Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Study on the coupling dynamic characteristics of flexible non-metallic pipeline considering clump
weight parameters
Lei Li1*, Yingxue Deng1, Wenhao Hou1
1.School of Naval Architecture and Maritime, Zhejiang Ocean University ，Zhoushan, Chinaloads. Therefore, the selection of economic and fast composite pipes
has become an urgent problem to be solved in the project. This researchmainly analyzes the mechanical characteristics of HDPE non-metallic
pipes and discusses the feasibility of laying HDPE non-metallic pipes
by using a reasonable clump weight method.
Based on the catenary theory, Plunkett(1967) proposed to describe
the deformation of the suspended-span pipeline by progressivedevelopment. Dixon(1968) derived the catenary equation with stiffnessby improving the natural catenary equation, which assumes that most of
the pipeline is still simplified as a natural catenary. Through thismethod, they obtained the required tension and laying angle of thepipeline under different working conditions. Senthil et al.(2015) used
OrcaFlex for dynamic analysis of pipelines, and compared with theresults of static analysis. They found that the influence of ship motion
on the mechanical properties of pipelines is the main one, and theinfluence of waves is less, while the influence of ocean currents isrelated to the direction of flow. It is also revealed that S-laying
operations depend on roller configuration and stinger radius. Large
plastic deformation occurs when pipes pass over stingers, and theplastic deformation is caused by the combined effects of the pipe-laying
vessel motion, roller reaction forces, axial tensions, and bending
moments (Wang et al. 2017). Gong et al.(2014) created an extensive
finite element model for S-laying systems that considered the contact
between stinger rollers and the pipeline, current, and surface waves
using OrcaFlex. Yuan Z.M.(2014) study on a hybrid mooring systemwith clump weight and buoys. He found that the tension on the line
could be reduced by using the present hybrid mooring system. Vicenteet al.(2011) investigated different mooring configurations with slack
chain mooring lines of a floating point absorber with or without
additional sinkers of floaters. It was found that the different
arrangements of the buoys and weights would bring significant
differences in terms of average and maximum tensions on the mooring
cables. Bruschi(2020) study on the influence of clump weight on theplatform response and on the mooring line tension.
In this paper, we studied the pipe-laying method and mechanicalbehaviors of HDPE pipelines instead of steel pipelines. Taking theZhoushan Island diversion project as an example, the feasibility ofemploying non-metallic HDPE pipe to pipe-laying take by using 101
pipe-laying vessel is studied. Firstly, the hydrodynamic calculation iscarried out by employing SESAM software, in which the hydrodynamic parameters of the vessel are obtained based on the potential
flow theory. And then, we performed dynamic coupling analysis ofpipe-laying vessel-mooring-pipeline by using the OrcaFlex program.

ABSTRACT
Freshwater is one of the most important factors in thedevelopment of sea islands. At present, steel pipelines are mainly used
for transportation in mainland water diversion projects by using
pipe-laying vessels. However, the pipeline connection process is very
complicated under the process of pipe-laying, and it is easy to bedamaged by the environmental load. At the same time, high density
polyethylene(HDPE) pipe has been widely used in land drinking waterand sewage pipelines, which has the advantages of easy connection,
corrosion resistance, and good flexibility. Therefore, this paper studies
the pipe-laying method and mechanical behaviors of HDPE pipes
instead of steel pipe-laying. Taking the Zhoushan Island diversion
project as an example, the feasibility of employing non-metallic HDPE
pipe to pipe-laying take by using 101 pipe-laying vessel is studied.
Firstly, the hydrodynamic calculation is carried out, which thehydrodynamic parameters of the hull are allowed based on the potential
flow theory. And then, we performed dynamic coupling analysis ofpipe-laying vessel-mooring-pipeline. The influence of the stinger on thecurvature radius of the pipe is considered. The results show thedynamic response characteristics of the floating structure, thetime-domain dynamic tension of the mooring line, and the mechanicalcharacteristics the HDPE pipeline. Finally, we discussed the clump
weight model and the distribution law of clumps under the pipe-laying
process. The coupling effect of block weight on the vessel-pipelinemodel is calculated, and the effective stress of HDPE pipes are alsoacquired under the different clump weight mode. The key clump weightparameters are confirmed based on the calculation. The results can also
provide a reference for the island water diversion project.
KEY WORDS: coupling analysis; clump weight; dynamic response;
HDPE pipe;

INTRODUCTION
Islands are an important part of the land area in each country.
There are more than 50,000 islands in the world. At present, freshwater
resource is still one of the main factors that plague island development,
and the most convenient and efficient method is to use submarine
pipelines to transport. In the mainland water diversion project ofZhoushan Island in my country, the "S-Lay" type pipe-laying vessel isused to lay steel pipes. But the steel pipes are greatly affected by factors
such as vessel motion, pipe stress, curvature radius, and environmental

1832