Extreme Valve Testing

       

Two commonly used low temperature tests today measure the degrees for liquid nitrogen and liquid natural gas.BY GREG JOHNSON

Valves today face more challenging conditions from a wider range of applications. As a result, users are asking for more and better testing.

Filling a valve up with water, adding pressure and looking for leaks might work for some valve specifications, but many of today's demanding valve requirements call for much more stringent testing and evaluation. Special service applications such as hazardous fluids, nuclear power plants, high-pressure pipelines and more dictate a much broader testing and inspection regimen than traditional simple tests.

Many users are requesting valve manufacturers prove their products will operate satisfactorily at the higher and lower temperatures and more extreme pressures that their valves are advertised to reach. These may be the lowest cryogenic temperatures or elevated temperatures close to 1000° F (538° C). Such tests call for specialized equipment and test procedures.

Cryogenic testing is generally performed at temperatures ranging between -50° F (-46° C) and -320° F (-196° C).The most common of these more extreme tests is cryogenic testing. Such testing is generally performed at temperatures ranging between -50° F (-46° C) and -320° F (-196° C)—most often at -320° F (-196° C), which is the temperature of liquid nitrogen (LN). Standard practice is for the valve to be immersed in the LN up to the packing gland area, if the valve is equipped that way. The packing must be kept out of the LN or it could freeze the packing, seizing the stem and causing the valve to lock up and fail to operate. Because polymer seals do not function well at cryogenic temperatures, valve end connections must be the type that makes a solid mechanical connection. These include threaded, flanged or caps welded onto buttweld-end ends. Socketweld-end and buttweld-end valves without welded-on caps are very difficult to test at the lowest cryogenic temperatures.

One of the most popular low temperature services today is liquid natural gas (LNG). Valves for LNG are sometimes tested at -320° F (-196° C), but a more accurate test is performed at the actual LNG temperature of -260° F (-162° C).

Cryogenic testing is costly and hazardous and should only be performed by experienced, trained personnel. The test procedures for cryogenics are available from several standards-making-organizations, as well as end users. The most significant differences in testing procedure documents are allowable leakage rates.

PIPELINE VALVES

Pipeline safety has come to the forefront lately because of catastrophic pipeline failures. These failures have occurred primarily on older pipelines because quality requirements for new pipeline construction are very stringent. Valves for pipeline service are also scrutinized very closely. While all pipeline valves are hydrostatically tested at the factory, usually in accordance with API 6D, additional tests are almost always performed. The most common extreme test for pipeline valves is a long duration shell test, which is carefully monitored by a recording device tracking the pressure and the temperature of the valve as it is tested.

During these enhanced duration shell integrity tests, the pressure on the valve must be maintained, or the pressure drop must coincide with a proportional drop in temperature to avoid valve failure. It is not uncommon for test durations to run several hours long.

FUGITIVE EMISSIONS TESTING

A valve is prepared to undergo fugitive emissions tests.The desire to keep our nation's air clean is manifested in the valve industry through the Clean Air Act and various state and local regulations. For manufacturers to meet today's low emissions requirements, valves must be tested to determine their ability to contain these fugitive emissions (FE). FE testing is now a requirement by most refiners and chemical companies that must contain hazardous fluids as part of their everyday processes.

FE testing requires the valve be pressured up with an easily measurable gas such as methane or helium, and then checking the body and seals, particularly the packing, for leakage. An alternative method is to create a vacuum drawn on the valve through a closed piping system and introducing a tracer gas into the areas of the valve exterior susceptible to FE leakage.

Two distinct schools of thought exist on what gas should be used to FE test a valve—schools separated by the Atlantic Ocean. In Europe, it is deemed unsafe to test with methane, so all testing must be performed with helium; in the U.S., the preferred test media is methane, which more closely resembles the molecular structure of the volatile organic compounds (VOCs) that both industry and government are working hard to control.

The procedures for FE testing generally require the test valve be mounted in a device that can firmly hold both the valve and its actuation mechanism. The valve is then cycled from dozens to hundreds of times while pressured up with methane or helium. As an added service simulation, the valve is heated at least twice to around 500° F (260° C) during the test sequence. The heating cycles simulate the temperature variances that might be acting on an installed valve. The temperature spikes also provide prototypical movement in the packing due to the expansion and contraction of the materials of construction. It is usually after a thermal cycle that a valve under test will show leakage.

The two schools of thought on the test media also relate into two schools of thought on the test procedures themselves. The International Organization for Standardization (ISO) has FE testing standards as do the American Petroleum Institute (API) and the International Society of Automation (ISA). The ISO standard 15848-1 is currently under revision to make it more user friendly. API is updating its FE packing qualification standard (API RP622) as well creating a new valve FE test standard (API RP 624).

FIRE TESTING

Fire testing involves pressuring the valve with water and then focusing several jets of flame onto the valve.The most visually exciting of the extreme valve tests is the fire test—when you mix high pressure, water and several gas-fueled "flame throwers" together, the result is certainly not boring. Fire testing is used to simulate a fire in a plant or refinery and determine how well specific valves and components will function during that fire and after it has been extinguished. The procedure involves pressuring the valve with water and then focusing several jets of flame onto the valve. After the test piece has attained the prescribed temperature, the valve is doused with jets of water, simulating the firefighting aspect of the process. The leakage rate of the valve or component is then measured and compared with acceptable leakage rate for the test standard.

Fire testing is performed regularly on soft-seated ball valves to determine if they are fire-safe, meaning that, after the initial polymer seal burns away, a secondary metal-to-metal backup seal can still prevent major flow through. Upstream valve manufacturers use a variety of fire-testing standards to confirm the efficacy of the seals in their products to withstand fires at the wellhead.

RADIOGRAPHY

Today's newer, low-cost manufacturing sources, combined with a loss in U.S. manufacturing expertise, are creating increased scrutiny on valves and other piping components. Castings are especially vulnerable to poor quality and workmanship. Because of the nature of their potential defects, unaided visual examination is not enough to instill a sense of security with many valve users. For this reason, users often call for additional nondestructive evaluation (NDE).

