- Ningbo Zhongli bolts manufacturing Co., Ltd. +86-574-86587617
- tan@nbzyl.com
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Engineered for upstream drilling, offshore platforms, subsea manifolds, and downstream refining units under high pressure and severe cyclic loads.
In the petroleum and petrochemical industries, bolting integrity is not merely a mechanical fastening requirement—it is the frontline defense against hazardous hydrocarbon leaks, catastrophic pressure loss, environmental disasters, and costly unplanned platform downtime. As drilling operations transition into ultra-deepwater reservoirs, sour gas fields with high H2S concentrations, and high-pressure high-temperature (HPHT) extraction wells exceeding 15,000 PSI and 200°C, the demand for premium-grade structural hex bolts and flange studs has reached unprecedented technical heights.
Modern oil and gas operators require structural hex bolts, heavy hex head bolts (DIN 6914, EN 14399, ASTM A325, ASTM A490), and flange connection studs (ASTM A193 Grade B7/B7M, A320 L7/L7M) to exhibit extreme tensile resilience, ductile toughness at cryogenic temperatures, high fatigue endurance under cyclical marine swell, and absolute resistance to Hydrogen Induced Cracking (HIC) and Sulfide Stress Cracking (SSC) in accordance with NACE MR0175 / ISO 15156 standards.
Maintenance of critical gasket stress under fluctuating thermal cycles. Heavy hex head configurations provide larger bearing surfaces, dispersing clamp pressure evenly across ANSI/ASME B16.5 high-pressure flanges without embedding or yielding.
Sour crude environments rich in hydrogen sulfide demand strictly controlled heat treatment and hardness limitations (≤ 22 HRC / 237 HBW for B7M/L7M) to prevent catastrophic Sulfide Stress Corrosion Cracking under load.
Severe offshore saline conditions (C5-M / CX corrosion zones) demand advanced multi-layer barrier coatings such as Hot Dip Galvanizing (ISO 10684), Fluoropolymer / PTFE Xylan coatings, and Zinc-Nickel electroplating with zero hydrogen embrittlement risk.
From exploration drilling to downstream refining, our heavy-duty hex bolts and structural fasteners anchor critical energy infrastructures across the globe.
Offshore drilling rigs, jacket structures, topside modules, Blowout Preventers (BOPs), subsea Christmas trees, and manifold clamp connections undergo extreme dynamic wave fatigue and hydrostatic sea pressures. Our high-tensile Gr 10.9, Gr 12.9, and ASTM A490 heavy hex structural bolts ensure structural integrity under extreme turbulence.
High-pressure cross-country pipelines, booster compressor stations, LNG receiving terminals, and cryogenic storage tanks utilize ASTM A320 Grade L7 low-temperature alloy hex bolts. These fasteners preserve high Charpy V-notch impact toughness at sub-zero temperatures down to -101°C (-150°F), eliminating brittle fracture risks.
Fluid Catalytic Cracking (FCC) units, hydrotreaters, heat exchangers, distillation columns, and ASME Section VIII pressure vessels rely on ASTM A193 Grade B7, B16, and DIN 931 / DIN 933 Gr 8.8 / 10.9 fasteners. These fasteners maintain strict tensile preload and creep rupture strength under elevated temperatures up to 593°C.
