Brief on Alloy Steel Round Bars

Alloy steel round bars are made of several metals which are combined together in a certain proportion. The addition of non-corrosive metals during the making of steel imparts the anti-rust properties making it more resilient to use. Depending on how the steel bars are made you have the cold finished bars or hot finished bars. A lot of testing on several parameters is conducted before the bars are declared fit for use. Some of the parameters on which testing is done are elongation, tensile strength, Brinell hardness and strength. Around 10% of chromium plus varied amounts of nickel, nitrogen, molybdenum etc go into the making of the steel bars. Being produced in controlled environments and with specific components, the bars are equipped with several properties of durability, resilience, resistant to breakages and rusting etc. The steel bars are used to a large extent in construction projects in addition to being used in the marine industry, mining, automotive industry, dairy processing plants, public transport and many more. Another form of this metal used in the same applications is the unequal angles. Steel in the form of stainless steel plates find their way into the household kitchens too. Stainless steel is again one of the common materials used in the construction of v belts which are an indispensable part of almost every industrial application.

The steel round bars are made in a blast furnace. As the furnace gets heated, specific amounts of nickel, nitrogen and molybdenum make contact with carbon electrodes which are aligned for the purpose. Temperatures are set at very high levels during this process. As the melting point of the blast furnace is reached the different metals bind together to form one single metal alloy. This is then led into a separate vessel created of argon. De-carbonization takes place here and after this procedure the process of casting and shaping for use in different applications begins. Depending upon the percentages of the metals used you have three types of stainless steel alloys namely austenitic, martensitic and ferritic. Today, the steel bars are available in a variety of finishes, sizes and dimensions to suit the needs of the varied customer. The list of industries that find use for them is just endless and hence extra attention is paid to the quality of the output that comes out of the manufacturing plant. Top quality raw materials and sophisticated techniques are used for the manufacture process. With the demand for them increasing globally, pricing of these products has also become competitive.

Today, alloy steel round bars have come a long way since earlier times and with the whole world being dependent upon them for a number of things it is a good thing that they have!

Controlled water-cooling prevents the formation of coarse carbides which has been cited as the main cause for the corrosive nature of common Stainless Steel Round Bars, Alloy Steel Round Bars.

Protecting Storage Tanks From Lightning

Providing adequate and effective lightning protection for storage tanks constitutes a beneficial and cost-effective step in assuring both personnel safety and reliability. Fortunately, securing such protection is not difficult or complicated, and guidance is readily available. It helps to become familiar with some basic recommended practices and standards for reference. We will be referring to the National Fire Protection Association NFPA 780, Standard for the Installation of Lightning Protection Systems; the American Petroleum Institute API 545, Recommended Practice for Lightning Protection of Aboveground Storage Tanks for Flammable or Combustible Liquids; and the American Petroleum Institute API 2003, Recommended Practice for Protection Against Ignitions Arising Out of Static, Lightning, and Stray Currents.

Whenever considering lightning protection, it helps to fall back upon the three basic steps: bonding and grounding, surge suppression, and structural lightning protection.

BONDING AND GROUNDING. The first consideration is bonding and grounding. According to API 545, flat-bottom tanks are inherently self-grounding for lightning protection purposes. The mass of the tank and surface area of its bottom in contact with whatever material it occupies provides a sufficiently low-impedance path to conduct lightning currents without increasing the risk of ignition. This applies whether or not a non-conductive containment membrane is in place under the tank.

It should be noted that, although adequate for lightning grounding, the path to ground may be high resistance, rendering it unsuitable for AC power grounding. In the event of an AC power ground fault, the lack of a low-resistance return path may leave the tank energized. Therefore, we recommend at least one, and preferable one each 100′ of tank perimeter, “solid” connection to ground. This usually consists of a conductor attached to a grounding tab at the base of the tank shell running to a ground rod or to the grounding grid.

Bonding is simply a matter of electrically connecting different masses of inductance (metallic masses) together to maintain them at the same potential, to equalize changing potential, and to provide a path for lightning current between them.

The major area of concern is obviously the floating roof. On an external floating roof tank, there are three lightning events that can cause arcing between the roof and tank shell. The first is a direct strike to the roof itself or its appurtenances. In this case, all of the lightning energy must flow across the seals to the tank shell and to ground. The second is a direct strike to the top of the tank shell. In this case, the lightning energy flows down the shell to ground, and the roof potential must be equalized to that of the tank shell. In the third case, a nearby strike changes the potential of the tank shell, and much less difference in potential must be equalized between the roof and tank shell.

Lighting energy consists of two components with an intervening transition component. The first is a high-energy, short-duration surge of energy. The second is a lower-energy, longer-duration event. The first segment, although conveying high amperage, is so short that it does not normally cause ignition. Think of passing your finger quickly through the flame of a candle. However, the second segment consists of a few hundred amps (about equivalent to the electrical service into your home) over half to three-quarters of a second. When faced with resistance between the floating roof and tank shell, it can easily produce sufficient heat to cause the ignition of any flammable gasses present. Think of your kitchen stove on steroids.

Therefore, two types of conductors are required between the floating roof and tank shell. The first is a sliding contact between the roof and shell, and is intended to handle the short-duration, high-energy pulse. This has historically been addressed by the use of shunts between the roof and tank shell. These were developed to overcome the shortcomings on non-conductive seals. However, most modern tanks employ metallic shoes as the primary seal between the roof and shell. These shoes have many times the surface area of shunts. According to wording which will presumable be adopted in the next revision of both NFPA 780 and API 545, the presence of primary metallic shoe seals will negate the requirement for shunts.