Some exterior NDE methods such as dye penetrant examination (PT) and magnetic particle examination (MT) are helpful. But what is often specified is a look inside the walls of the valve, or as this look is sometimes called, a volumetric examination. The best way to accomplish this for castings is by radiography. Radiographic examinations (RT) can provide a useful look inside the pressure-containing wall of the valve and help to determine the overall soundness of the casting, as well as determine if potentially hazardous defects are present.

In today's marketplace, castings are especially vulnerable to poor workmanship.A layman reviewing radiographs of a valve casting would be hard pressed to determine whether or not the valve metal is of good quality and fit for service. The subjective nature of comparing reference films and their "shades of gray" mean that even some experienced radiographers have a hard time evaluating what they are seeing. Radiographers that shoot valve castings every day and diligently scan their reference radiographs like the latest issue of Sports Illustrated have a better chance of providing correct and repeatable interpretations.

Casting defects are divided into various types and classes. These include shrinkage, porosity, gas and inclusions. The categorization of these defects is generally viewed as a good way to judge the overall soundness of the casting and the workmanship of the foundry.

Defects such as hot tears, which are areas of shrinkage open to the surface, or cracks are viewed as performance-affecting defects. Because of this, none of these defects are allowed in most casting evaluation standards. These types of defects can reduce the effective wall thickness of a casting, causing its pressure-retaining capability to be compromised. Another issue with cracks and hot tears is that they are "stress-raisers," which means they can act to initiate further cracking of the metal to the point that catastrophic failure could occur.

Despite its subjectivity and limitations, radiography is still the de facto method of valve casting evaluation, especially for critical refinery and power plant applications.

NUCLEAR TESTING

The most critical valve applications today are in the nuclear industry. Valves for use in nuclear power plants, including nuclear-powered navy ships, are subjected to very rigorous examination under a wide range of tests that would make for a separate article. One of the special tests required for on-shore nuclear power plant service, for example, is seismic testing, which simulates the stresses caused by earthquake activity. The joke in the valve industry used to be that the stack of paperwork certifying a nuclear valve was often bigger than the valve itself though today those test reports and traceability documents are stored on digital media.

CONCLUSION

With the widespread concern on safety these days, both valve manufacturers and end users have responded by creating appropriate tests for valve integrity, especially for critical flow control applications. Many of these extreme tests were randomly called out 50 years ago; but today, they are commonplace. And, as even more critical valve applications are developed, undoubtedly, there will be newer and tougher extreme valve tests to ensure product integrity for those yet-to-be designed products.

ANUP SHAH

Adroitt Flow Control Pvt Ltd

Cell +91 9820501463

(Sent from iPhone)

Valves In Pulp & Paper Industry

       

BY HARLAN DUNK

The pulp & paper industry has seen tough times, but the business will still be around for many decades; the product is too much in demand. Those involved in valves for this industry need to understand how the processes work.

Perhaps no manufactured product plays a more significant role in everyday human activity than paper and paper products. Paper provides the means for recording, storing and disseminating most of today's information. Even though people have extolled the coming of the paperless society, it has not yet arrived. Humans still print e-mails and other correspondence and information they get from the paperless communication channels of the computer and the Internet. And beyond that, paper is the most widely used wrapping and packaging material as well as a critical component today in everyday life. From drywall to napkins to office supplies, paper is used for many purposes, and that situation won't change for a long, long time.

The uses and applications of paper and paper products are truly vast, and new specialty products are constantly under development. At the same time, the industry itself faces a vast array of inroads and competition from other sectors, most notably plastics and electronic media. To remain competitive in existing markets and, at the same time, be receptive to new opportunities, the paper industry today is adopting new technologies and methodologies.

PROFITABILITY

Some time back, on a tour of the pulp and paper mills in Finland with a number of North American pulp and paper people, one customer expressed amazement at the investment in new machinery and processes the Finnish companies had recently completed. This customer referred many times to the return on investment in North American pulp and paper mills, which he said was less than 3%. Why would anyone spend money for a 3% return, he questioned, when you could keep your money in the bank and get a better return. This is one of the reasons there has been very little investment in North American pulp and paper mills in recent times. The other two are stringent requirements from the Environmental Protection Agency and a buildup of stock of finished goods.

This means most growth opportunities in pulp and paper are outside North America. And the areas where companies are making money are regions nearer to the major renewable resource that runs this market—trees.

MARKET TRENDS

Globally, pulp and paper companies are still merging, buying and selling mills in an attempt to get the right mix to make a profit. This trend will probably continue until there is less paper in storerooms and/or more demand for different types of products.

Several years ago, the buzz word used most often in the industry was "Process Variability," which meant using better process control to improve quality at the same time you use fewer raw materials and get higher production rates.

Another trend many mills adopted is "Life Cycle" analysis where a mill looks at a product to see if it can be repaired as opposed to being replaced and how many times it can be repaired to increase its life cycle. To accomplish this requires strong cooperation between the maintenance group and the procurement group to determine the best percentage cost balance of a new valve versus repair of a product. Is it 50% cost of new or upwards of 80% cost of new?

It also takes recognizing the value of a quality product in the first place. Quality means repair less often and often means less expense for that repair. The trend for some time has been toward mills repairing valves more frequently, leading more mills toward metal-seated ball and butterfly valves, which have a higher initial cost but longer life cycle. Also, some mills that traditionally used soft seats have moved to more rugged metal seats in many applications—not only for longer life but also because of higher pressure and temperatures in certain applications.

APPLICATIONS/LIMITATIONS

Beyond the usual maintenance, repair and operations issues in the paper industry are challenging applications where a valve in a mill is subjected to slurries, scaling, high velocities, high or low cycling, or where special attention is needed from the maintenance group.

