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P91 failure in China - 3 fatalities

P91 failure in China - 3 fatalities

P91 failure in China - 3 fatalities

WE understand that there was a failure of a P91 HP main steam line in China 1 week ago ( circa 4 Dec 06). The plant was a new 300 MWe coal fired plant, less than 1 month operating hours.

Can anyone advise what plant this was and more details?

RE: P91 failure in China - 3 fatalities

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?

RE: P91 failure in China - 3 fatalities

The original message I saw was dated 7 Dec by Jan R B. I have asked contacts in China to provide more details.

RE: P91 failure in China - 3 fatalities

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.

RE: P91 failure in China - 3 fatalities

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.

RE: P91 failure in China - 3 fatalities

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.

RE: P91 failure in China - 3 fatalities

In a different view of a photo that I received, it appeared that the initiating site was highly brittle (flaw, pre-existing crack?). As fracture progressed it changed to a ductile fracture near and at its termination.  

RE: P91 failure in China - 3 fatalities


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.



RE: P91 failure in China - 3 fatalities

My first experience with P-91 was reheater tubing that acted like spaghetti when it was stress relieved after bending and I have been leery of it ever since.


RE: P91 failure in China - 3 fatalities

Here is an excerpt of the email below;


Project:                Huadian Datong 2x300MW
Location:       Datong County, Xining City, Qinghai Province, Northwest of China
Design:         Northwest Electric Power Design Institute (NWEPDI)
Contractor:     Qinghai Power Construction Company
Supervision:    Sichuan Power Supervision Company
TIC:            2.643 billion RMB (330 million USD)
Construction Schedule:
-          First Concrete:      28 Mar 2004
-          168hr Unit 1:        30 Jun 2006 (27 months planned), 11 Feb 2006 (actual)    
-          168hr Unit 2:        30 Dec 2006 (30 months)
Fire Fatality Accident at same jobsite: 3 Oct 2005, fire occurred in suspending cage @145m while painting 210m height stack; 3 dead
Main Steam Pipe Rupture Accident:  31 Oct 2006 22:10
-          While 300MW Unit 2 Commissioning
-          Designed Parameter of Main Steam Pipe - Pressure: 17.5Mpa, Temp: 541 C-Degree
-          Material: ASTM A335P91
-          Pipe Dimension: 455.62x43.01 mm     (approx. 18" x 1-3/4")
-          Boiler Pressure Testing (Main Steam Pressure: 13.36Mpa, Temp: 483 C-Degree)
-          Longitudinal Rupture: 900mmx40~60mm
-          Distance from start point of rupture to the nearest welding: 2200mm
-          2 dead, 1 severely scalded; several other hurt
-          Faked as product of SMANT from US
Qualified Vendors:
The Four Primary Pipe Systems: Main Steam Pipe, Reheat Pipe (Cold Section), Reheat Pipe (Heat Section) and HP Water Intake Pipe used to be imported by vendors approved by the centralized Ministry of Electric Power:
-         Wyman-Gordon, USA                  <http://www.wyman-gordon.com/> http://www.wyman-gordon.com < <http://www.wyman-gordon.com/> http://www.wyman-gordon.com/>
-         Mannesmann, German                <http://www.mannesmann.com/> http://www.mannesmann.com < <http://www.mannesmann.com/> http://www.mannesmann.com/>
-          Sumitomo Metals, Japan            <http://www.sumitomometals.co.jp/e/index.html> http://www.sumitomometals.co.jp/e/index.html < <http://www.sumitomometals.co.jp/e/index.html> http://www.sumitomometals.co.jp/e/index.html>  (High Pressure Intake Water Pipe)
The government lost control over IPPs after split of Electric Power Ministry, however, the above brands are still recognized as high quality by the industy.
The Counterfeit Chain
Raw Materials of P91, P22 and WB36 - ordered from Fushun Steel Mill, a subsidiary of Northeast Special Steel Group, Fushun City, Liaoning Province
Pipe Piercing and Extending:
-          Chende Pipe Factory, Jiangdu City, Jiansu Province
-          Shengong Heavy Machinery Co Ltd, Taizhou City, Jiangsu Province, obtained license for Fabrication of Boiler & Pressure Vessel (billet only) license just in 15 Jan 2006
Pipe Surface Furnishing
-          Sumitu Special Steel Co Ltd, Taizhou City, Jiansu Province, founded in Mar 2005, a Joint Venture between Shengong Heavy Machinery (23%) and Japan Sumikin Special Steel Co Ltd (77%), not sure is there any relation between the latter with Nippon Steel & Sumikin Stainless Steel Corporation, Japan
-          Sumikin Sancang Special Steel Co Ltd, Tianjing, fabricator of “Hydratic” brand pipe
-          Tianjin Smant Steel Pipe Co Ltd, Tianjing (founded in 24 Nov 2004)
-          Representative Office, Tianjin Smant Steel Pipe Co Ltd, Beijing
-          Representative Office, American Hydratic (Int’l) Inc, Beijing, claimed to be agent of WT in USA
Trader and Dealers
-          China Hydropower Materials Co Ltd, Beijing
-          Huadian Piping Engineering & Tech Co Ltd, Beijing
-          Shangdong Power International Trade Co, Jinan, Shandong Province
-          Nancang,  Tianjin
-          Hudian Jinyuan Pipe Co Ltd, Zhenzhou, Henan Province
-          LuEnergy Storage and Transportation Co, Jinan, Shandong Province   
Fake Brand:
-          SMANT, USA
-          Hydratic, USA
-          WT USA
-          Sumito Japan
 -                                  22 June 2006 Main Steam Pipe Rupture occurred during testing/commissioning of Unit 2 of Yi Chuan 3rd Power Plant, Henan Province, where Hydratic Pipe is adapted and claimed to be imported from US.
-                                  An investigation by Henan Power Testing Research Institute, a subsidiary of State Power Grid, identified the so-call Hydratic Pipe and its raw material is all made in China. 
-                                  Recent investigation on Datong by the same institute also identified the so-call SMANT Pipe imported from USA is also made in China.
-                                  Actually, two and half years ago, Sinopec (China Petroleum Co Ltd) has already noted the numerous quality problems of Hydratic Pipe and issued a notice on 2004-06-07: Re Investigation to Hydratic Pipe.
Authority Action: 
-          It is believed that more than 40 plants have used the Hyrdatic or SMANT pipes.
-          The electric power watchdog, Power Supervision Commission requested an emergency examination on four primary pipes in as-built and under construction plants, which adapt so-called P91 pipe by SMANT from USA.  
-          The cost of bogus pipes is only 40% of those imported and margin from a 2x600MW could be 70 million RMB or 9 million USD.
-          Sometimes they do import some genuine product but only a small portion to cheat inspect and examination. 
-          The trader and dealer actually know the fact of forge and share the interest together with the counterfeiter, however, they pretend as to be deceived once the reality was disclosed.
-          Normally, owners order the critical pipes directly and then lack of strict inspection and examination.
-          For Huadian Datong Power Plant, the pipe trader, Huadian Piping Engineering & Technology Co is actually a related firm to the owner, both of which under the same umbrella of Huadian Group, one of the five major IPPs (State controls most of shares)
-          Plentiful plants built simultaneous with aggressive schedule furnish markets to low cost fake pipes.
-          Legal and administration penalty is too insignificant to deter to counterfeit manufacture. 
Black List
Tianjin SMANT Steel Pipe Co Ltd
Industry Park, Ba Li Tai, Jin Nan District, Tianjin City 
Tel:      86-22-88814785
Fax:     86-22-88814566
Representative Office, Tianjin SMANT Steel Pipe Co Ltd
Rm 602, F6, Modern Baili Tower, 20 South Road, East Third Ring, Chaoyang District, Beijing
Contact:Mr. Wang Xiao Ning (Manager)
Tel: 98-10-67702836
Mobile: 86-13521764045
Contact:Ms. Qian Min (Manager)
Representative Office, American Hydratic (Int’l) Inc
Rm 1310, Fortune Tower B, 3 North Road, East Third Ring, Chaoyang District, Beijing
Contact: Mr Lu BO
Tel: 86 - 10 - 64620153
Fax: 86 - 10 - 64620139
SUMITU Special Steel Co Ltd
Hi-Tech Park, Gaogang District, Taizhou City, Jiangsu Province

