ASTM A517 Pressure Vessel Steel Plate

GNEE ASTM A517 pressure vessel steel plate is a high-strength, quenched and tempered alloy steel plate specially designed for fusion welded boilers and other pressure vessels. Compliant with ASTM A517/A517M-17 (2023) standard, it features excellent toughness, high tensile strength, and reliable weldability, making it the first choice for high-pressure, high-temperature industrial environments.

 

As a professional manufacturer with years of experience in steel production and export, GNEE provides customized ASTM A517 steel plates to meet the diverse needs of global customers in energy, chemical, and power industries.

 

 

ASTM A517 pressure vessel steel plate is a high-strength quenched and tempered alloy steel designed for use in pressure vessels and structural applications requiring superior strength and toughness. With excellent mechanical performance, high yield strength, and good weldability, ASTM A517 is widely used in demanding industries such as oil & gas, power generation, and heavy equipment manufacturing.

 

GNEE Steel supplies premium ASTM A517 steel plates with strict quality control, fast delivery, and full certification for global projects.

 

Available Grades:

• ASTM A517 Grade A
• ASTM A517 Grade B
• ASTM A517 Grade C
• ASTM A517 Grade D
• ASTM A517 Grade E
• ASTM A517 Grade F
• ASTM A517 Grade H
• ASTM A517 Grade J
• ASTM A517 Grade P
• ASTM A517 Grade Q
• ASTM A517 Grade S

 

Different grades provide varying strength levels and thickness capabilities.

 

 

 

Element	Grade A	Grade B	Grade E	Grade F	Grade H	Grade P	Grade Q	Grade S
Carbon (C)	0.15-0.21	0.15-0.21	0.12-0.20	0.10-0.20	0.12-0.21	0.12-0.21	0.14-0.21	0.10-0.20
Manganese (Mn)	0.80-1.10	0.70-1.00	0.40-0.70	0.60-1.00	0.95-1.30	0.45-0.70	0.95-1.30	1.10-1.50
Phosphorus (P)	≤0.035	≤0.035	≤0.035	≤0.035	≤0.035	≤0.035	≤0.035	≤0.035
Sulfur (S)	≤0.035	≤0.035	≤0.035	≤0.035	≤0.035	≤0.035	≤0.035	≤0.035
Silicon (Si)	0.20-0.35	0.20-0.35	0.20-0.35	0.20-0.35	0.20-0.35	0.20-0.35	0.20-0.35	0.20-0.35
Molybdenum (Mo)	0.18-0.28	0.15-0.25	0.40-0.60	0.40-0.60	0.20-0.30	0.45-0.60	0.40-0.60	0.10-0.35
Boron (B)	0.001-0.005	0.001-0.005	0.001-0.005	0.001-0.005	0.001-0.005	0.001-0.005	0.001-0.005	0.001-0.005
Vanadium (V)	0.03-0.08	0.03-0.08	0.03-0.08	0.03-0.08	0.03-0.08	0.03-0.08	0.03-0.08	0.03-0.08

 

Property	Requirement (≤2.50 in. / 63.5 mm thick)	Requirement (>2.50-6 in. / 63.5-152.4 mm thick)	Significance
Tensile Strength	115-135 ksi (790-930 MPa)	105-135 ksi (724-930 MPa)	Maximum stress the material can withstand while being stretched, ensuring structural stability under high pressure
Yield Strength (Min)	100 ksi (690 MPa)	90 ksi (621 MPa)	Stress at which the material begins to deform plastically, key for design limits in pressure vessel applications
Elongation (Min)	16-18% (varies by grade)	16-18% (varies by grade)	Measure of ductility, indicating the ability to deform before fracture, reducing the risk of sudden failure
Charpy V-Notch Impact Test	Minimum values specified at various temperatures (e.g., -50 °F / -45 °C)	Minimum values specified at various temperatures (e.g., -50 °F / -45 °C)	Ensures excellent toughness, especially in low-temperature environments, preventing brittle fracture
Brinell Hardness	235-293 HB	235-293 HB	Resistance to surface indentation and wear, extending service life in harsh industrial conditions

 

 

ASTM A517 pressure vessel steel plate is widely used in fusion welded boilers and other pressure vessel applications, mainly in the following industries:

