Materials fit for Heat exchanger applications

Vigorous pitting occurred in moderator heat exchanger tubed with Incoloy 800 in pickering nuclear production unit. Pitting occurred on the cooling water side of the tubes and perforation occurred within 24 months. It was known from corrosion evaluation at CRNL that Incoloy 800 was not sensitive to pitting in Lake Ontario water in isothermal conditions. Corrosion evaluation with heat transfer around the tube wall was conducted and it was found that extreme pitting may occur in deposits developed on the tubes in Ontario lake water. After testing conducted to find the pitting resistance of other eligible alloys : Incoloy 825, stainless steel 904l, Inconel 625, CuNi alloy 70/30 and titanium. Among these materials titanium did not received pitting corrosion in silt containing lake Ontario water. In absence of slit, so deposits, no pitting occurred on the tested alloys.

All alloys tested at room temperature in natural fresh waters did not show any sign of corrosion after exposure to 24 hours. These alloys that suffered some extent of corrosion at  45oC and 70oC are Cu-Ni alloy 70/30 and 90/10. It was invariably crevice corrosion. In availability of silt and chloride contamination, nickel based and copper based alloys experienced some corrosion at room temperature. The extent of corrosion found to increase with temperature, however this study is based on visual testing only.

Incoloy 800 was sensitive to crevice corrosion in room temperature chloride-contaminated river water, the corrosion rate was 0.1mm/a. No direct comparison of pitting rate can b made with service data for Incoloy 800, 0.5mm/a or the heat flow test results, as the isothermal tests at 70oC for contaminated Lake Ontario water were not conducted. Although, it is evident that chloride contamination seems to be important in these isothermal tests to induce pitting corrosion of Incoloy 800 and the nickel based alloys.

The comparisons of the admiralty brass results with in-service data are sufficient. In-service admiralty brass condenser tube pitting rates of 0.13 mm/a over a 10 years duration seems to be standard and this value is in good agreement with isothermal lab test results varying from 0.03 – 0.2 mm/a depending on temperature and water composition. Similarly Cu-Ni alloy 70/30 in operation in PNGS has show nominal corrosion, often an insignificant surface etching and dealloying that is consistent with results received. Cu-Ni alloy 70/30, nickel and brass increase the corrosion rate in heat transfer conditions.

Heat transfer tests

The results showed limited alloys suitable formoderator heat exchanger service Inconel 625 wire. Where no slit crevices were used, no pitting was found on the tested materials. In cases, the results were very reproducible within the duplicates, however insufficient sampling was conducted to offer statistically considerable predictability. The outcomes in these cases offer a clear guide to type the alloy that would be fit for corrosion free service as tubing in moderator heat exchangers.

Incoloy 800 is quite sensitive to pitting corrosion, Incoloy 825 less however still sensitive and stainless steel 904L subjected to occasional deep pitting. The pit shapes are feature of under deposit chloride corrosion.

PNGS has operated adequately with CuNi alloy 70/30 tubes for couple of years. The only sign of corrosion on the material was under very adherent deposits where redeposition of leached copper was found. The corrosion in this region was limited to nominal etching that had penetrated below 1 micro in six months.

In various cases, the noticed corrosion on alloys experiencing corrosion was related with dark green or black deposits that had developed at formed at the tube-silt deposit interface. Evaluations of the dark areas showed to enriched of calcium, silicon and chlorine and containing considerable magnitudes of chromium. 

Behavior of high functional Nickel alloys in oil and gas wells

In the recent years the new face of oil and gas exploration will be in deep wells, and specifically those in deepwater. As compare to shallow wells, deep wells normally need equipment made with high performance nickel base alloys. Wells are classified as sweet or sour. Sweet wells are mildly corrosive whilst sour wells are extremely corrosive and contain hydrogen sulfide, carbon dioxide, chlorides and free sulfur. Besides to different levels of corrosive media compounded by temperatures up to 260oCand pressures to 25000 psi and normally deep wells have higher temperatures and pressures.

