Division B
Acceptable Solutions

Part 4 — Flammable and Combustible Liquids

Section 4.4. Leak Detection of Storage Tanks and Piping Systems

4.4.1. General

4.4.1.1. Application
1) Intent StatementExcept as provided in Sentence (2) and except as otherwise specified in this Code, this Section provides the minimum requirements regarding the detection of leaks in aboveground and underground storage tanks, piping systems and sumps.
2) Intent StatementThis Section shall not apply to storage tanks that have been taken out of service in compliance with the applicable provisions of Subsection 4.3.16.
4.4.1.2. Frequency and Methods of Leak Detection Testing and Monitoring
1) Intent StatementEvery storage tank, piping system and sump, including those at fuel-dispensing stations, shall be tested and monitored for leaks in conformance with Tables 4.4.1.2.A to 4.4.1.2.E, which establish the minimum requirements regarding the frequency and methods to be used for
a) commissioning testing,
b) subsequent in-service monitoring, and
c) testing when a leak is suspected.
change begin(See Appendix A.)change end
2) Intent StatementThe methods referred to in Sentence (1) shall conform to Subsections 4.4.2. to 4.4.4.
3) Intent StatementThe commissioning testing referred to in Sentence (1) shall be performed at the time of installation
a) once backfill and surfacing have been completed but before being put into service, in the case of an underground storage tank or underground piping system,
b) before being put into service, in the case of an aboveground storage tank or exposed piping system, and
c) once the final surface materials have been installed but before being put into service, in the case of a sump.
4) Intent StatementThe frequency of the in-service monitoring referred to in Sentence (1) shall be calculated from the date of the commissioning test.
5) Intent StatementImmediate action shall be taken when a leak is suspected and the leak detection testing referred to in Sentence (1) shall be performed if
a) a loss of liquid or a gain of water is indicated by any of the leak detection measures described in this Section, or
b) the level of water at the bottom of an underground storage tank exceeds 50 mm.
6) change beginWhere dispenser sumps, transition sumps and turbine sumps are provided with electronic monitoring devices in accordance withchange end  change beginSentence 4.3.9.3.(1)change end, change beginthe devices shall be interlocked with the dispenser or pump to shut it down upon detection of either product or a high liquid level.change end

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7) Intent StatementThe minimum requirements referred to in Sentence (1) shall not preclude the appropriate use of alternative solutions, innovative new technologies, or methods capable of achieving the same objectives. (See Appendix A.)
Table 4.4.1.2.A
Leak Detection Testing and Monitoring of Underground Storage Tanks
Forming part of Sentences 4.4.1.2.(1) and 4.4.2.1.(5)
Type of Containment Commissioning Test In-Service Monitoring Leak Suspected
Continuous Periodic

Single-walled(1)

N/A(2)

 Inventory Reconciliation

Precision Leak Detection Test every 2 years

Precision Leak Detection Test
Inventory Reconciliation and Monitoring Wells

Precision Leak Detection Test every 5 years

Statistical Inventory Reconciliation (SIR)
Automatic Tank Gauge None required
Continuous In-Tank Leak Detection

Double-walled(3)

change end

Precision Leak Detection Test or Secondary Containment Test(4)

 Secondary Containment Monitoring None required

Precision Leak Detection Test or Secondary Containment Test(4)
Notes to Table 4.4.1.2.A:
(1) Applies to single-walled storage tanks of typical construction, including storage tanks that do not meet the requirements for double-walled storage tanks.
(2) change beginNot applicable because underground storage tankschange end must be of double-walled construction as per Sentence 4.3.8.1.(1).change end
(3) Applies to double-walled storage tanks, which have an interstitial space that allows for monitoring using high- or low-tech methods.
(4) The Secondary Containment Test is a change beginprecision testchange end capable of detecting leaks in the interstitial space of the storage tank. Risers, connections and vents are also susceptible to leakage and must therefore also be precision-tested.
Table 4.4.1.2.B
Leak Detection Testing and Monitoring of Aboveground Storage Tanks
Forming part of Sentence 4.4.1.2.(1)

Type of Containment(1)