• Energy Industry: Boilers, heat exchangers, and pressure vessels in thermal power plants, nuclear power plants, and hydropower stations
• Chemical Industry: Pressure vessels for chemical processing, storage tanks for corrosive media, and reaction vessels
• Petrochemical Industry: Oil refining equipment, natural gas storage and transportation vessels, and offshore oil platforms
• Heavy Machinery: Pressure components in engineering machinery, hydraulic equipment, and heavy-duty trucks
• Other Fields: LNG storage tanks, hydrogen storage vessels, and high-pressure pipelines in energy storage projects

 

 

1. Strict Quality Control & Compliance

All ASTM A517 steel plates are produced in accordance with ASTM A517/A517M-17 (2023) standard, with strict heat and product analysis to ensure compliance with chemical composition and mechanical property requirements. The steel is killed and meets fine austenitic grain size requirements, ensuring uniform performance and high reliability. GNEE has advanced testing equipment to conduct tension tests, transverse Charpy V-notch impact tests, and other mechanical tests, with a product qualification rate of 99.8%.

 

2. High-Strength & Excellent Toughness

Through quenching and tempering heat treatment, GNEE ASTM A517 steel plate achieves a fine-grained martensitic or bainitic microstructure, combining high tensile strength (up to 135 ksi) and excellent toughness. It can withstand extreme pressure and temperature conditions, making it suitable for critical pressure vessel applications where safety and durability are paramount.

 

3. Superior Weldability & Processability

The optimized chemical composition (reasonable control of carbon, manganese, and alloy elements) ensures excellent weldability of ASTM A517 steel plate. It can be easily welded using common welding methods (such as arc welding, gas welding) without obvious welding defects, reducing welding difficulty and improving construction efficiency for customers.

 

4. Customization & Flexible Supply

GNEE supports full customization of ASTM A517 steel plates, including grade, thickness, width, length, and surface treatment (cleaning, painting) according to customer requirements. With an annual production capacity of 400,000 tons, we can meet large-order demand and ensure short delivery cycles (15-30 days for standard orders), solving the problem of long delivery cycles in the market.

 

5. Cost-Effective & Global After-Sales Service

As a direct manufacturer, GNEE eliminates intermediate links, providing competitive factory prices for ASTM A517 steel plates (price range: $500-$910 per ton, subject to grade and order quantity). We offer global logistics services (FOB, CFR, CIF, DDP) and 24/7 after-sales support, including technical consultation, installation guidance, and quality feedback processing, ensuring worry-free cooperation for customers worldwide.

 

 

Grade	Key Feature	Application
ASTM A517	Q&T, ultra-high strength	High-pressure vessels
ASTM A516	Carbon steel, general purpose	Medium-pressure vessels
ASTM A387	Cr-Mo alloy, heat resistance	High-temperature service

ASTM A517 is the best choice when maximum strength and weight efficiency are required.

 

 

Standard	Equivalent Grade	Description
EN (Europe)	S690Q / S700MC	High-strength quenched & tempered steel
DIN (Germany)	1.8928	High-strength structural steel
JIS (Japan)	SHY685 / HW685	High-strength pressure vessel steel
GB (China)	Q690D / Q690E	High-strength low alloy steel

Notes:

Exact equivalence depends on heat treatment, thickness, and impact requirements

ASTM A517 is typically supplied in quenched and tempered condition, similar to EN S690Q

 

 

GNEE Steel supplies ASTM A517 plates with:

• Thickness: 6mm – 200mm
• Width: 1500mm – 4000mm
• Length: 3000mm – 18000mm
• Delivery condition: Quenched & Tempered (Q&T)
• Surface: Shot blasting / Painting

Custom dimensions and processing are available.

 

 

At GNEE Steel, we provide tailored solutions for high-performance applications:

 

Customization Options:

• Cut-to-size plates according to drawings
• Grade selection (A, B, C, Q, etc.)
• Heat treatment control (Q&T)
• Impact testing at low temperatures
• Machining & processing (cutting, beveling, drilling)
• Third-party inspection (SGS, BV, TUV)
• Full MTC certification (EN 10204 3.1 / 3.2)

 

 

What is A517 steel equivalent to?

US T-1 steel materials
ASTM A517 is equivalent to US T-1 steel materials. A517 steel is typically used in fusion welded boilers and other pressure vessels, while A514 steel is often used in welded bridges and other structures. A514 steel is also equivalent to US A709 HPS 100W steel.

