1. Background of Corrosion in Industrial Pumps

With the development of technology, the application range of pumps is rapidly expanding. Due to the varying impact of operating environments and conditions, different levels of corrosion occur on surfaces such as the impeller, guide vanes, and pump body.

Corrosion in pumps due to contact with surrounding media generally occurs in two cases:

The first is corrosion caused by pure chemical reactions. For example, corrosion occurs when metals dissolve in acidic or alkaline solutions.

The second is electrochemical corrosion. For example, when two metals with different electrode potentials come into contact with seawater, they form a micro-battery, causing corrosion. Electrochemical corrosion occurs when a metal interacts with another conductor that has a higher electrode potential, forming a "galvanic cell" that causes corrosion.

I. Reference Standards

Current national standards, relevant regulations, and mandatory standard provisions;

"Code for Construction and Acceptance of Building Anti-corrosion Engineering" (GB50212-2002)

"Standard for Corrosion and Rust Removal Levels of Steel Surface Before Coating" (GB8923-1988)

"Safety Regulations for Coating Operations and Safety Management Rules" (GB6514-1995)

"Quality Requirements for Anti-corrosion Coatings" (GB6514-1991)

"Safety Regulations for Coating Operations, Paint Process Safety, and Ventilation Purification" (DJ/T6931-1999)

"Code for Construction and Acceptance of Industrial Equipment and Pipeline Anti-corrosion Engineering" (HGJ229-91)

"Safety Regulations for Coating Operations and Safety of Surface Preparation Process" (GB7692-87)

"Noise Limits at Construction Sites" (GB12523-90)

ISO9001 Quality Management System Documents

ISO14001 Environmental Management System Documents

GB/T28001 Occupational Health and Safety Management System Documents

I. Design Basis

Environmental Conditions: The corrosion level of atmospheric environments on steel structures can be determined according to Table 1.

I. Internal Wall Anti-Corrosion Plan

Chemical pumps are frequently exposed to corrosion from chemical atmospheres or corrosive liquids, requiring the use of corrosion-resistant coatings for protection, especially to prevent corrosion caused by corrosive liquids. The coating on the parts in contact with the liquid should be resistant to medium corrosion and electrochemical corrosion. A single large spring structure is used in mechanical seals, which should also be coated to prevent leakage.

Especially for large, complex chemical pumps, achieving a completely defect-free coating is difficult. Additionally, during the painting process and the operation, installation, and running of the equipment, it is challenging to guarantee no damage to the paint film. Therefore, in actual factory use, equipment that comes into contact with strong corrosive media must have coatings that are also resistant to abrasion. Coating layers are mainly used to prevent corrosion caused by gas media (chemical atmospheres or other gaseous media) or weaker corrosive liquid media.

Table 1: Anti-Corrosion Coating Technology for Internal Walls of Chemical Pumps

II. External Wall Corrosion Protection Plan

Pumps that transport corrosive liquids are suitable for chemical plants and all conditions involving corrosive liquids. The intensity of corrosion is usually classified based on pH value, with 7 being the dividing point. Typically, a pH value of 1-6 is acidic, 8-13 is alkaline, and 7 is neutral (meaning the liquid does not contain any acidic or alkaline components). The lower the pH value of acidic liquids, the stronger the corrosion. Acids are classified into weak acids and strong acids. Generally, a pH value of 1-4 is considered a strong acid, 5-6 is a weak acid, 8-10 is a weak base, and 11-13 is a strong base.

The ability of corrosion-resistant pumps to resist corrosion primarily depends on the material of the pump's flow components. For corrosion-resistant pumps, it is essential to choose the material of the flow components based on the medium being transported. The corrosion resistance of the material selection is a critical factor that cannot be overlooked. For the chemical production industry, the corrosion resistance of pumps is especially important.

Table 2: External Wall of Chemical Pumps Using Graphene Coating Technology

I. Internal Corrosion Protection of Hot Water Pump

In industrial production, hot water pumps are widely used in many industrial enterprises.

Most enterprises need heating in pipeline transportation, and when the temperature is below 100°C, a simple and economical hot water circulation system is often chosen. However, during use, hot water circulation pumps often exhibit abnormal phenomena such as vibration, noise, and pressure and flow issues. When these phenomena occur, cavitation of the pump is usually the primary cause.

Table 1: Internal Corrosion Protection Coating for Hot Water Pump

II. External Corrosion Protection of Hot Water Pump

In many modern chemical production processes, there is a need for heat tracing in pipeline transportation. In cases where the temperature is below 100°C, most enterprises choose a simple and economical hot water circulation system. When the temperature requirement is relatively high, such as above 95°C, hot water circulation pumps often experience abnormal situations, such as noise, vibration, and issues with output flow and pressure. When these phenomena occur, cavitation is often the main cause.

Cavitation is a phenomenon associated with fluid dynamics, which is constrained by the physical properties of the materials and the fluid’s dynamics. It is unique to fluid machinery and is significantly influenced by temperature, pressure, etc. The higher the temperature, the greater the vaporization pressure, and thus more bubbles are formed. When the pressure is lowered to the vaporization pressure at that temperature, bubbles also form. These bubbles reduce the pressure at the pump’s suction end, and when the pressure drops below the water's saturation vapor pressure, more bubbles form. The bubbles will collapse under the pressure difference, causing fatigue and cracking on the metal surface.

Table 2: External Corrosion Protection + Thermal Insulation for Hot Water Pump

1. Anti-Corrosion Plan for the Inner Wall of Clear Water Pump

Clear water pumps are the most widely used and refer to all liquids with a temperature below 80°C that do not contain corrosive elements or particles, known as clear water. They are used in factories, urban construction, mines, power plants, agricultural irrigation projects, and other fields. They are primarily used for transporting water without solid particles or liquids with similar physical and chemical properties to water.

Table 1: Use of Graphene Solvent-Free Coating Technology for the Inner Wall of Clear Water Pump

2. Anti-Corrosion Plan for the Outer Wall of Clear Water Pump

The corrosion of water pumps involves complex mechanisms that damage solid parts. Experimental studies show that the cavitation process, where bubbles form, grow, and collapse, generates shock waves at a frequency of 100,000 to 200,000 times per second, causing repeated impact loads on the turbine’s flow surface. Under these repeated loads, metal materials experience fatigue damage, which is the primary cause of corrosion.

Table 2: Use of Graphene Coating for the Outer Wall of Clear Water Pump

1. Sewage Pump Interior Anti-corrosion Solution

The sewage pump is a new generation of pump developed based on advanced foreign technology, combined with the characteristics of domestic pump usage. Due to the special working environment of sewage pumps, the structure of common materials is highly susceptible to corrosion. External factors such as temperature, humidity, and air can directly lead to the occurrence of corrosion.

Table 1: Graphene Coating Technology for the Interior of Sewage Pump

2. Sewage Pump Exterior Anti-corrosion Solution

Sewage pumps are increasingly used in industrial production, especially in the chemical industry, where they play an important role. Due to the special environmental conditions of sewage pumps, the materials used are highly prone to corrosion, with temperature, humidity, and air directly contributing to corrosion.

Table 2: Graphene Coating Technology for the Exterior of Sewage Pump