Material issues for large-diameter heat exchanger tube sheets
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There is currently a heat exchanger with a diameter of 3600 mm, and the pressure is very low, at only 0.1 MPa. The tube sheet is not made of forgings but rather from Q345R sheet metal. I would like to ask what other requirements need to be taken into account?
Personal opinion: 1. 100% ultrasonic testing of the sheets； 2. 100% radiographic inspection is required during splicing. 3. If expansion jointing is used between the heat exchange tubes and the tube sheet, the yield strength of the material chosen for the heat exchange tubes should be lower than that of the tube sheet
Personal opinion: 1. 100% ultrasonic testing of the sheets； 2. 100% radiographic inspection is required during splicing. 3. If expansion jointing is used between the heat exchange tubes and the tube sheet, the yield strength of the material chosen for the heat exchange tubes should be lower than that of the tube sheet
If the tube sheet thickness exceeds 50 mm, it should be supplied in normalized condition.
Reply to 2# 6mkl: What is the basis for ultrasound?
There is no specific standard that needs to be followed for this; it can be increased artificially. Moreover, for the gasket plates of such large-scale equipment, their thickness is definitely greater than 30 mm, and according to GB150’s 4.2.9, ultrasonic testing is also required
Agree with the 6th floor: handshake! Additionally, when the tube sheet is spliced, in addition to 100%-RT, stress-relief heat treatment is also required (for carbon steel and low-alloy steel). :)
This post was last edited by Reaching for the Moon in Nine Heavens on 2010-11-29 at 15:59. According to GB151 4.3.1.2, when the tube sheet itself has a shoulder and is joined to the cylinder (or head) by butt welding, forgings should be used. 4.3.2.3 For tube sheets with a thickness greater than 60 MM, forgings are preferred. 4.3.2.1 The steel plates used for manufacturing tube sheets, flat covers, and butt-welded flanges shall comply with the requirements of GB150. 6.4.1 The butt joints of the spliced tube sheets shall be subject to 100% radiographic or ultrasonic testing, and surface inspection shall be carried out in accordance with JB4730; the test results must show no cracks or pores, and the defect detection shall meet the requirements specified for grade II. 6.4.2 Except for stainless steel, the welded tube sheets shall undergo stress-relief heat treatment. According to GB150 4.2.5(b), 20R and 16Mn steel plates with a thickness greater than 50 mm used for other pressure components (flanges, tube sheets, flat covers) should be used in the normalized state. Refer to 4.2.9: The carbon steel or low-alloy steel plates used for the shell shall be subjected to UT test on a sheet-by-sheet basis: (a) for 20R and 16MnR with a thickness greater than 30 mm, the quality shall be at least grade II. The steel plate can be used for the tube sheet when it meets the above requirements.