254.2020.1759457 LianJun Chen, BalaAnand Muthu & Sivaparthipan cb (2021) Estimating snow depth Inversion Model Assisted Vector Analysis based on temperature brightness for North Xinjiang region of China, European Journal of Remote Sensing, 54:sup2, 265-274, DOI: 10.1080/22797254.2020.1771217 Yajuan Zhang, Cuixia Li & Shuai Yao (2021) Spatiotemporal evolution characteristics of China’s cold chain logistics resources and agricultural product using remote sensing perspective, European Journal of Remote Sensing, 54:sup2, 275-283, DOI: 10.1080/22797254.2020.1765202 Guangping Liu, Jingmei Wei, BalaAnand Muthu & R. Dinesh Jackson Samuel (2021) Chlorophyll-a concentration in the hailing bay using remote sensing assisted sparse statistical modelling, European Journal of Remote Sensing, 54:sup2, 284-295, DOI: 10.1080/22797254.2020.1771774 Yishu Qiu, Zhenmin Zhu, Heping Huang & Zhenhua Bing (2021) Study on the evolution of B&Bs spatial distribution based on exploratory spatial data analysis (ESDA) and its influencing factors—with Yangtze River Delta as an example, European Journal of Remote Sensing, 54:sup2, 296-308, DOI: 10.1080/22797254.2020.1785950 Liang Li & Kangning Xiong (2021) Study on peak cluster-depression rocky desertification landscape evolution and human activity-influence in South of China, European Journal of Remote Sensing, 54:sup2, 309-317, DOI: 10.1080/22797254.2020.1777588 Juan Xu, Mengsheng Yang, Chaoping Hou, Ziliang Lu & Dan Liu (2021) Distribution of rural tourism development in geographical space: a case study of 323 traditional villages in Shaanxi, China, European Journal of Remote Sensing, 54:sup2, 318-333, DOI: 10.1080/22797254.2020.1788993 Lin Guo, Xiaojing Guo, Binghua Wu, Po Yang, Yafei Kou, Na Li & Hui Tang (2021) Geo-environmental suitability assessment for tunnel in sub-deep layer in Zhengzhou, European Journal of Remote Sensing, 54:sup2, 334-340, DOI: 10.1080/22797254.2020.1788994 Hui Zhou, Cheng Zhu, Li Wu, Chaogui Zheng, Xiaoling Sun, Qingchun Guo & Shuguang Lu (2021) Organic carbon isotope record since the Late Glacial period from peat in the North Bank of the Yangtze River, China, European Journal of Remote Sensing, 54:sup2, 341-347, DOI: 10.1080/22797254.2020.1795728 Chengyuan Hao, Linlin Song & Wei Zhao (2021) HYSPLIT-based demarcation of regions affected by water vapors from the South China Sea and the Bay of Bengal, European Journal of Remote Sensing, 54:sup2, 348-355, DOI: 10.1080/22797254.2020.1795730 Wei Chong, Zhang Lin-Jing, Wu Qing, Cao Lian-Hai, Zhang Lu, Yao Lun-Guang, Zhu Yun-Xian & Yang Feng (2021) Estimation of landscape pattern change on stream flow using SWAT-VRR, European Journal of Remote Sensing, 54:sup2, 356-362, DOI: 10.1080/22797254.2020.1790994 Kepeng Feng & Juncang Tian (2021) Forecasting reference evapotranspiration using data mining and limited climatic data, European Journal of Remote Sensing, 54:sup2, 363-371, DOI: 10.1080/22797254.2020.1801355 Kepeng Feng, Yang Hong, Juncang Tian, Xiangyu Luo, Guoqiang Tang & Guangyuan Kan (2021) Evaluating applicability of multi-source precipitation datasets for runoff simulation of small watersheds: a case study in the United States, European Journal of Remote Sensing, 54:sup2, 372-382, DOI: 10.1080/22797254.2020.1819169 Xiaowei Xu, Yinrong Chen, Junfeng Zhang, Yu Chen, Prathik Anandhan & Adhiyaman Manickam (2021) A novel approach for scene classification from remote sensing images using deep learning methods, European Journal of Remote Sensing, 54:sup2, 383-395, DOI: 10.1080/22797254.2020.1790995 Shanshan Hu, Zhaogang Fu, R. Dinesh Jackson Samuel & Prathik Anandhan (2021) Application of active remote sensing in confirmation rights and identification of mortgage supply-demand subjects of rural land in Guangdong Province, European Journal of Remote Sensing, 54:sup2, 396-404, DOI: 10.1080/22797254.2020.1790996 Chen Qiwei, Xiong Kangning & Zhao Rong (2021) Assessment on erosion risk based on GIS in typical Karst region of Southwest China, European Journal of Remote Sensing, 54:sup2, 405-416, DOI: 10.1080/22797254.2020.1793688 Zhengping Zhu, Bole Gao, Renfang Pan, Rong Li, Yang Li & Tianjun Huang (2021) A research on seismic forward modeling of hydrothermal dolomite:An example from Maokou formation in Wolonghe structure, eastern Sichuan Basin, SW China, European Journal of Remote Sensing, 54:sup2, 417-428, DOI: 10.1080/22797254.2020.1811160 Shaofeng Guo, Jianmin Zheng, Guohua Qiao & Xudong Wang (2021) A preliminary study on the Earth’s evolution and condensation, European Journal of Remote Sensing, 54:sup2, 429-437, DOI: 10.1080/22797254.2020.1830309 Yu Gao, Ying Zhang & Hedjar Alsulaiman (2021) Spatial structure system of land use along urban rail transit based on GIS spatial clustering, European Journal of Remote Sensing, 54:sup2, 438-445, DOI: 10.1080/22797254.2020.1801356 Xia Mu, Sihai Li, Haiyang Zhan & Zhuoran Yao (2021) On-orbit calibration of sun sensor’s central point error for triad, European Journal of Remote Sensing, 54:sup2, 446-457, DOI: 10.1080/22797254.2020.1814164 Following publication, the publisher identified concerns regarding the editorial handling of the special issue and the peer review process. Following an investigation by the Taylor & Francis Publishing Ethics & Integrity team in full cooperation with the Editor-in-Chief, it was confirmed that the articles included in this Special Issue were not peer-reviewed appropriately, in line with the Journal’s peer review standards and policy. As the stringency of the peer review process is core to the integrity of the publication process, the Editor and Publisher have decided to retract all of the articles within the above-named Special Issue. The journal has not confirmed if the authors were aware of this compromised peer review process. The journal is committed to correcting the scientific record and will fully cooperate with any institutional investigations into this matter. The authors have been informed of this decision. We have been informed in our decision-making by our editorial policies and the COPE guidelines. The retracted articles will remain online to maintain the scholarly record, but they will be digitally watermarked on each page as ‘Retracted’.


