Analyzing the boiler industry – Boiler
Finite element analysis is being used more and more throughout the boiler industry to detect flaws in equipment. But a lack of uniform standards for its effectiveness in determining fitness for service is creating confusion.
Who would have thought that the boiler industry would heat up over such minute details? Finite element analysis (FEA) is technology that can detect even the slightest of flaws in a boiler. It can help to determine the cause of boiler accidents by showing a schematic of the boiler. While not new technology–FEA has been around since the 1970s–its use is increasing. Yet, there remains a rather large question mark about finite element analysis and its close relative, fitness-for-service analysis. There simply aren’t uniform standards.
Finite element analysis is a computer-based technology that simulates the deflections and stresses in such things as bridges, buildings, and boilers caused by applied forces, pressures, and gravity. FEA can also simulate temperature distributions in boilers and pressure vessels, according to the experts. It is used to help calculate whether a product design meets regulatory codes, and it can also help to determine how long a product will survive in service.
“Manual calculations have been used throughout the history of pressure vessels to set pressure vessel and boiler dimensions,” says a finite element analysis specialist engineer with a Canadian-based consulting company. “Manual calculations typically show that adequate vessel wall thickness and reinforcement of penetrations or pressure barriers such as nozzles have been included. Codes typically allow other methods of analysis, usually finite element analysis, to examine detailed stresses and demonstrate conformity with design codes. Detailed analysis can minimize costs by avoiding unnecessary over-design or reinforcement that can exist when only manual design calculations are used,”
According to this engineer, finite element analysis may catch details that are missed in manual calculations, including stress concentration or behavior involved ia loss of performance of a boiler.
FEA is used to determine a boiler’s fitness for service (FFS). “Fitness-for-service analysis is a standard that helps owners of equipment evaluate damage and determine the equipment’s ability to remain in service,” says Christopher Kent, director of loss prevention at Travelers Insurance Co., Hartford, Conn.
“It’s a run, replace, or repair decision-making tool,” says David Lang, account engineer at FM Global, Johnston, R.I. “This is as valid as any other engineering tool in our industry.”
A number of organizations have developed codes that are used as guidelines when determining a boiler’s fitness for service. The American Petroleum Institute (API) in Washington has what may be the most uniformly used code in the industry: API 579. The National Board of Boiler and Pressure Vessel Inspectors in Columbus, Ohio, has an inspection code that is also widely used. Another organization, The American Society of Mechanical Engineers (ASME International) in New York has yet another boiler code, the ASME Boiler and Pressure Vessel Code, that offers standards and guidelines.
These codes and guidelines recognize finite element analysis as a useful tool, says one expert. Each code sets forth its own recommendations on how to determine fitness for service, either by using finite element analysis or by other more traditional means.
The problem, say the experts, is that no one state or jurisdiction is using the same code. In fact, none of the codes have been compiled into one uniform industry standard. At the moment, states may adopt all or part of any of the codes or regulatory guidelines into their regulations. In Louisiana, the choice is left up to the individual companies, says one expert.
In fact, many of the codes include language that attempts to create a harmony within the industry. “The National Board inspection guideline says at the beginning of the documentation that it was created knowing there’s an API standard existing on the very same subject and it’s not intended to supercede the API standard,” says Kent. “This is a separate API standard that addresses the same things the National Board inspection code addresses, but a local jurisdiction can say that everything in that states per the National Board. The individual state makes interpretations of its own.”
“I don’t think any one state has adopted API 579, yet individual companies have decided to use either API 579 or principles from it,” says Allen Selz, president of Pressure Sciences Inc., Pittsburgh, Pa., a professional mechanical engineering design and analysis firm. “There are several inspection standards. API 510 and the National Board Inspection Code are two. Both tell you in essence that if you find something, you can use whatever methods of analysis you need to demonstrate that it’s either acceptable or not acceptable.”
That has the potential to create a confusing scenario in which different levels of analysis could return different answers to the same question. “The need in our industry is for standardized fitness-for-service analysis,” Lang says. “You can’t have people running around using all sorts of different assumptions for deciding run, replace, or repair. That’s the case now. There’s no standard way of doing fitness-for-service analysis.”
The Move Toward Standardization
The National Board is very close to recognizing fitness-for-service standards, but has not done so officially, says one industry source. “There’s also no place to look to see what states accept it and what states don’t. Until the National Board recognizes a uniform standard, the states will not have to decide whether they want to recognize it themselves.”
The API, in conjunction with the ASME, is working toward writing a standardized methodology. Early predictions are that the process is in the beginning stages and the industry could be facing a three to four year wait for anything resembling a national standard.
Until uniformity exists, the risk manager is left with few options. “The hard part for a risk manager is that he can get three different consulting companies coming in using three different techniques and coming up with three different answers,” Kent says. “This is where standardized fitness-for-service analysis is so important. One engineer may use the minimum normal stress allowed for a piece of metal. The second may use the average. The next may use the high-end value.”
At the moment, there is no benefit for using finite element analysis or fitness-for-service testing in terms of lower insurance premiums. “The overriding concern is fire,” Selz says. “Even if you do use the fitness-for-service analysis, it’s not going to reduce your insurance rates any. On the other hand, it will affect maintenance costs and how soon you’ll have to take this thing out of service.”
For now, insurers don’t require fitness-for-service analysis because of its lack of uniform standards. Yet these same insurers may play a significant role in developing standards, suggest some experts. Insurers are taking notice of the issue and are beginning to require their insureds to use good engineering practices and to recognize standards that do exist.
“Checks and balances are very important,” says Lang. “Our insurance industry plays a vital role in providing those checks and balances. A risk manager facing these types of issues has to be sure that all the parties involved are versed in the engineering aspects of fitness for service. He has to respect his own engineers, but he has to take in the advice and counsel of a knowledgeable insurance company. A good insurance team can assess and engineer risks and help prevent big losses from the misapplication of this technology. I don’t think many risk managers are engineers, so a risk manager needs people who can quantify and qualify these risks for him objectively.”
COPYRIGHT 2002 Axon Group
COPYRIGHT 2002 Gale Group