Valves are often chosen by a mill based on how they can handle these challenges. In high-scaling applications, where the media sticks to the surface of the valve, for example, most plants will consider a ball valve first. This is because these valves offer full flow characteristics. Ball valves also rotate 90 degrees, and with the proper scraper seats, the media that has scaled can be wiped off the ball so the ball is clean before it gets seated. In some multi-turn valves, the scaling could sit in the bottom of the pipeline, and the valve blade cannot get through the scale to seat the valve. Cycling the valve or even partial stroking the valve can alleviate the scale buildup. As an example, green liquor (which we discuss later in this article) is a high-scaling media that can stick to the sides of pipe causing a 6-inch pipe to have a 1-inch hole because of the severity of the scaling. In cases where the scaling is extreme, cycling the valve on a weekly basis is recommended to scrape the media off the ball face.

In high-cycling applications, care must be given to packing of the valve. For example, on the echo filters in the recaustisizing area, the filters separate the impurities in white liquor. In this area, a large-diameter valve may cycle every hour because the white liquor and lime mud that are the media in this area are abrasive so that, not only do the seats get worn, but the packing tends toward wear. For this reason, a double-packed valve with live-loading is often recommended. The bottom line in any of the liquor applications, however (mills deal with green, white, black, orange, red and brown liquors), is that high-quality valves are needed and the supplier of those valves should have expertise in this specific application.

Figure 1. Process Overview for Paper Mill

This need for expertise is one of the main problems in paper and pulp mills today. Plants have fewer people and many of those with knowledge and expertise have retired. They have to draw upon sales people, college students, engineering consultants, even the Internet for expertise. But each of these has a downside. For example, the salesman wants to sell what he has, which may not be what is best for the application. The college student has book smarts but may lack experience. Engineering consultants can be expensive; and there is no way to know if the information from the Internet is reliable. For these reasons, one of the best tools in the paper industry today is good communication between the vendor of the equipment that runs the mills and the paper mill customer.

For example, when buying a capping valve, a paper mill customer needs to have a level of comfort that the company selling the equipment understands the process. A capping valve lets chips into the digester when open and isolates the digester from the atmosphere when closed. A person involved with selling capping valves needs to know how to size the capping valve correctly, whether there is potential for bridging of the chips, and what type of chip chute is required. All of this may be beyond the normal valve sales training, but it's necessary to know the process (Figure 1).

In and around the digester, the predominant valve used is a rotary metal seated valve for both continuous and batch digesting. The differences, which are outlined in the next few paragraphs, can be seen in Figures 2 and 3.

Figure 2. The Pulping ProcessFigure 3. The Pulping Process (continued)

CONTINUOUS DIGESTER

Continuous digesters use a heated, pressurized chamber into which chips and chemicals are fed. This type of digester differs from the batch digest in that chips are processed in a downward flow through zones of steadily increasing temperatures and pressure until the cooking zone is reached. The cooking liquor is also continually circulated from the digester to heat exchangers, where the liquor is reheated and reinjected into the digester. The pH of the cooking liquors is 13.5 to 14 and the operating temperatures are 240° F (116° C) at 140 psi.

A high-pressure feeder (the heart of the digester) sends the chips to the digester inlet.

A rotating helical screw pushes down chips, and steam and liquor are used to cook the chips—impregnation, heating, cooking and washing of the chips is done in one continuous operation. The chips remain in this area from two to three hours and the mass is cooled, mixed with black liquor, and mechanically conveyed or "blown" to the blow tank.

BATCH DIGESTERS

In batch cooking, the digester is filled with chips, white cooking liquor and weak black liquor. The cooking liquor, which is drawn through screens, is circulated with a pump to a heat exchanger, where the liquor is heated with steam before being returned to the digester. The chips are cooked for about three hours in this caustic atmosphere. This cooking action dissolves the bond between the cellulose fibers and the glue-like material called lignin that cements the fibers together.

After cooking, the pulp is blown through a blow valve into a blow tank where the shock of the material hitting the tank wall separates the lignin and fibers.

There is also an enhanced cooking batch digester, where the liquor goes through heat exchangers to help cook the chips without using all the steam in a standard batch digester, which means more energy efficiency and economy.

The next area of the mill that uses metal-seated valves is the recovery area. The recovery area is where chemicals from the spent cooking liquors are recovered. The reconstitution of these chemicals can form fresh cooking liquor at the same time incinerating organic residuals creates energy.

While the main focus of pulp and paper mills is on the fibers that make the paper, the mills use every part of the tree. For example, the bark goes into the bark boiler to make steam. The lignin has high BTU value so mills try to recover the lignin to burn in the recovery boiler, which also recovers many of the chemicals used in the cooking process. The recovery process is achieved through a well-defined series of steps, starting with the weak black liquor coming from the brown stock washers. The process steps are then:

• Concentration of liquor in multiple evaporators and concentrators to get to heavy black liquor
• Addition of salt cake to make up for soda loss
• Incineration of heavy black liquor in the recovery boiler
• Dissolving smelt from the boiler to form green liquor (new liquor)
• Burning of lime mud to recover lime
• Causticizing of green liquor with lime to form white liquor.
  

Figure 4-5. Evaporators and Recovery
EVAPORATORS

After the blow tank, the stock is washed in a brown stock washer (Figure 4). The fibers are then transferred to the stock prep area, and the wash is recovered and sent to the evaporators. Evaporators take the water out of the liquor to create high-density black liquor to burn in the recovery boiler. The evaporator island may include as many as six evaporators which are called effects—for example, the vapor in one effect becomes the steam supply in the next unit. There are four types of evaporators: rising film, falling film, cascade and cyclone.

RECOVERY BOILER

Heavy black liquor is pumped to a black liquor storage tank at the recovery boiler (Figure 5) where the liquor is mixed with salt cake—sodium sulphate—as a make-up chemical to replace the chemicals lost during washing and evaporation. The black liquor is then pumped by the nozzle pump into the boiler, where the liquor is vaporized and burned, the organics in the liquor burn as fuel, while the chemicals fall to the bottom of the boiler and flow out as smelt. The smelt flows into a dissolving tank filled with weak wash liquor from the causticizing area. The smelt is agitated and recycled to break up the molten smelt and prevent an explosion. The liquor in the dissolving tank is called green liquor.