Material choice is particularly critical for sour gas wells. The materials of choice should be corrosion resistant, economical, reliable and have the desired strength for the well conditions. These conditions become more vigorous material selection varies from carbon steels for sweet wells to duplex stainless steel to nickel base alloys like Incoloy 825 and Inconel 725.

Materials required to meet criteria for corrosion resistance and mechanical properties in application media need increased reliability throughout the life of well. Age hardened nickel based alloys and cold worked solid worked nickel base alloys offering various benefits like high strength, hardness, low magnetic permeability and outstanding corrosion resistance. The choice of material for specific set of well environments depends on wide selection factors such as:

• ·         Mechanical properties
• ·         General corrosion resistance
• ·         Pitting and crevice corrosion resistance
• ·         Chloride stress cracking resistance
• ·         Sulfide stress corrosion cracking resistance

The strength levels of age hardened materials are increasing in significance, specifically for offshore applications showing high pressure deep well reserves where weight factors can influence the economic feasibility of a project. Material choice for down hole and wellhead equipment including hangers, sub surface safety valves, pump and packers need age hardenable alloys to receive the resuired strength  in heavier cross section that cannot be reinforced by cold processing.

Nickel alloys used in oil well applications are Monel 400wire, Incoenl 718, Inconel X750 and 725. The age hardened alloys are used at different strength levels considering the applications. Incoloy 925 is used at 758 MPa minimum yield strength level. The minimum yield strength level for Inconel 718 is 827 Mps. Inconel 725 is used at 965 Mpa minimum yield strength level. The improved strength properties of Inconel 725 HS have been received by suitable thermal and mechanical processing.

Galvanic Compatibility

Galvanic corrosion occurs when different materials are placed in contact in a conductive fluid. The Inconel grades are usually noble materials. In galvanic compatibility, tests conducted in ambient temperature seawater for three months for corrosion mechanism. Inconel 725 and alloy 625 were found to be galvanically compatible. Coupling a large area of Inconel 725 to Monel K500, increased corrosion of the component of Monel K500.

General Pitting and Crevice Corrosion

Traditionally corrosion resistant alloys are graded first by their PREN and then by the equivalent cracking data produced in sour brine condition.

The critical pitting temperature for an alloy is found by subjecting samples in acidified 6% ferric chloride solutions. New unexposed test samples and fresh ferric chloride solution are used at every test temperature. The minimum critical pitting temperature for alloy is 40oC for various offshore applications. 

How choosing insect screens is a wise decision?

Insect screens are ideally developed for regular vents, even are also fit for other types of vent. We work closely with roof suppliers on greenhouse construction projects. The insect screen gauze is virtually invisible and prevents any light loss.

The systems cannot always be fully configured on all types of existing vent even light loss remains negligible. Screens are installed in a way so they are less vulnerable to wear and tear and more durable that traditional screens. To decrease the amount of cold air on the crop, we develop advanced screens.

Why should you choose Heanjia insect screen

·         Feel your home more: Open windows and doors to allow fresh air without the insects

·         Wide range of options and individual safety: Precision fit screens are made in large range of choices.

·         Eco-friendly and durable : Certified screens for protection against insects without the need of chemicals

·         Safe and user-friendly : Simple to use and easy to remove screens

·         Easy care and clean: Wear resistant mesh has insect screen supplier have long service life.

·         Advanced and proven effectiveness: Latest insect protection technology that has proved itself in millions of houses.

·         Timeless design: Unobtrusive and elegant screens are of fine quality

·         Individual service: You receive individual service and specialized installation

·         Outstanding production means value for your money

      

We manufacture high quality and eco-friendly insect screens. The screens are recognized as the leading name in made to measure insect protection. We manufacture precision-fit screens for your doors and windows to prevent unwelcome visitors.

When it is about insect protection, we do the best for you. People love bright and air are good for wellbeing. As you don’t want to entertain unpleasing species, the best way to keep pests like flies and mosquitoes at bay with an insect screen, made to your specific measurements. It gives you a good night sleep with open windows, fresh air and reassurance of understanding that you have made the best choice for your family’s health.

The insect screens are available in different options to suit your situation, from simple screens to multi layers screens and with different mesh types.

