Distance Transmission Pipeline Research Articles

Key Points of Construction Management for Directional Drilling Crossing of Large Diameter and Long Distance Transmission Pipeline

Key Points of Construction Management for Directional Drilling Crossing of Large Diameter and Long Distance Transmission Pipeline

극한지 장거리 자원이송망 최적 배관 사양 검토

극한지 환경의 장거리 천연가스 고압 수송배관 설계 시 고려해야 할 중요한 요소 중의 하나로 배관 파괴제어 방안 수립이다. 가스배관의 연성파괴전파 저지 예측에 사용되는 방법은 간편 수치해, Battelle two curve 방법, 실제크기 배관 파열시험이 있다. 본 논문에서는 러시아 극한지 가스배관에 적용된 배관재료 요구조건을 알아보고, 배관재료 파괴인성 요구 값 설정 방안에 대하여 세 가지 방안을 대상으로 배관설계 적용 사례와 함께 비교 분석하여, 배관설계 시 적용할 최적방안을 파악하였다. 수정계수를 도입한 BTC 방법을 적용하는 것이 적절한 것으로 판단된다.

Similitude criterion derivation and pipe physical property test and suitable analysis for water hammner scale model of long distance district heating pipeline

Based on a new district heating (DH) based on absorption heat exchangers, long distance district heating pipelines are developed rapidly in China. Water hammer protection is one of the most important design issues encountered in district heating pipeline safety. In order to analyze water hammer in DH pipe systems, scale models are introduced in this paper. Traditional similitude criterion numbers are derived from the motion equations based on the assumption of incompressible fluid. Therefore, traditional similitude criterion numbers are invalid in water hammer analysis, considering that water hammer is caused by the elasticity of the fluid. Therefore, similitude criterions used in water hammer analysis are derived by us and put forward in the article. In order to find out suitable pipes for scale models of DH pipeline systems, seven kinds of pipes are tested in an experiment based on typical parameters in DH pipeline systems. The results show that PB pipes should be used in shorter pipelines with small altitude difference, and air pressure pipes should be used in longer pipelines with large altitude difference. At last, a long distance transmission pipeline for a CHP system in Shanxi Province is taken as an example.

Managing demand uncertainty in natural gas transmission networks

Natural gas transmission networks (GTNs) are widely used to transmit natural gas over long distances while the efficient management of GTNs requires as accurate as possible information about the demand of the customers. However, the demand of the users can only be predicted with a limited accuracy. Accordingly, the uncertainties resulting from the demand prediction errors should be addressed to increase the robustness of the daily planning of GTNs.An optimization algorithm based on chance-constrained programming technique is developed to consider the uncertainty of the forecasted future demands, whose solution is the set point of the compressor stations discharge pressure. An important prerequisite of chance-constrained programming formulation is the mean and variance of the objective function and constraints. Accordingly, unscented transform is used as the uncertainty propagation tool. Then, the methodology is applied to a long distance transmission pipeline with 8 compressor stations to illustrate the effectiveness of the proposed approach where the end user load is characterized by a Gaussian random variable with known mean and variance.The results of the optimization based on the proposed algorithm are compared to the deterministic ones where an optimum pressure buffer can be obtained based on the mean and the variance value of the customer demand which is required for the safe operation of the network. Pressure buffer is also affected by the probability assigned for the constraint satisfaction. The results of the algorithm are compared to deterministic approach in terms of power consumption and it is concluded that to gain robust solutions to overcome demand uncertainties, extra power usage is essential. Also, it is shown that demand uncertainty handling requires a specific strategy rather than operating the system based on the expected condition.

Full-scale Burst Test and Finite Element Simulation of 32 Inch Oil Pipe with Girth Weld Defects

Recently several leak accidents occurred due to girth weld defects in long distance transmission pipelines of PetroChina. To avoid possible failure accidents, in-line inspections were performed on some certain pipelines. In some new built pipelines, a large quantity of girth weld defects were detected in the inspections. Many fitness-for-service (FFS) assessment methods have been proposed for various kinds of metal loss in pipeline, however, it is still difficult to obtain a confident assessment of girth weld defects. Several types of girth weld defects were manufactured on 32 inch oil pipe in this study and full-scale burst tests were performed combined with 3D finite element simulation to study the influence of girth-weld defect geometry on the failure pressure. These defects were manufactured with different opening width and orientation. After full-scale burst tests, the real morphology of the girth weld defects were examined by fracture analysis. The defect data and experimental results were obtained and used to FFS assessment, where FFS methods included API 579, BS 7910, Miller, Kastner etc. Error analysis results were illustrated by comparing the experimental data and the assessment results, and suggested that fracture failure should be considered for girth-weld defects assessment in a conservative view at last.

A Cyclic Internal Pressure Characteristics Analysis of Long Distance Transmission Pipelines

The objective of this work is to present the cyclic internal pressure behaviors and generated reasons of different long distance transmission pipelines, considering transported fluid, in-service period, and pressure data sampling methods. Rainflow counting method is adopted to obtain pressure cycles, and the analysis results indicate that pipelines pressure show variously in respects of cycle number and amplitude value, and pressure cycling reasons and suggestions are specially discussed. The authors argue that suitable operation scheme should be carried out to avoid unnecessary pipeline damage according to the oil or gas pipelines’ special pressure fluctuation characteristics and generated reasons.

Investigation on the Key Technologies of Mechanical Expanding of Large Diameter LSAW Pipe

Long distance transmission pipeline is one of promising transportation methods developed in recent years. It is safe, economical, convenient and prompt. It is mainly used in transmitting gas, liquid, and other dispersed material. Oil and natural gas is especially suitable to be transmitted by high pressure large diameter longitudinal submerged arc welded (LSAW) pipelines. Mechanical expanding is one of the most important processes in the production of large diameter LSAW steel pipe for long distance transmission pipeline. Firstly, the LSAW steel pipe mechanical expanding is modeled. Two FEM models are established to simulate the mechanical expanding process at the cross section and longitudinal section of the LSAW steel pipe respectively. Secondly, the deformation characteristics of the LSAW steel pipe are simulated while mechanical expanding processes. Finally, main mechanical expanding process parameters and their influence on the quality of finished LSAW pipe are analyzed in detail according to the FEM simulation. The results presented by the analyses are very consistent with the experiment, and can be used to direct the production of LSAW steel pipe.