Tank leak detection

Last updated

Tank leak detection is implemented to alert the operator to a suspected release from any part of a storage tank system, what enables to prevent from soil contamination and loss of product.

Contents

In many countries regulated UST are required to have an approved leak detection method so that leaks are discovered quickly and the release is stopped in time.

Leak detection standards in Europe

European Committee for Standardization EN 13160 shows five different classes (technical methods) of leak detection systems to be used on tanks and pipes. [1]

The number of the class indicates the effectiveness of the installed leak detection system. Class 1 being the highest and class 5 being the lowest level. [2] [3] [4]

Class 1

System inherently safe. Leak is detected before any liquid enters the environment. These systems detect a leak above or below the liquid level of a double wall system. Once a leak is detected, fuel can be removed from the tank before any product enters the environment.

Class 2

System that monitors pressure of a liquid filling the interstitial space of a double wall system. The system alarms on any leak. However, once the tank is breached, the liquid contaminates the product or flows into the ground - in both situations contamination cannot be prevented.

Class 3

Liquid/vapour sensors are placed at the lowest point in a system and detect the presence of liquid or hydrocarbon vapour within the interstitial space. Once a leak is detected an alarm will sound. The sensors cannot detect the failure of outer wall. The product may enter the environment.

Class 4

The system analyses rates of change in tank contents (i.e. leakage into or out of the tank). If a leak is found when operating on a single wall system, the product will always be released to the environment before the leak is detected.

For tanks there are 2 subclasses of the system.

4a System based on fuel reconciliation (measurement of amount sold through the dispenser against the amount that goes out of the tank according to the tank gauge).Any discrepancies release an alarm.

4b Detection of tank leak in quiet periods (liquid level is changing while the tank is not dispensing fuel).

Class 5

In this system monitoring wells with installed sensors are located around the tank site. The sensors detect a leak from the installation. As in case of class 4, the product will always be released to the environment before the leak is detected.

Leak detection standards in the USA

In the USA, the Environmental Protection Agency (EPA) requires owners and operators detect releases from their UST systems. EPA allows three categories of release detection: interstitial, internal, and external. These three categories include seven release detection methods. [5]

Leak detection methods

The ATG must be operated in one of the following modes:

There are methods combining automatic tank gauges with statistical inventory reconciliation where gauge provides liquid level and temperature data to a computer running SIR software, which performs the analysis to detect leaks.

SIR was born in the early 1980s. In SIR methods statistical techniques are applied to inventory, delivery and dispensed data collected over time and are used to determine whether or not a tank system is leaking. On a regular basis, information about the current tank level and complete records of withdrawals and deliveries to UST are proceeded and calculated with the use of computer program that performs a statistical analysis of received data. [5] Replacing simple arithmetic with appropriate statistical procedures allows the leak detection capability of inventory reconciliation to be considerably improved. SIR vendors must demonstrate that they can detect leaks of 0.2 gallons per hour in order to be acceptable as a monthly leak detection method. [9] Such solution enables not only detected tank leakage but also possible theft, over-dispensing or short deliveries. [10]

Vapour Monitoring detects fumes from leaked product in the soil around the leaked tank. It can be categorised into 2 types. Active Monitoring where special tracer chemical added to the UST are detected. Passive Monitoring measures product vapours in the soil around the UST. Special monitoring wells or sampling points must be placed in the tank backfill. A minimum of two wells is recommended for a single tank excavation. Three or more wells are recommended for an excavation with two or more tanks. Used equipment can immediately analyse a gathered vapour or only gather a sample which is then analysed in the laboratory. The system is not inherently safe - by the time the vapor sensors go to alarm, the contamination has likely already occurred. [11] [12]

The method requires a secondary containment, it can be a double wall of the UST where the outer tank wall provides a barrier between the inner tank and the environment. Interstitial methods include the use of a hydrocarbon-sensitive sensor cables or probes connected to a monitoring console. Once the hydrocarbons is detected an alarm goes off. The other method is vacuum monitoring where vapour sensor monitors interstitial spaces of the tank. In case of the leakage the vacuum of the space begins to change. It is also possible to partially fill the interstitial space of the tank with a monitoring fluid (brine or glycol solutions ). Once the level of the fluid changes, a leak may be present. [5] [13]

Monitoring wells are placed close to the UST and allow continuous measurements for leaked product. This methods enables to detect the presence of liquid product floating on the groundwater. The wells can be monitored periodically (at least once every 30-days) with hand-held equipment or with the use of permanently installed monitoring devices. This method cannot be used at sites where groundwater is more than 20 feet below the surface and the subsurface soil or backfill material (or both) consists of gravels, coarse to medium sands, or other similarly permeable materials. A minimum of two wells is recommended for a single tank excavation. Three or more wells are recommended for an excavation with two or more tanks. Product is released to the environment before a leak is detected. [12] [8]