Our window screens are safe and easy to handle and can be easily installed without drilled. They can be used anywhere, robust and unobtrusive. The screens are durable and suitable for small spaces. They are easy and convenient to use. Insect protection is provided whenever required. 

Advanced design, durable functionality and fit for roof windows. The screens are robust, modern and user friendly. They are made from sturdy and ideal material for excellent versatility.

The mesh produced by Heanjia is made by patented technology. As compare to traditional insect screens, it offers decisive benefits such as more light transmittance and outstanding transparency. The screens are made in different formats and variants for different types of structures. They are secured, robust and durable. So contact us for your special window screen requirements.

Stress corrosion cracking behavior of Inconel 600 in primary waters

Stress corrosion cracking is a process categorized into many phases. After an incubation period that can last from several hours, short cracks can begin on the surface of a sample. Cracks are just found when their size is higher than detection threshold of the method used and the beginning stage is hence spread with the passage of time. After several hours then in a quick propagation regime where the velocity of the deepest cracks increase by an order of magnitude. The velocity of the shortest cracks slows down and can even stop because of the screening effects if the long crack density is high. It is widely accepted that the transition between the two propagation modes occurs when the stress intensity factor becomes higher than a critical value.

For large crack densities, cracks can coalesce that increases the crack propagation and can hence reduce dramatically the time to component failure.

Stress corrosion cracking of Inconel 600 is usually intergranular with a brittle aspect. The fracture surface can sometimes show a pseudo-intregranular appearance cracking covering about 10% of the fracture surface. The pseudo intergranualr cracking is featured by microfacets at the vicinity of the grain boundary often on grain boundaries developing on angle of less than 45 degree with respect to the applied loading.

Primary water stress corrosion cracking is a complex process and however it has been studied widely over the last 30 years, the cracking process is a matter of discussion. To fuel this discussion, the parameters effecting primarily water stress corrosion cracking are of major concern.

Stress corrosion cracking of austenitic stainless alloys in pure or chlorinated water was first performed. The general behavior for Iron-chromium-nickel alloys in both conditions. Intergranular stress corrosion cracking is a phenomenon involving the synergistic combination of a susceptible alloy, wide environment. The influence of these parameters on Inconel 600 is studied.

A general study of the stress corrosion cracking of austenitic stainless alloy in pure or chlorinated water was conducted. High temperature stress corrosion cracking occurs in alloys containing high iron concentration in chlorinated water whereas alloys with high nickel concentration are sensitive to IG SCC in both pure and chlorinated water. Inconel 600 and other nickel rich alloys are sensitive to SCC in pure water than Iron rich alloys. Alloys containing nickel concentration between 20% to 65% offer good resistance to stress corrosion cracking in high and low temperatures. Therefore preferred types of Inconel bar Inconel 600 and Incoloy 800.

In primary water condition, high stress corrosion cracking dependency on chromium concentration with continuous enhanced stress corrosion cracking resistance from 3 – 17% where no cracking is found. With increase in chromium content resistance to stress corrosion cracking of Inconel 600 increases in primary water condition. It is found that threshold chromium concentration is not confirmed at which stress corrosion cracking is prevented.

It is hard to explain the advantageous role of chromium, it is independent from any mechanistic consideration.

Pressure compensation with application of perforated plate

Perforated metal is commonly used to enclose electrical equipments to attenuate the EMI/ RFI radiation they release and to ventilate them at the same time. Many questions occur about which perforated pattern is fit to meet the design requirements and shielding effectiveness of different perforated patterns and materials.

Shielding effectiveness of 40 dB offers 99% attenuation of the electromagnetic radiation while a shielding effectiveness of 92 dB, the maximum shielding effectiveness offered to provide 99.997% attenuation. A shielding effectiveness of 40 dB is minimum in common applications. Effective shielding was offered by most samples to frequencies of 7GHz. Beyond that frequency some samples reduced below 99% effective, however some samples remained easily above 75% effective even at the maximum frequency level of 10 GHz. The conclusion is that there are various perforated patterns to be chosen by designers to meet their design needs.

