Hydrostatic Tests on Furnaces
A hydrostatic test should be applied to all furnace heating elements after replacement of tubes or headers and usually after routine tube cleaning operations.
During the test, all personnel should be out of the furnace except the inspectors.
The inspector should enter and inspect for leaks in the radiant and convection sections, paying particular attention to skin points and tube welds. All header box doors should be opened and headers and rolled joints inspected for leaks. Look closely behind the headers for cracks in the tubes, caused by excessive rolling, and at the plugs for leaks.
It may be necessary to test a furnace several times before all leaks have been stopped and the furnace is made tight.
Keys to a good hydrotest:
• Make sure there are highpoint vents of convection and radiant sections.
• Verify the type of liquid to use.
Some metallurgy requires soda ash to prevent polythionic stress corrosion cracking. It is very important to understand the metallurgy and the type of liquid to use.