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P91 failure in China - 3 fatalities 9
- Thread starter davefitz
- Start date
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6
- #2
davefitz;
Yes, I had heard about this incident in an email that made its way around. There was some question as to the heat treatment and number of hand-offs between the mill and supplier.
The folks at EPRI seem to know about this event. Did you see the email from the Chair of Section
VIII, Subgroup on Materials?
Yes, I had heard about this incident in an email that made its way around. There was some question as to the heat treatment and number of hand-offs between the mill and supplier.
The folks at EPRI seem to know about this event. Did you see the email from the Chair of Section
VIII, Subgroup on Materials?
- Thread starter
- #3
I have some pictures....let me see if I can post them.
This may be of intrest.
This may be of intrest.
FYI
Here are some pictures that came with the email;
This was supposed to be seamless Grade 91 pipe material. However, in looking at the second picture there is no evidence of any ductility in this material. This could imply there was either a seam weld (preferred path of failure) at this location or a pre-existing flaw (hard to tell from the photo) from fabrication.
davefitz let us know what you find. I suspect information will be difficult to obtain because of worker deaths.
Here are some pictures that came with the email;
This was supposed to be seamless Grade 91 pipe material. However, in looking at the second picture there is no evidence of any ductility in this material. This could imply there was either a seam weld (preferred path of failure) at this location or a pre-existing flaw (hard to tell from the photo) from fabrication.
davefitz let us know what you find. I suspect information will be difficult to obtain because of worker deaths.
- Thread starter
- #6
No news yet from China.
From the above posted pictures, it looks like a thick lipped failure- I'm not a metallurgist, but it looks similar to a brittle fracture ; a pre-exisiting crack ( from fabrication or from hydro test at too low a temperature) may have progressed to failure at full operating temp + press.
From the above posted pictures, it looks like a thick lipped failure- I'm not a metallurgist, but it looks similar to a brittle fracture ; a pre-exisiting crack ( from fabrication or from hydro test at too low a temperature) may have progressed to failure at full operating temp + press.
JohnSterling
Mechanical
A recent front page article in the Wall Street Journal details the numerous "illegal" power plants that have been constructed in China in the last few years. Some in the 300 MW size; one can only guess as to level of construction quality control under such conditions.
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gr2vessels
Mechanical
Gentlemen,
I have received the following email, to allert of the consequences of greedy / shonky dealings in the today market. The e-mail is in relation to the 300MW unit at the Datong Power Station Unit 2, the failure of HP main steam line:
"It is very important that we deal with reputable companies and know the origin of the materials we supply.
The material that failed was supplied by a company in Houston TX, called S.M.A.N.T,who certified it as US pipe when it came from questionable sources in China. These details have been confirmed by the Bechtel QA Manager of Power. Bechtel China has also conducted an investigation and the supply chain is ugly due to the extent of how many agents, brokers, and mills are involved. The Chinese Government has stepped in and has called for a formal
investigation. The Chinese Government has also banned Chinese made pipe for use in major power plant critical applications. Thus far there is evidence to support that over 30 plants contain similar or other “fake pipe” all over China."
I wander if anyone did/could read the original Chinese certificates.
Cheers,
gr2vessels
I have received the following email, to allert of the consequences of greedy / shonky dealings in the today market. The e-mail is in relation to the 300MW unit at the Datong Power Station Unit 2, the failure of HP main steam line:
"It is very important that we deal with reputable companies and know the origin of the materials we supply.
The material that failed was supplied by a company in Houston TX, called S.M.A.N.T,who certified it as US pipe when it came from questionable sources in China. These details have been confirmed by the Bechtel QA Manager of Power. Bechtel China has also conducted an investigation and the supply chain is ugly due to the extent of how many agents, brokers, and mills are involved. The Chinese Government has stepped in and has called for a formal
investigation. The Chinese Government has also banned Chinese made pipe for use in major power plant critical applications. Thus far there is evidence to support that over 30 plants contain similar or other “fake pipe” all over China."
I wander if anyone did/could read the original Chinese certificates.
Cheers,
gr2vessels
Fake seamless pipes is a huge racket prevalent in China. There are any number of unscruplous manipulators in this trade.
Last year I had an export enquiry for seamless pipes. My rates were high obviously by 20%. I was asked to quote a lower price,and win the bid. Thereafter I was asked to supply good original samples for approval. Thereafter I could supply fake ones just by placing the stamp of original manufacturer. I refused. The Chinese guy accepted and to this day the orders go to him and the business goes there.
Last year I had an export enquiry for seamless pipes. My rates were high obviously by 20%. I was asked to quote a lower price,and win the bid. Thereafter I was asked to supply good original samples for approval. Thereafter I could supply fake ones just by placing the stamp of original manufacturer. I refused. The Chinese guy accepted and to this day the orders go to him and the business goes there.
EdStainless
Materials
arunmrao, Who were you dealing with? A trader I supose.
