Key Measures to Extend the Service Life of Loading Arms
Loading arms are efficient and safe loading/unloading tools widely used in petroleum and chemical terminals. To prolong their service life, the following four measures should be taken:
1. Avoid Bending or Pulling the Loading Arm
Maintain the arm in a smooth and upright state. Loading arms are typically made of flexible materials that cannot withstand excessive pressure or tension, so avoid:
Excessive bending beyond the design angle (e.g., >150° for standard arms).
Lateral pulling forces exceeding 50N, which may deform swivel joints.
Ensure the balance system (spring cylinder/counterweight) is adjusted to offset the arm's weight, reducing stress on flexible components.
2. Regular Cleaning and Maintenance
Cleaning Procedure:
Use warm water and non-irritating detergents (pH 7-9), flushing from the end of the arm to the inlet.
Avoid using brushes or sharp tools that could scratch PTFE linings or seals.
Thoroughly dry the arm before reuse (air dry for ≥2 hours or use compressed air at ≤0.2MPa).
Special Note for Chlorine Loading Arms:
Remove residual chlorine by flushing with dry nitrogen (purity ≥99.9%) after each use to prevent chloride-induced corrosion.
3. Prevent Air Ingress into the Loading Arm
For liquid chlorine arms, air ingress accelerates seal degradation:
After loading/unloading, purge the arm with the medium (liquid chlorine) to displace air.
Ensure the dry-type valve closes tightly (verify with a pressure decay test: ≤0.03MPa pressure drop in 5 minutes).
Mechanism: Air moisture combines with chlorine to form hydrochloric acid, corroding the swivel joint's sealing surface (wear rate increases by 300% in humid conditions).
4. Routine Inspection and Maintenance
Monthly Inspections:
Check seal integrity (replace if cracks or swelling exceed 2mm).
Lubricate swivel joints with food-grade silicone grease (viscosity ≥300 cSt at 25°C).
Test the breakaway valve's tensile force (500-800kg disengagement).
Annual Overhaul:
Replace all PTFE seals (service life ≤12 months).
Perform hydrostatic testing at 1.5× working pressure (hold for 30 minutes, no leakage).
Calibrate the balance system to ensure the arm can be moved with ≤15N force.
Additional Safety Considerations
Always follow operational procedures:
Never exceed the design pressure/temperature limits (e.g., ≤0.6MPa for chlorine arms).
Use anti-static grounding clamps (resistance ≤10Ω) during operations.
Personnel Requirements:
Operators must receive annual training on loading arm maintenance (recorded in training logs).
Emergency response drills for leakage should be conducted quarterly.
Service Life Extension Benefits
Implementing these measures can:
Extend seal life from 6 to 18 months.
Reduce maintenance costs by 40-60%.
Decrease unexpected downtime by 75%.
Proper use and maintenance not only prolong the loading arm's service life but also enhance operational efficiency and safety.
