Design principles and basis for expansion joints
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I am currently working on a tank farm design, and the materials involved include propionaldehyde, acetic acid, n-propyl acetate, n-propanol, and ethanol. I’m not sure which of these materials require the installation of expansion vents By the way, what is the basis for setting the expansion ports? Thank you
The main principles for using large expansion joints are as follows: 1. Expansion joints are mostly used in high-temperature and low-pressure environments； 2. Special attention should be paid to the service life (number of safe cycles) of expansion joints for pipelines subject to fatigue factors ； 3. Expansion joints must never be used in areas subject to torsion ； 4. Special attention should be paid to the impact of expansion joints on the system under negative pressure. To be more specific, the common types of expansion joints include bellows expansion joints (which are further divided into constrained and unconstrained types) and stuffing box expansion joints (which are further divided into sleeve type and spherical type). When designing the flexibility of pipelines, natural compensation should be given priority. Bellows expansion joints should only be considered when the pressure of the fluid in the pipeline is not high but the temperature is high, the pipe diameter is large, the installation space is limited, or using natural compensation would require longer pipes or more elbows, which is not economical in such cases; moreover, they are only suitable for pipelines with an internal pressure of less than 0.7 MPa. Filler-type expansion joints are rarely used in petrochemical plants because leaks occur due to the easy relaxation of the fillers. Filler-type expansion joints are strictly prohibited in pipelines carrying highly toxic, flammable, and explosive media. GB50316-2000 also stipulates that expansion joints with stuffing box seals shall not be used for pipelines transporting A1 and A2 class fluids
Do you mean the expansion port by the term you used, referring to the port installed on the tank? When I was working on the asphalt tank, I installed an oil and gas expansion port; since asphalt has a very high viscosity at low temperatures, there is a pipeline designed to provide heating so that fluid can flow or circulate in the upper part of the tank.
Expansion must be taken into account for each pipeline, and the expansion joints of different pipelines carrying the same material should be located on the same tank. The types of expansion vents include those leading to the top of the tank, those entering from the bottom of the tank via a safety valve, and those entering from the bottom of the tank via a check valve.