Introduction
Besides the wind, wave and ocean current, the test string system also has to bear the influence of the motions of floating platform, such as the drift, swing and heave of the drilling boat or platform.So, it is of great practical significance to find out the influence of platform motion on the dynamic behavior of the test tube.
The static behavior analysis is of highly deformed risers were carried out successively by Chucheepsakul and Monprapussorn (2000), Karunakaran et al. (1999) and Santillan and Virgin (2011).The vortex-induced vibration responses of marine riser were investigated by Xue et al. (2015) and Gao and Low (2016) through numerically simulating and theoretical analysis.Ge et al. (2019) presented a method for the fatigue analysis of marine risers.Guo et al. (2001), Meng and Guo (2012), Zhang et al. (2015) and Paı¨doussis et al. (2007) discussed the coupled effects of internal and external flow on the dynamic behavior of testing tube by establishing dynamic models.The focus in the above studies was put on the lateral vibration of the riser under the internal and external flow excitation.The influence of platform motion on the lower pipe string kept unclear.
A matrix iteration method based on two dimensional pipe-beam was used by Zhu (1988) to solve the large deflection of marine risers and to investigate the effects of top tension, transverse drift of drilling boat and wave load on the pipe string.They found that the classical solution based on small displacement hypothesis will cause great deviation for the dynamic analysis of the riser of deep-water floating production system.Finite element method was used by Xie et al. (2011) to investigate the dynamic behavior and the variation of stress with time at different positon.In their computational model, the heave motion load which is compensated by the compensation system of the hook and the horizontal displacement of the drilling vessel were used respectively as the force boundary condition and displacement boundary condition of the top of the test tube.A nonlinear finite element analysis model of deep-water testing tube system was established by Liu et al. (2014) to determine the offset warning limits of the deep-water operation platform, the test work window and the safe operation boundary of the pipe disconnection.Based on the conceptual design of FDPSO-TLD, the dynamic model of the TLD (tension deck) system is established by Lei et al. (2015) to investigate the axial dynamic response of the riser caused by ship heave.Zhang and Li (2015) studied the influence of the phugoid motion of the floating ship on the axial tension.OrcaFlex software was used by Gong et al. (2014) to study the dynamic superposition effect, including surface wave, ocean current, pipeline transport ship motion, and the collision between the pipeline and the pipe support roller.Wang et al. (2015) proposed a dynamic analysis method of marine riser under the coupling action of forced excitation and parametric excitation which are respectively induced by transverse wave and the risefall motion of floating boat.
A new method to meet the requirements of riser stability and bottom tension allowance was developed by Yang et al. (2015) to investigate the influence of real axial force and effective axial force on the lifting mechanical properties.Liu et al. (2016) and Dai et al. (2014) proposed a drift dynamics model for the deepwater drilling platform and the riser system and studied the coupling dynamics characteristics of the deep-water drilling platform and riser system.
The comprehensive analysis of the motion of the platform and its influence on the mechanical behavior of testing tube is still lacking.Therefore, the purpose of this paper is to analyze the various possible motions of the platform and their mathematical description, based on which the influences of platform motion on the dynamic behavior of the testing tube are investigated.

