Flaw detection issues when using plates and coils for container takeovers
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I have designed a container before, and the DN300 nozzle was designed as a seamless pipe on the drawing, but the manufacturing unit changed it to steel plate rolling. This raises a question, what are the requirements for flaw detection of longitudinal seams? The explanation given by the manufacturing unit said that in this case, the weld must be 100% inspected for flaw detection, as long as it meets the requirements. I understand that there should be no problem, but I checked GB10 and found no clear instructions for this situation. Is it the same treatment method as the Class A longitudinal seam of the barrel?
Our non-destructive testing ratio is the same as in the design drawings, but it can only be changed after passing the strength calculation.
100% RT, Grade II qualified, weld coefficient = 1, the same as seamless pipe, no need to calculate it. ——If the material allowable stress is the same
Two comments: 1. The rolling of the nozzle can be the same as the non-destructive testing ratio in the design drawing. However, the calculation of the nozzle, including the opening reinforcement calculation, must be based on the actual weld coefficient. The nozzle on the equipment generally does not extend very long, so 100% inspection is generally done. ； 2. If the nozzle is made of carbon steel or low alloy steel, it should also be in accordance with the requirements of GB150 10.4.2.1 Consider whether to perform heat treatment.
We did it according to what was said on the 3rd and 4th floors. There are many situations where this kind of material is borrowed.
Review the opening and reinforcement, the proportion is 100%, and the qualified level is based on the cylinder.
We take over and recalculate by coil, conduct 100% RT testing, pass Level II, and then perform heat treatment. Recently, there is a product that does this.
In addition to what is mentioned above, material substitution changes should also be made.
Our unit’s experience is: 1. 100% RT testing, the qualification level depends on the main body of the equipment 2. Fill in the material substitute tape, and have it signed and archived by the relevant departments. This post was last edited by wangxjlx on 2009-4-10 16:49 ]
The applicable scope of GB150 includes a diameter >150mm. From this perspective, it must be viewed according to the cylinder.
The heat treatment here is easily overlooked, so please pay attention and remember! ! !
Our company originally used coiled cylinders instead of steel pipes, which are 100% non-destructive testing. The qualification level is the same as ring seam non-destructive testing. The pot inspection institute also agreed with this approach. The heat treatment problem mentioned above refers to the relationship between the thickness and the inner diameter of the cold coil section! If the thickness of carbon steel and 16MnR plates is greater than or equal to 3% of the inner diameter of the barrel, or the thickness of other low alloy steel plates is greater than or equal to 2.5% of the inner diameter of the barrel, heat treatment should be performed after forming.
The process I am doing now happens to have a rolled nozzle, which is 1040mm long, and the main cylinder is 20% qualified for Level III. Then my nozzle must also be 100% qualified for Level III. I personally think 20% is enough, and of course it must meet the strength requirements.
For the standards for non-destructive testing, please refer to GB150 10.8 for detailed instructions to see what kind of material to use as the main material.
Article 86 The requirements for selection of testing methods for pressure vessel welded joints are as follows:: 1． When the wall thickness of the pressure vessel is less than or equal to 38mm, its butt joints should be inspected by radiography ； When radiographic testing cannot be used due to structural and other reasons, recordable ultrasonic testing is allowed. 2. When the wall thickness of the pressure vessel is greater than 38mm (or less than or equal to 38mm, but greater than 20mm and the lower limit of the specified tensile strength of the material used is greater than or equal to 540Mpa), if the butt joints are subject to radiographic testing, each weld should also be additionally subjected to local ultrasonic testing. ； If ultrasonic testing is used, each weld should also be additionally subjected to local radiographic testing. When radiographic testing or ultrasonic testing is not possible, other testing methods should be used for additional local non-destructive testing. The additional partial inspection shall include all weld intersections, and the proportion of additional partial inspection shall be 20% of the original non-destructive inspection proportion specified in Article 84 of this Regulation. 3. For corner joints and T-shaped joints that require non-destructive testing and cannot be subjected to radiographic or ultrasonic testing, 100% surface testing should be performed. 4. Magnetic particle testing should be preferred for surface testing of ferromagnetic material containers. 5. Butt joints of pressure vessels made of non-ferrous metals should be tested by radiography whenever possible. Article 87 For pressure vessels other than those specified in Article 85 of this Regulation, the butt joints shall undergo local non-destructive testing and shall meet the provisions of Articles 84 and 86. The parts for local non-destructive testing shall be designated by the inspection department of the manufacturing unit based on actual conditions. However, all weld intersections and the weld parts in the open area that will be covered by other components must undergo radiographic inspection. The spliced heads (excluding spliced heads that are formed first and then assembled and welded) and the butt joints of spliced tube plates must undergo 100% ultrasonic or radiographic inspection, and their qualification levels are consistent with the corresponding butt joints of the pressure vessel shell. The spliced head should be subjected to non-destructive testing after forming. If non-destructive testing is performed before forming, then non-destructive testing should be done in the arc transition area after forming. The welded joints of the upper and lower connecting rings and jackets of glass-lined equipment, and the welded joints of glass-lined equipment with a nominal diameter less than 250mm are exempt from non-destructive testing, but the welding process evaluation should be carried out according to JB4708, and practical welding process regulations should be prepared. After approval by the technical person in charge or the chief engineer of the manufacturing unit, the welded joints connecting the upper and lower connecting rings and the cylinder should be strictly inspected and a leakage test should be done. For welded joints that have undergone local radiographic testing or ultrasonic testing, if excessive defects are found at the testing site, supplementary local testing of no less than 10% of the length of the welding joint should be performed immediately. ； If it is still unqualified, all welded joints should be tested. Article 88 The non-destructive testing of pressure vessels shall be carried out in accordance with JB4730 "Non-destructive testing of pressure vessels". Perform full (100%) or partial (20%) non-destructive testing of pressure vessel butt joints: When radiographic testing is used, the transmission quality should not be lower than AB level, and the qualification level is level III, and no incomplete penetration is allowed. ； When ultrasonic testing is used, the qualification level is Level II. For pressure vessels that are stipulated in GB150, GB151 and other standards to undergo all (100%) non-destructive testing, Class III pressure vessels, pressure vessels with a weld coefficient of ⒈0, and pressure vessels that cannot be subjected to internal and external inspection or pressure test, their butt joints must be subjected to all (100%) non-destructive testing: When radiographic testing is used, the quality of the transillumination should not be lower than level AB, and the qualification level is level II. ； When ultrasonic testing is used, the qualification level is Level I. The nominal diameter is greater than or equal to 250mm (or the nominal diameter is less than 250mm. The non-destructive testing ratio and qualification level of the butt joints of pressure vessel nozzles with walls larger than 28mm should be the same as the requirements for the welds of the main body of the pressure vessel shell. ； If the nominal diameter is less than 250mm and the wall thickness is less than or equal to 28mm, only surface non-destructive testing will be performed, and the qualification level will be Level I specified in JB4730. The non-destructive testing qualification level and radiographic quality of candle joints of non-ferrous metal pressure vessels shall be determined by corresponding standards or specified by design drawings.
1. It should be 100% RT tested, which is the same level as the main body of the device. 2. Write material substitution (strength calculated). 3. See page 124 of GB150 for heat treatment. 10.4.2.1