 

What is the difference between A514 and A517?

ASTM A514 is a standard specification for high-yield-strength, Quenched and Tempered alloy steel plate for use in welded bridges and other structures. ASTM A517 covers high-strength quenched and tempered alloy steel plates intended for use in fusion welded boilers and other pressure vessels.

 

What is ASTM A517 Grade F mechanical properties?

ASTM A517 Grade F is a high-strength, quenched and tempered alloy steel plate intended for pressure vessel applications. A517 Grade F is available in thicknesses up to 2.5 in. and has a minimum yield strength of 100 ksi. ASTM A517 Grade F also has required Charpy V-notch impact property requirements.

 

What is SA 517 equivalent to?

A517 Gr. S and SA517 Gr. S are the same grade, ASTM A517/A517M is equivalent to ASME SA-517/SA-517M.

 

What is the difference between SA 516 and SA 517?

SA 517 Grade Q is used in high-pressure reactors, LNG storage, and nuclear vessels, offering up to 30% weight savings over SA 516 grades. Its high strength reduces material usage, and nickel content ensures low-temperature toughness, ideal for cryogenic applications.

 

What is ASTM A517 used for?

It is used for high-strength pressure vessels and heavy-duty structures.

 

What makes ASTM A517 special?

Its quenched and tempered condition provides very high strength and toughness.

 

Which grade is most popular?

Grade Q is widely used due to its high yield strength.

 

Is ASTM A517 weldable?

Yes, with proper welding procedures and preheating if required.

 

What industries use ASTM A517?

Oil & gas, power plants, offshore, mining, and heavy equipment.

 

What is the yield strength of A517?

Typically around 690 MPa or higher depending on grade.

 

What is the equivalent EN grade?

S690Q is a common equivalent.

 

Can ASTM A517 be customized?

Yes, size, testing, and processing can be tailored.

 

What is the delivery condition?

Quenched and tempered (Q&T).

 

What is the difference between ASTM A517 and other pressure vessel steel plates (such as ASTM A516)?

ASTM A517 is a high-strength quenched and tempered alloy steel plate, with higher tensile strength (115-135 ksi) and yield strength (min 90-100 ksi) compared to ASTM A516 (a carbon steel plate). It is suitable for high-pressure, high-temperature critical applications, while ASTM A516 is more suitable for general pressure vessel scenarios with lower strength requirements.

 

Can GNEE provide ASTM A517 steel plates with non-standard thickness or size?

Yes. GNEE has advanced production equipment and can produce ASTM A517 steel plates with customized thickness (within the grade limit), width, and length according to customer drawings or requirements, meeting the special needs of different projects.

 

What certifications does GNEE ASTM A517 steel plate have? Can it meet the requirements of international projects?

Our ASTM A517 steel plates have passed ISO, SGS, BV, CE, API certifications, fully complying with ASTM international standards. They have been widely used in international projects in Southeast Asia, the Middle East, Africa, and Europe, and can meet the quality inspection requirements of various international third-party institutions.

 

 

GNEE is a professional manufacturer and exporter of ASTM A517 pressure vessel steel plates, with rich experience in serving global customers. Whether you need standard or customized products, we can provide high-quality products and professional services to help you reduce costs and improve project efficiency.

Request A Quote

 

Call Us Now: +86 15824687445

Email Us: alloy@gneesteelgroup.com

 

Relying on many first-class equipment, such as CNC Shearing machine, Press Brake machine, Straightening machine, Roll Bending machine, Flat Bar Machine, Deburring machine etc, GNEE STEEL could provide various semi-productsand extensive forming services to customers.

 

GNEE STEEL  PROCESSING

1.CTL & SL SERVICE (141 SETS)

Currently, GNEE STEEL has imported manyadvanced CTL/SL equipment from Italy and Korea and could provide customized CTL/SL services from cold rolled stainless steel and carbon steel to hot rolled stainless steel and carbon steel as well as strips and ultra-wide sheet.

