Bayshon & Caged Ladder Components

1

Eye Bolt in Tail

M12×80 GB31.1-86 (6.8 Grade)

M12×80 GB31.1-86(M12×80-6.8)

45# Carbon Steel (Quenched & Tempered + Zinc Plating Passivation)

1. Stress corrosion cracking induced by chloride ions in coastal/offshore environments; 2. Thread wear and galling from repeated assembly/disassembly during maintenance; 3. Fatigue failure at the eye-root transition due to cyclic load from wind-induced structural vibration; 4. Overload deformation caused by exceeding the 6.8-grade rated load (15.7kN for M12).

1. Prior to installation, verify the bolt’s rated load matches the application’s actual load (safety factor ≥ 2.5); 2. In coastal/marine environments, apply additional anti-corrosion grease (compatible with zinc plating) to thread and eye surfaces; 3. Use a torque wrench for installation (recommended torque: 42-50 N·m) to avoid over-tightening and thread damage; 4. Conduct quarterly visual inspections and annual magnetic particle testing (MPT) to detect hidden cracks at the eye root; 5. Avoid lateral loading—ensure the load direction aligns with the bolt’s central axis to prevent shear stress concentration.

2

Eye Bolt in Tail

M12×100 GB31.1-86 (6.8 Grade)

M12×100 GB31.1-86(M12×100-6.8)

45# Carbon Steel (Quenched & Tempered + Zinc Plating Passivation)

1. Corrosion under insulation (CUI) in heat-insulated equipment sections, leading to hidden rust and material degradation; 2. Thread loosening-induced abrasion due to long-term structural vibration; 3. Bending deformation caused by improper installation (misalignment between bolt and mounting surface); 4. Hydrogen embrittlement from improper post-plating baking processes.

1. Ensure the mounting surface is flat and perpendicular to the bolt axis; use shims if necessary to avoid angular loading; 2. After installation, secure with matching slotted nuts and cotter pins (do not rely solely on thread friction for locking); 3. For insulated applications, conduct periodic insulation removal inspections to check for CUI; 4. Confirm the manufacturer’s post-plating baking record (minimum 200℃ for 2 hours) to eliminate hydrogen embrittlement risks; 5. Avoid using in high-temperature environments exceeding 250℃, as this degrades zinc plating and reduces material strength.

1

Bolt

M16×60 GB31.1-88 (8.8 Grade)

M16×60 GB31.1-88(M16×60-8.8)

40CrMo Alloy Steel (Heat Treated + Black Oxide Coating)

1. Thread fatigue failure due to cyclic dynamic loads from equipment vibration; 2. Corrosion-induced pitting in high-humidity or chemical-exposed environments; 3. Torque overload during installation, leading to thread deformation or bolt shank fracture; 4. Galling between bolt head and washer due to insufficient lubrication.

1. Use calibrated torque wrenches to apply the recommended tightening torque (120-135 N·m) for 8.8-grade M16 bolts; 2. Apply anti-seize compound (graphite-based for high-temperature applications) to the bolt thread and under-head surface before installation; 3. Conduct annual ultrasonic testing (UT) to detect internal fatigue cracks in critical load-bearing positions; 4. Replace bolts if the thread runout exceeds 0.2mm (measured via thread gauge); 5. In corrosive environments, upgrade to Dacromet coating or stainless steel variants for extended service life.

2

Slotted Nut

M16 GB5178-88 (8 Grade)

M16 GB5178-88(M16-8)

35# Carbon Steel (Carburizing Quenching + Zinc Plating)

1. Slot deformation caused by improper cotter pin installation (using oversized tools); 2. Thread stripping due to uneven load distribution during tightening; 3. Corrosion-induced thread locking (seizing) in humid environments; 4. Fatigue cracking at slot roots from repeated vibration.

1. Use a slotted screwdriver or specialized cotter pin pliers for installation—avoid hammering the slot edges; 2. Ensure the nut is fully seated on the bolt thread (no cross-threading) before applying final torque; 3. Clean thread surfaces with a wire brush and apply anti-corrosion oil prior to assembly; 4. Inspect slot width periodically—replace if wear exceeds 0.3mm or cracks are visible; 5. Match with the specified 8.8-grade bolt only; do not mix with lower-grade fasteners to avoid uneven load bearing.

3

Washer

16 GB93-87

16 GB93-87(16)

65Mn Spring Steel (Heat Treated + Zinc Plating)

1. Plastic deformation due to exceeding the washer’s load-bearing capacity; 2. Corrosion-induced loss of spring elasticity in humid environments; 3. Abrasion between washer and contact surface from structural vibration; 4. Cracking at the inner hole edge due to improper hole deburring.

1. Do not stack multiple washers—use one washer per bolt to maintain spring force; 2. Ensure the washer’s inner hole is free of burrs (use a deburring tool if necessary) to avoid stress concentration; 3. Replace washers if they fail to rebound to their original shape after compression (indicates loss of elasticity); 4. In high-temperature applications (above 200℃), use Inconel alloy washers instead of 65Mn to retain performance; 5. Store washers in a dry, sealed container to prevent pre-installation corrosion.

