Cavitation phenomenon, generally not for people to pay attention to and understanding. The actual production of cavitation problems are often the main cause of centrifugal pump impeller damage. The general understanding of impeller rot and aging. But how did this happen? The mechanism is unclear. So it is necessary to understand how cavitation is caused and how to avoid it. Here to talk about cavitation problems and preventive measures. As we all know, water heated to a certain extent will become water vapor, and water vapor to a certain temperature will condense into water, and, at an atmospheric pressure, the water heated to 100 ℃, It starts to boil, producing a lot of bubbles (called vaporization). While temperature and pressure are the conditions for their conversion to one another. When the pressure on the water surface is high, the temperature needed to vaporize the water is high. When the pressure on the water surface is low, the temperature required for water vaporization When the pressure acting on the water surface is low to a certain extent, the water can vaporize to generate a large amount of bubbles even at normal temperature. The pressure at which the liquid begins to vaporize at a certain temperature is called vaporization pressure. Cavitation of the pump is caused by the vaporization of the liquid. People on the principle of centrifugal pump water are more clear, in order to make the water pump sucked up the lower, you must make the import of the pump impeller vacuum, which created the conditions for the evaporation of water. At a certain temperature, when the impeller inlet pressure is low to a certain extent, the water entering the pump begins to vaporize, resulting in a large number of bubbles. These bubbles and a small amount of gas dissolved in water, with the water into the impeller. Since the pressure changes as the water flows in the pump impeller runner, the bubble re-starts at high pressure as the water moves the bubble from the low pressure zone (the inlet of the pump) to the high pressure zone (the outlet of the pump) Condensation into water and loss of the bubble disappears, the surrounding water at a high rate of impact to the rupture of bubbles, like numerous small warheads, continuously acting on the metal surface of the impeller. Impeller wall in a continuous blow at high-speed water, over time will appear honeycomb-shaped cavities, the shape of a random distribution. This phenomenon is called cavitation. People used to regard this phenomenon as impeller decay. Centrifugal pump impeller is very sensitive to cavitation. A long time will eclipse the impeller wall. Pump cavitation will produce a lot of noise and vibration. At this time the pump head was significantly reduced, the flow rate decreases, the more serious cavitation will make the pump off. Therefore, the pump is not allowed to operate in the case of cavitation. A chemical centrifugal pump, when its speed and flow rate of a certain time, the production of cavitation limit the water pump suction height. General pumps on the nameplate are mentioned "to allow suction on the vacuum height" or "necessary NPSHr NPSHr" is based on the pump at rated speed and flow without cavitation principle, determined by the manufacturer's test The maximum water absorption height limits the pressure at the pump impeller inlet not to fall below a certain value in order not to cause cavitation. In other words, the pump impeller inlet vacuum can not be higher than a certain value. Therefore, the lowest allowable pressure at the inlet of the pump impeller, which is also called the "allowable suction of the vacuum" of the pump, is the same as "allowable suction of the vacuum". 2 Cavitation Prevention Shielded pump actual installation height, must be lower than or equal to the actual water pump height. Water pump inlet pipe to shorten the length of as much as possible, less elbows and valves, and some aquaculture production units make a straight elbow bend, rather than the way shrimp shell bend, it will increase the resistance of the suction pipe, Cavity capacity to produce cavitation. Strictly observe the rated parameters on the pump nameplate. Water inlet pipe joints, pads must be tight and reliable, should always check the fastening flange bolts. Bottom suction valve should be flexible opening and closing (especially for a long time without using the pump unit). Stop pumping in the process of continuous stop pump. Do not think the submerged suction pipe will increase the absorption of water depth, in fact, this is counterproductive. Because of the excessive flooding depth lengthened the suction pipe, thereby increasing the loss along the way, the result has reduced the water absorption height, but also easy to absorb air and produce cavitation. Tide pumping times pumping aquaculture production units, should pay more attention to changes in seawater levels.

HASTELLOY®

Hastelloy Availability

Yuhong Group supplies Hastelloy C276, C22, X, B3 and B2. Most of these alloys are available in the form of plate, sheet, bar, pipe, tubing, pipe fittings, flanges and welding material. Request a Quote today on any of these alloys.

The registered trademark name, Hastelloy, is applied as the prefix name to more than twenty different highly corrosion resistant metal alloys produced by Haynes International, Inc. Thesesuperalloys, or high performance alloys, developed by Haynes International, are nickel-based steel alloys that exhibit traits that include high resistance to uniform attack, localized corrosion/oxidation resistance, stress corrosion cracking resistance and ease of welding and fabrication.

Alloys of identical chemical and mechanical properties are available from other manufacturers and offer excellent alternatives to the various Hastelloy® brand alloys.

The corrosion-resistant superalloys are widely used by the chemical processing, aerospace, and industrial gas turbine and marine industries. Additionally, due to the their reliable performance, areas of energy, health and environmental, oil and gas, pharmaceutical and flue gas desulfurization industries are increasingly using them.

What are the Characteristics of Hastelloy ?

High resistance to uniform attack
Outstanding localized corrosion resistance
Excellent stress corrosion cracking resistance
Good resistance to acids such as sulfuric, nitric, hydrochloric, hydrofluoric and chromic
Ease of welding and fabrication
High resistance to oxidation at elevated temperatures

In what Applications are Hastelloy alloys used ?

Chemical Processing Industry
Aerospace
Pharmaceutical
Oil and gas production
Components where exposure to high mechanical stress and sea water are required
Components exposed to flue gas or flue gas desulfurization plants

Superalloys, also known as high performance alloys, have become the steel of choice for corrosion resistance and versatility.

*Hastelloy® is a registered trademark of Haynes International, Inc.

Hastelloy Fitting

Hastelloy Fitting,Hastelloy Pipe Fitting,Hastelloy C276 Fitting

YUHONG GROUP CO.,LIMITED , http://www.alloypipeline.com