What is crude oil washing, and how can we prevent it from hurting our environment? Crude oil washing operations require some expertise; therefore, obtaining optimal results requires some competences from the cleaners. Oil tankers are not only those vessels that transport crude oil but also those that carry refined petroleum products.
What is Crude Oil Washing?
Crude oil washing involves the use of preheated crude oil as solvents to speed up the cleaning process of crude oil tanker ships. The current method of washing makes use of modern technology; thereby, making crude oil washing an environment-friendly exercise.
Furthermore, the modern crude oil washing makes use of a liquefying process that helps in removing the dregs stuck to the tank and liquefying it into a usable product.
The process entails spraying the cargo itself with pressure on the interior surfaces and walls of the tanker. Therefore, the method eliminates the use of slop tanks and enables the pumping of liquefied crude into shore tanks.Also, it eliminates marine pollution and helps in maintaining a cleaner environment.
For effective and environment-friendly crude oil washing (COW) operations, there are procedures to be followed. These procedures serve as guides for effective COW operations as well as safety measures to protect humans and the environment.
However, the success of crude oil washing operations is subject to the tanker’s possession of the approved COW system. Also, it requires an efficient equipment manual, trained personnel, as well as good discharging strategy.
Things to do Before Crude Oil Washing Operation
What are the instructions that tank cleaning companies have to follow to avoid polluting the environment?
Before-arrival checks: Certify that, you carry out before-arrival checks.
Operations Briefing: Discuss the mode of COW operation with the ship and offshore staff.
Letting up of communication channels: Set up a COW communication channel between the ship and the offshore crew.
Emergency signs: Discuss set up signals and emergency signs with the ship as well as the offshore staff.
The oxygen content of inert gas: Make available a working inert gas plant with oxygen content less than 5%.
Calibration of Oxygen analyzer: Check and calibrate a fixed oxygen analyzer for a smooth and efficient operation.
Functional oxygen analyzer: Make available a portable, well-functioning oxygen analyzer.
Oxygen reading from both sides: In swash bulkhead tanks, make sure you take oxygen reading from both sides.
Efficient inert gas: Check to know if all tanks inert gas pressure is okay.
Proper setting up of valves and lines: Check to see that all faucets and lines for the ship to shore for the COW system are in order.
Functional equipment: Make sure that all equipment for COW operations is functioning right before work commences.
Assignment of Responsibilities: Assign duties to each staff for effective and efficient operation.
Things to Do During COW Operation
Inert gas and tank pressure check: Check inert gas, tank pressure, and 02 values regularly.
Cleaning the right tank: Ensure that you carry out COW in the proper tanks.
Appointment of deck staff: Appoint a permanent deck staff throughout the operation.
Lines and valve checking: Check all hoses and valves regularly to avoid leakages.
Raising of ullage guage: Raise Ullage gauge for the washed tanks.
Consistent check on machinery: Always check the parameter and running conditions of the machines in use during operation.
Trim availability: Ensure availability of enough trim to help in washing off tanks’ bottom.
Monitoring of holding tank: Always monitor the level of holding tanks to avoid spillage.
Know when to stop operation: Stop COW operation if an inert gas failure occurs, or if there is an increase in 02 content and a drop in cargo pressure.
Things to Do After Operation
- Evacuate crude oil from the tanks’ wash lines.
- Close all valves in the hoses used.
- Stop and wash all machinery that you use for the operation.
- Empty all crude oil pumps at the end of the COW operation.
When Are you Supposed to Suspend COW Operations
Here are reasons to suspend or discontinue work.
First, suspend operations if there is an increase in the oxygen content of inert gas beyond regular volume.
Second, stop the process if the IG system malfunctions, because it may turn the internal pressure of the crude oil tank negative.
Third, suspend the exercise if you suspect any leakage or failure in the COW system.
Fourth, stop washing activities if there is a deviation in an agreed plan for the COW operation.
Fifth, suspend the job if there is a loss of communication between CCR and the main deck.
Sixth, stop all washing activities if the weather condition is bad.
Seventh, stop crude oil washing activities if the washing plan lacks required safety precautions.
Eighth, do not disobey authorities; suspend the job if the terminal instructs you to do so.
Advantages of Crude Oil Washing on Tankers
There will be increase in future cargo out turn: COW operations increase cargo out turn and helps prevent unnecessary remnants after cargo discharge.
COW does preserve storage tank: Unlike water washing, COW protects crude oil storage tanks against rust; thereby, increasing its lifespan.
It reduces oil spill: Leaving less oil in tanks after an operation, COW enhances substantial decrease in environmental pollution. Also, it prevents oil-contamination.
COW is time-saving and cost effective: Unlike water washing that requires a lot of time and resources to clean an oil tanker, the cost of carrying out COW is low.
It reduces sludge buildup: Oil sludge piles up in tanks over time, but with proper oil washing operations, there will be less sludge build-up.
COW reduces ROB ( remaining onboard ): The lesser the ROB, the higher the volume of your cargo in the next voyage.
Disadvantages of COW Operations
First, the job requires skilful manpower: One of the downsides of crude oil washing is that tanker owners cannot do it without the help of experts. Therefore, it is not wrong to say it is not economical.
Second, salt water washing is still necessary: COW operations cannot replace saltwater washing in cases where the vessel has to enter the repair yard.
It is not suitable for all Crude Oil blends: Crude oil washing (COW) is not ideal for all crude oil blends. Therefore, you need to consult an expert for proper advice.
Likelihood of Pollution: Undetected leaks in COW lines may result in an oil spill and invariably pollute the port and its environs.
Few Takeaways From This Article!
Crude oil washing involves the use of preheated crude oil as solvents to speed up the cleaning process of crude oil tanker ships. It is a modernized method that makes use of a liquefying process for dregs removal, and in turn, liquefy removed dregs into a usable product.
Washing of oil tankers require few considerations; Operations Briefing, Setting up of communication channels, a functional inert gas plant with oxygen content less than 5%, calibration of Oxygen analyzer, efficient inert gas, functioning equipment, and assignment of duties to each staff.
The essence of cleaning tankers is to keep them in good condition and ensure they don’t pose dangers to the environment.