The method requires keeping the tank undisturbed (no liquid is added/subtracted) for a designated period (e.g. 36hours). The length of the testing period depends on the size of the tank and whether the method is used alone or in combination with tank tightness testing. During this period the contents of the tank are measured manually twice, at the beginning and at the end of the period. Significant changes in the volume of the tank’s contents over the test period can indicate a possible leak. [14]

Related Research Articles

<span class="mw-page-title-main">Telemetry</span> Data and measurements transferred from a remote location to receiving equipment for monitoring

Telemetry is the in situ collection of measurements or other data at remote points and their automatic transmission to receiving equipment (telecommunication) for monitoring. The word is derived from the Greek roots tele, 'remote', and metron, 'measure'. Systems that need external instructions and data to operate require the counterpart of telemetry: telecommand.

<span class="mw-page-title-main">Radioactive contamination</span> Undesirable radioactive elements on surfaces or in gases, liquids, or solids

Radioactive contamination, also called radiological pollution, is the deposition of, or presence of radioactive substances on surfaces or within solids, liquids, or gases, where their presence is unintended or undesirable.

<span class="mw-page-title-main">Orica</span> Australian based multinational corporation.

Orica Limited is an Australian-based multinational corporation that is one of the world's largest providers of commercial explosives and blasting systems to the mining, quarrying, oil and gas, and construction markets, a supplier of sodium cyanide for gold extraction, and a specialist provider of ground support services in mining and tunnelling.

<span class="mw-page-title-main">Security alarm</span> System that detects unauthorised entry

A security alarm is a system designed to detect intrusions, such as unauthorized entry, into a building or other areas, such as a home or school. Security alarms protect against burglary (theft) or property damage, as well as against intruders. Examples include personal systems, neighborhood security alerts, car alarms, and prison alarms.

<span class="mw-page-title-main">Underground storage tank</span> Storage tank that is partially or fully underground

An underground storage tank (UST) is, according to United States federal regulations, a storage tank, including any underground piping connected to the tank, that has at least 10 percent of its volume underground.

<span class="mw-page-title-main">Red Hill Underground Fuel Storage Facility</span> Military fuel storage facility in Hawaii

The Red Hill Bulk Fuel Storage Facility is a military fuel storage facility in Hawaii. Operated by the United States Navy, Red Hill supports U.S. military operations in the Pacific.

<span class="mw-page-title-main">Bunding</span> Retaining wall around pollution source

Bunding, also called a bund wall, is a constructed retaining wall around storage "where potentially polluting substances are handled, processed or stored, for the purposes of containing any unintended escape of material from that area until such time as a remedial action can be taken."

<span class="mw-page-title-main">Water tank</span> Container for storing water

A water tank is a container for storing water, for many applications, drinking water, irrigation, fire suppression, farming, both for plants and livestock, chemical manufacturing, food preparation as well as many other uses. Water tank parameters include the general design of the tank, and choice of construction materials, linings. Various materials are used for making a water tank: plastics, fiberglass, concrete, stone, steel. Earthen pots, such as matki used in South Asia, can also be used for water storage. Water tanks are an efficient way to help developing countries to store clean water.

Level sensors detect the level of liquids and other fluids and fluidized solids, including slurries, granular materials, and powders that exhibit an upper free surface. Substances that flow become essentially horizontal in their containers because of gravity whereas most bulk solids pile at an angle of repose to a peak. The substance to be measured can be inside a container or can be in its natural form. The level measurement can be either continuous or point values. Continuous level sensors measure level within a specified range and determine the exact amount of substance in a certain place, while point-level sensors only indicate whether the substance is above or below the sensing point. Generally the latter detect levels that are excessively high or low.

A particle counter is used for monitoring and diagnosing particle contamination within specific clean media, including air, water and chemicals. Particle counters are used in a variety of applications in support of clean manufacturing practices, industries include: electronic components and assemblies, pharmaceutical drug products and medical devices, and industrial technologies such as oil and gas.

<span class="mw-page-title-main">Kongsberg Maritime</span> Norwegian technology company

Kongsberg Maritime (KM) is a Norwegian technology enterprise within the Kongsberg Gruppen (KOG). Kongsberg Maritime deliver systems for positioning, surveying, navigation, and automation to merchant vessels and offshore installations. Their most well known products exist within dynamic positioning systems, marine automation and surveillance systems, process automation, satellite navigation, and hydroacoustics.

