How to Prevent Leakage Accidents in Loading Arms
Leakage in loading arms can be caused by material defects, seal failure, improper operation, or insufficient maintenance. Below are systematic preventive measures:
I. Source Control: Material and Design Selection
Targeted Material Selection
Choose materials based on medium characteristics (corrosiveness, temperature, pressure):
Strong acids/alkalis (e.g., anhydrous hydrogen fluoride): Use stainless steel lined with PTFE or carbon steel lined with PTFE to avoid metal corrosion from direct medium contact.
Flammable and explosive media (e.g., methanol, LPG): Select corrosion-resistant and anti-static 316L stainless steel or fluoroplastic-lined materials to prevent aging and cracking.
Key components (swivel joints, valves, pipes) must pass pressure tests (hydrostatic test, airtight test) to ensure material strength.
Optimized Seal Structure Design
Swivel joints adopt double seals (e.g., lip seal + O-ring) with PTFE or graphite seals for enhanced wear and medium resistance.
Use metal wound gaskets or PTFE gaskets at flanged connections to avoid seal failure from medium erosion of ordinary rubber gaskets.
II. Standardized Installation and Debugging
Precise Installation Craftsmanship
Ensure coaxiality (error ≤2mm) for all loading arm components during installation to prevent abnormal wear and leakage of swivel joints due to offset.
Adopt high-precision welding (e.g., argon arc welding) for pipes, and perform 100% non-destructive testing (e.g., X-ray flaw detection) on welds to prevent leakage from welding defects.
Pressure and Sealing Tests
Conduct strength tests (1.5x rated pressure) and airtightness tests (1.1x rated pressure) after installation, maintaining pressure for ≥30 minutes with ≤0.5% pressure drop as qualified.
Check swivel joints, valve interfaces, and flanged connections for bubble leakage, and repair or replace seals promptly.
III. Routine Inspection and Maintenance
Periodic Patrol System
Daily Check:
Visually inspect pipes and joints for liquid residue, frosting (for low-temperature media), or corrosion marks.
Test swivel joint flexibility; add special lubricant (e.g., fluorosilicone grease) if stuck.
Monthly Check:
Use an ultrasonic leak detector on sealing parts; investigate immediately if abnormal high-frequency noise is detected.
Calibrate safety accessories like pressure gauges and safety valves for sensitivity.
Annual Maintenance:
Disassemble swivel joints to replace aged seals and inspect bearing wear (replace if wear >0.5mm).
Perform wall thickness detection on pipes; replace if corrosion margin is less than 80% of original thickness.
Regular Replacement of Vulnerable Parts
Set replacement cycles (e.g., every 1-2 years) for seals, gaskets, and O-rings to avoid seal failure from aging.
Shorten inspection intervals (quarterly) for balance spring and hydraulic cylinder seals on frequently used loading arms.
IV. Operational Standards and Personnel Training
Standardized Operation Procedures
Before loading/unloading: Confirm tanker alignment, slowly dock the loading arm, and avoid strong collisions deforming interfaces.
During operation: Control flow rate ≤4m/s (for Class A/B liquids) to prevent static electricity or impact pressure damaging seals.
After operation: Close valves in order, separate the loading arm, and check if interface covers are sealed to avoid residual medium volatilization.
Operator Training
Conduct regular leakage emergency drills, covering:
Identifying leakage signs (abnormal odor, pressure fluctuations, abnormal liquid levels).
Location and use of emergency shut-off valves.
Initial plugging techniques (e.g., emergency sealant, ).
V. Corrosion and Static Electricity Protection
Anti-Corrosion Measures
For highly corrosive media (e.g., liquid chlorine), spray Teflon coating or use lining technology on pipe inner walls to isolate medium from metal.
Regularly apply anti-corrosion treatment (e.g., epoxy zinc-rich primer + polyurethane topcoat) to loading arm exteriors to prevent atmospheric corrosion.
Static Control
Connect static grounding wires (resistance ≤10Ω) between loading arms and tankers, and test conductivity before operation.
Install jumper wires (cross-sectional area ≥6mm²) at pipe flanges to avoid static accumulation and sparks.
VI. Safety Devices and Emergency Preparedness
Leakage Early Warning System
Install combustible gas detectors (for flammable media) or toxic gas alarms under loading arms, setting alarm thresholds (e.g., 20% of lower explosive limit, 1/2 of occupational exposure limit).
Equip anti-overflow controllers to automatically cut off feed when tanker liquid level reaches the upper limit.
Emergency Response Plan
Stock emergency supplies:pressure tools, neutralizers (for corrosive media), positive-pressure breathing apparatus, etc.
Formulate leakage procedures: Discover leakage → Cut off gas/liquid source → Activate ventilation/adsorption devices → Isolate and warn → Professional repair.
VII. Supplier and Quality Control
Choose suppliers with special equipment manufacturing permits (e.g., TS certificate), requiring:
Material certificates, pressure test reports, third-party inspection certificates.
After-sales commitments (24-hour response, regular maintenance guidance) to avoid leakage risks from equipment defects.
These multi-dimensional preventive measures effectively reduce loading arm leakage probability. Regularly update protection plans in line with industry standards (e.g., API 2000, GB 50160) to ensure safe operation.
