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ASME B18.31.2
GYF
Black Oxide Threaded Rod B7 B7M L7 L7M is a high-performance industrial threaded fastener, manufactured to meet rigorous ASTM A193 material grade standards, delivering exceptional tensile strength, temperature adaptability, and load-bearing reliability. Available in four specialized alloy grades—B7, B7M, L7, and L7M—this threaded rod is tailored for diverse extreme working conditions: B7 for medium-high temperature high-pressure environments, B7M for improved corrosion resistance in critical sealing applications, and L7/L7M for extreme low-temperature cryogenic services. The uniform black oxide finish enhances anti-rust and anti-corrosion performance, while the continuous full-thread design enables flexible length adjustment and universal compatibility with matching nuts, washers, and fastening components. It is purpose-built for industrial manufacturing enterprises, oil and gas project operators, and heavy engineering contractors requiring customizable, dependable fastening solutions for harsh industrial environments.
Each grade is precision-formulated and heat-treated to meet ASTM A193 standards: B7 chromium-molybdenum alloy steel for medium-high temperature high-pressure applications; B7M grade with optimized hardness and ductility for critical sealing and sour service environments; L7 and L7M alloy steels engineered for extreme low-temperature service down to -101°C, with superior impact toughness to prevent brittle fracture in cryogenic conditions.
The advanced black oxide treatment creates a dense, consistent protective layer, significantly improving atmospheric corrosion resistance, anti-rust performance, and scratch resistance. It also optimizes thread friction coefficient, ensuring smooth nut meshing, reducing installation torque loss, and maintaining consistent preload force for long-term fastening stability.
Adopting high-precision thread rolling technology, the continuous full-thread design delivers uniform, burr-free thread profiles with strict compliance to UN, ISO, and BS standards. The full-length thread enables on-site cutting to any required length, supporting flexible installation in non-standard scenarios, with perfect meshing to eliminate thread slipping and seizure risks.
Every threaded rod undergoes rigorous mechanical performance testing, including tensile strength, yield strength, hardness, and impact toughness verification, to ensure full compliance with the corresponding grade standards. All production processes are managed under the ISO 9001 quality management system, with full batch traceability and complete certified material test reports provided for every order.
Parameter | Standard Specification | Customization Range |
Material Grade | ASTM A193 Grade B7, B7M, L7, L7M Alloy Steel | Custom alloy grades per project requirements |
Thread Standard | UNC, UNF, ISO Metric (Coarse/Fine) | BSW, BSP, ACME, custom thread profiles |
Nominal Diameter | #10 to 4" (M3 to M100) | Non-standard diameters available on request |
Standard Length | 1m, 2m, 3m, 6ft, 10ft, 12ft | Cut to custom length, up to 6m full length |
Surface Finish | Black Oxide (Black Finish) | Zinc plating, hot dip galvanized, PTFE, Xylan coated |
Minimum Tensile Strength (B7) | 860 MPa (125 ksi) | Custom mechanical tuning available |
Compliance Standard | ASTM A193, ANSI B18.31.2, ISO 898-1 | RoHS, REACH, NACE MR0175 compliant options |
Widely applied in wellhead equipment, pipeline flanges, pressure vessels, and valve assemblies. B7/B7M grades are ideal for medium-high temperature high-pressure refining processes, while L7/L7M grades are tailored for LNG storage and cryogenic transportation systems, with NACE-compliant options available for sour service environments.
Used in thermal power, nuclear power, wind power, and solar mounting systems. B7 grade delivers reliable performance in boiler and steam turbine high-temperature fastening applications, while L7 grade is optimized for cryogenic cooling systems, with the full-thread design enabling flexible on-site adjustment for diverse installation requirements.
Applied in bridge construction, steel structure buildings, hoisting equipment, and shipbuilding. The high tensile strength of the alloy steel supports heavy structural loads, while the black oxide finish provides long-term atmospheric corrosion resistance for outdoor applications, with custom length options to meet non-standard structural design needs.
Essential for general machinery, injection molding equipment, mining machinery, and conveyor systems. The high fatigue resistance of B7 grade ensures stable performance in high-vibration operating conditions, while the full-thread design supports flexible equipment assembly, alignment, and support applications, reducing maintenance frequency and extending equipment service life.
We offer flexible bulk supply solutions for industrial bulk purchasers, original equipment manufacturers (OEMs), and project contractors, ranging from small-batch prototype orders to large-volume annual framework agreements, with ample standard inventory to support fast delivery and stable lead times. Our custom manufacturing services cover non-standard diameters and lengths, special thread profiles, custom alloy materials, specialized surface treatments, and secondary processing including cutting, chamfering, and tapping, as well as laser marking for logos, batch numbers, or grade identification. Every batch of Black Oxide Threaded Rod B7 B7M L7 L7M is fully traceable, with third-party testing support available to meet strict project compliance requirements.
Grade B7 is a chromium-molybdenum alloy steel optimized for medium to high-temperature high-pressure applications, while B7M offers controlled lower hardness and improved ductility for critical sealing and sour service environments. Grade L7 and L7M are specially alloyed and heat-treated for extreme low-temperature service, with exceptional impact toughness to prevent brittle fracture in cryogenic conditions down to -101°C.
Yes, our Black Oxide Threaded Rod B7 B7M L7 L7M features a continuous full-thread design along the entire length, allowing for easy on-site cutting to your required exact length, with no loss of thread integrity or fastening performance after proper cutting and deburring.
Yes, every batch of our threaded rods comes with a complete Certified Material Test Report (CMTR) that details the chemical composition, mechanical properties, heat treatment records, and compliance certifications, ensuring full traceability and adherence to relevant industry standards.
For industrial manufacturing enterprises, engineering contractors, and project operators seeking high-performance threaded fastening solutions, we offer a free, no-obligation custom quote service, including sample application support, technical selection guidance, lead time planning, and cost optimization solutions. Contact our professional technical sales team with your required material grade, specification parameters, batch volume, and project timeline, and we will deliver a tailored solution and detailed quote within 24 hours, along with free engineering consulting to help you select the optimal threaded rod for your specific application.