CTL FACILITIES
Max Length:16500mm

Max Width:2200mm

Max Thickness:25.4mm

Max Yield Strength:1500Mpa
SL FACILITIES

Max Width:2200mm

Max Thickness:18mm

Max slit Quantity:31

Max Yield Strength:1200Mpa

 

2.CUTTING SERVICE

GNEE STEEL imported lots of advanced cutting machines from Germany, Sweden, America and Japan, including plasmas cutting machine, water jet cutting machine, laser cutting machine, flame cutting machine and saw machine. In order to meet customers' diversified needs, GNEE STEEL also adopts nest working multi-cutting methods and intensive production to improve production capacity and save costs for the customers.

Laser Cutting Machine

Max Cutting Length:40,000mm

Max Width:4,600mm
Max Thickness:100mm

 

Flame Cutting Machine

Max Cutting Length:40,000mm

Max Width:8,000mm
Max Thickness:500mm

Plasmas Cutting Machine

Max Cutting Length:30,000mm

Max Width:5,000mm
Max Thickness:100mm

 

Water-jet Cutting

Max Cutting Length:12,000mm

Max Width:4,010mm
Max Thickness:250mm

3.FORMING SERVICE

Steel Plate Roll Bending
Maximum Rolling Thickness: up to 200mm
Maximum Width: 4200mm

   

Automatic Bending Machine-Press Brake
Max Bending Capability:3000Ton
Max Bending Length:15,000mm

Expert in Bending High-Strength & Wear-Resistant Steels

  

  

Punching Machine

Max Width:3,070mm
Max Thickness:8mm

Max Pressure:250t

BEVELING SERVICE

GNEE STEEL beveling platform has edge milling machine, edge planer, flame / plasma groove cutting machine, flame groove cutting robot, desktop chamfering machine, gantry planerand other advanced equipment to provide customers with parts prefabrication services,daily processing of V-type, Y-type, X-type and U-type grooves, and guarantee subsequent processes such as welding and assembly of products.

 

Milling：
Max Cutting Length:18,000mm

Max Width:4500mm
Max Thickness:120mm

 

  

Beveling:
Max Length:16,000mm

Max Thickness:80mm

MACHINING SERVICE

GNEE STEEL owns CNC Portal-type Boring and Milling machine,CNC Floor-type Boring and Milling machine, Vertical Precision 5-axis Milling Machine, Portal-type Planer, Vertical Lathe, Cylindical Grinding machine, Hydraulic Planer and CNC Lathe and could provide fine machining of large spare parts and structural parts for customers.

Gantry Type Boring & Milling Maching Center

Max Length:48000mm

Max Width:12500mm
Max Height:8000mm

Max Diameter:10500mm

Deep-hole Drilling Equipment
Max Driling Depth:1,100mm
Max Bore Diameter:φ80mm
Max Diametar:φ4,500mm

MMulti-hole Drilling Equipment

Max Length:13,000mm
Max Width:10,000mm
Max Bore Diameter:φ105mm
Max Drilling Depth:250mm

Floor Boring And Milling Machine
Max Length:24,000mm
Max Height:8,000mm
Turntable Dimensions:9x5m

Vertical Lathe

Max Height:6,000mm

Max Diametar:φ22,00mm

Automated Edge Milling Machine

The Automated Edge Milling Machine is a leading product in heavy-duty milling equipment. It is primarily used for weld groove preparation (beveling) on large-format plates made of stainless steel, carbon steel, and special steel grades. It can process plates with a maximum thickness of up to 90mm, a length of 16 meters, and a width of 4 meters.

 

It is equipped with dual milling units and a fully automatic milling cutter head changing system, enabling automated 4-edge beveling. Its standout feature is the profiling technology used when milling wavy plates and irregularly shaped products, which ensures absolute consistency of the groove after milling.

 

Utilizing specially designed milling cutter heads, it can execute highly difficult and complex groove profiles in a single pass.

 

Materials: Plain carbon steel, pressure vessel steel, wear-resistant steel, high-strength steel, stainless steel, nickel-based alloys, etc.
Width: 1200 - 4200 mm
Length: 5800 - 16000 mm
Thickness: 5 - 90 mm
Weight: Up to 35 tons

 

This edge milling machine is the world's premier automated bevel milling equipment. With its excellent structural design and advanced data algorithms, it achieves full automation from plate detection to the actual milling process, significantly improving processing efficiency while guaranteeing high precision.

 

• Processing Accuracy

Length accuracy: ±1mm when L < 10m; ±2mm when L > 10m;

Width accuracy: ±1mm;

Diagonal accuracy: ±2mm;

Root face accuracy (blunt edge): ±1mm for Y-grooves; +0.5mm for X-grooves.