 Commissioning Test In-Service Monitoring Leak Suspected
Continuous Periodic

Contained open(2)

vertical tank

Visual inspection(3) during Liquid Media Test

Inventory Reconciliation and Secondary Containment Monitoring

API 653 or

Tank floor inspection every 10 years

API 653 or

Tank floor inspection

Contained open(2)

horizontal tank

Visual inspection(3) during Liquid Media Test

None required

Visual inspection(3)

Double-walled(4)

Visual inspection(3)

 Secondary Containment Monitoring None required Secondary Containment change beginTestchange end
Notes to Table 4.4.1.2.B:
(1) See Subsection 4.3.7.
(2) Applies to storage tanks contained in an open arrangement that do not meet the requirements for double-walled storage tanks and do not conform to Subsection 4.3.7.
(3) Visual leak detection may apply to single- or double-walled storage tanks and piping. See Sentence 4.4.2.1.(8).
(4) Applies to double-walled storage tanks, which have an interstitial space that allows for monitoring using high- or low-tech methods.
Table 4.4.1.2.C
Leak Detection Testing and Monitoring of Underground Piping Systems
Forming part of Sentence 4.4.1.2.(1)
Type of Containment Commissioning Test In-Service Monitoring Leak Suspected
Continuous Periodic

Single-walled(1)change beginand single-walled, buried mechanical threaded connectionschange end(2)

change end		 N/A(3) Inventory Reconciliationchange end

Pipe Leak Detection Test(4) every 2 years change begin(annually for mechanical connections)change end

 Pipe Leak Detection Test(4)
Inventory Reconciliation and Monitoring Wells

Pipe Leak Detection Test(4) every 5 yearschange begin(annually for mechanical connections)change end
SIR

Single Check Valve(5)
change beginElectronic Line Leak Detection (with a detectable limit of 0.76 L/h monthly)change end change beginElectronic Line Leak Detection (with a detectable limit of 0.38 L/h annually)change end
change beginContinuous Electronic Line and Tank Leak Detection (with a detectable limit of 0.76 L/h monthly)change end change beginContinuous Electronic Line and Tank Leak Detection (with a detectable limit of 0.38 L/h annually)change end

Double-walled(6)

Pipe Leak Detection Test change beginandchange end Secondary Containment Test(7)

Secondary Containment Monitoring

 None required

Pipe Leak Detection Test(4) or Secondary Containment Test(7)
Notes to Table 4.4.1.2.C:
(1) Applies to single-walled piping systems of typical construction, including piping systems that do not meet the requirements for double-walled piping systems.change end
(2) change beginSee Article 4.5.5.6.change end
(3) change beginNot applicable because underground piping systems must be of double-walled construction as per Sentence 4.5.6.1.(1).change end
(4) change beginThe Pipe Leak Detection Test results shall conform to Sentence 4.4.3.4.(9) with a probability of detection of 0.95 or greater and a probability of false alarm of 0.05 or less.change end
(5) Applies to suction line only.
(6) Applies to double-walled piping systems, which have an interstitial space that allows for monitoring using high- or low-tech methods. Monitoring in a sump can be done in accordance with Table 4.4.1.2.E.
(7) The Secondary Containment Test shall conform to Article 4.4.3.3.
Table 4.4.1.2.D
Leak Detection Testing and Monitoring of Exposed Piping Systems
Forming part of Sentence 4.4.1.2.(1)
Type of Containment Commissioning Test In-Service Monitoring Leak Suspected
Continuous Periodic

Single-walled(1)

 Pipe Leak Detection Testchange end Visual inspection(2) None required Identify and repair
Flexible hose lines over water Pipe Leak Detection Test(3) every 12 months

Double-walled(4)

 Secondary Containment Monitoring None required change beginIdentify and repairchange end

Contained open(5)

