Pipeline stress issues
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1. Which pipes require consideration of stress issues? 2. Do stress issues need to be considered for pipelines carrying extremely hazardous and highly hazardous media, as well as those carrying flammable and explosive media? 3. Is it not necessary to consider stress issues for large-diameter pipes in general media? 4. The screenshot is taken from “SH∕T 3108-2017 Code for Design of Process and Thermal Piping Systems in Petrochemical Plants”. What does clause 6.3.2 mean? Is it true that in the figure, the value of a should not be less than one-third of the value of b?
According to Article 45 of the \"Regulations on Safety Inspection of Pressure Piping – Industrial Piping\", the strength calculation of piping components shall comply with the provisions of GB/T20801. Pipeline stress analysis should be conducted for all pipelines that are connected to rotating equipment such as pumps, are used under high temperature and pressure conditions, have a circulation equivalent value greater than 7000, or are subject to strict requirements in the engineering design.
Whether stress calculation is required depends on the specific conditions of the pipeline. In some cases, the temperature and pressure are not high, but since the pipes are connected directly, a stress calculation might still be necessary. In other cases, the temperature is around 200 or 300 degrees, and the flexibility of the pipes is high; in such situations, it seems sufficient to rely on visual inspection. However, for GC1 pipes operating at high temperatures, it’s better to use software for stress calculations
Clause 6.3.2 means that the Π bend should be placed as close as possible to the midpoint between the two fixed supports, so as to help balance the thermal expansion stresses in the straight sections on both sides.
Generally, pipelines with a diameter greater than 100 mm and an operating temperature above 100°C (i.e., 200-series pipelines) require a detailed stress analysis to be carried out by a pipeline stress specialist. The following pipelines should undergo detailed stress analysis using computer-based methods: (1) Pipelines of all diameters whose operating temperature is greater than 250°C or less than -50°C ； (2) Pipelines with an operating temperature greater than 200°C and a diameter greater than 200 mm ； (3) Pipelines with an operating temperature greater than 150°C and a diameter greater than 400 mm ； (4) Large-diameter (DN1200) and thin-walled pipelines (δ≤0.20 D). (5) High-temperature pipelines entering and exiting the heating furnace and steam generator ； (6) High-temperature pipelines entering and leaving the reactor ； (7) Steam pipelines entering and leaving the turbine ； (8) Inlet and outlet process pipelines for centrifugal compressors, reciprocating compressors, blowers, exchangers, etc.
This post was last edited by qldch2306 on 2019-11-3 at 13:56. The regulations for pipeline stress analysis and design—those issued by Global Standards in 2003—are already very professional and detailed. Refer to the classification principles for stress analysis of pipelines. In principle, all pipelines should undergo stress analysis, and the method and level of detail for such analysis are determined based on the pipeline’s characteristics (temperature, pressure, diameter, wall thickness, load requirements of the connected equipment, etc.). If not specified in the project, the stress analysis pipelines can be classified using the following method. I, II, III, IV, . . . . .