Calculation of heat exchanger expansion joints
Thread Content
It is a liquid ammonia heat exchanger made of S30408 material; the drawings were provided by a chemical engineering design institute, but no calculation documents were supplied. The owner asked us to convert those drawings into our own format and to prepare the calculation documents ourselves. But in my calculations, under the same design conditions, without using expansion joints (the design drawings specified the use of expansion joints), the tube sheet passed the verification ； The tube sheet verification failed after adding the expansion joint; it is suggested to use an expansion joint with lower stiffness, but it’s not clear what the situation is~~~
Shell side: Design pressure 2.75 MPa, design temperature -40/60°C, wall temperature -12°C, fluid is liquid ammonia; corrosion allowance of 2 mm, weld joint factor of 1.0, single pass. Tube sheet: Design pressure 0.8 MPa, design temperature 60°C, wall temperature 15.4°C; medium is fire-fighting water; corrosion allowance of 2 mm; welding joint factor of 0.85/1.0 (for end caps); single pass. Material: Plate/tube S30408, forging S30408III, heat exchange tube S30408. Horizontal, fixed tube sheet type; equipment diameter DN500. Heat exchange tubes: 25*2.5*5000 mm. Welding method: strength welding + expansion bonding. Cylinder thickness: 10 mm; tube sheet thickness: 50 mm. Difference in thickness between tube sheet and flange: 11 mm ； Expansion joint ZDW(II)U500-4.0-1*10*1, material S30408 ； Tube box flange - FM500-6.4
The actual yield strength of the expansion joint material is taken as 1.5 times the standard value.
The calculation I gave you will pass. Actually, the temperature difference isn’t very large, so it’s possible to operate without expansion joints.
Can the tube sheet verification with expansion joints be passed?
:'(I was told that the stiffness calculated with expansion joints was too high; however, I’ve asked the client to obtain the calculation report from the design institute.)
Mm. You’ll know by checking the calculation sheet. Check whether it is calculated according to the 2018 new standards.
Send over the calculation program to take a look; see if it can pass according to SW6-2011 V4.0.