• Processing Efficiency

The processing efficiency is more than 10 times that of conventional edge milling or edge planing equipment.

HEAT TREATMENT

Heat Treatment Furnace
Max Furnace Size:36x12x13.5m
Max Rated Temperature:1100℃
Max Loading Capacity:800t

Heat Treatment of Pressure Vessels
Heat Treatment of Mining Equipment
Heat Treatment of Tube Sheet
Heat Treatment of Pressure Vessel Head

 

 

GNEE STEEL is currently participating in the procurement phase of a 100,000m³ full containment ammonia storage tank project, supplying high-quality steel plates for critical tank components. Due to the corrosive nature of ammonia and the risk of Ammonia Stress Corrosion Cracking (SCC), the project requires strict metallurgical control of materials according to EN 10028-3 standards.

 

One of the most important technical requirements of this project is the strict limitation of the actual Yield Strength (Re) for all NL2 grade materials. To prevent SCC risks in ammonia storage environments, the actual yield strength must not exceed 390 MPa, regardless of the nominal values specified in the standard or plate thickness ranges. This requirement places higher demands on steelmaking process control, heat treatment stability, and material testing.

 

Raw high-strength steel plates ready for the 100,000 m³ full containment ammonia storage tank production

 

Project Materials and Technical Requirements

 

The project mainly uses P355NL2 and P275NL2 normalized pressure vessel steel plates, which are widely applied in low-temperature storage tanks due to their excellent toughness and weldability.

 

Key technical specifications include:

• Material grades: P355NL2 and P275NL2 (Normalized)
• Yield strength: Standard minimum / Maximum limited to 390 MPa
• Hardness: ≤ 225 HBW in base material
• Impact testing: Charpy-V notch test at -50°C, minimum 27J
• Certification: EN 10204 3.1 certificate, with optional 3.2 certification

 

These strict requirements ensure that the steel plates maintain stable mechanical properties and high resistance to ammonia-induced stress corrosion during long-term operation.

 

Precision rolling and forming of steel plates into curved sections for the 100,000 m³ ammonia storage tank.

 

Project Plate Quantities and Thickness Distribution

 

The total steel demand for this ammonia storage tank project is several thousand tons, mainly distributed across different tank sections:

 

P355NL2 – Inner & Outer Tank Shell Plates

• Lower shell courses: 50 mm thickness – approx. 2,000 tons
• Middle shell courses: 25 mm thickness – approx. 1,400 tons
• Upper shell courses: 10 mm thickness – approx. 500 tons

 

P275NL2 – Tank Bottom Plates

• Thickness: 10–15 mm – approx. 750 tons

 

P275NL2 – Suspended Roof Structure

• Thickness: 5–8 mm – approx. 180 tons

 

S275JR – Outer Roof (Ambient Structure)

• Thickness: 10 mm – approx. 450 tons

 

To improve tank fabrication efficiency and reduce circumferential welds, the project also requires wide steel plates to minimize welding joints, which helps reduce the potential risk of SCC in ammonia service conditions.

 

Formed steel segments wrapped and racked for protection, ready for 100,000 m³ ammonia storage tank assembly.

 

GNEE STEEL provides high-precision steel plate rolling and cylinder fabrication solutions for tank manufacturers worldwide. Send us your plate specifications or fabrication drawings for a fast quotation.

Request A Quote

 

