Watermelon
Structural
Hello.
I have a 20" pipe, 30' long, 1" wall, for use in some industrial process equipment. While the pipe is rotating, heavy process material is dropped on it, normal to the major axis. Loads are substantial and shock/impact applied. The rotating pipe is subject to significant bending type loads. It is a hostile environment.
On the pipe there are numerous circumferential collars (donuts)which support teeth. The collars are 2.5" thick, stand 2" high from the pipe and occur every 9" along the length of the pipe. Each collar is welded to the pipe by 1/4" fillet welds on each side. Each fillet is 6" long. The welds occur generally at 12, 3, 6 and 9 o'clock.
Numerous welds have cracked. Most of the cracking occurs at midspan (center) of the pipe. Some welds have cracked down the center, others have cracked at the toe of the fillet on the pipe. The crack follows the pipe circumferentially and extends into the pipe on the pipe cross-section. The metals have been tested and are certified as weldable grade materials.
I'm sure the problem is related to bending and fatigue, but also to welding procedures.
Questions: What is the most likely source of the problem?
What kind of welding procedures can be used to help prevent future problems?
Muchas gracias for your help.
I have a 20" pipe, 30' long, 1" wall, for use in some industrial process equipment. While the pipe is rotating, heavy process material is dropped on it, normal to the major axis. Loads are substantial and shock/impact applied. The rotating pipe is subject to significant bending type loads. It is a hostile environment.
On the pipe there are numerous circumferential collars (donuts)which support teeth. The collars are 2.5" thick, stand 2" high from the pipe and occur every 9" along the length of the pipe. Each collar is welded to the pipe by 1/4" fillet welds on each side. Each fillet is 6" long. The welds occur generally at 12, 3, 6 and 9 o'clock.
Numerous welds have cracked. Most of the cracking occurs at midspan (center) of the pipe. Some welds have cracked down the center, others have cracked at the toe of the fillet on the pipe. The crack follows the pipe circumferentially and extends into the pipe on the pipe cross-section. The metals have been tested and are certified as weldable grade materials.
I'm sure the problem is related to bending and fatigue, but also to welding procedures.
Questions: What is the most likely source of the problem?
What kind of welding procedures can be used to help prevent future problems?
Muchas gracias for your help.