CAUSTICIZING

Green liquor from the dissolving tank is pumped to the causticizing area (Figure 5) where it is treated with milk of lime, calcium hydroxide, to form white liquor. Because green liquor contains impurities called dregs, it must be filtered in a clarifier. The clarified green liquor is then pumped to the slaker where it is mixed with burnt lime, calcium oxide. The lime-green liquor mixture flows to two or three causticizers in a series to complete the reaction. The liquor is separated from the lime mud and becomes white liquor. The calcium carbonate precipitate is burned in the lime kiln to form calcium oxide for use in the causticizing area.

Once the process has passed through the third effect on the evaporators, metal-seated valves are normally used because the black liquor is becoming heavier and more abrasive. If the process has over half black liquor or the material is going into the concentrator, metal-seated ball valves are required.

When the fiber leaves the brown stock washer, it either goes to the paper machine or to the bleach plant, where the stock will be whitened. Many different processes are used to whiten the fibers—chlorine dioxide bleaching, ozone bleaching, oxygen bleaching, peroxide bleaching, etc. Many of these processes require higher alloy valves or valves with liners.

In regards to these higher alloy valves, a trend in the last few years is that many mills that use 316 stainless steel are complaining that steel isn't lasting as long as the 316 stainless steel they bought years ago. This is because environmental regulations have forced many mills to close up their systems. At one time, the paper processing systems were open, and many chemicals could go downstream. Now, those processes are closed, which means that chlorides and other chemicals are building up. It also means chemical concentrations are becoming higher and higher, which is what is causing accelerated corrosion.

Because of this, valve manufacturers have had to look at sturdier materials for their valves and valve trims. For example, one popular material is AVESTA 254 SMO. For metal-seated ball valves, manufacturers are finding that the standard chrome coating is not withstanding the aggressive nature of these chemicals. HVOF (high velocity oxygen fuel) or spray and fused coating can be considered a solution, depending on the application.

Lastly, one key area for metal-seated ball valves is low-pressure shut-off. Many metal-seated ball valve manufacturers use springs to energize the ball into the seats.

Special care must be taken in specifying the testing requirements for metal-seated valves. The criteria many use is ANSI FCI 70.2, which separates the valve shut-off into classes. Most metal-seated on/off valves are class V, though some can get to class VI with special attention and lapping. The ANSI FCI 70.2 specification does not state the pressure of the test to achieve the class shut-off. Therefore, most manufacturers use the full ANSI rating of the valve.

Some manufacturers believe, however, that using the full-rated pressure makes the test less valid because the higher the pressure, the tighter the shut-off. For this reason, people seeking valves for these purposes should ensure their vendors can do a low-pressure test to meet the shut-off requirements. This low-pressure test is much harder to conduct and more valid as a result.

CONCLUSION

The pulp and paper industry has hit the doldrums, but they still require valves to keep the mills operational. With the state of the industry, mills will be looking to purchase high-quality valves from people with an idea where the valves are used and how to apply them properly. With quality products, the mills can run longer between shutdowns and repair what they have purchased instead of buying new ones every year.

ANUP SHAH

Adroitt Flow Control Pvt Ltd

Cell +91 9820501463

(Sent from iPhone)