TYPE	GRADE	SPECIFICATIONS
Carbon Steel / Low Alloy Coil	Q235A/B/C/D/Q355B(Q345B)/C/D/E/SS400/SAPH400-C/ASTMA283Grade C	0.7~2.0*1250/1500mm*C 2.3~19.5*1250/1500/1800/2000mm*C
Medium Heavy Plate	Q235B/Q355B(Q345B)/C/D/E	6.0-200x150mm-4000mmxL
Vessel Plate	Q245R/Q345R/HP295/SA516MGR485/SA516GR70/P355NL2/P275NL2/ S275JR//SPV490/ASTM A537 Class 1/Class 2	2.5-120x1500mm-3000mmxL
High Strength Steel	510L/610L/700L/750L/BS600MCK4/BS700MCK2/BS700MCK4/ BS960E/BWELDY700QL2/L4/BWELDY960QL4/HG60D/70D/785D/ Q460D/Q550D/690D/690E/TQ600MCD/TQ700MCD/S700MCD/ WYS600/700/STRENX700MCE/Q490E/Q490D	1.2-60x 1500mm-2500mmxL
Patterned Steel	HQ235A|B	1.2-60x 1500mm-2500mmxL
Wear-resistance Steel	NM360/400/450/500/NM300TP/400TP/450TP/ ABREX400/450/500/B-HARD450XKY/ CREUSABRO4800/8000/EH C400LE/450LE/500LE/ HADOX450/500	3.0-50x1250mm-3300mmxL
Cold Rolled Coil	DC01/RECC/REDT/SPCC/ST12	0.5-3.0x1250mm-1500mmxC
Galvanized Plate	DC51D+AZ/DC51D+Z/DX51D+Z/SGH340+Z275/Z275/Z120/S350GD+ZM275	0.45-3.0x1250mm-1500mmxC
Pickled Coil	DD11/SPHC	2.0-6.0x1500xC

Stainless Steel Material and Surface Specifications

TYPE	GRADE	THICKNESS	SURFACE
Austenitic	304/304H/304L/304J1	0.25-150mm	2B/BA/NO.4/8K/SB/HL/NO.1
Austenitic	321	0.4-80mm	2B/BA/NO.4/8K/SB/HL/NO.1
Austenitic	316/316L/317L/316Ti	0.3-80mm	2B/BA/NO.4/8K/SB/HL/NO.1
Austenitic	201(J1/J2/J5)	0.35-12mm	2B/NO.1/1D
Ferrite	430	0.4-3.0mm	2B/BA/NO.4/8K/SB/HL
Ultra Pure Ferrite	443	0.4-2.0mm	2B
Ultra Pure Ferrite	436L/439/444/441	0.5-3.0mm	2B/2D

Special Steel / Nickel Base Alloy

TYPE	GRADE	GRADE (ASTM)	GRADE (EN)	THICKNESS
Heat-resistant Steel	309S	S30908	1.4833	0.5-40mm
Heat-resistant Steel	310S	S31008	1.4845	0.5-40mm
Duplex Stainless Steel	2101	S32101	1.4162	1.5-50mm
Duplex Stainless Steel	2304	S32304	1.4362	3.0-50mm
Duplex Stainless Steel	2205	S32205/S31803	1.4462	0.5-60mm
Duplex Stainless Steel	2507	S32750	1.4410	1.0-60mm
Super Austenitic-Steel	904L	N08904	1.4539	0.6-50mm
Super Austenitic-Steel	254SMO	S31254	1.4547	0.5-50mm
Super Austenitic-Steel	1.4529	N08926	1.4529	0.5-50mm
Super Austenitic-Steel	AL-6XN	N08367	1.4478	0.5-50mm
Nickel Base Alloy	Alloy 31	N08031	1.4562	1.0-50mm
Nickel Base Alloy	800	N08800	1.4876	0.8-50mm
Nickel Base Alloy	800H	N08810	1.4958	0.8-50mm
Nickel Base Alloy	800HT	N08811	1.4959	0.8-50mm
Nickel Base Alloy	Alloy 28	N08028	1.4563	1.0-20mm
Nickel Base Alloy	Alloy 20	N08020	2.4660	1.0-20mm
Nickel Base Alloy	825	N08825	2.4858	0.8-40mm
Nickel Base Alloy	C276	N10276	2.4819	0.5-50mm
Nickel Base Alloy	C22	N06022	2.4602	1.0-50mm
Nickel Base Alloy	625	N06625	2.4856	0.8-20mm
Nickel Base Alloy	400	N04400	2.4360	1.0-20mm
Nickel Base Alloy	600	N06600	2.4816	1.0-50mm
Nickel Base Alloy	Pure Ni 201	N02201	2.4061	0.5-20mm
Titanium	TA1	Gr.1	Class 1	0.5-50mm
Titanium	TA2	Gr.2	Class 2	0.5-50mm

Hot Tags: astm a517 pressure vessel steel plate, China astm a517 pressure vessel steel plate manufacturers, suppliers, factory, Hot Rolled Boiler Pressure Vessel Plate, C15 Carbon Steel Round Bar, Pressure Vessel Steel