The heat exchange tube cracked under water pressure; I need help online, it’s urgent.
Thread Content
There is a closed-loop cooling water heat exchanger; the heat exchange tubes are made of 316L material with dimensions of 25X0.8. The hydraulic test pressure is 0.6 MPa, and no abnormalities were detected in terms of pressure before leaving the factory. However, upon arrival at the site, the pipes cracked due to pressure. It’s the vent for regulating water pressure in the pipe; the flushing function isn’t activated. What could be the reason?
The heat exchange tube is cracked, with a relatively smooth fracture surface
Is it that the quality of the pipe itself is substandard? Is the crack facing outward or inward? Is there a sleeved pipe?
It appears to be a brittle fracture; seamless tube
With a wall thickness of 0.8, using a pressure test of 0.4 MPa is sufficient; 0.6 MPa is a bit high
Locate the leaking pipe and weld both ends shut； For new heat exchangers in general, they should be sent back to the factory for replacement ；
The pressure in this case is low. If the owner does not require 100% non-destructive testing, then general factories will only conduct partial inspections, or no inspections at all, which results in welding defects in the weld joints leading to cracks and leaks ； Furthermore, if the quality of the pipe is poor, it can also cause cracking in the base material.
May I ask whether the heat exchanger cracked during the hydrostatic test of the shell side or the tube side? Is the cracking located in the base material of the tube or at the weld joint with the tube sheet? Not long ago, a 316L heat exchanger developed a leak during the hydrostatic test prior to leaving the factory; after the tubes were removed, many longitudinal cracks appeared in various sections of those tubes. We can have a conversation. Thank you!
This problem arises when the quality of the pipes is poor; generally, 25*1.5 or 2 is used more often, as 0.8 is too extreme
It must have broken near the baffle; the pipe is too thin