The major single source of leakage is contact surfaces between two components. If a tightly sealed electrical connection is not made, leakage through interface can be more than through structure.

Pressure loss through perforated plate

In various perforated plate applications, the estimated energy loss or pressure loss through plates is one of the design factors. A lab system maintain a non-swirling flow impacting perpendicularly on the sample. Different perforated gauge plates were inserted in a uniform velocity air flow stream. Pressure loss for ambient air flow was then measured at a range of velocities and counted as inches of water column loss for ever flow. It provides the best flow condition value of loss.

Pressureloss by decorative wire mesh can be measured depending on ratio of anticipated velocity of the highest tabulated velocity. This ratio squared multiplied by the tabulated pressure loss can be used to approximate the higher velocity loss. Pressure loss can be evaluated from the different gas density values by using the ratio of the expected gas density to the measured density as a multiplier of the measured loss. Distorted flow patterns with high velocity zones increase the plate loss, as direction flow will not perpendicular to the plate surface.

To punch that array of holes needs special cluster tooling that not just is costly even also takes time to develop. Additionally the tooling you make will be limited in its service on a  specific material and a limited range of thickness because of clearance requirements. If the type and thickness of a material for a component changes, new tools will be required.

Punching the holes with a cluster tool, simply as the name refers, allows punching only a small cluster of holes with every stroke of the press. The machine time needed will make the holes very costly.

Maintaining accuracy in the arrangement of holes and uniformity in their spacing will be tough due to the damage in the work piece that occurs with each press stroke.

When the component is prepared from the punching process, it will be deformed and require flattening. Without a roller leveler, you will require to send the component to retain the shape. It means even more time and money. 

Market requirements of insect screens for new and existing constructions

Heanjia is a premier supplier of standard insect screens of excellent uality and expertise is unrivalled when it is about delivering a screen to meet the market requirements. We lead the way in delivering advanced products to the market and consistently are ahead of industry trends. Our aim is to focus on the fastest growing mesh screen evident in the combination we offer to our customers.

We have extreme knowledge of window and market. Our world class R & D facilities- initially to market with new screening solutions. The pet resistant screen in the market is leading the industry. We offer excellent performance and service with wide product availability. Strong and durable screens resist rust and prevent sag. A security finish prevents corrosion and reinforces the weave. Made available in different finishes, the insect screen reduces glare for higher visibility.

The easy to install insect screens prevent crease, dent or unravel. The widely used screens for new construction are made available in different shades.

We understand the market needs depending on different focus groups. Homeowners have preference to special screens to suit their specific functional requirements and are willing to pay a premium. Our screens offer consumers premium performance they need. For a nominal investment over standard fibreglass, particularly screens provide higher profit potential with every sale. Increasing profits by providing special screens.

Visually perfect screens are the clear-cut choice for outstanding quality and clarity. We used an improved tighter weave and finest mesh woven from smaller refined yarns as compared to standard fibreglass screens. This construction allows for sharp and outstanding visibility through windows, doors and better airflow and insect inspection.

Screens for small insects

A closed fibreglass mesh to protect from no seeums, gnats, sand flies and other tiny insects that are usually seen in low marshy and coastal areas.

Pollen Guard

Pollen guard screens are specifically designed to prevent 50% more particles as compared to traditional insect screen. It is a unique mesh woven to create a barrier for pollen, dust and other allergen particles making it fit for allergy sufferers. Pollen Guard screen allows air to flow in while preventing the entrance of dust and pollen particles.

Higher Strength

High strength screen by insect screen supplier is our strongest screen. It is a heavy weight weave 40% stronger than standard fiber mesh offering higher protection and long lasing durability while offering outstanding visibility.

Pet resistant

Ultra strong screens resist tear and damage by dogs and cats while offering supreme visibility. Fit for areas where children and pets push against the screen.

Sun Guard

A woven wire mesh screen crafted to block up to 75% of the sun rays entering a building . Decreases cost of air conditioning and prevents color loss of furniture and carpet indoors. Ideal for patios, decks, sliding doors and windows.