Understanding SIL & Valve Industry

BY MICHAEL A. MITCHELL A good deal of misunderstanding exists about what an SIL is and how it is assigned. Yet anyone involved in products that are to be used in Safety Instrumented Systems should know how this designation came to be and what it means. Many valve end users, piping engineers and valve manufacturers are responsible for products to be used in Safety Instrumented Systems (SIS). But these "valve people" tend to be mechanically oriented, not particularly oriented toward instrumentation. Nonetheless, these days any valve person may very well be responsible for equipment to be used in what is typically, but perhaps incorrectly, referred to as an "SIL [Safety Integrity Level] application." But the issue of specifying or using products with an SIL can be confusing and intimidating for people not familiar with what the term means. This article seeks to provide non-instrumentation personnel with a basic overall understanding of what SIL is and how to think about it in terms of the selling, use or purchase of valve and actuator products, particularly as it applies to partial stroke valve testing (PST). It deals with broad concepts and generalities of SIL, recognizing there are always exceptions to the rules. Taking this topic that, for many, is shrouded in mystery, confusion and intimidation and making it into something that can be understood in general terms should help all valve people serve their companies and customers better. WHAT IS SIL? Understanding SIL begins with learning where SIL came from, and what is involved. As a result of industrial accidents such as the Bhopal pesticide plant disaster and the Piper Alpha offshore platform explosion in the 1980s, increasing attention has been paid to the risks within industrial processes. Today, we are constantly weighing the relative risks involved with the hazardous processes-such as refined fuels, hydrocarbons, petrochemicals-so necessary for our modern way of living. We also look for ways to meet demands for continuous operations for as many months and years as possible because plant shutdowns result in reduced revenue stream. These demands on plant operations, coupled with the advent of more recent safety procedures, reliability engineering and much more have led to greatly extended times between routine "maintenance shutdowns" (a time to close down process plant operations and concentrate on maintenance of equipment and testing of safety systems). This, in turn, has led to increased attention to reducing operational risk. The increasing number of industrial accidents and the resulting pressure from insurance companies and governmental oversight/safety agencies created a movement to set standards for the classification of SIS. The oversight bodies posed this question to process plants: If the plant is going to remain operational for an extended period of time, how can we be assured that the valve plant safety systems will function correctly when called upon? Industry responded to this question with accepted industry standards (essentially self-governing practices) such as ISA-S84.01 and IEC61508/61511 to measure the acceptable level of performance of these systems. Adherence to the standards became a best practice. Note that the standards are not prescriptive-they are performance oriented. They say what level needs to be achieved, not how to reach those levels. Ultimately, it is up to the end user to make the decision of how that's to be done. An SIS is designed to prevent or reduce hazardous events by taking a process to a safe state when predetermined conditions are violated. An SIS can typically be an emergency shutdown system (ESD), a safety interlock system or a safety shutdown system. Each SIS will have one or more Safety Instrumented Functions (SIF). Such a function might be something like: When the tank pressure gets too high, a safety valve opens. When the solution in the tank gets too hot, the inlet steam valve closes. Of course, each SIF loop will be a combination of logic solvers, sensors, solenoids and final control elements, such as an automated valve. Every SIF within an SIS will have an SIL level. These levels may be the same or they may differ, depending on the process. A common misconception is that an entire system must have the same SIL level for each safety function. Figure 2. PFDAVG and Valve Life Cycle Graphs reprinted by permission from ANSI/ISA-TR96.05.01-2008. ©ISA 2008 An SIL is essentially a measure of the system performance in terms of Probability of Failure on Demand (PFD). If the goal is to reduce risk, we need to understand what that risk is. The simplified equation for risk is: Risk = Probability X Consequence We can think of probability in terms of hazard frequency (how often will a process exceed normal conditions and need to be brought to a safe state?); and consequences in terms of hazard consequences (what happens to the plant, employees, environment and community if the process upset is not brought to a safe state?). Where the SIL number comes from or how it is determined might be described in the following simplified sequence: A decision is made that a process plant needs to comply with the international standards for process safety systems, usually IEC 61511. The plant forms a HAZOP (Hazard and Operability Study) team. Essentially the HAZOP procedure involves taking a full description of a process and systematically questioning every part of it to establish how deviations from the design intent could arise. Once identified, an assessment is made whether such deviations and their consequences can have a negative impact upon the safe and efficient operation of the plant. If considered necessary, action is then taken to remedy the situation. In a sense, this is based upon Murphy's law: Anything that can go wrong, WILL go wrong. What the HAZOP team attempts to determine is: What will go wrong? The team might be comprised of process design engineers, operations personnel, maintenance and instrumentation engineers, etc. As part of the HAZOP, all instrument safeguards, i.e., SIS, are identified and validated for their primary capability to prevent an incident from occurring or to mitigate the consequences of an accident. SIL classification of an SIS is the next step after the HAZOP to ensure that the SIS provides sufficient risk reduction. Essentially, the HAZOP team identifies which systems will create the highest level of risk if the SIF fails and then determines the impact of the failure, i.e., the consequence of failure. Consequences of failure might include escalating examples, but the possibilities are endless. In other words, the list might address: "If the system fails...:" The plant will lose $15,000 per day. The plant will lose $1 million per day. The plant will become damaged and will shut down for three weeks. A high degree of probability exists for injury or loss of life to company personnel in the immediate area. A high degree of probability exists for explosion and loss of life to non-company personnel outside the parameter of the facility. Ultimately, it is up to the plant owner and operator to determine what level of risk is acceptable based on their own criteria (best practice, company philosophy, insurance rates and requirements, budgets, etc). Therefore, risk tolerance is subjective and site-specific. Once the level of risk tolerance is established, SIL levels may be established for specific SIF within an SIS. Figure 3. PFDAVG is decreased due to PST combined with full cycle testing Graphs reprinted by permission from ANSI/ISA-TR96.05.01-2008. ©ISA 2008 THE ROLE OF PROBABILITY Before discovering how the numerical value of SIL is derived, a better understanding of PFD is needed. It's easier to express probability in terms of failure, rather than in terms of proper performance. As published in the aforementioned standards and some product brochures, four levels of SIL are listed, enumerated 1-4-the higher the SIL level, the higher the associated safety level, and the lower probability that a system will fail to perform properly (Figure 1). These various SIL levels might be correlated to the above mentioned examples of consequences of failure. For purposes of this article, it is appropriate to think of SIL as "the degree of likelihood that our system will work when we want it to." (Generally, SIL 4 is beyond the scope of what we see in the process industries.) Again, we might want to think of a "function" as an emergency shutdown valve system, typically consisting of a sensor of some type (pressure, level, temperature) and a logic controller that will send a signal to an automated valve. The automated valve package might consist of an actuator (pneumatic, electric, hydraulic, etc.), solenoid valves, quick exhaust valves and the final control element, the valve. The "system" may consist of many functions; it