Corrosive liquid is a kind of fluid that will corrode and damage the materials in contact with it. Metal, stone, glass and even some types of plastics are simply corroded by corrosive liquids or chemicals, which can be roughly divided into six categories: strong acid, weak acid, strong base, weak base, dehydrating agent and oxidant. Some chemicals may belong to more than one category. For example, sulfuric acid is a strong acid, dehydrating agent and oxidant. Corrosive data can also fall into other risk categories, such as toxicity (toxic) or flammability.
If corrosive liquids can damage materials such as glass and metal, they are obviously dangerous to human beings. The U.S. Occupational Safety and Health Administration (OSHA) is aware of the possible health risks of these substances, They are defined as "a chemical substance that will damage the skin tissue, that is, visible necrosis that enters the dermis through the epidermis, at least four hours after exposure of one or three test animals. The typical characteristics of the corrosion reaction are ulcer, bleeding, bloody scab, and at the end of the 14 day investigation, the skin became white and discolored, completely lost hair and left scars."
When using pumps to transport dangerous liquids in oil and gas dehydration - such as flammable, explosive, toxic and corrosive chemicals - it is necessary to consider several factors. These considerations are critical in selecting the right pump for the job.
matters needing attention
One is fluid characteristics. What type of fluid will be pumped? What are the characteristics of this liquid? This information can be found in the fluid safety data sheet (SDS, formerly known as the Material Safety Data Sheet or MSDS).
According to OSHA's briefing on SDS: "HCS 29 CFR 1910.1200 (g) requires chemical manufacturers and distributors to provide each risky chemical with SDS to downstream users to convey information about these hazards, such as the hazards of each chemical to health and environmental health, protective measures, and safety precautions for handling, storing, and transporting chemicals." The fluid SDS can provide vital data, such as details of concentration, specific gravity, temperature resistance, viscosity, flammability (if any) and solid content.
Application requirements
In order to ensure that the pump size is appropriate, the user also needs to consider the pump manufacturer's head capacity curve. The pump curve (also known as the pump selection curve, pump power curve or pump function curve) provides the information needed to confirm that the flow of the pump can occur under conditions that affect the function of the machine.
Accurately read the pump curve or consult a pump expert to ensure that the user can obtain the correct pump according to the use variables, such as: head (the energy required to discharge the water in the pump to the equivalent height expressed in feet or meters); Flow (volume of liquid moving within a given time interval, i.e. gallons per minute [gpm] or cubic meters per hour [m3/h]); Revolutions per minute (rpm); Impeller dimension, related to pump function; strength; Power; And NPSH.
Suitable pump
Centrifugal pumps are the most commonly used equipment for transporting corrosive oil and gas fluids. The centrifugal pump has high energy efficiency, can supply standard submerged suction or self suction, and has a variety of planning scales, which can pump from several gpm to thousands of gpm.
When pumping corrosive liquids, centrifugal pumps provide another advantage - mechanical seals. These seals will prevent leakage of the internal rotating shaft through the stationary pump casing. This is similar to how a car's water pump uses a mechanical seal to prevent coolant from leaking from the pump. The mechanical seal uses a flat ring of carefully machined durable material (such as ceramic carbon or silicon carbide), one of which rotates with the shaft and the other is stationary. The pumped fluid moves between the sealing surfaces and supplies the lubricating film. If the pump runs without liquid (idling), friction will cause the sealing surface to rise rapidly, and then lead to seal failure.
If the mechanical seal fails due to dry operation, the liquid will leak from the pump. If the liquid being pumped is water, this may cause inconvenience. As for corrosive fluid, leakage may cause harm to human body, extensive damage to surrounding infrastructure, and may cause users to violate environmental protection requirements of regulatory authorities. In addition, when it is necessary to stop the pump for maintenance, the downtime and cost (or mean time between failures [MTBF]) should also be considered. ALLWEILER screw pump , ALL WEILER Screw pump Manufacturer, ALLWEILER screw pump agent
Suitable pump structure information
It is important to select appropriate pump structure information. This is particularly important when moving corrosive liquids. Failure to do so will result in corrosion of components (such as gaskets and O-rings) that encounter corrosive fluids, which will affect the function and service life of the pump.
According to the corrosion encyclopedia, corrosion is defined as "the deterioration and loss of data and its key characteristics due to the chemical, electrochemical and other reactions between the exposed data surface and the surrounding environment. The corrosion of metals and nonmetals occurs due to the gradual environmental interaction of the data surface."
Now, corrosion itself is generally not a big problem. Suitable structural information (such as cast iron, bronze, manganese bronze, nickel aluminum bronze, cast steel and stainless steel) is easily obtained and can safely and effectively handle most corrosive fluids. It is very important to understand various corrosion types and factors affecting corrosion rate in order to select appropriate data.
It is difficult to select data that can withstand corrosion and other factors (such as corrosion and cavitation). The general rule of thumb for selecting suitable structural materials is to first select corrosion resistant materials, and then select the materials with the most appropriate wear resistance and/or cavitation resistance. The following are some examples of corrosion that users may encounter when using centrifugal pumps to transport corrosive fluids.
Wear corrosion
Wear or abrasive wear is metal removal caused by mechanical cutting or wear effect of solids carried in pumped liquid. When the corrosive liquid being pumped also contains abrasive solids (abrasion corrosion), it is generally required to use stainless steel and other high alloy materials to ensure the function and life of the pump. In centrifugal pumps, the impeller is particularly simple to be affected. Although the casing may be damaged as a result, the bigger problem is usually the impeller and wear ring.
Cavitation wear corrosion
Most often occurs in high energy absorption pumps. Cavitation is due to the high local stress on the metal surface caused by the implosion of cavitation steam bubbles. In the abrasive cavitation and corrosive environment, with the abrasive particles accelerating towards the impeller surface under the effect of the internal explosive force of cavitation bubbles, the base material is corroded away, accelerating the corrosion process.
Consulting professionals
Although this is not a comprehensive strategy for selecting pumps when delivering corrosive fluids, it is expected to provide users with a simple reference and some key elements to consider when selecting pumps. There are many factors to be considered from the type of fluid conveyed to the selection of appropriate pump structure information.
The user should first collect information about the fluid to be pumped. Secondly, collect information about use requirements and environmental conditions. Then, please consult the pump professionals, who can recommend selecting the appropriate pump for your enterprise, taking into account all the above elements.
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