In order to ensure the quality of tube expansion, it is necessary to determine the tools, measuring tools, and operators before tube expansion

In order to ensure the quality of tube expansion, it is necessary to determine the tools, measuring tools, and operators before tube expansion

1. Before expanding the tube, attention should be paid to checking the tube expander, and the expanding rod and ball should not be bent. When using the expansion tube, the expansion beads should be coated with an appropriate amount of butter. For lubrication purposes. When officially expanding the pipe, it is recommended to clean it once in kerosene and observe for any wear or damage. The expander that has been cleaned with kerosene should be lubricated with butter again during use.

2. To ensure the quality of tube expansion, the tube expansion operation must comply with the following requirements:

(1) Technical workers with experience in expanding pipes must be selected for the expansion work.

(2) Measure or spot check the pipe holes, and mark the pipe holes that exceed the standard. So that you can take your seat accordingly. The inner wall of the pipe hole must not have burrs or longitudinal grooves, and the inner wall of the pipe hole must be polished smooth with sandpaper to meet technical requirements.

(3) The outer diameter and inner diameter of the heat exchange tube must be smooth, without burrs, and the tube mouth must not have blunt edges. If the above phenomenon occurs, it must be treated and meet the requirements before it can be used.

(4) Before threading, the outer end of the pipe must be cleaned to ensure that there is no oil or other dirt contamination.

(5) Before expanding the pipe, strict inspection should be carried out on the pipe. The surface of the pipe shall not have cracks, flattening, grooves, pitting, or other defects. Pipes that do not meet the requirements must not be used, and the expansion degree should be controlled to ensure the quality of the expansion.

(6) The expansion tube must start from the center of the tube plate and gradually spread into a circular (or equilateral triangle) shape around it. Gradually eliminate stress. The expansion length of heat exchange tubes should be 70-80% of the depth of the tube hole as the standard, and full expansion is not required. When inserting the tube expander into the tube, the accounting rod should be aligned with the center of the tube hole. Always maintain the correct relative position during operation, and the movement of the expansion rod should be smooth and uniform, without sudden changes in speed, nor should pressure be applied to the expansion rod.

(7) Lift the equipment in place. Complete leveling and alignment. After fixing the equipment. Only then can the tensioning work be carried out. When expanding the pipe, visual inspection should be carried out simultaneously with the account. Is there any significant change in the expansion transition section. Is the connection between the pipe and the hole wall of the tube plate good. The swelling should be controlled within 5% -6% according to relevant regulations.

3. Water pressure test

4. After the completion of expansion and tensioning, a water pressure test must be carried out on the Rongfu. The operation of water pressure test shall be carried out in accordance with relevant regulations.

The pipes that fail this pressure test must be accounted for, and the accounting should be carried out as soon as possible after the water pressure test. The number of times to make up for it shall not exceed two. If it still fails to meet the standards after two additional checks. Convert to atmospheric pressure container treatment.

5. Precautions for expanding tube machine

(1) The hardness of stainless steel heat exchange tubes before expansion fully meets the requirements of expansion, and there is no need for annealing process.

(2) The tube plate and tube hole must have two sealing grooves, which is a necessary process to ensure the quality of tube expansion.

(3) The processing of sealed grooves is carried out using specialized cutting tools, which can ensure the accuracy of the machining process

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