might have five emergency shutdown valves protecting a pressure vessel cooking a process. Or, it might have only one function (the SIF) making the entire SIS. To summarize, the HAZOP team will determine SIL levels based on determined PFD. Michael Young of General Monitors has summed this issue up nicely in his paper, SIL 101: How Safe Do I Need to Be? A simple example will help illustrate the concepts of SIS, SIF, and SIL. Consider the installation of a pressure vessel containing flammable liquid. It is maintained at a design operating pressure by the Basic Process Control System (BPCS). If the process control system fails, the vessel will be subjected to an over-pressure condition that could result in a vessel failure, release of the flammable contents and even fire or explosion. If the risk in this scenario is deemed to be intolerable by the facility owner, an SIS will be implemented to further reduce this risk situation to a tolerable risk level. The SIS system will be independent from the BPCS and will act to prevent or mitigate the hazardous condition resulting from pressure vessel overpressure. The SIS will have an SIF which might include a pressure transmitter which can sense when an intolerable level of pressure has been reached, a logic solver to control the system logic, and a solenoid valve which might vent the contents of the vessel into a safe location (flare stack, environment, storage tank, etc.), thus bringing the pressure vessel to a safe state. If the risk reduction factor required from the Process Hazard Analysis is a factor of 100 then an SIL 2 level of SIF performance would be specified. Calculations for the components of the entire SIF loop will be done to verify that the PFD of the safety function is 10, meaning that the SIF is SIL 2 or reduces the risk of the hazard by a factor of 100. This one SIF may constitute the entire SIS, or the SIS may be composed of multiple SIFs that are implemented for several other unacceptable process risks in the facility. Now we see from the chart in Table 1, and the example, above, the SIL numerical values relate directly to the minimum risk reduction factor. For example: SIL 1 = 10, SIL 2 = 100, etc. This is helpful in allowing us to get a feel for what SIL is. SIL AND THE VALVE INDUSTRY Since this article is primarily for those who are not instrumentation engineers, it is helpful to also know how SIL applies to the valve and actuator industries. A HAZOP team will look closely at automated valve systems that need to perform an action to return the process to a safe state when design or operating parameters have been exceeded. To keep the discussion simple, we will use the term ESD, assuming we are concerned with an emergency shutdown valve. The HAZOP team will want to know: What is the likelihood of my valve working when I need it to work? They will perform a risk analysis and assign an SIL level to that ESD system. The SIL will cover the entire ESD system-from initial process sensor to the valve itself, and everything in between. It is important to note that SIL covers systems comprised of individual products. Products are not "SIL rated." There is no such thing, for example, as an SIL 3 actuator, an SIL 3 digital valve controller or an SIL 3 solenoid valve. There are only products that are reliable to the degree they are suitable for an SIL 3 environment. So, as industrial fluid control representatives, it would be inappropriate to say of a product: This is SIL 2. The correct nomenclature would be: This is suitable for an SIL 2 environment. Likewise, as a consultant or end user, it is inappropriate to ask a vendor: What is the SIL rating of your product? It would be more appropriate to ask for specific failure rates. In determining whether a product is suitable for use in a given SIL environment, the important factors are failure rates such as PFD. PFD average (PFDAVG) is relevant to the valve industry and users of valves. As the graphs in Figures 2 and 3 indicate, the probability of operational failure for a valve escalates soon after every full cycle test. It has been demonstrated that partial stroke testing (PST) of the valve (when full stroke testing is not practical) significantly lowers the PFDAVG.To say it another way, partial stroking increases the probability that the system and valve will work when it needs to work (Figure 3). Page 3 of 3 Based on the need to increase reliability and the desire by end users to comply with new safety standards, a PST industry has emerged. It has spawned a plethora of increasingly sophisticated products and systems promising to make the SIS more reliable. The end result has been confusion not only for vendors, but for consultants and end users as well. A good way to think about this situation is in simple terms of a safety system that requires 10 components and must maintain a desired level of SIL 2. This might fall along the lines of the following example: Consider a container that will hold a maximum one liter of liquid. The container will represent the maximum amount of potential failure allowed in the safety system. In other words, for this example, we have a budget of only 1,000 milliliters of failure. If we exceed that safety budget, we will not have an SIL 2 system. Visualize the container surrounded by 25 individual 200 milliliter vials, each holding different levels of liquid. Some are more than half full, many are almost full. If we were to combine the liquid from all 25 vials, the total would be well in excess of one liter. The 25 vials represent a variety of individual components that might be selected for our 10-component safety system; various valves, solenoids, controllers, etc. The liquid levels in the vials represent the different PFDAVG of the individual components. Taken individually, the volume of liquid from each vial will easily fit into the one liter container. But only by selecting components that-in total-have a combined volume equal to or less than 1 liter will give us a successful SIL 2 system. The components can be thought of in the following way: Each of the 25 individual components may have a PFDAVG that will allow use in a SIL 2 environment. But if the combined failure rates of our 10 selected components exceed the SIL 2 requirements, the system will not qualify as an SIL 2. We must select the right combination of components that satisfy our safety budget. The main point of this example is to stress the fact that one or more SIL 2 products (if there were such things) will not necessarily make the system an SIL 2 system. Ultimately, the end user or the end user's consultant will have to perform the calculations based on failure rates and other criteria to determine the impact of each individual component on the system SIL. Statements such as: "our assessment indicates Product X can be used up to SIL 3 as a single device" have been made. That statement may be true, but it is also misleading and of limited value. After all, how many safety systems are comprised of a single device? We would need to know the failure rates, etc., of that individual product to actually know if it was suitable for use in a specific SIL system. The end user cannot just buy the product and assume suitability. Neither can a valve or actuator vendor just sell the product and assume it is suitable for use in a given SIL environment. (NOTE: A safety relief valve would be an exception and is an example of a single device SIL system. It detects overpressure and stops further elevation. Our primary discussion is concerning automated valve packages). Making Sense of the Whole Thing Occasionally, it might be wise to clear our heads of all the technical jargon, numbers and calculations and remember that the ultimate goal is the safety of human beings and our environment. In considering SIL products and their application, it is easy to become sidetracked by details. But it is important to remember we are dealing with human systems, and because we live in a world governed, albeit unofficially, by Murphy's Law, elimination of all risk is impossible. Vendors and users alike need to pay particular attention not only to a product's rating and certifications, but also the real world implications of actually installing and using a given product in the industrial process environment. To conclude, the basic concepts of SIL are: SIL is an indication of system reliability. The end user (often through the analysis of a HAZOP team) determines the desired SIL level for a SIS. Based on a product's reliability (in essence, the reciprocal of PFDAVG), products may by suitable for use in a desired SIL environment. Using a product marketed, for example, as SIL 3 does not ­necessarily mean it is suitable for use in a specific SIL 3 ­environment. By understanding these basic concepts, some of the mystery of SIL can be diminished for valve industry professionals and end users.