| Bolting Specification | Material / Grade | Tensile Strength (MPa / ksi) | Operating Temperature Range | Primary Oil & Gas Application |
|---|---|---|---|---|
| ASTM A193 Grade B7 | AISI 4140/4142 Chromium-Molybdenum | ≥ 860 MPa (125 ksi) | -29°C to 427°C (-20°F to 800°F) | Pressure vessels, high-pressure pipeline flanges, valve bonnets |
| ASTM A193 Grade B7M | Quenched & Tempered Alloy Steel (Hardness Controlled) | ≥ 690 MPa (100 ksi) | -29°C to 427°C (Max 22 HRC) | NACE MR0175 sour crude lines, H2S rich processing units |
| ASTM A320 Grade L7 | AISI 4140 Alloy Steel (Charpy Impact Tested) | ≥ 860 MPa (125 ksi) | -101°C to 427°C (-150°F to 800°F) | Cryogenic LNG transport, Arctic exploration, refrigeration units |
| DIN 6914 / EN 14399-3 (HV 10.9) | High Tensile Structural Boron/Alloy Steel | 1000 - 1200 MPa | -40°C to 300°C | Offshore platform topside structural frameworks, crane towers |
| ASTM A325 / EN 15048 | Medium Carbon / Boron Steel (HDG Coated) | ≥ 830 MPa (120 ksi) | -20°C to 200°C | Petrochemical plant pipe racks, modular structural skids |
Ningbo Zhongli Bolts Manufacturing Co., Ltd. founded in 2003, is a professional manufacturer of high-strength fasteners in different specifications for various models, which is covering an area of about 10,000 square meters, registered capital of 1500,000 RMB, with the total annual productivity of 8,000 tons per year. The company has set up several sales branches in different provinces in China. Meanwhile, the company's products are exported to Europe, USA, Middle East, Africa, Southeast Asia and other regions. The company has strong technical ability, complete testing equipments and a variety of fully automatic multi-station cold and hot heading machines, so as to provide you with reliable and high quality products.
Our main products ZYL brand fasteners include structural hex bolts ASTM A325 type 1, A490, hex head bolts DIN931, DIN933, EN14399, DIN6914, ISO4014, ISO4017 Gr8.8 Gr10.9 Gr12.9, ANSI B18.2.1 UNC and UNF Gr5, Gr8, fine pitch hex bolts DIN960, DIN961 Gr8.8 Gr10.9 Gr12.9, hex socket cap screws DIN912, ISO4762 Gr8.8 Gr10.9 Gr12.9 with surface Black, Zinc plated, Hot dip galvanized. Diameters from M10 to M48, length no limited. Hex Flange bolts DIN6921 Gr8.8 Gr10.9 with serration, thread rod A193 B7 long sizes and short sizes with 2H nuts, stud bolts. We also can supply hex nuts DIN934, DIN6915, plain washers DIN125, DIN126, DIN6916, spring washers DIN127 with Black, Zinc plated and Hot dip galvanized surface.
Our physical and mechanical test results can reach to ISO898-1 for bolts and ISO898-2 for nuts. Through scientific management, Ningbo Zhongli Bolts Manufacturing Co., Ltd. obtained ISO9001 certificate of Quality Management System. Quality is the most important for us. We have strict production and inspection equipments to support this point. We hope to establish business relationship with all over the world, and our business can bring in mutual benefits for both parties.
Every critical bolting component undergoes end-to-end metallurgical control and automated multi-station cold/hot forging to achieve superior grain flow and flawless mechanical integrity.
Equipped with heavy multi-station cold formers, automatic hot heading lines, continuous mesh belt heat treatment furnaces, and in-house laboratory testing facilities producing over 8,000 tons annually.
Oil and gas bolting demands zero tolerance for defect propagation. In accordance with ISO 898-1 and ISO 898-2 quality standards, Ningbo Zhongli operates a fully equipped independent laboratory conducting multi-tier inspection protocols before dispatch:
Two decades of manufacturing expertise powering global energy infrastructure projects with uncompromised fastener reliability.
A Professional Sales and Technical Team with More Than 20 Years History.
We Have Our Own Testing Equipment and Laboratory, Our Products Have Initial Inspection, Patrol Inspection, And Final Inspection.
Our Factory Has Its Own Cold Forged, Hot Forged, And Heat Treatment Equipment.
Standard Fasteners in Stock, Non-standard Fasteners Can Be Customized.
We Have Passed Iso 9001, En 15048, En 14399, Ad2000 and Ce Certificates.
We hope to establish business relationship with all over the world, and our business can bring in mutual benefits for both parties.
EN 15048 CE Certification, EN14399 CE Certification, ISO9001 Certificate, AD2000 Pressure Vessel Compliance.
Grasp first-hand information from worldwide engineering contractors and oilfield operators.
Explore our full line of ASTM, DIN, ISO, and ANSI high-tensile structural bolts, flange stud rods, and heavy hex hardware.
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