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China Classification Society Fasteners Supplier - Certified Marine Engineering Fasteners from Factory
Product Features
ðĐ 1. Material Selection
In high-temperature environments (>200â), 42CrMo chromium-molybdenum alloy steel (such as A193 B7) should be used. It can withstand temperatures up to 480â and has a tensile strength of âĨ860 MPa.
Extremely cold environments (<-50â) recommend A320 L7 material with nickel-chromium-molybdenum composite strengthening.
ð 2. Anti-Loosening Technology
The wedge-shaped lock washers (such as the Nord-Lock system) are used. The geometric structure with a slope angle greater than the thread rise angle is adopted to prevent vibration loosening. The radial fine teeth form indentations on the contact surface.
The creep vibration test is used to verify anti-loosening performance and is applicable to scenarios with dynamic loads such as wind turbine towers and ship decks.
Application
Classification Society Fasteners (Certified Shipbuilding Fasteners) are specialized fasteners rigorously certified by international ship classification societies (such as DNV, ABS, LR, etc.). Their application fields mainly focus on ships, marine engineering, and related industries.
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(1) Ship Structure Connection
Bolt/nut combinations for critical parts such as decks, bulkheads, and keels must comply with ISO 3506-3 standards (salt spray corrosion resistance grade âĨ 720 hours).
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(2) Power System Fixed
Main unit base bolts must pass dynamic load tests (tensile strength âĨ 800 MPa); material is mostly 316L stainless steel.
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(3) Offshore Platform Construction
Mooring frame connection components must pass the -40â low-temperature impact test and comply with DNV-OS-C501 specification.
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(4) LNG Storage Tank Installation
Low-temperature flange bolts made of nickel-based alloys (such as Inconel 718) ensure sealing performance under -196â conditions.
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(5) Dock Mooring System
Locking nuts must have self-locking function (torque attenuation rate âĪ 5%); material is duplex stainless steel 2205.
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(6) Offshore Wind Turbine Tower
Foundation ring bolts must meet ISO 4014 tolerance grade (M24âM64) with shear strength of âĨ 600 MPa.
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(7) Tidal Energy Device
Underwater fasteners require bio-adhesion protection treatment with a coating thickness of âĨ 50 Ξm.
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(8) Anchor Fixation of Cross-Sea Bridge
Prestressed anchor components must undergo 2 million fatigue tests and comply with the EN 1090 standard.
Frequently Asked Questions (FAQ)
Q1
What material is recommended for fasteners used in high-temperature environments above 200â?
For environments exceeding 200â, 42CrMo chromium-molybdenum alloy steel (such as A193 B7) is recommended. It can withstand temperatures up to 480â and provides a tensile strength of âĨ860 MPa, making it suitable for demanding thermal conditions.
Q2
How does the Nord-Lock wedge-shaped lock washer system prevent vibration loosening?
The Nord-Lock system uses a geometric structure with a slope angle greater than the thread rise angle, which mechanically resists loosening under vibration. Additionally, radial fine teeth form indentations on the contact surface, further securing the connection. Performance is verified through creep vibration testing.
Q3
Which classification societies certify shipbuilding fasteners, and why is certification important?
Major international classification societies such as DNV, ABS, and LR certify shipbuilding fasteners. Certification ensures that fasteners meet rigorous safety, material, and performance standards required for marine environments, including corrosion resistance, tensile strength, and low-temperature impact performance.
Q4
What material is used for LNG storage tank flange bolts, and why?
Nickel-based alloys such as Inconel 718 are used for LNG storage tank flange bolts. These materials maintain structural integrity and sealing performance at extremely low temperatures down to -196â, which is critical for safe LNG containment.
Q5
What standards must offshore wind turbine tower foundation ring bolts comply with?
Foundation ring bolts for offshore wind turbine towers must conform to ISO 4014 tolerance grades (M24âM64) and achieve a shear strength of âĨ 600 MPa. These requirements ensure structural reliability under the dynamic wind and wave loads experienced in offshore environments.
Q6
What special treatment is required for underwater fasteners used in tidal energy devices?
Underwater fasteners for tidal energy devices must undergo bio-adhesion protection treatment with a minimum coating thickness of 50 Ξm. This treatment prevents marine organism attachment and corrosion, extending the service life of fasteners in submerged, high-biofouling environments.