When hoisting a 1.0Mpa 43-meter-high tower, whether the lifting lugs can be welded at any location on site?
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When hoisting a 1.0Mpa, 43-meter-high tower, can the lifting lugs be welded at any location on site? I found lifting lugs being welded on the pressure vessel at the site. The construction personnel said that the plan had been approved by the supervisor. When I asked the construction site commander, they said that China Petroleum Corporation No. 1 Construction Company had always done this. I asked them to perform partial annealing and report it to the design institute for approval. I asked everyone to discuss and give good suggestions. This post was last edited by lxzzl on 2009-3-26 10:16 ]
Do not weld anywhere you want； Complex welding stress will be generated after welding, which may become a weak link in future use and cause corrosion to aggravate. It is recommended to ask the design institute for review and approval before construction. It is best to perform local heat treatment after welding. This post was last edited by lxzzl on 2009-3-26 10:17 ]
Then you must find a suitable place to weld the lifting lugs. The backing plate should be made of the same or similar material as the shell material, and welded with a suitable welding process. After cutting off, the surface must be inspected to ensure that there are no cracks on the surface. The thickness of the polished shell should not be less than the designed thickness of this part. The original equipment has heat treatment requirements and requires local heat treatment. This post was last edited by lxzzl on 2009-3-26 10:18 ]
Now that one has been welded, how can I fix it? This post was last edited by lxzzl on 2009-3-26 10:18 ]
It should be cut off, surface treated, inspected, and then backing plates added and lifting lugs welded.
JBT 4710-2005 Steel Tower Vessels 9.3 9.4 stipulates that welding is not allowed. How should we require supervision and rectification now? This post was last edited by lxzzl on 2009-3-26 10:19 ]
The tower is a pressure vessel. According to the capacity regulations, welding is not allowed after the pressure vessel is manufactured. The welded lifting lugs need to be locally heat treated.
The lifting lugs of non-heat treatment equipment can be welded on site by the construction and installation team.； The lifting lugs can be selected and welded according to HGT21574-2008 chemical equipment lifting lugs and engineering technical requirements. This post was last edited by lxzzl on 2009-3-26 10:20 ]
Not only lifting lugs, but also ladders and platform pads attached to non-heat treatment equipment are welded on-site by the construction and installation team, as long as they meet the drawing requirements and relevant specifications.
The person in charge of on-site construction said that the equipment does not need heat treatment at the manufacturer, nor does it need to be heat treated after welding on site. I have not seen the drawings, so I don’t know if what he said is correct. The equipment is a methanol vaporization tower with a design pressure of 0.88Mpa, an operating temperature of 160-180 degrees, a height of 42 meters, a wall thickness of 8mm, a weight of 25 tons, and a material of 16MnR. This post was last edited by lxzzl on 2009-3-26 10:20 ]
In the absence of stress corrosion, heat treatment is required only if the thickness of the 16MnR plate is greater than 30mm. The vaporization tower you mentioned should not require heat treatment.
It is very common to weld lifting lugs on site. The initiative lies with the construction unit. Generally, the installation unit selects the type and position of the lifting lugs based on the weight of the equipment and the orientation of the nozzle before installation. If the equipment has not left the factory at this time, the construction unit can coordinate and arrange for the equipment manufacturing unit to weld according to the requirements of the installation unit before leaving the factory.； Lifting lugs and platform ladder pads will be considered in the drawings of equipment that require heat treatment. There is no need to mention them separately. If not, it is the responsibility of the design unit. This post was last edited by lxzzl on 2009-3-26 10:21 ]
Is it necessary to win the approval of the design unit?:handshake
Were there no lifting lugs designed during the design of the 42-meter-tall tower? If the tail lifting lugs welded on the skirt on site do not need to be processed, support must be added inside the skirt to prevent the container from deforming during lifting. Many of these do not require design approval, but sufficient strength must be ensured. If welding is performed in the pressure-bearing section, design approval is required. This post was last edited by lxzzl on 2009-3-26 10:21 ]
The place 500mm away from the top of the tank should be the pressure-bearing section； Although it is 43 meters, there are no lifting lugs, only davits. ； The plan seems to be to use a 200-ton crane, a 50-ton crane, and a 25-ton crane, and the 200-ton and 50-ton cranes can lift the 25-ton crane. This post was last edited by lxzzl on 2009-3-26 10:22 ]