RE: P91 failure in China - 3 fatalities

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.

RE: P91 failure in China - 3 fatalities

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

RE: P91 failure in China - 3 fatalities

Government tenders are always cornered by the traders,middlemen and are considered a largessse doled out to political beneficiaries. This is a standard practice in Asian countries.For government is the biggest buyer.

RE: P91 failure in China - 3 fatalities

a star to Meteng and gr2vessels! Thanks for clearing this up.  Now we will need to wait and find out the metallurgical cause of the failure.

RE: P91 failure in China - 3 fatalities

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?  

RE: P91 failure in China - 3 fatalities

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

RE: P91 failure in China - 3 fatalities

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.

RE: P91 failure in China - 3 fatalities


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.

RE: P91 failure in China - 3 fatalities

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.  

RE: P91 failure in China - 3 fatalities

Thanks , Meteng. Would this calc be affected by an incorrect heat reatment of CS in the fabrication phase, ie, woule graphitization/ sheroidation have been accelerated if a CS pipe had undergone a P91 style   N+T under zero stress ?

RE: P91 failure in China - 3 fatalities


RE: P91 failure in China - 3 fatalities

While I am on the topic of creep rupture in Power Piping from my previous post, I can provide some insight from "those" individuals that are close to the situation;

The general feeling among several of my close metallurgical peers in the Power industry is that the failed main steam pipe was Grade 91 material. The caveat is that this pipe material was not properly heat treated. Here is where I believe the introduction of an axial flaw could have occurred. My best guess is that this material (spool) was either not tempered or was inadequately tempered (high hardness). This high hardness, low toughness, pipe material could set the stage for either an axial crack introduced during a hydrostatic test or stress corrosion crack from exposure to moisture. Both of these damage mechanisms could indeed explain why the pipe ruptured with little to no ductility in service and exhibited a predominantly brittle-looking fracture surface. In reviewing the pictures once again, there was little to no oxide that would be expected if the spool failed from creep rupture (as with CS).

Unfortunately, my colleagues don't believe we will ever get to the bottom of this because the Chinese government confiscated this material.

RE: P91 failure in China - 3 fatalities

Sounds like the failures that occurred in the US in the 1950's blamed on " temper embrittlement"- excess trace amounts of phosphorus , sulphur , etc.- .

RE: P91 failure in China - 3 fatalities

Great thread fellas.

Any additional information and photos would be great.

I especially enjoyed reading "metengr's" analysis of the problem. Good work and great information for future work.

Best regards - Al

RE: P91 failure in China - 3 fatalities


Excellent information..... This is an excellent thread

You state:

"The Chinese Government has also banned Chinese made pipe for use in major power plant critical applications."

Where did you get your information ?

Is there not just a little bit of irony here ???

Will there be a comprehensive report ever ??



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