Fasteners engineered for extreme service
Precision bolts, studs, nuts, washers and custom components--manufactured to international standards and protected with advanced Sherardizing and Xylan® coating systems.
From material selection and machining to surface engineering, inspection and validation, DUROX INDUSTRIAL supports critical applications in oil and gas, offshore, chemical processing, steel structures and bridges.
- Facility
- 8,000 m²
- Coating Capacity
- 5,000 t/yr
- Spraying Capacity
- 3,000 t/yr
A complete range, made to spec
Standard and custom fasteners are available in a broad range of dimensions, materials, finishes and configurations, with traceable quality documentation to suit project requirements.
Bolts, Studs & Screws
Hex head bolts and screws, structural high-strength bolts, full-thread and double-end stud bolts, socket head cap and set screws, welded studs and anchor bolts.
API 20E BSL1, BSL2 and BSL3 bolts are available for applicable project requirements.
Nuts & Washers
Hex, heavy hex, structural high-strength and lock nuts, plus plain washers, spring washers, square taper washers and direct tension indicator (DTI) washers.
Matching fastener assemblies can be supplied to suit the application and coating system.
U-Bolts & Clamps
U-bolt sets, pipe clamp sets and insulation clamp sets are manufactured to project dimensions, with coating options selected to suit service conditions.
Custom Components
Non-standard fasteners and engineered components can be produced to drawings, specifications and customer-defined inspection requirements.
API 20E Bolting
Bolts and nuts can be supplied to API 20E BSL1, BSL2 and BSL3 requirements, subject to the specified design, material and verification scope.
Standards & Dimensions
American, ISO, German, Russian and Chinese dimensional standards are supported, including ASME B18.2.1, B18.2.2, ISO 4016, ISO 4017, ISO 4032, ISO 4033, DIN 933, DIN 934 and GOST R 52643-52645.
Other applicable GB, HG, SH, NB and JB requirements can also be accommodated.
Material options for critical service
Carbon and alloy steels, stainless steels, duplex grades, nickel-base alloys and copper alloys are available. Final material selection is based on the design code, mechanical requirements, temperature, corrosion exposure and project specification.
Carbon & Alloy Steel
Bolts
ASTM A193 Gr. B7, B7M, B16; A320 Gr. L7, L7M, L43; A307 Gr. A, B; A325/A325M Type 1; A490/A490M Type 1; F1554 Gr. 36, 55, 105; A540 Gr. B21, B22, B23, B24.
ISO 898-1 / GB 3098-1 / GOST R 52627 property classes 4.8, 5.6, 5.8, 8.8, 10.9 and 12.9; GB/T 1231 Gr. 8.8 and 10.9; 30CrMo, 35CrMo and other grades.
Nuts
ASTM A194 Gr. 2H, 2HM, 4, 7, 7M; A563 Gr. O, A, B, C, D, DH, DH3; A563M Gr. 5, 9, 8S, 10S, 12, 8S3 and 10S3.
ISO 898-2 / GB 3098-2 / GOST R 52628 property classes 4, 5, 8, 10 and 12; GB/T 1231 Gr. 8 and 10.
Stainless Steel
Bolts
ASTM A193 Gr. B8 (S30400), B8C (S34700), B8M (S31600), B8T (S32100), B8MLCuN (S31254); A320 Gr. B8, B8C, B8M and B8T.
ISO 3506-1 / GB 3098.6 Gr. A2-70, A4-70, A2-80, A4-80; F593 S304, S304L, S316 and S316L; A453 Gr. 660A, 660B, 660C and 660D.
Nuts
ASTM A194 Gr. 8 (TP304), 8C (TP347), 8M (TP316), 8T (TP321), 8MLCuN (S31254); ISO 3506-2 / GB 3098.15 Gr. A2-70, A4-70, A2-80 and A4-80; F594 S304, S304L, S316 and S316L.
Duplex & Nickel-Base Alloys
Duplex stainless steel: ASTM A1082 S31803 and S32760, with other project-approved duplex grades available on request.
Nickel and nickel-base alloys: A1014 (B637) N07718; B572 N06002; F468/F468M N06625 and N04400; F467/F467M N06625 and N04400.
Copper Alloys
Aluminum bronze: F468/F468M C63000 and F467/F467M C63000.
Brass: F468/F468M C27000, F467/F467M C27000 and H65.
Sherardizing thickness
15-85 μm
Typical comparison range shown
Neutral salt spray
Up to 5,000 h
Based on specified system and test conditions
Protection selected for the environment
DUROX combines base layers and top coats to balance corrosion resistance, coating uniformity, adhesion, dimensional fit and torque-tension performance. Coating selection is matched to substrate, geometry, service conditions and customer specifications.
Base Coatings
Zinc plating, zinc phosphate, manganese phosphate, zinc-nickel plating, Whitford® Xylar® 2, Whitford® Xylan® 4090 Sherardizing and other specified treatments.
Top Coatings
Whitford® Xylan® 1424, 1014, 1070 and 1052, plus other specified Xylan® 1000 and 1400 series coatings.
Coating Colors
Blue, green, yellow, red, black and other colors are available subject to the selected coating system.