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Adroitt Flow Control Pvt Ltd

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Vedanta focuses on Jharsuguda Alumina Smelter Project

With the 5-million-tonne greenfield Lanjigarh aluminium refinery plant expansion on hold, the Anil Agarwal-led Vedanta Aluminium (VAL) has decided to focus on completing its aluminium smelter plant at Jharsuguda in Orissa to achieve its targeted capacity of 1.75 mt.

"The work is on, on a war-footing, at the proposed project site at our Jharsuguda plant and we will achieve 1.75-mt capacity by the end of the next financial year," VAL President and Chief Executive Mukesh Kumar said.

The company has so far invested around Rs 35,000 crore in its Jharsuguda project and around Rs 10,000 crore at the Lanjigarh plant, and plans to invest the balance of Rs 15,000 crore by 2013 to complete its planned expansion.

VAL plans to up its smelting capacity at Jharsuguda plant to 1.75-mt from the present 0.5-mt by 2013.

"The first phase of our 0.5-mtpa smelter and 1-mtpa alumina refinery has already been completed and work on the second phase is on, except the alumina refinery which is under hold as per the Union Environmental Ministry directives," he said.

The company has set up a greenfield aluminum refinery plant with a capacity of 1 mt at Lanjigarh and plans to ramp up it to 5 mt. "We are awaiting the environment ministry's clearance to ramp up capacity at Lanjigarh plant in Kalahandi district," Kumar said.

The expansion of the refinery plant ran into rough weather after the Union Environmental Ministry refused to give clearance on October 21, 2010.

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BHEL Targets 20,000MW By 2012

The country's largest power equipment-maker, BHEL, today said it ramp up its manufacturing capacity to 20,000 MW by March, 2012.

BHEL's capacity addition strategy for the current financial year also envisages an improvement in product cost-competitiveness and quality, said BHEL Chairman and Managing Director B Prasada Rao at the 47th Annual General Meeting of the company here today.

He said BHEL is well on track to becoming a 20,000-MW company by March, 2012.

The company also plans to diversify into the emerging business areas like R&D and people management, he said.

BHEL recorded a profit of Rs 9,006 crore for the 2010-11 financial year and an all-time high turnover of Rs 43,337 crore, he added.

The company declared a dividend of Rs 1,525 crore. BHEL secured orders worth a record Rs 60,507 crore in FY2010-11.

The company secured orders for seven boilers and nine turbine generators with supercritical parameters from public as well as private sector utilities during the fiscal.

With an order book worth over Rs 1,64,145 crore at the close of the financial year, the company expects to achieve robust growth in 2011-12 and beyond, Rao added.

Outlining the trends in the power sector, Rao said that environmental compulsions are driving the demand for sustainable development worldwide.

BHEL also plans to develop economically viable solar power equipment and it would be the company's focus area this fiscal.

BHEL is also developing Advanced Ultra Supercritical (Adv-USC) technology in association with the Indira Gandhi Centre for Atomic Research (IGCAR) and NTPC, as part of the National Mission for Development of Clean Coal (Carbon) Technologies.

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Ice-Cream maker Vadilal Industries Expansion-Cum-Modernisation Plan

With its Rs 80-crore expansion-cum-modernisation plans completed, Vadilal Industries Ltd, India's second largest ice-cream maker after Amul, is all set to increase its production capacity from the existing 2.25 lakh litres per day to 3.25 lakh litres at its two manufacturing plants in Gujarat and Uttar Pradesh, from Friday.

The Rs 40-crore expansion at each of the plants — Pundhra in Gandhinagar district and Bareilly in Uttar Pradesh — has been carried out with internal accruals and borrowings, Mr Rajesh Gandhi and Mr Devanshu Gandhi, both Managing Directors, told presspersons here today.

The 80-year-old company has also set up India's fastest cone-making machine with a capacity of 18,000 cones an hour, as against 6,000 in the case of the existing machines. Since 60 per cent of sales come from cups, cones and candies, Vadilal plans to increase its share in the organised market from the current 20 per cent to 24 per cent by focusing on these as also small-value packs which are new growth drivers. Its candy-making capacity, 15 lakh pieces per day, is the largest in India.

With a view to achieving a growth of 40 per cent, as against the industry's growth 15 per cent, Vadilal is increasing its ad-spend by 40 per cent, with a focus on electronic media.

While the Chinese ice cream market size is around Rs 20,000 crore per annum, India's is only Rs 2,500 crore, of which the organised sector market is estimated at Rs 1,500 crore. Problems such as weak cold chains, logistics and reach to the rural areas are hampering the growth of this industry, they added.

Currently, Vadilal has 150-plus flavours, sold in a variety of more than 250 packs and forms.

The range includes cones, candies, bars, ice-lollies, small and big cups, family packs and economy packs.

The BSE-listed company, whose turnover in 2010-11 was around Rs 270 crore with a PAT of Rs 10 crore, is increasing the network of retailers from the current 50,000 to 70,000 across India. Currently, it procures 70,000 litres of milk per day and is planning for backward integration to increase it in the near future.

“The company's national ice-cream market share would have been even higher but for the fact that it does not operate in major consuming regions such as Maharashtra and the four southern states as these are covered by another faction of the Vadilal family,” the Gandhis said.

 

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Solvay acquires Rhodia SA

Belgian chemicals and plastics company Solvay SA has announced plans to acquire specialty chemical producer Rhodia SA in a deal valuing the French company at 3.4 billion euros ($4.8 billion).

Brussels-based Solvay is offering 31.60 euros for each Rhodia share in cash as part of a friendly deal. The new group will have sales of 12 billion euros.

“We have a shared vision in that we want to create a new group to achieve our goal of sustainable growth and development in chemistry”, Christian Jourquin, CEO of Solvay, said in a statement. “We see the possibility of doubling our [recurring earnings before interest and taxes, depreciation and amortization] to almost 2 billion euros and creating a major global chemicals platform under the banner of Solvay.”

The acquisition will be earnings accretive from 2011, with annual cost synergies of 250 million euros expected within three years, which will be achieved through the reduction of external costs and “without major downsizing plans.”

The aim of the deal is to create a global chemical company with an enlarged business portfolio. Solvay is a leader in high performance specialty polymers, soda ash and hydrogen peroxide, while Rhodia is strong on specialty materials (silica and rare earths), products for consumer markets and engineering plastics based on nylon 6/6.

Solvay says the group will also concentrate on growth in emerging markets, which already generate 40 percent of sales for the combined group.

Jean-Pierre Clamadieu, chairman and CEO of Lyon, France-based Rhodia, will take on the role of deputy CEO once the offer is closed. He is also expected to succeed Solvay’s current CEO Christian Jourquin when he retires.

The deal is conditional upon approval from EU and US anti-trust authorities.

During the recession, Solvay announced major reorganisation plans, including the sale of its pharmaceuticals business to focus on chemicals and plastics. Last year it reorganized further, reducing annual costs by 65 million euros and making 800 redundancies.

