How valve interlock solutions helped a tank storage company avoid product contamination during cargo loading

Tank storage company


In the tank storage industry, product contamination resulting from product transfer is an obvious risk. Costs related to clean-up, product loss, waste disposal and reputational damage easily mount up to hundreds of thousands of dollars.

Once cause of contamination is the incorrect line-up of valves between the storage tanks and the jetty, resulting in loading an incorrect product or an undesired product mix.


Rather than using a padlock and key to lock hand-operated valves to prevent contamination, the company sought a smart solution. The former approach offers no information about the status of the valves and could lead to incorrect valve line-up when an operation checklist is carried out.

They reviewed various solutions, including position indication and valve automation.

They considered installing motor-operated valves (MOVs) to automate line-up procedures. While automation would make these procedures fast, easy and seemingly flawless, it would also prove costly. After further investigation, they realised an automated system would not offer sufficient security. MOVs are operated remotely or with local controls. Remote operation is regulated by the Distributed Control System (DCS). But local operation would happen outside the control of the DCS. This leaves the risk of unauthorised valve operation.

They also considered the use of position indicators on their manual valves, so valve positions could be monitored in real-time by the DCS. This solution ensures all valves are in their correct position before loading can commence, but it cannot avoid unauthorised operation of valves during the loading process.

When they discovered Sofis’ Valve Line-up Systems, they felt they had identified the most robust and practical solution for guaranteeing valve positions during loading operations.

THE SOLUTION: a valve management system to ensure correct valve line-ups

The Sofis solution to mitigate incorrect valve line-ups is found in many tank terminals around the world. The vital characteristics are mechanical valve interlocks and a reliable Key Management System.

Valve interlocks regulate manual valve operation

Those manual valves operated during critical loading operations are equipped with dedicated interlocks. These double-key interlocks block the manual valves in their fully open or fully closed position. A valve can only be operated when two unique operating keys are inserted into the valve interlock – one open key and one close key. Upon reaching the valve end-stop, one key is trapped and the other released. The free key is then housed in the Key Management System.

OUTCOME: Key Management System issues keys based on DCS input

The tank storage company installed Key Management Systems in different locations in their plant. Operators house free operating keys in such systems. These systems control the issue of operating keys according to operator identification and input from the DCS. The DCS determines the required valve line-up based on the loading operation at hand. It then sends information about the valves that are to be released to the Key Management System in the respective area. This ensures no valves are mistakenly operated or overlooked. After operating the valves, the operator returns the keys to the Key Management Systems. This then confirms the end of the valve changeovers to the DCS, which initiates the loading procedure.


Eliminate risks and improved efficiency

  • Using the SOFIS contamination control system, the tank terminal eliminates the risk of product contamination, while improving the efficiency of their line-up operation.

Eliminate risk of incorrect valve line-ups

  • As all valve operations are authorised by DCS input, incorrect valve operations cannot happen.

Easy and fast valve change-overs

  • Operators carry out their tasks right the first time.
  • With portable actuators, they operate valves up to 80% faster and with less physical effort.
  • Based on real-time valve status information, the DCS automatically starts the loading operation once the valve line-up is completed.

Simultaneous valve line-up operations

  • The terminal consists of three plant areas, which are all involved in a single line-up. Their Key Management System enables our customer to operate in the different areas in parallel, which saves them up to 67% line-up time.

Advanced analytics by logging key movements

  • A Key Management System logs all key movements to offer advanced analytics about changeover procedures.
  • It notices significant deviations from typical valve changeover times.
  • It collects operational line-up and loading data, to add to big data analysis.

Need a valve interlock solution? Teksal Safety is the Australian distributor for Sofis (formerly Smith Flow Control) valve interlocking and process safety systems, and supports Sofis’ complete range, including supply, installation, commissioning and training services.

For more information about any of these products, call our office, email