4

Cotter Pin

4×28 GB91-86

4×28 GB91-86(4×28)

65Mn Spring Steel (Zinc Plated)

1. Fatigue fracture due to repeated bending from structural vibration; 2. Corrosion-induced brittleness in salt spray or chemical environments; 3. Shear failure from oversized opening angles during installation; 4. Wear at the pin ends from contact with moving components.

1. Bend the pin ends to 60°-90° after installation—avoid over-bending (exceeding 90°) to prevent fatigue; 2. Replace cotter pins immediately if rust spots or cracks are visible; 3. In marine or chemical environments, use 316L stainless steel cotter pins for enhanced corrosion resistance; 4. Ensure the pin length matches the nut slot depth—avoid excessive protrusion that may catch on moving parts; 5. Do not reuse cotter pins that have been removed and re-bent (spring steel loses elasticity after repeated bending).

1

Slotted Nut

M12 GB6178-86 (6 Grade)

M12 GB6178-86(M12-6)

30# Carbon Steel (Zinc Plating Passivation)

1. Thread wear from repeated assembly/disassembly during routine maintenance; 2. Corrosion-induced thread seizing in humid or dusty environments; 3. Slot damage caused by using mismatched cotter pin sizes; 4. Fatigue failure due to vibration-induced cyclic loads.

1. Use only M12×3.2 cotter pins (matching slot width) to avoid slot expansion; 2. Clean thread surfaces with industrial alcohol before assembly to remove dust and debris; 3. Apply a thin layer of anti-rust oil to the thread after installation for long-term storage or outdoor use; 4. Inspect slot integrity during each maintenance cycle—replace if edges are rounded or cracked; 5. Do not use in high-load applications exceeding the 6-grade nut’s rated load (29.4kN for M12).

2

Spring Washer

12 GB93-87

12 GB93-87(12)

65Mn Spring Steel (Zinc Plating)

1. Loss of spring elasticity due to over-compression during installation; 2. Corrosion-induced brittleness in coastal or chemical environments; 3. Abrasion between washer and nut/bolt head from vibration; 4. Cracking at the outer edge due to material fatigue.

1. Ensure the washer is installed with the concave side facing the nut (correct load-bearing orientation); 2. Avoid over-tightening the bolt, which can cause permanent washer deformation (use torque wrench to control load); 3. In corrosive environments, replace with stainless steel (304) spring washers; 4. Check washer deflection regularly—replace if it does not recover to within 0.5mm of original thickness after bolt removal; 5. Store in a dry environment to prevent pre-installation rusting, which weakens spring performance.

3

Cotter Pin

3.2×22 GB91-86

3.2×22 GB91-86(3.2×22)

65Mn Spring Steel (Zinc Plated)

1. Fatigue fracture from repeated vibration-induced bending; 2. Corrosion in humid environments, leading to reduced tensile strength; 3. Shear failure due to improper installation (pin not fully seated in the nut slot); 4. Wear at the bent ends from contact with surrounding components.

1. Ensure the pin is fully inserted through the nut slot and bolt hole—no gap between pin and slot edges; 2. Bend the pin ends symmetrically to distribute stress evenly; 3. Replace cotter pins every 6 months in high-vibration areas (proactive maintenance to prevent fatigue failure); 4. In areas with frequent water exposure, use galvanized cotter pins with additional anti-corrosion grease; 5. Do not cut the pin ends too short, as this may cause them to disengage from the slot.

1

Bayshon Assy

Customized for Industrial Equipment Matching

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Q235B Carbon Steel (Shot Blasting + Epoxy Primer + Polyurethane Topcoat)

1. Coating degradation and corrosion due to long-term UV exposure and chemical fume contact; 2. Weld joint fatigue failure from cyclic vibration of associated equipment; 3. Mechanical damage from collision with on-site construction or maintenance tools; 4. Deformation caused by overloading (exceeding the designed load-bearing capacity).

1. Inspect the surface coating annually—touch up with matching paint if chipping or rust is found; 2. Conduct annual non-destructive testing (NDT) of weld joints (MPT or UT) to detect hidden cracks; 3. Install protective guards around vulnerable areas to prevent collision damage; 4. Strictly adhere to the designed load limit—post load-bearing warning signs in visible locations; 5. Clean the assembly regularly to remove dust, chemical residues, and salt deposits (critical for coastal applications).

2

Cagged Ladder Assy

Model: CL-2.5/CL-3.0 (Customizable Length)

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Q235B Carbon Steel (Hot-Dip Galvanizing) / 304 Stainless Steel (Corrosion-Prone Areas)

1. Galvanized layer wear at foot contact points from frequent use; 2. Corrosion in galvanized layer defects (pinholes) in humid environments; 3. Step deformation due to excessive load or impact; 4. Fastener loosening in high-vibration areas, leading to structural instability.

1. Use anti-slip mats on high-traffic steps to reduce galvanized layer wear; 2. Inspect the galvanized layer for defects—repair with galvanizing spray for small pinholes; 3. Conduct quarterly step load tests (using 1.25× rated load) to check for deformation; 4. Retighten all fasteners semi-annually and replace any missing or damaged cotter pins; 5. In corrosive environments (e.g., chemical plants, offshore platforms), select 304 stainless steel variants for extended service life.