France-based Rhodia has 14,000 employees worldwide and generated sales of 5.23 billion euros in 2010. Solvay had sales of 7.1 billion euros last year.

In related news, Solvay has also announced to plants to unite Solvay Advanced Polymers, Solvay Padanaplast, Solvay Solexis and SolVin PVDC as a single business unit: Solvay Specialty Polymers.

Headquartered in Bollate, Italy, the company’s activities employ more than 2,500 across 26 locations throughout North and South America, Asia and Europe.

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Wilo SE inaugurates hi-tech mfg plant at Kolhapur

Pump and pumping system manufacturer Wilo SE has inaugurated a hi-tech manufacturing plant at Kolhapur.

Built at an investment of Rs 100 crore, the new facility will manufacture standardised water handling pumps and pumping systems.

It will produce the latest range of Wilo products for the domestic market as well as for its subsidiary Mather & Platt Pumps Ltd for the global market. The company expects a turnover of Rs 150 crore a year from the Kolhapur plant, 80 per cent of it coming from domestic sales.

INVESTMENT PLANS

Wilo SE also has plans to infuse more funds in India to expand capacity and upgrade technology, plant and machinery both at Kolhapur and Pune. Dr Jochen Oplender, Chairman Emeritus, said over Rs 200 crore will be invested for the purpose in the next five years.

"We also will create job opportunity for 1,000 skilled and semi-skilled manpower by 2015," he added.

Wilo SE considers the Asian market, especially India as a prominent growth opportunity. It has also set up an R&D centre at Pune, the first such Wilo facility outside of Germany, where 40 engineers are working on new generation product development.

In India, Wilo operates through its subsidiary Mather and Platt Pumps Ltd, which it acquired in 2005.

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Hindustan Copper Plans Expansion

State-run Hindustan Copper plans to invest Rs 3,677 crore to almost quadruple its existing copper ore production capacity to 12.41 million tonnes per annum (mtpa) by 2016-17.

"The company has prepared an ambitious expansion plan to expand the capacity of 3.21 million tonnes to 12.41 million tonnes at an estimated cost of Rs 3,677 crore, which would be funded from internal resources, fresh issue of shares and debt," the Mines Ministry's Outcome Budget for 2011-12 said.

The entire expansion would be completed by 2016-17 and in the meantime, the company would also take up greenfield projects for exploration and ore production, it said.

The company would spend a total of Rs 297 crore next fiscal through internal sources for part-funding the expansion of the Khetri, Kolihan, Banwas and Singhbhum mines and reopening of the Rakha and Kenadadih mines.

The only copper ore producer in India, Hindustan Copper's existing capacity caters to about 3 per cent of the requirement of optimum utilisation of installed capacity for smelting/refining of copper in the country.

"The gap in supply and demand provides a huge opportunity to the company to expand its operations in the mining of copper ore," the note said.

The company plans to invest a total of Rs 174 crore for expansion of the Khetri mines from 0.5 mtpa to 1 mtpa. In the Kolihan mines, it would invest Rs 275 crore for expanding the capacity to 1.5 mtpa from 0.5 mtpa and Rs 91 crore to develop the Banwas mine with a capacity of 0.6 mtpa.

The Surda mine's capacity will be expanded to 0.9 mtpa from 0.42 mtpa at a total cost of Rs 216 crore. Hindustan Copper would also invest Rs 347 crore to reopen the closed Rakha mine and Rs 87 crore for enhancing the capacity of the Kendadih mines to 0.21 mtpa.

The note said that the company has already applied for prospecting leases across the country for greenfield exploration and it proposes to explore and develop these mines through a joint venture with global mining majors.

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Essar Energy to acquire Shell refinery for US $350 million

Essar Energy to acquire Shell refinery for US $350 million

Essar Energy said it expects to sign a deal to acquire Royal Dutch Shell’s Stanlow refinery in northwest England for US $350 million by month-end.

The company, announcing financial results for 2010 full year, in a press statement, said it is “expecting to sign deal to acquire Stanlow, the UK’s second biggest refinery, from Shell over the next 10 days, by March 31. Acquisition price will be US $350 million plus inventory at cost price,” Essar said.

Essar had on February 18 announced acquisition of the Stanlow refinery to make the Ruias-promoted firm the first Indian refiner with “truely global footprint.”

Essar owns a refinery at Vadinar in Gujarat which can process 2,80,000 barrels of crude oil per day.

It also owns a 90,000 bpd unit in Kenya and is expanding Vadinar to 4,00,000 bpd (20 million tons). Stanlow has a nameplate capacity of 2,96,000 bpd but currently operates at 2,20,000 bpd.

Together, it will now have a little less than one per cent of global oil refining capacity of 88 million bpd. Essar will also pay for Stanlow’s crude and oil product inventory, which will be about US $780 million at current rates, the statement said.

Essar said the phase-I expansion of Vadinar refinery on the west coast will be completed this year at an estimated cost of US $1.85 billion. Following the expansion, the refining capacity will rise to 3,75,000 bpd and lift complexity from 6.1 to 11.8, allowing it to produce Euro V standard petrol and diesel of UK and European quality.

“We also have a further optimisation project underway at the Vadinar refinery costing US $380 million to take capacity to 4,05,000 bpd by September 2012,” the statement said.

In power, Essar said it has US $8.02 billion investment underway. These include 10 power plants under construction totalling 8,070 megawatt of electricity generation capacity. Besides, two other power plants are at a development stage totalling 1,800 Mw at US $1.56 billion. They will move to construction once the company has fuel and funding secured. “By end of 2014, we will have 11,470 Mw operational altogether against just 1600 Mw now,” Essar said.

“We are focused on delivering our growth projects including securing the necessary approvals to move forward with our coal mine developments,” the statement said.

Essar Energy Chief Executive Naresh Nayyar said demand for energy in India is expected to continue to grow sharply. “We remain focused on delivering our key projects, which in 2011 includes the first phase of our Vadinar refinery expansion and another 2,910 Mw of power generation capacity,” he added.

 

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