Several questions regarding pressure vessel design
Thread Content
1. GB150 specifies several conditions under which no reinforcement is required for the nozzles, such as pressure, spacing, nozzle specifications, and wall thickness. However, there are two notes; one of them states that the corrosion margin should be 1 mm. So what should be done in cases where the corrosion margin is greater than 1 mm? 2. It is a Class 2 pressure vessel with a highly hazardous medium; the material used is Q345-R. The pressure is 0.6, the diameter is 1200, and the height is 2000. For Class AB vessels, 100% RT inspection is required. So what is the procedure for Class CD vessels? Which standard specifies this? 3. Does all stainless steel need to be acid-treated? Can it be left untreated? 4. For fillet welds and T-joints, radiographic or UT inspections cannot be carried out; MT or PT can be used for inspection. I would like to know under what circumstances fillet welds or T-joints require RT or UT inspections. 5. Horizontal vessels have saddle supports and ring supports; I would like to know where I can find information on the relevant standards and technical requirements for ring supports. 6. Today I saw that stainless steel specifications are written as 304/NO1. I want to know what meaning NO1 has after 304. Last edited by nanjingdaxue on 2009-2-26 12:10.]
Several questions regarding pressure vessel design 1. GB150 specifies several conditions under which no reinforcement is required for the nozzles, such as pressure, spacing, nozzle specifications, and wall thickness. However, there are two notes; one of them states that the corrosion margin should be 1 mm. So what should be done in cases where the corrosion margin is greater than 1 mm? 2. It is a Class 2 pressure vessel with a highly hazardous medium; the material used is Q345-R. The pressure is 0.6, the diameter is 1200, and the height is 2000. For Class AB vessels, 100% RT inspection is required. So what is the procedure for Class CD vessels? Which standard specifies this? 3. Does all stainless steel need to be acid-treated? Can it be left untreated?
1. The conditions for exemption from reinforcement must be strictly met; a corrosion margin of less than 1 mm means these conditions are not satisfied, and reinforcement through drilling is required. 2. Surface inspection is carried out in case of CD category, in accordance with tolerance specifications or GB150. 3. After the pressure test, stainless steel containers must undergo acid washing and passivation, followed by inspection using the blue dot method – no blue dots indicate compliance.
That can’t be right; the medium is highly hazardous, and a pV product of ≥0.2 MPa should classify it as a Category 3 vessel.
1. GB150 8.3: Maximum hole diameter without additional reinforcement. Holes in the shell do not require additional reinforcement if they meet all of the following conditions. A corrosion margin of more than 1 mm means these conditions are not met, so reinforcement is necessary for such holes. 2. When the medium is highly hazardous and the pV product is ≥ 0.2 MPa, the container belongs to category III pressure vessels. For welds of category CD, our unit generally performs magnetic particle or penetrant testing on their surfaces. 3. Stainless steel containers usually need to undergo acid washing and passivation treatment. Acid washing is done to clean the surface and form an oxide layer, while passivation is intended to prevent surface oxidation and rusting. Last edited by Ya Qiong on 2009-2-26 at 11:24
1. The required corrosion allowance increases; different organizations have varying views on this. Some believe that it can be omitted as long as the wall thickness of the pipe fitting is increased accordingly, while others disagree with this approach and maintain that the corrosion allowance must be taken into account whenever it increases. 2. From a standard perspective, no requirements are specified for CD-type welds under such operating conditions; however, from a safety standpoint, the vast majority of design agencies conduct surface inspections on CD-type welds. 3. Pickling is used to remove oil and impurities from the surface, while passivation is intended to prevent corrosion. Generally, pickling is always performed, while passivation is done depending on the circumstances; if corrosion protection is not required, it can be omitted.
Someone has posted a similar request for help; you can take a look
1. If the corrosion margin is greater than 1 mm, calculations for reinforcement through opening are required. 2. In accordance with Article 10.8 of GB150, there is no mandatory requirement for MT or PT testing on containers of categories C and D. However, given that the medium is highly hazardous, it is recommended to raise this requirement and conduct 100% MT or PT testing on containers of categories C and D. 3. When used with corrosive media, stainless steel generally needs to be acid-treated; whereas when used with non-corrosive media, acid treatment is not necessary.
1. When the corrosion allowance is greater than 1 mm, the excess amount is deducted and then compared with the value specified in GB150-1998; if the wall thickness is greater than or equal to that value, no additional reinforcement is required. Otherwise, perform hole-strengthening calculations. 2. It is a Class 2 pressure vessel with a highly hazardous medium; the material used is Q345-R. The pressure is 0.6, the diameter is 1200, and the height is 2000. For Class AB vessels, 100% RT inspection is required, while for Class CD welds, magnetic particle or penetrant testing is generally carried out, with no mandatory regulations in this regard. 3. For applications requiring corrosion resistance, pickling and passivation are necessary ； For hygiene requirements, this is not required; however, current manufacturers polish those with hygiene requirements. 4. For example, the fillet welds between the tube sheet and the shell. 5. At present, ring supports are rarely used; the \"Training Manual for Pressure Vessel Design Engineers\" contains relevant calculations for horizontal vessels supported by ring supports in section 22.10.
1, 2, 3, 4, 5 have all been answered. The No. 1 among the 6 is hot-rolled stainless steel, with a surface quality equivalent to that of the original hot-rolled sheet.
You can look up books on pressure vessel design.
1. GB150 specifies several conditions under which no reinforcement is required for the nozzles, such as pressure, spacing, nozzle specifications, and wall thickness. However, there are two notes; one of them states that the corrosion margin should be 1 mm. So what should be done in cases where the corrosion margin is greater than 1 mm? – In such cases, it is sufficient to refer to the specifications for pipes with a corrosion margin of 1 mm and add the corresponding wall thickness; no additional reinforcement is needed. 2. It is a Class 2 pressure vessel with a highly hazardous medium; the material used is Q345-R. The pressure is 0.6, the diameter is 1200, and the height is 2000. For Class AB vessels, 100% RT inspection is required. So what is the procedure for Class CD vessels? Which standard specifies this? ——For the inspection standards for CD-type welds, refer to the relevant provisions in JB/T4730.3~4-2005. 3. Does all stainless steel need to be acid-treated? Can it be left untreated? －－－－Stainless steel equipment should be subjected to acid washing and passivation as much as possible. As clearly stated above, regarding steel pipes, it’s not clear whether all of them need to be treated.
The specifications only require pickling and passivation for corrosive media; other aspects are determined by the design or usage.
1. The corrosion margin for the grooved seamless fittings specified in GB150-1998 is 1 mm, which corresponds to the corrosion margin of 2 mm for the shell； If the corrosion margin of the grooved seamless fitting is greater than 1 mm, reinforcement calculations for the groove must be carried out. 2. Welds of categories C and D shall be subject to magnetic particle or penetrant testing, which is equivalent to the treatment required for welds of categories C and D in category III pressure vessels. 3. Article 108 of the Code of Practice: Pickling and passivation are required for applications with corrosion resistance requirements ； For applications with hygiene requirements, there is no need for pickling or passivation treatments. 4. For fillet welds, T-joints, etc., which cannot be inspected by radiography or UT, MT or PT can be used for inspection. Fillet welds under severe service conditions, such as those between the tube sheet and the shell, require RT or UT inspection. 5. Ring seats are used in large thin-walled horizontal vessels, and relevant calculations are required to verify various stresses. 6. Check ASME; we don’t have this book here, so you can look it up by yourself.