I don't have a contact for you, but in the past I have spoken with the regional power research institute about similar issues. These institures are all around China. It actually makes these guys look good to the Power Supervision Commission when they can 'uncover' cases of this activity.
= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
I don't have a contact for you, but in the past I have spoken with the regional power research institute about similar issues. These institures are all around China. It actually makes these guys look good to the Power Supervision Commission when they can 'uncover' cases of this activity.
= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
- Thread starter
- #15
Has anyone heard any additional information on this failure? From the pictures, the failure isn't close to any weld, so I am wondering what the causes could be. Can anyone tell me if there is a resource that lists past failures of this type of material and the causes?
EdStainless
Materials
Plain carbon steel is what I heard from my sources.
Trust me, this one is getting a lot of play in ASME.
= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
Trust me, this one is getting a lot of play in ASME.
= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
I would be very surprised if this was carbon steel. Even at that, I have seen carbon steel inadvertently installed in main steam drains right off of the header that lasted much longer than the reported pipe failure (June until October of 2006).
If I had to provide an educated guess, it would be a pre-existing flaw on the ID surface of the pipe that was introduced some time during fabrication. If this was carbon steel, the failure would occur from stress rupture and you would expect to see a whole lot more rupture ductility.
If I had to provide an educated guess, it would be a pre-existing flaw on the ID surface of the pipe that was introduced some time during fabrication. If this was carbon steel, the failure would occur from stress rupture and you would expect to see a whole lot more rupture ductility.
- Thread starter
- #19
meteng:
You may be right, but it should be easy to compute. There are correclations for graphitization as a function of temperature and time, and such graphitization would lead to a brittle failure.
Likewise, there are creep correlations for CS also. This could be an opportunity to see if the old HP 42s still works.
You may be right, but it should be easy to compute. There are correclations for graphitization as a function of temperature and time, and such graphitization would lead to a brittle failure.
Likewise, there are creep correlations for CS also. This could be an opportunity to see if the old HP 42s still works.
davefitz;
I am always up to the challenge, especially when it comes to Power Plant metallurgy. Ok, assuming a design temperate of 541 deg C, (1006 deg F), and assume we had a 0.9 capacity factor during operation, and we operated lets say 4 months,
0.9 x 4 x 31 days(average)x 24 hours = 2678 operating hours
In checking with the best available resource material in my possession (EPRI Metallurgical Guide Book for Fossil Plant Boilers), spheroidization and graphitization damage mechanisms compete with one another in the temperature range of 850 deg F to 1300 deg F.
In reviewing a semi-log plot of metal temperature versus time for carbon steel, there are two linear curves one for spheroidization and another for graphitization. The curve for spheroidization dominates for carbon steel between 1050 deg F and 1275 deg F. Below 1050 deg F the graphitization curve dominates down to 850 deg F. The intersection between these two curves is about 2,000 hours at 1050 deg F.
Assuming a service temperature of 1006 deg F, (which in my estimation is conservative because the actual temperature is probably lower), the time to graphitization is +5,000 hours. This is a ball park estimate and only serves as an approximation, I would suspect the value should be well above 5,000 operating hours at this temperature.
Keep in mind that prior to reaching the graphitization region, the main steam pipe would be subjected to noticeable swelling and distress from accelerated creep deformation. The allowable stress value for carbon steel at 1006 deg F decreases to only about 2.5 Ksi. So, I stick by my conclusion that the pipe material was probably not carbon steel, given the limited visual evidence.
I am always up to the challenge, especially when it comes to Power Plant metallurgy. Ok, assuming a design temperate of 541 deg C, (1006 deg F), and assume we had a 0.9 capacity factor during operation, and we operated lets say 4 months,
0.9 x 4 x 31 days(average)x 24 hours = 2678 operating hours
In checking with the best available resource material in my possession (EPRI Metallurgical Guide Book for Fossil Plant Boilers), spheroidization and graphitization damage mechanisms compete with one another in the temperature range of 850 deg F to 1300 deg F.
In reviewing a semi-log plot of metal temperature versus time for carbon steel, there are two linear curves one for spheroidization and another for graphitization. The curve for spheroidization dominates for carbon steel between 1050 deg F and 1275 deg F. Below 1050 deg F the graphitization curve dominates down to 850 deg F. The intersection between these two curves is about 2,000 hours at 1050 deg F.
Assuming a service temperature of 1006 deg F, (which in my estimation is conservative because the actual temperature is probably lower), the time to graphitization is +5,000 hours. This is a ball park estimate and only serves as an approximation, I would suspect the value should be well above 5,000 operating hours at this temperature.
Keep in mind that prior to reaching the graphitization region, the main steam pipe would be subjected to noticeable swelling and distress from accelerated creep deformation. The allowable stress value for carbon steel at 1006 deg F decreases to only about 2.5 Ksi. So, I stick by my conclusion that the pipe material was probably not carbon steel, given the limited visual evidence.
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