<span class="mw-page-title-main">Ultrasonic transducer</span> Acoustic sensor

Ultrasonic transducers and ultrasonic sensors are devices that generate or sense ultrasound energy. They can be divided into three broad categories: transmitters, receivers and transceivers. Transmitters convert electrical signals into ultrasound, receivers convert ultrasound into electrical signals, and transceivers can both transmit and receive ultrasound.

A gas detector is a device that detects the presence of gases in an area, often as part of a safety system. A gas detector can sound an alarm to operators in the area where the leak is occurring, giving them the opportunity to leave. This type of device is important because there are many gases that can be harmful to organic life, such as humans or animals.

The Verifier refers to a proprietary fuel gauge technology, used for advanced measurement of heating oil in residential and commercial tanks ranging from 1,000 – 20,000 gallons. First developed in 2005, by U.S. Energy Group’s Jerry Pindus, Verifier technology was granted Patent Approval 11/095,914 as “The Verifier Digital Fuel Gauge” from The United States Patent and Trademark Office on September 21, 2007. The Verifier is also ETL SEMKO certified.

A flame detector is a sensor designed to detect and respond to the presence of a flame or fire, allowing flame detection. Responses to a detected flame depend on the installation, but can include sounding an alarm, deactivating a fuel line, and activating a fire suppression system. When used in applications such as industrial furnaces, their role is to provide confirmation that the furnace is working properly; it can be used to turn off the ignition system though in many cases they take no direct action beyond notifying the operator or control system. A flame detector can often respond faster and more accurately than a smoke or heat detector due to the mechanisms it uses to detect the flame.

Pipeline leak detection is used to determine if a leak has occurred in systems which contain liquids and gases. Methods of detection include hydrostatic testing, tracer-gas leak testing, infrared, laser technology, and acoustic or sonar technologies. Some technologies are used only during initial pipeline installation and commissioning, while other technologies can be used for continuous monitoring during service.

<span class="mw-page-title-main">Instrumentation in petrochemical industries</span>

Instrumentation is used to monitor and control the process plant in the oil, gas and petrochemical industries. Instrumentation ensures that the plant operates within defined parameters to produce materials of consistent quality and within the required specifications. It also ensures that the plant is operated safely and acts to correct out of tolerance operation and to automatically shut down the plant to prevent hazardous conditions from occurring. Instrumentation comprises sensor elements, signal transmitters, controllers, indicators and alarms, actuated valves, logic circuits and operator interfaces.

A double-walled pipe is a secondary contained piping system. It is a pipe within a pipe, or encased in an outer covering, with an annulus between the two diameters. The inner pipe is the primary or carrier pipe and the outer pipe is called the secondary or containment pipe. The great majority of double-walled piping applications involve wastewater, groundwater, and process safety.

LEDDAR is a proprietary technology owned by LeddarTech. It uses the time of flight of light signals and signal processing algorithms to detect, locate, and measure objects in its field of view.

<span class="mw-page-title-main">Continuous glucose monitor</span> Blood glucose monitoring device

A continuous glucose monitor (CGM) is a device used for monitoring blood glucose on a continual basis instead of monitoring glucose levels periodically by drawing a drop of blood from a finger. This is known as continuous glucose monitoring. CGMs are used by people who treat their diabetes with insulin, for example people with type 1 diabetes, type 2 diabetes, or other types of diabetes, such as gestational diabetes.

References

  1. ↑ "EN 13160 - SGB leak detectors". www.sgb.de.
  2. ↑ "Class 1 Leak Detection - The ultimate protection". www.petrolplaza.com.
  3. ↑ "Choosing the Correct Leak Detection for Tanks". www.petrolplaza.com.
  4. ↑ Unknown [ permanent dead link ]
  5. 1 2 3 US EPA, OLEM (June 9, 2014). "Release Detection for Underground Storage Tanks (USTs)". US EPA.
  6. ↑ "Automatic Tank Gauging (ATG)" (PDF). secure.apps.nd.gov.
  7. ↑ "T2 Center". www.cti.uconn.edu.
  8. 1 2 "Release Detection and Inventory Control for Underground Storage Tanks" (PDF). Archived from the original (PDF) on 2022-07-20.
  9. ↑ L.U.S.T.Line, Bulletin 82, June 2017, p. 1-16.
  10. ↑ "Fuel Prime". www.fuelprime.com.
  11. ↑ Unknown [ permanent dead link ]
  12. 1 2 "Leak Detection Methods For Petroleum Underground Storage Tanks And Piping" (PDF). www.acgov.org.
  13. ↑ "Class I - SGB leak detectors". www.sgb.de.
  14. ↑ "Manual Tank Gauging" (PDF). secure.apps.nd.gov.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.