ASME pressure vessel impact issues
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Ladies and gentlemen, regarding the impact testing of ASME pressure vessels, I have a few questions for you: Question 1: Suppose a vessel has a shell thickness of 54 mm, is made of SA-516 70N material, and the design requirement for MDMT is -25°. According to UCS-66, the reduced MDMT value is -23°; therefore, this material needs to undergo impact testing. I currently have two options. Option 1 is to require the material manufacturer to perform impact testing at -25°, with the average impact energy determined according to UG-84 to be 20 J； Option 2: I specify in the purchase order that impact testing should be carried out in accordance with requirement S5 outlined in the additional requirements for material SA-516 70, without telling the manufacturer the impact temperature and impact energy. In that case, will the manufacturer proceed as follows: The impact requirements specified in S5 for SA-516 70 should be followed based on the general requirements of SA-20; according to Appendix A2.15 of SA-20, SA-516 70 requires impact testing at -40°C with an average impact energy of 20 J. Is it correct for the manufacturer to proceed this way? Question 2: In Table A-2.15 of SA-20, the average impact energy for all thicknesses is 20 J. However, for UG-84 with a thickness of over 60 mm, the average impact energy is greater than 20 J. Should priority be given to UG-84 in such cases? Question 3: For materials specified in GB150, the minimum temperature that each material can withstand can generally be found in the relevant section of GB150; if the temperature is lower than this value, it is necessary to use a material capable of withstanding lower temperatures. It seems that SA-516 70 mentioned earlier can also be handled in this way – the minimum temperature it can withstand, as indicated in Table A2.15, is -46°C, but impact testing is required to confirm this ； If I encounter the corresponding temperature and thickness next time, I will be able to determine whether SA-516 70 can be used. However, I cannot find information regarding the appropriate temperature for SA-105. Could you please tell me how to find this information? (Is it sufficient to simply follow UCS-66 and UG-84?) I just need to have at least a rough idea of the lowest temperature that SA-105 can withstand.
Question 3: If designed according to ASME standards, the 150 regulations should not be applied; the concept of 150 is not yet as advanced as that in ASME standards
This post was last edited by Changkong Poyang on 2016-3-19 08:51. If it is not clearly specified in the procurement instructions, it is correct for the manufacturer to follow SA20
UCS-66(c) specifies clear requirements for the impact test of flanges
Personally, I believe that as long as the MDMT is not lower than -48°, we can use UCS-66 to determine whether SA-105 is suitable for use.
Personal understanding: 1. Technical requirements for ordering are S5, with a requirement for a horizontal layout. II. For overseas projects, the impact energy requirement is in accordance with SA20 ； For domestic projects, the specifications are based on Q345R ； III. Information on the low-temperature impact properties of SA-105 can be found in UCS-66; this chapter includes 9 categories of materials, so you can refer to it there. Based on past experience with overseas projects, both SA-516 and the accompanying SA-105 can be used at -48 degrees (according to UCS-66), but below -40 degrees, Gr60 is more commonly used.