When HG/T20592 pipe flanges are used as equipment flanges, is it necessary to use SW6 software for verification?
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This post was last edited by 311yj on 2023-4-15 at 14:35. It is a small device made of 304 material, with an outer diameter of 159, a wall thickness of 6, and an inner diameter of 147; the cylinder body is constructed from a steel pipe with dimensions of φ159×6. Operating pressure is 3.2 MPa, design pressure is 4.0 MPa; the SW6 software for hydrostatic testing calculates it to be 6.4 MPa. Operating temperature: 320°C, design temperature: 400°C. The upper head and the cylinder are connected using HG/T20592 flanges WN150-63RF. Question 1: This device has an inner diameter of 147 and a total volume of over 30L; is inspection required? Question 2: Referring to the pressure and temperature rating table in standard HG/T20592, for PN63, 2C1, with an operating temperature of 350°C, the maximum allowable operating pressure (gauge pressure) is 34.5 bar, which is equivalent to 3.45 MPa. However, the operating temperature of my device is only 320°C, and the operating pressure is 3.2 MPa, which is lower than the 3.45 MPa specified in the table. Can the WN150-63RF be used directly as the equipment flange? (I used SW6 software for the calculations, and found that the WN150-63RF case could not be processed successfully; the calculations could be completed only after increasing the effective thickness of the flange by 5 mm.) But many people on the Internet say that the SW6 software is too conservative in its calculations, and many standard flanges fail to pass the checks). Since the customer does not need to provide a calculation sheet, should the WN150-63RF standard flange be chosen directly? Is it still necessary to thicken it?
1. According to the Code for Design of Pressure Vessels (GB 150), supervision and inspection are required when the inner diameter of the equipment is greater than 50 mm and the wall thickness is greater than 6 mm. Therefore, since the total volume of this device exceeds 30L, it requires supervision and inspection. 2. Based on the information you provided, the operating pressure and temperature of this device are below the specified values for the flange WN150-63RF as defined in standard HG/T20592; therefore, it is possible to use this standard flange directly, without the need for thickening or any other modifications. It should be noted, however, that due to the conservative nature of the calculations performed by SW6 software, some standard flanges may fail the checks, although they are safe for actual use. If the customer requires higher security, considering the use of flanges of a higher grade or applying thickening treatments is an option. .
1. Reference tolerance specification: Scope of application on page 1； 2. Direct selection is not recommended; non-standard calculations are advised.
For the first item, according to TSG21-2016, supervision and inspection are required only when the inner diameter is greater than 150. For the second item, its use is permitted by the standards; it does not need to be included in the calculations. If it is to be treated as a non-standard item, then a calculation report must be prepared.
Without supervision and inspection, the flanges should be designed as non-standard flanges
1. Supervision and inspection are necessary; no word games allowed! 2. The original design must meet the design operating conditions!
According to regulations, equipment is subject to inspection only if its volume is 0.03 m3 or more and its inner diameter is 150 mm or more; both conditions must be met. Why is inspection required now when the inner diameter is less than 150 mm? If it is “or”, then supervision and inspection are required; in the case of “and”, supervision and inspection are necessary only for devices that meet both criteria of a volume of ≥30L and an inner diameter of ≥150mm.
1. Not subject to jurisdiction, no inspection required； 2. Pipe flanges can be used, but not only the maximum allowable operating pressure should be considered; the impact of pipeline loads and other types of loads on the system must also be taken into account.
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1. Not in the category. 2. It is not acceptable to use flanges of PN63; flanges of PN100 can be used without any calculations, or non-standard flanges can be designed as long as the calculations show they are suitable.