Recently, GNEE STEEL supplied a batch of reinforcing rings to a renowned pressure vessel manufacturer, utilizing laser bevel cutting. This approach significantly optimized costs for the customer and greatly shortened the delivery cycle, earning their full satisfaction.
Traditionally, beveled products require beveling machines, involving a process of cutting followed by a milling operation. Leveraging its leading high-efficiency laser equipment, GNEE STEEL can provide superior processing services. For products requiring beveling, laser bevel cutting offers faster and better results.
Recently, GNEE STEEL received an order from this well-known pressure vessel customer where some products required beveling, and the customer required a tight delivery schedule. To meet the customer's request, GNEE STEEL decided to employ high-performance laser equipment. This equipment features both 2D vertical cutting and 2D bevel cutting capabilities, providing bevel cuts from 0° to 45° for customers, with a maximum bevel cutting thickness of 25mm. The beveled parts can be used directly for welding by the customer.
Ultimately, by leveraging the advantages of the equipment and extensive experience, the high-quality and high-efficiency service gained the customer's high recognition and trust.
GNEE STEEL Group is a modern, integrated steel service enterprise specializing in processing, sales, and technical services within the stainless steel and carbon steel sectors. GNEE STEEL Group possesses global steel processing equipment, a modern physical and chemical testing center, and 9 processing platforms encompassing cutting, grinding, forming, welding, heat treatment, machining, spraying, and final assembly.
What is PVQ Steel Plate?
Pressure vessel quality (PVQ) steel plate is used to produce pressure vessels due to its tensile strength, notch toughness, ductility and fatigue characteristics.These plates also known as Chrome Moly Steel Plates.
Before examining the properties of PVQ grades, here are a few terms used to describe the properties of steel, defined:
Strength: the load the steel can bear. Steel strength is determined by yield point and tensile strength. A yield point is the point at which a material is stressed to the point where it deforms but does not break. Tensile strength is the amount of stress needed for the material to break.
Notch Toughness: the level of impact steel can absorb before denting, typically measured by a Charpy Impact test.
Ductility: the capability of a material to be stretched out before it becomes weak or brittle. Ductility is measured by elongation, which is the percent the length of a stretched material increases before it breaks.
Properties of Primary PVQ Grades
While there are multiple grades of PVQ steel, ASTM A516 and ASTM A537 are most commonly used for pressure vessel applications due to their balance of strength and ductility.
ASTM A516
ASTM A516 is a low-to-medium carbon steel that boasts high strength relative to weight, high ductility and high machinability. It is available in four grades of varying strength: 55, 60, 65 and 70.
Compared to other grades, A516 is a highly machinable PVQ steel grade, making it ideal to produce welded vessels where materials are manipulated to form the curved shape of a storage tank or boiler.
To increase strength while keeping carbon levels low, other elements are added to harden and strengthen, such as manganese, phosphorus, sulfur and silicon. Each grade has varying levels of each element, which are detailed in the chart below.
| ASTM A516 | Grade 55 | Grade 60 | Grade 65 | Grade 70 |
| Carbon | 0.18-0.26% | 0.21-0.27% | 0.24-0.29% | 0.27-0.31% |
| Manganese | 0.60-1.20% | 0.60-1.20% | 0.85-1.20% | 0.85-1.20% |
| Phosphorus Max | 0.025% | 0.025% | 0.025% | 0.025% |
| Sulfur Max | 0.025% | 0.025% | 0.025% | 0.025% |
| Silicon | 0.15-0.40% | 0.15-0.40% | 0.15-0.40% | 0.15-0.40% |
A516 can be supplied in two conditions:
As-rolled: the plate is supplied without heat treatment. As-rolled plate is typically not as strong as heat-treated plate because heat treatment alters the grain structure of steel plate, increasing strength, hardness and ductility.
Normalized: the plate receives a heat treatment in which plate is heated to an extremely high temperature and held at that temperature for a sufficient time (typically up to an hour minimum for every 1" of thickness). After holding this high temperature, the plate is then cooled to room temperature. Normalizing a plate increases its hardness.
A516 grades have a relatively high yield and tensile strength, allowing the steel to endure high levels of stress, energy and weight without breaking or changing shape. Yield and tensile strength are important in PVQ steel to ensure the vessel does not break or deform, risking the leakage of materials inside the vessel. Below is a chart detailing the yield point, tensile strength and elongation of each grade of A516.
Other PVQ Grades
While A516 and A537 are common PVQ grades and can be used in a variety of applications, other PVQ grades can be used for more specific pressure vessel applications.
| Grade | Common Uses |
|
ASTM A537 Class 1,class 2 |
A537 is normalized, heat treated and displays greater yield and tensile strength that the more common A516 grades. |
| ASTM A612 | A high-strength carbon steel used to produce pressure vessels for moderate and lower temperature use. |
| ASTM A285 | A carbon steel intended to be used in the production of fusion-welded pressure vessels. |
| ASTM A533 Type 1,Type 2 | A553 grade covers nickel alloy steel plates that are used in the fabrication of cryogenic pressure vessels. |
|
ASTM A387 |
A387 Grade 11 Class 1,A387 Grade 11 Class 2 A387 Grade 22 Class 1,A387 Grade 22 Class 2 |
| 16Mo3 | 16Mo3 steel have improved corrosion and temperature resistance over the standard carbon steels but without the cost of stainless steels (due to their lower nickel and chromium content). |
|
Stainless Steel Vessel Grades |
304 304L 316 316L |
By adding the certain percent of chromium, nickel and molybdenum, will increase highly resistant of stainless steel plates, for to use in critical applications that require highly resistant to the environment. Such as used in food or chemical industries.
The manufacture of pressure vessels is tightly regulated as a result of the risks involved and as a consequence the materials that can be used in vessels is also tightly specified. The most common specifications for pressure vessel steels are the EN10028 standards – which are European in origin – and the the ASME/ASTM standards which are from the US.
