The Complete Checklist for Safe Crude Oil Washing (COW)

Crude oil washing (COW) is a critical procedure in tanker operations, designed to improve the efficiency of oil discharge and reduce waste while maintaining high safety standards. However, improper implementation or failure to follow essential guidelines can increase risks, including accidents, environmental hazards, and equipment failures.

This blog aims to provide a detailed guide to the industry’s best practices, covering pre-arrival, pre-discharge, and operational checks that ensure safety and compliance during crude oil washing.

Introduction to Crude Oil Washing (COW)

Crude oil washing, introduced in the 1970s, revolutionized tanker operations by using crude oil itself to wash off residues left in cargo tanks after discharge. Beyond improving the discharge process and minimizing waste, COW has significant environmental benefits as it reduces the amount of dirty ballast water discharged into the seas.

To maintain safety and efficiency, meticulous preparation and execution are paramount. This starts with a strictly adhered-to checklist that ensures each step runs smoothly and within international regulatory compliance, such as MARPOL Annex I.

Why Is a COW Checklist Crucial?

A comprehensive checklist is non-negotiable for crude oil washing. Here’s why:

  • Safety Assurance: Prevent accidents caused by negligence, equipment failure, or operational oversight.
  • Regulatory Compliance: Align with MARPOL regulations and flag state controls to avoid penalties or detentions.
  • Operational Efficiency: Reduce time spent troubleshooting or correcting mistakes during operations.
  • Environmental Responsibility: Ensure the highest standards of environmental care by minimizing oil residue discharge into the marine ecosystem.

Now, let’s explore the step-by-step checklist to ensure your COW operations meet the highest standards.

Pre-Arrival Checklist

Before the vessel arrives at the terminal, certain preparations are essential to ensure safety and efficacy during COW operations. Here’s what you need to check:

  1. Terminal Notification

Ensure the terminal has been informed about the incoming vessel and COW operation plans. Communication must be established well in advance.

  1. Oxygen Analyzing Equipment

Test and confirm that oxygen analysers are functioning correctly to monitor tank atmospheres for explosive gas levels.

  1. Tank Washing System Isolation

Confirm that the tank washing pipeline system is isolated from the water heater and engine room systems to prevent contamination or pressure mismatch.

  1. Hydrant Valves

Verify that all hydrant valves on the tank washing lines are blanked, preventing leaks or accidents.

  1. Valves to Fixed Tank Washing Machines

Ensure all these valves are securely shut before operations commence.

  1. Line Pressurization

Pressurize the tank cleaning lines to the required working pressure and inspect for any leakage, addressing issues immediately.

  1. Drive Units Inspection

Inspect drive units for the tank washing machines to confirm they are functioning as expected.

  1. Pressure Gauges

Check all pressure gauges on discharge lines, manifolds, and tank cleaning mains to ensure accurate readings and reliability.

  1. Communication Systems

Test onboard communication systems, enabling teams to stay connected during operations.

  1. Stripping System Monitoring

Evaluate the stripping system’s performance to ensure it functions efficiently during washing.

  1. Crew Responsibilities

Post a clearly outlined organizational plan, detailing crew duties and responsibilities for the COW operation.

  1. COW Operation Plan

Prepare and post a written COW operation plan for crew adherence, aligning with MARPOL regulations.

  1. Radio Communication with the Terminal

Complete and transmit the terminal’s standard radio checklist to ensure synchronized communication.

Before Crude Oil Washing Checklist

Before starting the crude oil washing process, perform the following checks to establish a safe operational environment:

  1. Ensure all tanks not involved in the washing process are isolated.
  2. Verify that the inert gas system is fully operational, keeping oxygen content below 8%.
  3. Confirm proper drainage of slop tanks and measure ullage levels to avoid overflows during washing.
  4. Check for any safety alarms and ensure they are functional.
  5. Inspect and secure portable equipment for observing COW progress.
  6. Conduct a final walkthrough with senior officers, confirming all safety precautions are in place.

Steps During COW Operations

Once all initial checks are completed, carefully execute the COW process while observing the following:

  1. Rotate washing machines to ensure complete tank coverage.
  2. Monitor oxygen levels in the tanks throughout the procedure using certified gas analyzers.
  3. Keep a sharp eye on pressure levels in the pipelines and washing machine drives to prevent malfunctions.
  4. Regularly update the bridge team and terminal on progress and any anomalies.
  5. Safeguard against over-pressurization in tanks by constantly monitoring pressure gauges.
  6. Post crew members in critical positions ready to respond to unforeseen situations.

Post-Operation Checklist

After completing COW operations, ensure the following steps are conducted:

  1. Inspect all equipment for wear or damage during the operation.
  2. Test the stripping system again to remove residual oil efficiently.
  3. Perform ullage measurements in all tanks to confirm adequate washing.
  4. Document final reports for submission to the terminal and flag state authorities.
  5. Debrief the crew to discuss lessons learned and areas for improvement.

Key Safety Tips for Crude Oil Washing

To reinforce operational safety, consider these additional tips:

  • Use flameproof and explosion-proof tools and equipment during operations.
  • Prohibit smoking or use of open flames anywhere near the washing zones.
  • Make sure all crew involved are trained in accordance with regulatory standards and continuously updated on safety protocols.
  • Conduct regular maintenance and checks on all COW-related equipment, even when not in use.

Taking Operational Excellence to the Next Level

By adhering to this checklist, you not only ensure compliance and safety standards but also enhance the efficiency of your crude oil washing operations. A well-executed COW plan contributes to operational excellence, environmental protection, and long-term cost savings.