Oil Storage facilities (terminals) are usually designed with a pressure rating lower than the rating of the pipeline transporting the fluids. During abnormal operations, terminal piping can be subject to unexpected transient pressure surges that can exceed the allowed values. Mitigations are required a common one is installing a relief system.
When a relief valve is installed, it is connected to a tank and the location of this relief tank is critical for the proper operation of the relief system and the overall mitigation of pressure surges. Relief design needs to take into account the length and layout of the piping. Facilities in the northern hemisphere contain pipes installed above ground and prone to experiencing cold temperatures during winter months. If the fluid is stagnant in these pipes, the cold weather increases the viscosity of the fluid. If the relief valve activates, the fluid that has been stagnant in the pipe needs to be pushed out of the pipe and into the tank. This requires a high pressure from the system and is directly affected by the distance of the pipe and the properties of the stagnant fluid.
This paper will show how transient pressures change for length of pipe and for varied viscosities of the stagnant fluid. With these findings, engineers can improve their understanding of the effects of temperature and length on surge pressures and they can design safer systems for liquid transportation and storage.