Overfill Prevention and Tank Gauging

Hazardous liquid storage facilities face significant challenges when it comes to mitigating the risks of overflows. Overflows can result in severe consequences, and all liquid storage facilities must continually safeguard against storage errors and breakdowns that can result in costly or life-threatening accidents.

Health, safety, and environmental damage are major consequences of hazardous liquid overflows, and lawsuits and fines often follow. The hazardous liquids industry has established API/ANSI Standard 2350 to define and prevent overfills in facilities that store hazardous liquids. In this post, we discuss a few of the biggest aspects of these regulations, as well as some best practices regarding how your facility can adequately prevent overfills and overflows.


Safety Management Systems and Management’s Roleoverfill prevention process

The first priority of overfill prevention is to define your facility’s safety management system (SMS) and draw from your management’s experience to mitigate the risk. A good SMS includes information on the following topics to implement a quality overfill protection process (OPP):

  • Protocol
  • Training
  • Sensors
  • Equipment
  • Infrastructure
  • Expertise
  • Emergency response

After several costly overfill events occurred in the 1970s and 1980s, industrial organizations developed proactive protocols and information intended to prevent these mistakes from damaging the wider community. These organizations determined that good OPPs start from the top, and senior-level management must support, develop, and execute OPPs. The most well-known OPP, known as the Shewart Cycle, uses the acronym PDCA (Plan, Do, Check, Act) and has become a common guideline used by hazardous liquid storage facilities.

OPP implementation is a critical aspect of a facility’s SMS. Setting up these standards will help you develop protocols for:

  • Formal emergency action procedures (EAPs)
  • Proper training of personnel
  • Installation of necessary equipment
  • System inspection and follow-up procedures

OPPs within an SMS accomplish several goals in safeguarding a storage facility’s health, safety, and environmental obligations. These include: 

  • Prioritizing OPPs within the SMS
  • Providing tools and equipment for hazard prevention
  • Establishing processes that evaluate events and near misses
  • Dedicating specialized budgets to implement OPPs
  • Training personnel in overfill prevention 

An SMS that focuses on OPPs significantly reduces the risk of potential overflow events and the damage they cause. Implementing quality OPPs also helps facilities prevent overfills before they cause catastrophic damage.


API 2350 and Overfill Preventionhazardous liquid overfill prevention

Applying OPPs will also improve your facility’s operational efficiency and capacity. Additional benefits include reduced litigation costs, improved public relations, and the protection of equipment and assets, all of which significantly improve an organization’s bottom line.

Current API 2350 regulations establish the following procedures:

  • Individualized OPPs
  • Adequate overfill risk assessment
  • Instrumentation and control equipment technology upgrades
  • Inclusion of OPPs within other control system–based safety standards 

API 2350 standards seek to be proactive instead of reactive, and as such, they’re continually updated based on data from liquid storage facilities located around the world.


Regulatory Framework and Best PracticesRegulatory Framework and Best Practices

Process safety management is not new. However, although liquid storage facility management procedures have been in place since the birth of liquid storage facilities, great strides have been taken in recent decades to standardize and regulate against the wide range of potential risks most industrial practices now pose. Regulators and other third parties have developed integrated systems that act as the first line of defense against catastrophic events. 

Best SMS practices take a multilayered approach to OPPs, and each layer helps contain overfills or prevent them entirely. Some of these layers include: 

  • Alerts and operator interventions to maintain normal function
  • Emergency shutdown procedures
  • Triggering of automated risk-prevention systems
  • Containment procedures
  • Emergency action plans 

Implementing a proper SMS will help your facility’s personnel develop procedures that will enable them to work as a team to prevent overfills and other safety risks.


Risk Assessment and Managementoverfill risk assessment and management

Most facilities face dilemmas when it comes to maintaining the health and safety of their employees and wider community while optimizing processing, transportation, and distribution. The choices that facility managers face mean that having good risk assessment and risk management procedures is more necessary than ever for overfill prevention.

Risk assessment and risk management have similar aims, but they also carry some important distinctions:

  • Risk assessment determines the likelihood of an overfill event and its potential consequences. Risk assessment procedures define an organization’s strategic objectives and then specify the actions or decisions necessary to execute these objectives.
  • Risk management procedures kick into gear after one or more risk factors have already taken place. These procedures allow employees to assess the level of risk and quickly determine the necessary steps to mitigate this risk’s effects on the facility or environment.

Tank GaugingTank Gauging

Many facilities use tank gauging systems to monitor their storage tanks for fluctuations and other irregularities. Tank gauging systems can be either manually or automatically operated:

  • Manual gauging requires an operator to periodically measure tank liquid levels using either measuring tape or an electronic hand line.
  • Automatic gauging relies on electronic measuring systems to continuously monitor tank levels.

Both tank gauging practices are essential parts of a facility’s OPP because each reinforces the accuracy of the other.


Level Measurement Reliability

The worst type of system failure is one where the danger goes undetected for far too long. Most facilities protect against this risk by performing careful reliability assessments of their parts and equipment.

Many companies keep careful logs that track each part’s failure rate. They also ensure that all systems include redundancies or backup circuits, which provide alternatives in case the main avenues of repair are blocked.

Failure levels are also tracked across the entire industrial sector. Some third parties collect data regarding the failure rate of a given part or component across the entire industry. They use this macrodata to calculate a part’s functional safety aspect, which they categorize as the part’s Safety Integrity Level (SIL).

safety integrity levels


Facility managers must tailor their emergency-response procedures so they can be as effective as possible within the constraints of their environment. Factors such as the facility’s size, materials handled, and amount and level of training of its employees must all be taken into account when developing OPPs.

Procedures designed to prevent overfills touch on all aspects of a plant’s operation. Areas that require risk-management procedures include:

  • Basic and unique operations
  • Operator training
  • Maintenance and inspection
  • Testing and calibration
  • Abnormal operations
  • Equipment systems
  • Management of change
  • Safe operating limits
  • Pre-startup and post-shutdown
  • AOPS

How to Develop an OPP

OPPs must be integrated into a company’s existing SMS, but doing so can pose some challenges. Good risk assessment and risk-management procedures can be hindered by budgetary constraints,the level of training your employees possess, and the efficiency of the equipment they use. The system you develop must also be able to adapt to changing rules and equipment, as integrating new management systems with existing ones can get tricky if not properly handled.

Endress+Hauser designs a wide range of overfill prevention systems for hazardous liquid storage management facilities across the country. We’re experts in fluid storage and transport, and we provide experienced consulting and quality products that will optimize your facility’s health and safety procedures without sacrificing its ability to operate efficiently.

Contact us to learn more about how Endress+Hauser provides both technology and guidance for overfill protection risk prevention and management.

API 2350 Guidebook

Why download the new API 2350 Guidebook?

  • An overfill event is one of the most significant sources of risk
  • This guidebook provides best practices to prevent overfill events
  • The new edition helps you understand the requirements and includes the latest updates
Download the Guide