Liquefied Gas Carrier

Home page||| LNG handling ||| LPG handling||| Other Gas products||| Fire & Safety||| Emergency response |||

Loss of instrumentation during loading operations - Recommended actions by liquefied gas carriers

An emergency can occur at any time and in any situation. Effective action is only possible if pre-planned and practical procedures have been developed and are frequently exercised.

Anti-surge Failure
: The Anti-surge is tested before loading takes place, therefore, any malfunctions will be detected during that test. The Anti-surge is a shore side protection system and the shore personnel should assess the risk and decide what to do in case it fails.

Capacitance Level Gauge (Transonic) Failure

Note: In this scenario, the High level alarm is disabled and possibly the Very High level alarm will not function (even if there is an independent sensor). Monitor closely the level readings in tank(s) by frequent readings with Whessoe tape
For topping up, have ready the right figures corresponding to Whessoe readings (corrections to be kept in mind)
That failure may happen when we are close to topping up operations, therefore, final levels for Whessoe should always be ready beforehand

ESD Failure

Try to disable ESD (normally optical) and go with the back-up (pneumatic)
If both ESD fail, stop cargo operations
Try to detect the problem and solve it
Do not resume loading operations till ESD is functioning

Liquefied natural gas ship underway
Fig:Liquefied natural gas ship underway

Gas Detection System Failure

Stop cargo operations
Resolve the problem
Restart cargo operations

High Duty Compressor Failure

Advise Terminal both HD compressors failed
Reduce Loading rate as vapour return will be by free flow. Watch the pressure in cargo tanks closely in order to adjust loading rate if required.
If pressure can not be controlled by reducing loading rate, stop loading operations

Hydraulic System for Cargo Valves Failure

Stop cargo operations
Advise the Terminal as to the nature of the problem
Try to repair hydraulic system. Check hydraulic oil tank level if loss is noticed check for leaks. Check filter
Resume loading when problem has been solved

Safety Valves in Cargo Tank Failure

Stop cargo operations
Advise Terminal
Evaluate reason for failure. If Pilot valve suspected to be failing, replace pilot valve
If safety valve has to be overhauled or replaced, consider - leaving the terminal and after repair job has been completed returning to the terminal
Consider - gas free the tank to carry out the repair
Consider - isolating the tank from the other tanks and continue loading in the other tanks. If that is the case monitor pressure in isolated tank.

Water Curtain Failure

The water curtain is used during both Loading and Unloading operations - it is essential for safe operation. Stop cargo operations
Restore the water curtain. Consider - connecting a fire hose to one end of the pipe curtain.
Restart cargo operations

Pumps failure in a Moss cargo tank

In the case of both cargo pumps failing in a Moss cargo tank, the discharge will be carried out by pressuring the tank containing the failed pumps and forcing the liquid into one or more of the other cargo tanks. Manufacturer’s recommendations regarding the arrangement for the tank relief valves has to be referred to. If liquid were transferred to two tanks instead of one tank, then the time to both transfer the liquid to the tanks at sea and the time to discharge the liquid to the terminal once the ship returns would be greatly reduced. Reducing the vapour pressure in the receiving tanks will further increase the transfer rate.

Because of the long time required to pressurise the tank and transfer the liquid, the vessel will normally have to depart the terminal and make the transfer at sea.

One of the ships spray pumps and the LNG vaporiser will be used to create the pressure which is required for discharge.

This procedure is an emergency procedure and as such all relevant ships manuals should be studied prior to commencement of the operation and the ships superintendent kept informed at all times.

Pumps failure in a MEMBRANE cargo tank

In the event of both main cargo pumps failing in a single tank, then the emergency cargo pump must be used. The procedure for this will be found in the ships specific cargo manual. The ships superintendent must be kept informed at all times when this procedure is necessitated.

Related Information:

  1. Liquefied gas carrier safety training

  2. Tackling fire onboard liquefied gas carrier ship

Maintaining tank pressure during a laden voyage

Minor or major leaks from LNG tanks

Compressed air system - Gas carrier immediate actions

Risk of Overfilling of Cargo Tank during Loading

Cargo tank ruptures due to increased pressure - emergency procedure for gas carriers

Loss of power supplies - emergency actions

Emergency Procedures for rescue

// Home page/// LNG handling /// LPG handling/// Sea transport /// Gas products///

Cargo work ///Fire precautions ///Health hazards ///Safety Precautions

///Emergency response ///

Copyright © Liquefied Gas All rights reserved.

The content published in this website are for general reference only. We have endeavoured to make the information as accurate as possible but cannot take responsibility for any errors. For latest information please visit . Any suggestions, please Contact us !

///Links &Resources // Terms of use/// Privacy policy///Home page///