Pool & Patio

Heavy duty mesh screens are designed for use in pool, porch and sun room enclosures. They are fit for larger openings where additional strength is required. 

How damage occurs to a metallic material during Pitting corrosion

Corrosion of metallic materials by pitting comprises of a major failure. Damage initiates through perforation and engender stress corrosion cracks. Pitting is a common damaging mechanism to several metals. It is normally associated with specific anions in solutions, particularly the chloride ions. Early identification of pits needs techniques that measure nominal events.

Stainless steels are used in numerous applications for their corrosion resistance. Chromium in steel interacts with oxygen in the air to develop a thin and invisible layer of chrome based oxide called the passive layer. The size of chromium atoms and their oxides are similar that are neatly packed on the metal surface, developing a stable layer. If a metal is cut or scratched and the passive film is disrupted, more oxides are formed to recover the open surface, securing it from oxidative corrosion.

Oxygen is required to repair the passive layer, so the stainless steels have nominal corrosion resistance in low-oxygen and poor circulation conditions. In the seawater, chlorides in the salt will damage the passive layer rapidly.

Few metals show preferential sites of pit nucleation with metallurgical microstructural and microcompositional characteristics stating the sensitivity. Although, it is not the phenomenal origin of pitting, as the site specification is featured for a few metals only. Nucleated pits that do not propagate should repassivate. Although there are numerous states of propagation with a finite survival probability, various factors add to this survival probability.

The evolution of corrosion pits on stainless steels occurred in chloride solution occurs in three different stages- nucleation, metastable growth and stable growth. A microcrack developed by pitting corrosion, develops the initial origin for fatigue fracture. However fatigue failure is not specifically resulted at the deepest interior pitting deep. Considering the different shape of the interior pitting deeps, some are hard to begin or to continue the crack propagation and has a major role as crack locker. If the fracture is created by the pitting deep, continuous plastic deformation can be discovered around the pitting deep. The dimples are normally equalized by the overloaded tension and elongated by shear or tearing.

Cleavage failure occurs by the separation along crystallographic planes. The transgranular fracture is classified to be the brittle fracture in the fracture area. There are many characteristic that can be identified to be the cleavage..

At the grain boundaries the fracture surface cleavage surface changes due to differences between crystallographic orientations. Cleavages are not just related with transgranular fracture, infact also with brittle particles.

Few metals can fail in brittle way however do not cleave. These fractures are recognized as quasi-cleavage. They are identical to cleavage however their characteristic are often flat and smaller.

You should choose a metallic material that is resistant to pitting corrosion in the diverse conditions. The recommended pittingresistant alloys are Hastelloy bars and Inconel bars. 

Uses of Mesh Screens for filtration of variety of fluids

Use of Monel mesh screen is proven for the filtration of different types of fluids for long term performance of filters and increase their life.

Ballast Water

Water provides ballast depending on the load condition of the ship. There has been the risk of sea life being transported to areas harming to the ecosystem as a result of the exchange of ballast water.

Therefore, ballast watr treatment systems are to  be configured on ships in future. By using double stage systems that initially comprise of pre-filtration stage followed by disinfection harmful microorganisms and viruses are killed.

Automatic back flushing filter is fit for pre-filtration and has a proven track record in various configurations.

Cooling Lubricant

Cooling lubricants are used in advanced manufacturing for cutting and forming with machine equipments and basically for the following tasks:

The relative significance and emphasis of the basic criteria are based on specific machining process. All cooling lubricants for metal machining are suitable customized to different secondary requirements that also have positive implications for the user:

·         Consistent stability for prolong use due to excellent filtration

·         Outstanding corrosion protection

·         Neutrality towards compatible machine coatings

·         Decreased outlay for machine failures and maintenance with regular conditioning

·         Easy to dispose

Filtration of cooling lubricant

Excellent cooling lubricant will no perform without conditioning

To become able to receive maximum usage from the cooling lubricant over a long time, suitable filtration is necessary. All contamination that enters the system should also be eradicated from the system through filtration.

Polymer Melts

A specialist area of fluid filtration is in the production and processing plastics. Besides to the impurities entered from outside and resulted by the production of raw materials, presence of gels and specks usually causes further issues in production quality assurance.

