Pipeline design for driving – with future maintenance in mind
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This post was last edited by jinqhuaxz on 2016-11-19 00:52. For a 40MW biomass power generation unit that is about to be put into operation, there are twenty or thirty high-temperature medium-low pressure steam pipelines that need to be designed and subjected to stress analysis. Temperature: 425 deg, pressure: 1.0 MPa. Does the design approach, as well as the stress calculations, differ from those used in regular pipeline design? I would like some suggestions regarding the design basis, safety factors, material selection, pipe racks, supports, etc. Thank you in advance!
There’s another question: can the piping for driving be removed in the future? That’s the plan for now; it will be removed after driving. But what if the system needs to be restarted for a major overhaul in the future? Also, can it be used for maintenance?
Pipes at 425 degrees, with diameters of DN40~50 and above, all require stress analysis; this is a requirement for pressure pipes. The piping specialty prepares axonometric diagrams showing the locations of the supports. After analysis, the stress analyst will tell you what the sliding friction, weight, and thrust (for fixed supports) are for each support of that pipeline Including the stress conditions during pressure testing. The piping team calculates the force on each pipeline (the maximum combined value) and submits it to the civil engineering team. The civil engineering department provides supports for pipes based on the magnitude of the forces. The stress analysis report will indicate the displacement of the pipeline at each support point. Based on these displacements, you can determine whether it is necessary to lengthen the pipe supports, in order to prevent them from falling and getting stuck on the supports. When the pipeline contracts during shutdown, this can either damage the supports or tear the pipe supports apart. In severe cases, the pipes get torn apart. The stress analysis report will also tell you the magnitude of the thrust at the pipe ends, to prevent damage to the equipment.
The design for starting up, shutting down, and maintenance must be taken into consideration. There is no device that does not stop operating temporarily, nor is there any device that is not maintained. Temporary pipelines must also be arranged in a standardized manner. Pipes that are in use or not in use – which are not needed on a regular basis – are distinguished by their paint color.
ZQJ, thanks for the great advice! The largest pipe diameter is 500! It is indeed quite important. A106 GR.B is being used, and the material is right at the limit! It’s really stressful. I hope there are good calculation templates available, preferably in Excel format. I don’t know where I can find it. Thank you first! Thank you again for your advice. Pipes at 425 degrees, with diameters of DN40~50 and above, all require stress analysis; this is a requirement for pressure pipes. The piping specialty prepares axonometric diagrams showing the locations of the supports. After analysis, the stress analyst will tell you what the sliding friction, weight, and thrust (for fixed supports) are for each support of that pipeline Including the stress conditions during pressure testing. The piping team calculates the force on each pipeline (the maximum combined value) and submits it to the civil engineering team. The civil engineering department provides supports for pipes based on the magnitude of the forces. The stress analysis report will indicate the displacement of the pipeline at each support point. Based on these displacements, you can determine whether it is necessary to lengthen the pipe supports, in order to prevent them from falling and getting stuck on the supports. When the pipeline contracts during shutdown, this can either damage the supports or tear the pipe supports apart. In severe cases, the pipes get torn apart. The stress analysis report will also tell you the magnitude of the thrust at the pipe ends, to prevent damage to the equipment.
It is said that this pipeline will be removed once construction begins. Sigh.
Generally, the weight of water in the thickest pipes, plus the total weight of all other pipes on that support under normal operating conditions, constitutes the maximum vertical load on that support. Water pressure testing is carried out one pipe at a time.
Is the pressure value for hydrostatic testing different for pressure vessels? !
Generally, a water pressure test at 1.5 times is carried out.
Is it also necessary to multiply by a ratio coefficient of the allowable stress values at the water pressure and temperature as well as the design temperature?
Americans are like that. Allowable stress at room temperature / Allowable stress of 425.