Search results

The purpose of this paper was to investigate the corrosion behaviour of API X65 pipeline steel in the simulated CO₂/oil/water emulsion using weight loss technique, potentiodynamic polarization technique and characterization of the corroded surface techniques.

The weight loss analysis, electrochemical study and surface investigation were carried out on API X65 pipeline steel that had been immersed in the CO₂/oil/water corrosive medium to understand the corrosion behaviour of gathering pipeline steel. The weight loss tests were carried out in a 3L autoclave, and effects of temperature, CO₂ partial pressure, water cut and flow velocity on the CO₂ corrosion rate of API X65 pipeline steel were studied. Electrochemical studies were carried out in a three-electrode electrochemical cell with the test temperature was 60°C, and the CO₂ partial pressure was 1 atm by recording open circuit potential/time and potentiodynamic polarization characteristics. The surface and cross-sectional morphologies of corrosion product scales were characterized using scanning electron microscopy. The phases of corrosion product scales were investigated using X-ray diffraction.

The results showed that water cut was the main controlling factor of API X65 steel corrosion under the conditions of CO₂/oil/water multiphase flow, and it had significant impact on corrosion morphology. In the case of higher water cut or pure water phase, general corrosion occurred on the steel surface. While water cut was below 70 per cent, corrosion morphology transformed into localized corrosion, crude oil decreased corrosion rate significantly and played a role of inhibitor. Crude oil hindered the corrosion scales from being dissolved by corrosive medium and changed dimension and accumulation pattern of the crystal grain, thickness and structure of the corrosion scales; thus, it influenced the corrosion rate. The primary corrosion product of API X65 steel was ferrous carbonate, which could act as a protective film at low water cut so that the corrosion rate can be reduced.

The results can be helpful in selecting the suitable corrosion inhibitors and targeted anti-corrosion measures for CO₂/oil/water corrosive environment.

The purpose of the paper is to explore impacts of financing and supplier subsidy on capital-constrained retailer and the value of returns subsidy contract under a situation where the retailer makes joint operations and finance decisions.

This paper considers a two-level supply chain, including a retailer and a supplier. Facing problems of capital constraints and even customer returns, the newsvendor-like retailer orders from a well-capitalized supplier. The supplier allows the retailer a delay in payment and provides a subsidy contract to alleviate its problems if it is profitable. Considering their difference of initial capital status, the retailer is assumed to be Follower of Stackelberg Game and the supplier is the Leader.

The supplier return subsidy contract has some merits for both of partners in the chain. And it does not coordinate the supply chain when the retailer has enough initial capital; however, when the retailer is capital constrained, it does. In addition, the retailer’s initial capital level significantly affects the supplier’s subsidy decision.

Return rate is simplified to a fixed proportion of completed demand. In addition, trade credit is only financing source in this paper, and other types of financing methods, such as bank credit, can be taken too.

This paper first incorporates trade credit financing and customer returns into a modeling framework to investigate the capital-constrained retailer’s joint operations and finance decisions and the value of supplier’s subsidy contract.