Filtration by special filter elements, in filtration ratings of about 1 and 100 micro-m absolute, has proven to be very effective in this field. The filter elements are supplied in pleated develop as standard or customized elements.

Seal Gas

Gas filters are specially developed for use in dry gas seal systems for turbo compressors. Dry gas seals of turbo machines are complex systems and highly sensitive to contamination by solid particles, aerosols and condensates. With shaft rotation, a small gap of about 3 micro-m develops on the seal by which the seal gas distributes. To secure these seals, the seal gases are filtered to ensure the seal has long service life as much as possible. Filter elements with coalescing actions are invariably used in all seal gas filters. The filter elements comprise of pleated filter materials that define the micron rating and the contamination holding capacity, coalesce materials that cause the fluid phase to coalesce.

Hydrogen

Hydrogen is receiving more importance as an alternative fuel particularly in the automotive industry. Hydrogen cleanliness is significantly important for the lifetime of the fuel cell powered vehicles. The measuring cell for monitoring the hydrogen gas cleanliness on 700 bar hydrogen fuel pumps, considerably high levels of particle contamination could be detected regardless of the compressor design or fuel pump producer. With the gas filter GF1, particularly developed by Process Technology for hydrogen fuel pumps up to 1000 bar.

Performance of heavy duty filter screens in fluid filtration

Metal screen and Super Metal Screen filters are made from stainless steel wire cloth offering perfect particle removal efficiency. The super metal screens incorporate a filter media made from weaving fine wires. A unique structure is developed by sintering and calendaring the metal mesh to develop a highly resistant pure metal bond at every wire to wire contact point. It develops a depth media. Super metal screen cartridges provide high porosity and particle removable efficiency at low micron ratings. Every metal screen includes a wire mesh sintered to either side of the filter media to support and strengthen it.

The metal screen filter cartridges made from a woven metal screen media comprising of stainless steel wires of a specific size. Meal screen rating is determined by the weaving process, the wire spacing and wire diameter used.

The heavy duty tungsten mesh screen filters are particularly developed by 3M purification for fluid filtration with wide range of characteristics such as high viscosity, high temperature, high purity and corrosive characteristics.

Characteristics and Performance

·         Wide range of standard filer ratings and configurations

·         Standard configurations available with short times and ensured prices

·         No strand movement in fact at high differential pressures

·         Made for high temperature applications up to 450oC

·         Fit with wide range of process fluids

·         Withstand high pressure differentials across the cartridge allowing the filtration of high viscosity fluids

·         Stable particle removal efficiency

·         Cleanable and fully recyclable

·         Lab tested

·         Industry standard format for use in different types of vessels and interchangeable with other cartridges in the same vessel

Super Metal screen cartridges can be used for special applications that desire specific parameters like:

·         Specific diameters and lengths

·         Higher differential pressures than standard

·         Special corrosion resistant materials such as Hastelloy wire mesh and Inconel mesh

The mesh screens are developed to particular codes for various industrial activities like aeronautics, nuclear power, pharmaceuticals, chemicals and food processing.

Our Super Metal filter screens are made under extreme quality control during production. The filter cartridges undergo integrity testing to verify their pore ratings.

The screens are easy to clean by using different types of methods such as back flushing, chemical cleaning and ultrasonic cleaning. The woven wire screens are fit for use among many and diverse industries such as:

·         Nuclear

·         Pharmaceutical

·         Food Processing

·         Oil and Gas

·         Paints and Resins

You should understand that the core of every filter is the mesh screen element. To a large level, they decide the efficiency. The filters are made by using the best filter elements that meet the highest standards considering stability, long life and cleanability.

Surface filtration

Particles are basically separated at the surface of filter material. As soon as pre-set pressure drop is achieved, the filter materials are cleaned and the filtration process continues regularly or intermittently.

Depth filtration

The operating fluid cleaned penetrates the filter structure. The contaminating particles are held in the deeper layers of the filter. The flow resistance increases with more clogging of the media that the filter element should be replaced.