Shunt Primary Metallic Shoe Seals

However, contacts sliding on contaminants produce arcing and sparking, raising the need for a second type of conductor, the bypass conductor. This is a hard electrical connection between the floating roof and tank shell. Because the bypass conductor must be of sufficient length to allow full range of motion of the tank roof, it requires time to become conductive. When it becomes conductive, it quenches any arcing at the sliding contacts, and conducts the long-duration, lower energy second segment of the lightning strike.

Bypass conductors

Another area of concern is thief hatches. The hatch itself rests on a rubber seal and is connected to its collar by a pin-type hinge. In the field, we have measured a high resistance between the thief hatch and its collar. Lightning current flow across that resistance is capable of producing sufficient heat and arcing to cause ignition. Therefore, a flexible jumper between the hatch and collar should be added to each.

SURGE SUPPRESSION. The second step in securing adequate protection is surge suppression. Any conductor running to or from a tank is perfectly capable of introducing all types of mischief. A surge suppressor is simply a device that keeps that from happening. Typical conductors found on a tank include AC power for site lights, pumps, valves, etc., and for data collection including levels, temperatures, flow rates, etc. Surge suppressors should be installed at the tank end of such conductors and also at their origin. This will limit the transient gremlins in their mischief.

STRUCTURAL LIGHTNING PROTECTION. The third step in securing protection is structural lightning protection. When we think of structural lightning protection we normally think of lightning rods on the roof of a building. It is important to remember that the purpose of a lightning rod system is to convey lightning energy around a non-conductive structure, such as a house or barn, thereby keeping that structure from burning down.

Note that there is absolutely no benefit to installing lightning rods on a tank. According to NFPA 780, the tank itself is inherently self-protecting. There are three components that make up a lightning rod system: the lightning rods, conductor system and grounding system. On a tank, the tank itself is of sufficient thickness to be substituted for the lightning rods, the shell is of adequate cross section to be substituted as the conductor system, and the site ground is more than adequate for lightning protection purposes. Therefore, the tank is self-protecting without the need to install additional components. Lightning rods would only tend to attract lightning to the tank.

There is, however, a technology alternative to conventional lightning rods. These are streamer-delaying air terminals. These air terminals, colloquially known as “fuzzy ballâ„¢” lightning rods, are designed to interrupt the lightning completion process by delaying the formation of lightning-completing streamers from objects on the surface of the earth.

A lightning strike begins with the formation of stepped leaders from the base of the storm cloud. These leaders jump in steps of around 150′, working their way downward towards the surface of the earth. When they reach to within 500′ or so of the surface, they begin pulling streamers of ground charge off of objects on the surface. Whichever streamer meets a stepped leader first determines what gets hit. As the ground charge builds on a streamer-delaying air terminal, the sharp points break down into corona under a low potential. When it comes time for a streamer to form from a protected object, the ground charge that would constitute the streamer has been partly dissipated into the atmosphere, thereby reducing the likelihood of a direct strike.

We use NFPA 780 as the design standard for protecting a tank. As the tank contains flammable material, we reduce the diameter of the rolling sphere to 100′, reducing the spacing between air terminals to jus over 12′. We install them around the perimeter of the tank shell on the foam injection plates and rim, and on the gauging platform. We also install them on the walkway handrail, if one is installed.

Streamer delaying air terminals on storage tanks

API 2003, Annex C, Direct Stroke Lightning Protection, C.1 notes that conventional lightning protection systems do not protect against indirect lightning currents or induced voltages. These are both major causes of ignition, particularly in production tanks. It further notes in C.2.1 that, according to vendor claims, streamer-delaying systems may have some benefit in protecting against indirect lightning currents of induced voltages. This type of performance is obviously preferable.

A Review of The Amarant by Author Tricia Barr

Tricia Barr’s The Amarant, beckons readers into a fantastical vampire-filled world, where a young woman’s crush on a fictional character leads her into an incredible reality where romance, the paranormal and an untapped legacy of fantastic supernatural power merge to change her world, forever.

The heroine of the story, Crimson Wilkinson, portrays a complex and strong-willed young woman, who refuses to let the darkness of a hurt-filled past take over her life. Being only seventeen, she lives with her mother in Tucson, Arizona, a locale which is wanting when it comes to excitement. As with any high schooler, Crimson undergoes some common experiences; an angry teacher, a bullying nemesis, ditching classes, an attraction to a hunky football player, and boredom. Her only real escape from the doldrums of her life concerns either hanging with her best friends Robert, Reina and Amber or getting lost in her favorite series of paranormal fiction novels which centers on a reclusive, handsome vampire named Nicholae Albaric who she crushes on and obsesses over.

Crimson’s story begins with the start of another seemingly uneventful high school year. Seeking excitement, her curiosity and infatuation for her crush sends her on a whim to search online for the fictional Nicholae. However, things change drastically and the true adventure starts when her search fatefully reveals that her vampire crush, Nicholae Albaric, is a real living vampire. Determined to turn dream into reality Crimson finds a way to meet her crush and the romantic sparks fly seemingly a destiny fulfilled. Consequently, their meeting sets off a series of events both romantic and adventurous, as she quickly becomes acquainted with Nicholae’s extraordinary world, which in turn, also leads to a startling revelation concerning her own untapped supernatural powers. Meanwhile, dark forces with other than friendly intentions focus their sinister machinations on Crimson abruptly throwing her world into utter chaos with danger and blood curdling action ensuing, as Nicholae and other supernatural denizens become her immortal protectors.