Sherardizing Benefits
- Uniform coating thickness and coverage
- Strong bond to the steel substrate
- High hardness and abrasion resistance
- Good resistance to flaking and wear
- Effective corrosion protection in damp and marine environments
- Suitable for complex fastener geometries, including U-bolts
Sherardizing compared with other systems
The table summarizes typical comparative values provided for these coating systems. Actual performance depends on substrate, part geometry, coating specification, application and test conditions; confirm project requirements before selection.
| Property | Zn Plating | Zinc + Xylan® | Zn-Ni Plating | Zn-Ni + Xylan® | Xylar® 2 + Xylan® | Hot-Dip Galvanizing | Mechanical Zinc Plating | Sherardizing |
|---|---|---|---|---|---|---|---|---|
| Coating thickness (μm) | 8-13 | 23-38 | 8-13 | 23-38 | 35-55 | 45-120 | 25-110 | 15-85 |
| Corrosion resistance | Short | Comparatively long | Long | Comparatively long | Comparatively long | Long | Normal | Long |
| Hydrogen embrittlement | Yes | No | Yes | No | No | Less likely | No | No |
| Effect on component strength | None | None | None | None | None | Yes | Yes | Yes |
| Effect on component fit | Low | Low | Low | Low | Low | High | Low | Low |
| Coating adhesion | Good | Good | Good | Good | Good | Good | Poor | Good |
| Coating uniformity | Good | Fairly good | Good | Fairly good | Fairly good | Very poor | Normal | Good |
| Zinc utilization | High | High | High | High | -- | Low | High | High |
| Production efficiency | Comparatively high | Comparatively high | Comparatively high | Comparatively high | Comparatively high | High | Comparatively high | Comparatively high |
| U-bolt suitability | Good | Fairly good | Fairly good | Fairly good | Fairly good | Poor | Poor | Good |
| Neutral salt spray (hours) | 96 | 2,500 | 5,000 | 5,000 | 5,000 | 2,500 | 2,500 | 5,000 |
| Relative price level | Low | Moderate | High | High+ | High++ | Low | Low | Low |
Comparative figures are indicative and are not a substitute for the approved coating specification, qualification test results or project acceptance criteria.
Xylan® coating for demanding service
Since 2002, DUROX has developed corrosion-resistant coated bolts and nuts for oil and gas applications. Whitford® Xylan® coatings provide corrosion protection, wear resistance and dry-film lubricity, offering an effective coating option for fasteners used in demanding environments.
Performance Benefits
- Reduced friction and dry-film lubrication
- Resistance to abrasion and coating wear
- Corrosion and chemical resistance
- Performance across temperature changes
- Non-stick, easy-to-clean surface
- Environmentally compliant coating options
Application Equipment
- DeVilbiss spray guns
- Zahn No. 3 viscosity cup
- Temperature and humidity instruments
- Environmental spray equipment
- Recirculating and continuous energy-saving ovens
Zinc + Xylan® 1424
2,000+ hours
Salt spray resistance reported for the specified system.
Controlled processes, verified performance
Integrated production and inspection processes help maintain repeatability from raw material verification through finished fastener testing, coating application and final packing.
Manufacturing Lines
- Robotic Xylan® spraying line
- Automated cutting, chamfering, marking and thread rolling
- Hydraulic hot forging for bolts, nuts and U-bolts
- Solution annealing and quench-temper furnaces
- Sherardizing and automatic packaging lines
Material & Mechanical Tests
- Raw material chemical composition
- Mechanical property testing
- Low-temperature impact testing
- Rockwell hardness testing
- King 3000 Brinell hardness testing
Coating Inspection
- Visual appearance and cure testing
- Dry-film thickness and coating hardness
- Adhesion testing
- Neutral salt spray testing
- 5% sulfuric acid, acetic acid and sodium bicarbonate film tests
Fastener Verification
- 100% bolt and nut fit checks where specified
- Go/no-go gauges and thread gauge inspection
- PT and MT non-destructive testing
- Hydrogen embrittlement risk control
- Torque-tension verification and process SPC
Quality Management
ISO 9001
Quality management systems support consistent production and documented inspection.
Occupational Health & Safety
ISO 18000
Company operating systems include occupational health and safety management.
Project Standards
EN · NORSOK · GOST
Supply can be aligned with EN 14399, Norsok M650, GOST R and other specified standards.
Whitford® quality-approved coater
DUROX applies specified zinc activation, zinc plating, Sherardizing, zinc-nickel plating and Xylar® 2 base layers, with Whitford® 1000 and 1400 series fluoropolymer top coats. Coating systems are supported by process control and verification appropriate to the approved specification.
The zinc plus Xylan® 1424 system has demonstrated salt spray performance exceeding 2,000 hours under specified test conditions. Zinc-nickel-based systems can be specified for higher salt spray performance, including reported results of 5,000 hours.
Built around your operating conditions
DUROX INDUSTRIAL supports projects from material selection and structural design through manufacturing, surface coating, inspection and field assembly--helping customers pursue longer service life, higher reliability and better lifecycle value.