Products 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
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.
Radial fine teeth form indentations on the contact surface.
⥠Performance Verification: The creep vibration test is used to verify anti-loosening performance â applicable to dynamic load scenarios such as wind turbine towers and ship decks.
Application
ð 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.
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).
2
Power System Fixed
Main unit base bolts must pass dynamic load tests (tensile strength âĨ 800 MPa); material is mostly 316L stainless steel.
3
Offshore Platform Construction
Mooring frame connection components must pass -40â low-temperature impact tests and comply with DNV-OS-C501 specification.
4
LNG Storage Tank Installation
Low-temperature flange bolts use nickel-based alloys (e.g., Inconel 718) to ensure sealing performance under -196â conditions.
5
Dock Mooring System
Locking nuts must have self-locking function (torque attenuation rate âĪ 5%); material is duplex stainless steel 2205.
6
Offshore Wind Turbine Tower
Foundation ring bolts must meet ISO 4014 tolerance grade (M24âM64) with shear strength âĨ 600 MPa.
7
Tidal Energy Device
Underwater fasteners require bio-adhesion protection treatment (coating thickness âĨ 50 Ξm).
8
Cross-Sea Bridge Anchor Fixation
Prestressed anchor components must undergo 2 million fatigue tests and comply with EN 1090 standard.
Frequently Asked Questions (FAQ)
Q
What material should be selected 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 offers a tensile strength of âĨ860 MPa, making it suitable for demanding thermal applications.
Q
How does the Nord-Lock wedge-shaped lock washer system prevent fastener loosening?
The Nord-Lock system uses a geometric structure where the slope angle exceeds the thread rise angle, physically blocking rotation under vibration. Combined with radial fine teeth that create indentations on the contact surface, it ensures reliable anti-loosening performance even under dynamic loads.
Q
Which classification societies certify shipbuilding fasteners, and why is certification important?
Major classification societies include DNV, ABS, and LR. Certification ensures fasteners meet strict standards for corrosion resistance, tensile strength, and temperature tolerance â critical for the safety and longevity of marine structures operating in harsh environments.
Q
What fastener material is recommended for LNG storage tank installations at -196â?
Nickel-based alloys such as Inconel 718 are recommended for LNG storage tank flange bolts. These materials maintain structural integrity and sealing performance at cryogenic temperatures as low as -196â, preventing leaks and ensuring operational safety.
Q
What are the key requirements for fasteners used in offshore wind turbine tower foundations?
Foundation ring bolts for offshore wind turbine towers must comply with ISO 4014 tolerance grades (M24âM64) and achieve a shear strength of âĨ600 MPa. These specifications ensure the bolts can withstand the significant mechanical stresses and environmental exposure typical of offshore wind installations.
Q
How are underwater fasteners for tidal energy devices protected against marine biofouling?
Underwater fasteners used in tidal energy devices are treated with bio-adhesion protection coatings with a minimum thickness of 50 Ξm. This treatment prevents marine organisms from attaching to the fastener surface, reducing corrosion risk and maintaining the structural integrity of the device over time.
BSF
