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Click on the Thumbnails to see a better view. I have no information about the operating conditions at the time of failure. I have heard people indicating this is a weld related failure. The piping had been in service for many years. It seems odd that the Unwelded base metal would fail in this manner under operating conditions suitable for these types of welds. And thanks to all on Eng-Tips for looking
Thanks. G Austin
Name: Gerald CommentsEnter your comments here
Name: Randy Zimmerman CommentsEnter your comments here Interesting picture. I sure looks like a brittle fracture with no crack site starting the fracture. Five degrees isn't that cold. I am wondering what the pipe was carrying. I looks to me like a failure you would see in old drill stem. When you find out the cause please post.
Name: Faron Breaux CommentsIt's like to me the pipe was in a cold service. It looks like something I've seen happen a low grade of cs pipe put where it doesn't belong. Just because it had papers for the pipe doesn't make it so. I had a vender in Memphis try to change the papers on a peace of pipe so they won't have to change out the pipe.
Name: Hawk CommentsEnter your comments here Hi Gerald, What are those pieces from? I guess any carbon will fail in time, but I suspect the fracture may be attributed to a high sulfer content in the original base metal. I remember about 8 or 9 years ago seeing some laminated metal from a poor recycled mill. What you have there is probably impossible to trace the origins from , but it would be interesting to find out where it came from. Anyway, Take care. Hawk
Name: Mark Mruczek CommentsEnter your comments here If I had to venture a guess, at this point I would say that the material dropped below its Ductile to Brittle Transition Temperature (DBTT). This is after looking at the photos on your web page. I have been trying to find the DBTT for A53 material, but no luck. You might suggest that during the metallurgical anaylsis that they test to see what the DBTT is for this material. For reference, “certain metals are tough at high temperatures but fragile at low temperatures. If a component is made from one of these metals is used at or below the temperature at which it becomes fragile, the component may fail unexpectedly in service.” (From ASM Handbook 8th edition). Save as many pieces as you can and try to look for the initiation site. I would start at the weld especial at the toe of the butt weld. See if there are any sharp notches that formed during welding (i.e. undercut). If you find nothing, there work your way out. The other thing that makes me believe that the failure might be attributed to DBTT is the fact that it was carrying compressed inert gas. If I am not mistaken when a gas is compressed it undergoes a change in temperature. (in this case a drop in temperature). In other words the material being carried by the pipe was cold and then we add the ambient temperature. I had a similar failure happen to a moment beam. The beam was hung with no external load on it. “Rat Tail” holes were cut into the beam web to allow access for welding. When the welders came back the next morning, the beam had failed and was on the concrete. Ambient temperature was 10 degrees F. During the failure anaylsis, it was determined that the DBTT was 70 degrees F!!!! Also keep in mind that fatigue failures are very similar in appearance to a brittle failure. However, with fatigue failures there might be evidence of “Ratchet marks” or “Beach Marks” on the surface of the fractured parts. If you cannot see them with the naked eye, try a 10X magnifier, or have a lab look for this evidence. Hope this helps. Mark Mruczek Welding Engineer
Name: DION MOLTON CommentsFROM WHAT I CAN SEE IN THESE PICS IT APPEARS TO BE A FAILURE OF THE PIPE (UNRELATED TO THE WELD). I WORK AT A STEEL MILL THAT MANUFACTURES PIPE(LONE STAR STEEL CO.)AND FROM WHAT I HAVE SEEN ,SOME TIMES YOU GET A BAD HEAT OF STEEL,IMPURITIES ,THAT SORT OF THING .I AM AFRAID THAT I CAN`T REALLY GIVE YOU ANY USEFUL INFO ON THIS ,JUST THOUGHT THAT I WOULD COMMENT.BUT THIS APPEARS TO BE UNRELATED TO THE WELD ,IF YOU KNOW IF THIS WAS SEAM WELDED OR EXTRUDED PIPE MAY HELP IN YOUR INVESTIGATION.HOPE YOU FIND THE CAUSE ,AND IF YOU HAVE TIME I WOULD BE INTERESTED IN YOUR FINDINGS.THANKS FOR YOUR TIME ,DION MOLTON
Name: steve smith CommentsI am not sure what caused the failure, but I am sure that whom ever welded that joint needs more practice at putting the cap on a pipeweld. An inspector's nightmare. He even left weld spatter on the pipe. Rule of thumb-- a good looking weld is usually a sound weld.
Name: jon CommentsGot too cold .. too long .. plus maybe some "water hammer" You got certs on the steel? http://www.civeng.carleton.ca/ECL/abstracts/ecl1007.html
Name: John A. Barandon CommentsMetal detearation. Not falure of weld.
Name: ak Commentswhat the hell is that thing clay
Name: Bob Larson CommentsHave you considered hydrogen embrittlement as a cause? I do not think this failure was weld related - the weld just happens to be in the area of failure. A good look at the microstructure would help answer many questions.
Name: Martin CommentsHi. You have very nice website! Beautiful design.
Name: Mike Blaha CommentsGerald: What was the product running through this piping? Tempature of operating system? Did you do a chemical analysis and if so, did they tell you anything? Mike
Name: Bill CommentsI am very happy it’s an excellent and unforgettable recourse. Very useful for everybody in net!!
Name: Jeniffer CommentsA great site where one can enjoy the thought of a great mind long departed. Cheers for the good work!
Name: John Sisk CommentsThanks for the great site. I am both a welder and a metallurgical engineer. The weld appears to have undercut which could localize stresses. I have not welded for a few years, but its not rocket science to see an ugly weld. Many cracks will start in the HAZ and work in the direction of stress and into the base metal. A small crack can grow with time if the pipe goes through both thermal and or cyclic fatigue. A few other people reveiwing the fracture have noted its brittle appearance, and I would agree. The ductile to brittle transition temperature, mentioned by Mark, depends upon the steels chemisty and impurities such as sulfur and phospurus, but higher carbon can also increase suseptibility. Newer steels use less carbon and add other elements such as Cb, V to increase strength, and are calcuim treated to improve low temperature fracture toughness. The calcuim helps to ties up sulfur and to reduced its nasty effect. Mark also mention A53, and I asume he may have ment ASTM A53 which is a specificaiton for line pipe. A53 B is not typically tested for low temperarute toughness properties, unless required by the purchaser. API also has their own spec and they require low temperture testing on some grade. Another reader noted the material may have experince hyrrogen embrittlement, that is a possiblity, but can be hard to prove. Service condtions in a sour environment, ie high sulfur levels can also cause problems. I have seen pipe tested to sour gas requirments. A chemistry and metallographic analysis would be conducted in a formal failure investigation. Actually, I found this site because I'm looking for information on flame straightening. If any one has info please let me know. Thanks for the great site. I will need to come back and check it out. Mark, good job on your comments. Best regards, John
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