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Golden Steel Material is a premier ISO-certified stockist based in Al Jubail. We supply high-performance pipes, fittings, valves, and flanges to the Oil & Gas and Industrial sectors across Saudi Arabia and the GCC.

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+966 54 662 1439
Al Jubail 35526, Saudi Arabia

SS B688 Plates

Design Standards: ASTM B688, ASME SB688

Material Grade: UNS N08367 (AL-6XN), S31254 (6-Moly)

Alloy Category: High-Alloy Super-Austenitic Stainless Steel

Corrosion Index: High PREn (Pitting Resistance Equivalent Number)

Thickness Range: 0.188" (4.76 mm) to 2.0" (50.8 mm)

Surface Condition: Annealed, Descaled, Ground, or Polished

Performance Edge: Superior to 904L and Duplex in Chlorides

Target Industries: Offshore Oil & Gas, Flue Gas Desulfurization (FGD)

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SS B688 Plates are high-performance super-austenitic stainless steel plates manufactured in strict accordance with the ASTM B688 and ASME SB688 specifications. These plates are engineered for the most aggressive industrial environments, typically covering chromium-nickel-molybdenum-iron alloys like UNS N08367 (AL-6XN). With a high molybdenum content (often exceeding 6%), these plates provide a level of resistance to pitting and crevice corrosion that far surpasses standard 300-series and even 904L grades, making them essential for high-chloride applications.

These plates are specifically designed to handle oxidizing chloride solutions, such as those found in seawater cooling systems, desalination plants, and offshore oil platforms. The B688 specification ensures that the material maintains high mechanical strength and exceptional ductility, even in heavy-wall thicknesses. Due to their "Super-Austenitic" nature, they offer an ideal combination of corrosion resistance and cost-effectiveness when compared to nickel-based alloys. Whether used in flue gas desulfurization (FGD) scrubbers or chemical reactor vessels, our SS B688 plates provide reliable, long-term structural integrity against stress corrosion cracking.

SS B688 Plates Features

» "6-Moly" Corrosion Resistance: Contains high molybdenum (6%+) and nitrogen, providing exceptional resistance to pitting and crevice corrosion in high-chloride and seawater environments.
» High PREn Value: Boasts a high Pitting Resistance Equivalent Number (PREn), ensuring reliability in aggressive oxidizing chloride solutions where standard stainless steels fail.
» Immunity to Stress Corrosion: The high nickel and nitrogen content provides excellent resistance to chloride-induced stress corrosion cracking (SCC), even at elevated temperatures.
» Superior Mechanical Strength: Offers significantly higher yield strength than standard austenitic stainless steels, allowing for thinner wall sections and weight savings in vessel design.
» Excellent Ductility and Toughness: Despite its high alloy content, the material maintains high impact strength and ductility, even at cryogenic temperatures.
» Advanced Weldability: Can be successfully welded using over-alloyed fillers, maintaining the corrosion-resistant properties of the heat-affected zone (HAZ) in heavy plate fabrications.
» Erosion Resistance: Highly resistant to erosion-corrosion, making it an ideal choice for high-velocity fluid systems such as pumps, piping, and heat exchangers.
» Cost-Effective Alternative: Provides a more economical solution compared to expensive nickel-based or titanium alloys while offering comparable performance in specific acidic and marine environments.

SS B688 Plates Specification

Standard Specs

ASTM: B688 (Standard Spec)
ASME: SB688 (Code Case)
UNS Number: N08367 / S31254
Common Name: AL-6XN / 6-Moly

Chemical Profile

Molybdenum (Mo): 6.0% – 7.0%
Nickel (Ni): 23.5% – 25.5%
Chromium (Cr): 20.0% – 22.0%
Nitrogen (N): 0.18% – 0.25%

Mechanical Data

Tensile Strength: 655 MPa (Min)
Yield Strength: 310 MPa (Min)
Elongation: 30% (Min)
Density: 8.06 g/cm³

Size & Supply

Thickness: 4.76mm to 50.8mm
Width: Up to 3000mm
Length: Up to 12000mm
Forms: Plates, Sheets, Strips

Corrosion Specs

PREn Value: > 45 (High Resistance)
Magnetic: Non-Magnetic
Service: High-Chloride & Acidic
Temp Limit: Up to 540°C

Processing

Cutting: Precision Waterjet / Laser
Testing: G48 Corrosion Test, PMI
Finish: Annealed & Pickled (No.1)
Certification: MTC EN 10204 3.1

SS B688 Plates Detailed Specifications

Property	Specification
Standard	Equivalent Grade
UNS N06690 (USA)	DIN 2.4858 (Germany)
EN 2.4858 (Europe)	JIS Inconel 690 (Japan)

SS B688 Plates Chemical Composition

Element	Composition %
C (Carbon)	Max 0.20
Cr (Chromium)	22.0-24.0
Ni (Nickel)	32.0-37.0
Fe (Iron)	Balance
Mo (Molybdenum)	2.0-3.0
Nb (Niobium)	0.90-1.20
Mn (Manganese)	1.0
Si (Silicon)	1.0
P (Phosphorus)	Max 0.04
S (Sulfur)	Max 0.03

SS B688 Plates Mechanical Properties

Property	Value
Tensile Strength	750-1000 MPa
Yield Strength	450 MPa (Min)
Elongation	40% (Min)
Hardness	90 HRB (Max)
Modulus of Elasticity	200 GPa
Density	8.0 g/cm³

Industrial Locations & Keywords

Industrial Locations & Keywords
Riyadh Industrial Cities (1st, 2nd, 3rd & Sudair)
Jeddah Industrial Cities (1st, 2nd & 3rd)
Dammam Industrial Areas (1st, 2nd & 3rd)
Jubail Industrial City
Yanbu Industrial City
Rabigh Industrial City
Al Khobar Industrial Area
Al Ahsa Industrial City
Madinah Industrial City
Makkah Industrial City
Taif Industrial City
Tabuk Industrial City
Jazan Industrial City
Industrial supplier in Saudi Arabia
Pipe fittings supplier in Jubail / Dammam / Riyadh
Flange and valve supplier Saudi Arabia
Fast delivery industrial materials KSA