Dynamic boundary analysis of floating platform
Under the action of ocean environment loads (wind, wave and current), the floating platform mainly produces six kinds of motion responses, such as surging, swaying, heave, pitch, rolling and flat rolling, among them, the effect of flat rolling on the floating platform is the smallest and can be ignored.Pitching and rolling are related to the swing characteristics of the floating platform.Surging and swaying belong to the motion in horizontal direction, which directly affects the positioning of the floating platform.In general, the assumption that the wind, wave and ocean currents act in the same plane is made to analyze the limiting conditions of the pipe structure.In the analysis of the influence of the platform motion on the testing string, the main consideration is the pitching and heaving motion of floating platform.

Motion limit of floating platform
The allowable motion limit, which is related to the motion compensation device and the operator's proficiency, is the basic requirement for the platform designer and is also the basis for the evaluation of the platform motion performance.In fact, motion limit is not only related to the seabed condition, but also to the water depth and the motion period.The deeper the water, the smaller is the allowable range of motion.The smaller the period, the smaller is the allowable range of motion.The allowable motion limits of semi-submersible platform and drilling ship of a well in Liwan in South China Sea are listed in Table 1.

Heave motion analysis of floating platform
Being considered as a single degree of freedom system, the sketch map of the force analysis of floating platform with heave motion is shown in Figure 1, in which S w is the cross sectional area of platform in sea level (m).Z 0 is the draft depth of platform in stationary state (m).G is the gravity of the platform (N).
As the floating platform is still in the water, it's gravity and buoyancy are equal and can be written as Where m is the mass of platform (kg), ρ is the seawater density (kg/m 3 ), g is gravity acceleration (m/s 2 ).The equation of vertical vibration is given by Where F 0 b and a are respectively instantaneous buoyancy (N) and acceleration of platform (m/s 2 ).
Equation ( 2) can written as the following differential form Equation ( 4) is a harmonic vibration equation of natural vibration with angular frequency ɷ (rad) and period T (s).
As the effect of seawater on the platform is considered, Equation ( 6) can be further written as

R E T R A C T E D
where k is added mass coefficient depending on the shape of the lower part of platform, for circular section k ¼ 1, for rectangular section K is selected in Table 2 The amplitude of heave motion of floating platform under wave force can be determined according to the method proposed in the literature (Guo et al., 2001) Where u w is the amplitude of wave motion (m).

Nonlinear dynamic response of testing tube under platform motion
Establishment of finite element model The 4½-inch Q-125 test tube of a well in Liwan in South China Sea is taken as the studied object.In actual operation, as the wellhead on the mud line is fixed by a hanger shown in Figure 2, it can be seen as a fixed constraint.So the dynamic response of test tube in deep-water is mainly affected by the marine environment and platform motion and its numerical model is established in this section.
(2) Displacement and load boundary conditions Pipe element is used to discretize the testing tube shown in Figure 3, the static liquid column pressure in the annulus between the test tube and riser, and the gas pressure inside the test tube being taken into account.According to the actual condition, the wellhead on the mud line is simplified to a fixed constraint and the platform motion is taken as the dynamic boundary of the upper end of testing tube.The wave period of deep water is taken as 9 s and the amplitude of platform heave motion is assumed to be 1 m after the heave displacement is compensated by a compensation system.For the horizontal motion of the platform, 2% of the water depth is used to represent the average offset.According to these analysis, the dynamic boundary of the floating platform and load are shown in Table 3.

