Pressure sensors are widely used in various fields such as ship systems, desalination plants, subsea equipment, and environmental monitoring. These fields are distributed in marine, offshore, and coastal areas. However, seawater is one of the most corrosive natural media because it contains a high concentration of sodium chloride, and chloride ions are highly corrosive. Therefore, traditional stainless steel materials perform poorly in marine environments. This article aims to introduce our pressure sensor specifically designed for seawater corrosion resistance.
Case Sharing
A customer from Singapore previously used ordinary pressure sensors to measure seawater pressure. Due to the high salinity of seawater, the 316L stainless steel diaphragm was quickly corroded, causing the pressure sensor to fail. The customer then saw our pressure sensor on our website and contacted us. We customized a pressure sensor for him based on his measurement conditions, with the following specific parameters:
- Pressure Sensor
- Measurement Medium: Seawater
- Pressure: 10 bar
- Normal Temperature
- Signal Output: 4-20 mA
- ¼-inch NPT (Medium-Length) Threaded Mounting
- PTFE Material
- Ceramic Diaphragm
- No Local Display
- Pressure Sensor
- Measurement Medium: Seawater
- Pressure: 100 bar
- Normal Temperature
- Signal Output: 4-20 mA
- ¼-inch NPT (Medium-Length) Threaded Mounting
- Titanium Material
- No Local Display
Material Introduction
One of the pressure sensors uses titanium alloy for both the housing and diaphragm. In seawater, titanium is much more corrosion-resistant than stainless steel. Titanium alloys possess characteristics such as high specific strength, excellent corrosion resistance, and good high-temperature performance.
In common perception, metals are highly susceptible to rusting and corrosion in humid environments, as if this were an inherent “destiny” for metals. However, titanium alloys break this convention. Titanium is almost unaffected by corrosion in seawater or acidic environments, and even after being buried underground for decades, it can still remain bright and shiny, as if “refusing to participate in the chemical reactions of nature.” The key to titanium alloy’s excellent corrosion resistance lies in its unique protective oxide film mechanism. Furthermore, it is worth noting that although the density of titanium alloy is only 60% of that of steel, its strength is comparable to that of steel.
Another type of pressure sensor uses polytetrafluoroethylene (PTFE) for its casing and alumina ceramic as the diaphragm. PTFE is famously chemically inert – it’s virtually impervious to strong acids, strong bases, and organic solvents. The fundamental reason for this is the exceptional strength of its carbon-fluorine bonds, which are among the strongest single bonds in organic chemistry, making the entire molecule very stable.
Aluminum oxide ceramic (Al2O3) derives its corrosion resistance primarily from its unique physicochemical properties and structural characteristics. High-purity aluminum oxide hardly reacts with strong acids, strong bases, and organic solvents, and may only be corroded in hydrofluoric acid and high-temperature concentrated alkalis. Well-sintered aluminum oxide ceramics have extremely low porosity (<1%), effectively preventing the penetration of corrosive media and avoiding internal corrosion. Aluminum oxide ceramics are irreplaceable in combined “high corrosion + high temperature + wear resistance” working conditions, especially in industrial equipment requiring long-term stability. Although new materials (such as silicon nitride and silicon carbide) can replace it in some areas, aluminum oxide remains the mainstream choice for corrosion-resistant applications due to its cost advantage, mature technology, and comprehensive performance.
Application Scenarios
1. Seawater Desalination
Entering the 21st century, the freshwater crisis is increasingly affecting the production and development of many countries. Solving the freshwater crisis, seawater desalination will be an effective way. Converting saltwater into freshwater is usually done through high-pressure reverse osmosis. These systems require continuous pressure from the pump system to maintain membrane health and maximize system efficiency. Therefore, continuous monitoring of pressure by pressure sensors is important in seawater desalination systems.
2. Marine Systems
Pressure sensors are very useful in ship ballast water management, monitoring tank liquid levels, inflow and outflow rates, and system pressure, allowing crew members to adjust the draft in real time. They are equally crucial in seawater cooling systems for engines or industrial equipment—continuously monitoring pipe pressure to ensure stable operation of the main engine.
3. Subsea Equipment
Control systems for aquaculture facilities require accurate water pressure data, and our sensors are perfectly suited for this purpose. They are even more critical in deep-sea oil and gas production: monitoring wellhead pressure 24 hours a day to ensure safe production and pipeline integrity.
More Solutions For Pressure Measurement
Summary: Our pressure transmitters are custom-designed for marine environments. Simply put, they can withstand being submerged directly in seawater. Critical components can be made from titanium alloy, ceramic, PTFE, or Hastelloy – all proven materials resistant to seawater corrosion. Ordinary stainless steel is prone to pitting and crevice corrosion in seawater and will fail quickly. Our material selection avoids these problems, ensuring accurate and reliable long-term performance. The specific material depends on your actual operating conditions. Send an email to our technical team, and we’ll provide you with a tailored solution.