What is Pressure Vessel Steel?
Pressure Vessel Steel is a low-alloy carbon steel that can withstand high temperatures, high pressure, and provides good resistance against corrosion. Unlike other ordinary steels, this steel maintains the integrity of its structure and has excellent reliability against harsh environments. This steel offers excellent toughness, strength, and weldability. Due to these properties, this steel is used to manufacture pressure vessels, storage tanks, and heat exchangers that hold liquid and gases at high pressure.
This pressure vessel steel provides excellent fatigue, creep resistance, and avoids brittle failure. This steel is produced under ASTM/ASME standards such as A516, A285, and A537 to ensure consistency and safety in service. The pressure vessel steel is often alloyed with chromium, molybdenum, and nickel to perform better in harsh environments.
Key Properties and Requirements
The following are the key properties and requirements to ensure the maximum performance, reliability, and safety of pressure vessel steel under harsh environments:
1) Tensile and yield strength: To withstand the internal pressure under the extreme loading conditions, the pressure vessel steel should have high tensile and yield strength. This ensures maintenance of the integrity of the material without deformation and rupture.
2) Toughness: Toughness is important for the pressure vessel steel to avoid sudden failure under high pressure. The material will absorb the maximum energy before the failure of the material.
3) Temperature resistance: This steel is designed to withstand temperatures from cryogenic to high temperatures. The pressure vessel steel avoids oxidation, loss of strength, and degradation of material in the low to high temperature range.
4) Welding: smooth welding is the key requirement of the pressure vessel steel. The low carbon and low alloy composition in pressure vessel steel avoids the intergranular cracking, distortion, and residual stress across the heat-affected zone.
5) Corrosion resistance: The presence of molybdenum, nickel, and chromium in pressure vessel steel helps the material to have excellent corrosion resistance against sulfide, acids, or seawater. These alloying elements help the material provide excellent corrosion resistance against high temperatures.
6) Fatigue resistance: The pressure vessel steel must resist the pressure and depressurization cycle to prevent the crack initiation and propagation over time.
7) Hydrogen induced cracking: To avoid the hydrogen embrittlement and cracking in crude oil production, natural gas processing, and water waste treatment industry, it is important to have low Sulphur content and fine grain structure.
Common Standards and Grades
Pressure vessel steel is manufactured through strict international standards to ensure the quality and maintain structural integrity across the various industries. These standards discuss the chemical composition, mechanical properties, dimensional tolerances, testing methods, and heat treatment conditions. Different types of standards are used for different pressures, temperatures, and service conditions. The most common standards are discussed below:
1) ASTM Standards (American Standards):
The ASTM standard specifications are commonly used in the oil, gas, and power generation industries. The material grades according to different ASTM standards are discussed in Table 01, and they are known for consistent performance under low to high pressure and temperature resistance.
Table 01: Common ASTM standards, grades, and their key features for pressure vessel steel
Standard | Grade | Type | Key Features / Applications |
ASTM A516 | Grades 55, 60, 65, 70 | Carbon Steel (Normalized) | It is used for moderate and lower temperature pressure service. It offers excellent weldability, notch toughness, and is commonly used in boilers and storage tanks. |
ASTM A285 | Grades A, B, C | Carbon Steel (Low to Intermediate Strength) | It has good forming, weldability and is commonly used in tanks and low-pressure vessels. |
ASTM A537 | Class 1, 2, 3 | Carbon-Manganese-Silicon Steel (Heat-treated) | It has higher strength due to heat treatment (normalized or quenched & tempered). It is used in high-pressure vessels and elevated temperature service. |
2) EN Standards (European Standards):
The European standard 10028 series specifies the requirements for the use in boilers and pressure vessels. The EN 10028-2 standard specifies requirements for weldable non-alloy and alloy steels with specified elevated temperature properties. Table 02 discussed the European standard for non-alloy steel and its common features/applications.
Table 02: The EN 10028 series standard and commonly used material grade for pressure vessel steel
Standard | Grade (non-alloy steel) | Key features/Applications |
EN 10028-2 | P265GH | It has excellent weldability, machinability, and it is commonly used in heat exchangers and steam boilers for high-temperature services. |
EN 10028-2 | P295GH | It has higher strength than P265GH and is suitable for elevated pressure and temperature. It is commonly used in industrial boilers and pressure tanks. |
EN 10028-2 | P355GH | It offers higher strength and toughness for demanding service conditions. It is preferred for high-pressure steam and chemical process vessels. |
EN 10028-3 16Mo3 | Alloy Steel (Cr-Mo) | It enhanced creep resistance and oxidation resistance. It is suitable for high-temperature applications like furnace components and reactor vessels. |
3) Japanese standard:
JIS G3115 is a Japanese Industrial Standard for hot-rolled steel plates with good weldability. It is used for pressure and temperature applications and is known for consistent performance. Table 03 discussed the JIS G3115, steel grades, and their applications.
Table 03: The JIS G3115 standard and commonly used material grade for high-pressure services.
