Rapid increase in the demand for gas has turned what was a buyer's market to a seller's market. As a result, pricing of gas price has become an ever more important issue that is under discussion by many experts. There are various methods of pricing defined with regard to theoretical issues and trade principles, but only some of these are applicable at the present time and others have remained more theoretical. Most gas exporting countries wish to have their gas priced at the equivalent level of oil prices, in terms of energy content or at least have gas price changes at the same rate as for petroleum prices, in order to encourage expansion of gas development projects. This is why in European countries the index of Oceania and Asian LNG prices is based on petroleum prices. This is also the case in Japan as the main LNG importer. It is expected that gas demand increases significantly in the long run, compared to other fuel resources. It is therefore expected that natural gas prices will continue their upward trend in the future.A study of the natural gas pricing process shows that unlike LNG, the price of natural gas is often lower than other energy alternatives (petroleum and oil products). There are two specific features of gas trade that are different from petroleum transactions, namely: 1) intense interdependence of exporter and importer due to the impossibility of saving gas at least during the contract period and 2) high risk of investment. Considering these particular features, prices mentioned in contracts should be calculated in such a way as to maintain gas supply security while providing the possibility of changing the contract price in case there is a change in other fuel prices (especially competing fuels), in order to maintain suppliers' interest. Thus, main principles to be considered in negotiation of gas export are: determining the relational index of gas and petroleum prices, the fixed portion of price, minimum and maximum prices, and determining the time period for price revisions in the gas pricing formula. The gas price has to be fixed in a competitive manner in relation to other fuel prices the present paper assesses the mechanisms of pricing gas export through Pipelines and compares it to the other mechanisms and analyzes its future challenges.

This paper is concerned with asphaltene deposition in fluid flowing through Pipelines. Brownian diffusion and drag, gravitational, thermophoresis, buoyancy, and shear removal are considered as possible mechanisms in the asphaltene deposition process. The thermo-physical properties of the fluid were obtained from Iranian oil fields. A model was used in the pipeline deposition modeling to predict the asphaltene deposition rates under flow conditions. The effects of particle size, temperature gradient, and fluid velocity were studied on asphaltene deposition rate. The results showed that, among the above-mentioned mechanisms, the gravitational and thermophoresis forces played a significant role in the formation of the deposit under the flow conditions. To verify the model, some predictions were compared with the available aerosol deposition data in the literature.

In conditions of gas Pipelines operation, significant longitudinal deformations may occur at the sections adjacent to the receiving/ launching chambers of pig and diagnostic equipment. These deformations, caused by stress and temperature fluctuations, lead to undesirable deformations and damage of piping elements. To reduce the magnitude of longitudinal deformations the device of expansion joints is proposed. Geometric parameters of the expansion joint are determined based on the results of strength and stability calculations of the gas Pipelines. The use of the software package START allowed to simulate the behavior of the pipeline before and after installation of the expansion joint and to analyze changes in longitudinal deformations.  An important part of the work is the methodology of calculation justification of the necessity to install such units to reduce longitudinal deformations. Optimization of the expansion joint design and calculation of its parameters contributes to the reliability of gas pipeline systems.

Various destructive and nondestructive methods are used for in line inspection of Pipelines. A pipe may fail because of different causes such as corrosion, pitting, stress corrosion cracking (SCC), weld cracks and mechanical impacts and damages. Corrosion failures in a pipe can take place in different ways, some of them are easy to detect and others require special facilities and methods. The best selection of the inspection tools depends on the type of application, mechanism of corrosion, chemical environment and the material. This paper investigates and compares different types of in-line inspection tools for Pipelines and compare their advantages and disadvantages. Today, the most common method for In Line Inspection of Pipelines is Magnetic Flux Leakage (MFL), which is used for detection of wall thickness reduction of Pipelines, various cracks, corrosion and pitting in pipes. Therefore, it can’t be applied for nonmagnetic materials. The Eddy Current (EC) test is a non-contact test with relatively low velocity which is sensitive to the stand off from the material surface during the test and it is used only for conductive materials. Ultrasonic testing is a common method with high accuracy. It is widely used for detection of different defects and is based on sending short wavelength high frequency ultrasonic waves into the material and receiving their reflections. By interpreting the results, various defects and reduction in the wall thickness of the pipes can be detected. Acoustic Emission (AE) testing, which is based on interpretation of elastic deformations, elastic strain energy changes and stress distribution, is not considered as a common test for inspection of Pipelines, yet. Electromagnetic Acoustic Transducers (EMAT) are a new type of ultrasonic testing method which do not require liquid coupling but should be used at a definite distance from the pipe wall during the test. It is concluded that the fastest and most reliable method for In-Line Inspection (ILI) of Pipelines is currently the Magnetic Flux Leakage (MFL) method.

Six polymeric coatings viz 3LPE, 3p/2p CAT, PU, VE, LE, and HSS have been selected, and each type of coating has been applied separately on SS316L pipe external surface. The test samples were subjected to Specific Electrical Insulation Resistance (SEIR) test in 0.1 mol/liter of NaCl solution and the Electrochemical Impedance Spectroscopy (EIS) test in 3.5 % NaCl solution. After completion of the tests, SEIR values of PU, 3LPE, and LE are found to be about 2.5×109, 8.9×108, and 3.9×108 ohm.m2, respectively. In contrast, the electrochemical impedance values at low frequencies (100 mHz) of 3LPE, 3p/2p CAT, and HSS are found to be about 7.9×1011, 5.4×1011, and 4.5×1011 ohm.cm2, respectively. The experimental results are analyzed, and the ranking of coatings has been made based on each test's performance. The overall ranking of coatings is evaluated for the determination of the suitability of the coating for buried SS316L Pipelines in the petroleum, petrochemical, and natural gas industries.

Pipelines are widely used in transporting large quantities of water and sewage over long distances. These valuable infrastructures attract public attention only when they fail. The quantitative and early detection of defects in sewer Pipelines is very important in order to avoid severe consequences. In many countries, sewer pipeline inspection is usually carried out using CCTV (Closed-Circuit TV) cameras and off-line human surveys through raw image assessment for failure identification. CCTV-based techniques have some limitations that restrict their implementation. One of the disadvantages of CCTVbased techniques is the lack of visibility in the interior of the pipes. The other disadvantage of CCTVbased techniques is the poor quality of the obtained images because of difficult lighting conditions. In consequence, CCTV-based techniques can only detect gross defects reliably. In recent decades, thermography, microwave, laser, and sonar-based techniques have been proposed to complement the conventional CCTV-based technique and to improve inspection results. Also, new inspection devices employing multiple sensors and being capable of carrying out remote sewer inspection tasks have been proposed. This paper presents an overview of the conventional and novel inspection technologies for sewer Pipelines. Furthermore, different types of robots for in pipe inspection tasks are discussed.