Effect of average offset of floating platform
The floating platform has an average deviation under the ocean environment load, which is mainly due to the effect of the steady current load and is the main part of the horizontal motion of the platform.To investigate the influence of the average deviation of the platform on the testing tube, the offset value is taken as 1%~6% of water depth.
Figure 4 shows that the stress in the testing tube varies linearly with water depth, except for the sudden change on the tube section closed to mud well head.With the platform offset increasing, the stress level in test tube overall increase.This phenomenon is similar to the influence of the top tension on the strength of the riser.The reason for this is that when the offset is

R E T R A C T E D
increased, the test string is stretched, and the hook load will be increased accordingly, resulting in increased stress in the test tube.The effect of average offset on the transverse displacement of test tube is shown in Figure 5, which indicates the linear relation between the displacement and water depth.
In fact, excessive offset will have a greater effect on the deep-water test operation.For instance, for a excessive deflection angle of the tube section near mud line, it is difficult to rise and land the test string and to disconnect the underwater test tree in emergency condition.In severe cases, the test tree may be stuck and unable to escape.So, in general, the deflection angle of the deep-water test string should not exceed 2 degrees.Because of the relatively small size of the drill string, it's maximum deflection angle can reach about 9 degrees.

Combined effects of heave motion and mean offset
The dynamic behavior of the testing tube under the combined influence of mean offset and platform heave motion with 9 s cycle is investigated.Dynamic boundary of the platform and load parameters are shown in Table 4.The time-history responses of the stress, displacement, velocity and acceleration of the top, middle position and the position of mud line are shown in Figures 6-13.As can be seen from the figures, the stress and displacement amplitudes of the deep-water test tube decrease gradually from top to bottom.Whereas the alternating amplitudes of the upper and lower ends are larger than that of the middle point.This is related to the top boundary of the test tube, the constraint of the mud line and the distribution of the damping.The velocity and acceleration decrease gradually from the top to the bottom evidently because of the damping effect.The dynamic response of the test string is random under the condition of platform heave and mean deviation.Moreover, wave motion, as well as the response of platform is stochastic.So, the response of the testing tube under the condition of heave motion and average deviation is also a stationary stochastic process.

R E T R A C T E D
Stress of the test tube under the limit displacements of platform As the floating platform heaves to the longitudinal limit positions y = ±1 m and offsets to the horizontal limit position x = ±40.5151m (mean deviation plus slow drift amplitude, namely 2% × water depth +03024 ffiffiffiffiffiffiffiffiffi ffi 1450 p Þ, the Mises stress in testing tube is shown in Figure 14.It can be found in the figure that as the floating platform sinks to the limit position, the maximum stresses (131.754MPa and 176.565MPa) of the test tube appears at the bottom end connected to the hanger.Whereas, with the floating platform rising to the limit position, the maximum stresses (228.616MPa and 263.194MPa) appears at the top which is the position of the hook on the platform deck.The main reason for this phenomenon is that the falling motion counteract the axial force produced by the offset of the platform, and the axial tension load of the testing tube increases due to the superposition of rising motion and the offset of the platform.

Conclusion
The dynamic boundary of floating platform has been analyzed and the its influence on the dynamic response of deep-water testing tube has been investigated.The following conclusions are drawn from the results obtained:

R E T R A C T E D
Larger offset of platform cause greater hook load and Mises stress in testing tube.Moreover, an excessive offset, resulting in deflection angle of the lower end of the test tube, will lead to operation difficulty of rising and landing testing tube.The average offset value should not exceed 6% of the water depth.
It has been displayed in the coupling analysis of heave motion and mean shift that the response of   It is shown in the stress analysis of the test tube under the limit displacements of platform, As the floating platform sinks to the limit position, the maximum stresses of the test tube appears at the bottom

Figure 1 .
Figure 1.Force analysis of floating platform in heave motion direction.

Figure 2 .
Figure 2. Schematic diagram of simplified wellhead on mud line.

Figure 3 .R
Figure 3. Element partition of test tube.

Figure 4 .
Figure 4. Effect of platform offset on the stress of test tube.

Figure 5 .
Figure 5.Effect of platform offset on the displacement of test tube.

Figure 6 .
Figure 6.Longitudinal displacement time-history response of upper node.

Figure 7 .
Figure 7. Longitudinal Mises stress time-history response of upper node.

Figure 8 .
Figure 8. Longitudinal acceleration time-history response of upper node.

Figure 9 .
Figure 9. Longitudinal velocity time-history response of the top node.

Figure 10 .
Figure 10.Longitudinal displacement time-history response of middle node.

Figure 11 .
Figure 11.Longitudinal velocity time-history response of the middle node.

Figure 12 .
Figure 12.Longitudinal acceleration time-history response of middle node.

Figure 13 .
Figure 13.Longitudinal Mises stress time-history response of middle node.

Figure 14 .
Figure14.Mises stress distribution of test tube as floating platform is in limit position.

Table 1 .
Allowable motion limits of semi-submersible platform and drilling ship.

Table 2 .
Added mass coefficient of platform with rectangular lower body.

Table 4 .
Dynamic boundary of the platform and load parameters.
3 Pressure in testing tube From mudline head to the platform Wellhead 28.63 ~25.11MPa Measured Gravity Density of pipe 7850 kg/m 3