Standard | Material Grade | Key features/ Applications |
JIS G3115 | SPV235, Carbon Steel | It has good weldability and formability. It is commonly used in tanks and low-pressure boilers. |
JIS G3115 | SPV315, Carbon-Manganese Steel | It is designed for high temperature pressure service and offers good toughness, heat resistance. It is used in refinery and power plant vessels. |
JIS G3115 | SPV410 / SPV450, Alloy Steel (Cr-Mo) | It enhanced strength, creep, and corrosion resistance. It is best for high-temperature service in the petrochemical and power industries. |
Applications in Oil, Gas, Petrochemical, and Power Industry
The pressure vessel steels play a critical role in ensuring the safety, reliability, and efficiency of high-pressure equipment used across the oil, gas, petrochemical, and power sectors. Their combination of mechanical strength, corrosion resistance, and structural integrity makes the pressure vessel steel a perfect choice for modern industrial infrastructure. Table 04 and the following section discuss the usage, typical application, commonly used material grade, and required properties of pressure vessel steel across different industries:
1) Oil industry: Pressure vessel steel plays an important role in the movement of oil, especially under high temperature, high pressure, and corrosive environments. The pressure vessel steel is used to manufacture the storage tanks, separators, dehydrators, and refinery reactors in the oil industry. Pressure vessel steels such as ASTM A516 Gr.70 provide excellent resistance against harsh environments.
2) Gas industry: For the gas industry, the steel should have a high strength-to-weight ratio, excellent toughness, and resistance to hydrogen embrittlement to ensure safe gas handling, transport, and storage. This is why pressure vessel steel is used in the gas industry to manufacture LPG and LNG storage tanks, gas separators, filters, pipeline components, and manifolds. The common materials grades, such as Grade 70 (ASTM A516), SPV315 / SPV410, and P355GH, are used in the gas industry.
3) Petrochemical industry: In this industry, the material should have high-temperature strength, excellent corrosion and chemical resistance, toughness, and creep resistance, as well as hydrogen-induced cracking resistance against the aggressive environments. The pressure vessel steel is commonly used to manufacture reactors, heat exchangers, condensers, storage tanks, and autoclaves for chemical processing. Typical materials used for this industry include ASTM A516 Grade 70 for moderate-pressure vessels, EN 10028 P355GH for high-pressure and high-temperature applications.
4) Power industry: In the power industry, creep and fatigue failures are common due to high temperature, cyclic, and thermal loading. To avoid these types of common failures, pressure vessel steel is used to manufacture the feedwater heaters, nuclear reactor pressure vessels, steam drums, and steam boilers. The material grade is selected based on the service condition, but the most commonly used grades are Grade 70 (ASTM A387), Cr-Mo alloy steels, P355GH (EN 10028), and low-alloy steels like 16Mo3.
Table 04: Pressure vessel steel usage in different industries and their typical applications, required properties.
|
Industry |
Applications |
Properties |
|
Oil & Gas |
Reactors, separators, storage tanks, pipelines |
HIC resistance, weldability, corrosion resistance |
|
Petrochemical |
Heat exchangers, reactors, and chemical tanks |
High temperature and corrosion resistance |
|
Power Generation |
Boilers, steam drums, turbine casings |
Creep strength, fatigue resistance, thermal stability |
Quality Testing and Certification (MTC, ISO, ASME)
To get the long-term service, safety, and performance, it is important that steel meet the properties required for various industries. The different testing methods and international standards are used to ensure the required composition, mechanical properties, and dimensional tolerances. The following section will discuss in detail the quality testing methods and certifications required for pressure vessel steel:
Quality testing:
To ensure the quality, the pressure vessel steel undergoes a series of tests to ensure the required composition, mechanical properties, and environment-specific testing. Some of them are discussed below:
1) Chemical analysis: To ensure the required composition of carbon, manganese, sulfur, phosphorus, and key alloying elements like chromium, molybdenum, and nickel, XRF and OES are used.
2) Mechanical testing: The tensile test is used to check the yield strength, ultimate tensile strength, elongation, and rupture. For low-temperature applications, Charpy V-notch impact tests are used to avoid brittle failure.
3) Non-destructive testing (NDT): It is commonly done after the composition and destructive testing analysis. In Non-destructive testing, ultrasonic testing (UT) and radiographic testing are used to detect internal flaws like porosity, cracks, and inclusions in the material.
4) Microstructure examination: Different microscopes are used to check the grain structure, phase distribution, and presence of harmful inclusions.
5) Specialized testing for applications: For LNG/LPG storage, cryogenic toughness testing is necessary to avoid brittle failure at low temperatures. Hydrogen-induced testing is required for an environment that contains H₂S.
Certification:
The certification assures that the materials’ properties are according to international standards. The most common certifications are discussed below:
1) MTC: Mill test certificate issued by the steel manufacturer to confirm that the chemical composition and mechanical properties are according to the customer’s requirements. The typical international standards used for MTC include EN 10204 3.1 and 3.2.
2) ISO Certification: ISO 9001 ensures the quality management system, consistent production processes, traceability, documentation, and product quality.
3) ASME Certification: The ASME certification, in which the boiler and pressure vessel code (BPVC) ensures the design, fabrication, inspection, and testing of pressure vessels. This certification ensures that pressure vessel steels are safe and suitable for high-pressure and high-temperature service across various industrial applications.
Conclusion
Pressure vessel steels are used in oil, gas, petrochemical, and power generation industries to ensure the safety and maintain structural integrity. The pressure vessel steel is a perfect choice across various industries due to its high strength, toughness, weldability, and resistance against harsh environments. It is important to produce the pressure vessel steel according to different international standards, testing, and certificates to ensure the safety, performance, and long service life of the material.
Contact the Zhaojian Steel for pressure vessel steel plate because they have advanced production lines, cutting-edge technology, and reliable delivery schedules. They can provide the MTC certification, global supply capability, and reliable technical support to ensure your equipment meets the toughest industrial requirements.
