The drawings for the heat exchanger spare parts are actually different
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The old heat exchanger had its spare parts replaced due to tube corrosion; when checking the drawings today, it was found that the spare part cylinder was equipped with expansion joints, whereas those on the removed unit were not. The design temperature is 400 degrees, and the actual pressure is also 1 Mpa. Also, the thickness of the tube sheet on both devices is the same; why is it different then? Have you encountered similar problems before?
Are the old heat exchanger and the spare parts not based on the same set of drawings? Or was the old heat exchanger not manufactured or inspected in accordance with the drawings?
Are there spare cylinders available as well? How is this prepared? Is it a heat exchanger with fixed tube sheets? How then does one replace the cylinder? It seems the original poster didn’t explain things very clearly.
The entire device was replaced; the only difference is that the new device cylinder has an expansion joint added to it. I’m not sure if I expressed myself clearly
It’s hard to say; it depends on the specific calculations and the considerations of the designer. If the design parameters remain unchanged and the equipment materials are the same as well, then… There are several situations that can cause this phenomenon: 1. One party made a calculation mistake. 2. The use of different wall temperatures for the heat exchanger has a significant impact on the calculations resulting from those temperatures. 3. The designer felt that the calculation results without expansion joints were extreme, so expansion joints were added as a precaution. But since the original equipment had problems due to corrosion, I think you should have replaced the materials Was the carbon steel tube bundle replaced with a stainless steel tube bundle? If the material changes, everything changes; it’s normal to add expansion joints.
The heat exchanger is entirely made of stainless steel; the corrosion was caused by operational factors, and it has nothing to do with the material. Both the spare parts and the corroded equipment were designed and manufactured by the same entity during the same period (2015). It is unsafe without expansion joints; in that case, attention should be paid to another piece of equipment under the same operating conditions – with exactly identical operating conditions and no expansion joints.
Is it supplied by the same company?
Under the same operating conditions, if an expansion joint is required, this issue can possibly be resolved by increasing the thickness of the tube sheet. Taking into account manufacturing and material costs, it may be possible to design different types of equipment
A complete replacement – it’s not then a spare part
If it wasn’t designed on the same day in 2015, then this is possible. It turns out there were no expansion joints before, and now they are available; that’s not a problem. What’s concerning is when there were expansion joints before but none exist now. Additionally, if there was originally a special equipment use registration certificate, it must be reported to the Special Equipment Section of the Technical Supervision Bureau. This falls under the category of renovation. It is estimated that it wasn’t managed as a pressure vessel either.
Floating head heat exchanger? If it’s inconsistent with what was there before, how was it accepted at that time? It is best to find the relevant personnel and suppliers who were involved in handling that matter at the time.