 Visual inspection(2) None required change beginIdentify and repairchange end
Notes to Table 4.4.1.2.D:
(1) Applies to single-walled piping systems of typical construction, including piping systems that do not meet the requirements for double-walled or contained open piping systems.
(2) change beginSee Sentence 4.4.2.1.(8).change end
(3) change beginThe Pipe Leak Detection Test results shall conform to Sentence 4.4.3.4.(9) with a probability of detection of 0.95 or greater and a probability of false alarm of 0.05 or less.change end
(4) Applies to double-walled piping systems with an interstitial space contiguous to the primary containment that can be monitored using high- or low-tech methods.
(5) Applies to piping systems contained in an open arrangement that do not meet the requirements for double-walled piping systems and do not conform to Subsection 4.3.7.
Table 4.4.1.2.E
Leak Detection Testing and Monitoring of Turbine, Transition, Dispenser change beginand Spill Containmentchange end Sumps
Forming part of Sentence 4.4.1.2.(1)
change beginType of Containmentchange end Commissioning Test In-Service Monitoring Leak Suspected
Continuous Periodic
change beginDispenser, turbine and transition sumpschange end

Static Liquid Media Leak Detection Test(1)

change end		 change beginWeekly visual inspection or electronic monitoringchange end(2) change beginAnnual visual inspectionchange end Identify and repair
change beginSpill containment sumpschange end change beginWeekly visual inspection at fill pointchange end
Notes to Table 4.4.1.2.E:
(1) See Article 4.4.3.5.
(2) change beginElectronic monitoring devices need to be tested at least once annually in conformance with the manufacturer’s recommendations.change end

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4.4.1.3. Remedial Action
1) Intent Statementchange beginExcept as provided in Sentence (2),change end when a leak detection test required by this Section detects a leak in a storage tank, piping system or sump, the leaking components or system shall be
a) repaired and tested,
b) replaced, or
c) removed.
2) Intent Statementchange beginWhen a leak detection test required by this Section detects a leak in a single-walled construction underground storage tank or piping system, the leaking components or system shall be
a) replaced in conformance with Articles 4.3.8.1. and 4.5.6.1., or
b) taken out of service in conformance with Subsection 4.3.16.
3) Intent StatementWhere a leak is detected as described in Sentence (1) or (2), the escaped liquid shall be removed in conformance with Subsection 4.1.6.change end
4.4.1.4. Retention of Records
1) Intent StatementRecords of the tests referred to in this Section shall be retained in conformance with Article 2.2.1.2. of Division C.

4.4.2. Leak Detection Testing and Monitoring Methods

4.4.2.1. Definition and Performance of Leak Detection Testing and Monitoring Methods
1) Intent StatementThis Subsection applies to the leak detection testing and monitoring methods referred to in this Section.
2) Intent StatementInventory reconciliation referred to in this Section shall
a) change beginfor the time period designated, determine product loss or gain based on the reconciliation ofchange end
i) change beginchange in physical inventory,change end
ii) change begininventory additions (deliveries),change end
iii) change begininventory removals (sales), andchange end
iv) change beginmiscellaneous inventory alterations, andchange end
b) change begindetermine the level of water in the tank.change end
change begin(See Appendix A.)change end
3) Intent Statementchange beginA leak detection method that monitors vapours in the soil or liquids on the groundwater shall conform to good engineering practice and meet the requirements of vapour monitoring or groundwater monitoring systems.change end (See Appendix A.)
4) Intent StatementStatistical inventory reconciliation (SIR) methodology shall change beginbe capable of detecting a leakchange end
a) change beginof 0.38 L/h with a probability of detection of 0.95 or greater and a probability of false alarm of 0.05 or less, based on an inventory record of specified length to be considered as an annual test, orchange end
b) change beginof 0.76 L/h with a probability of detection of 0.95 or greater and a probability of false alarm of 0.05 or less, based on an inventory record of specified length to be considered as a monthly test.change end
(See Appendix A.)
5) Intent StatementWhere inventory reconciliation is performed using automatic tank gauging referred to in Sentence (2), the system shall conform to change begingood engineering practice and meet the requirements of a precision leak detection test when a leak is suspected in conformance with Table 4.4.1.2.A (See Appendix A.)change end
6) Intent StatementA continuous in-tank leak detection system shall conform to good engineering practice and meet the requirements of a precision leak detection test. (See Appendix A.)
7) Intent StatementHigh-tech secondary containment monitoring referred to in this Section shall include the use of an automatic device that continuously monitors the interstitial space between the inner tank or inner piping and the secondary containment. (See Sentence 4.3.7.7.(1).) (See Appendix A for low-tech method.)
8) Intent StatementVisual inspection referred to in this Section shall,
a) in the case of an exposed piping system, conform to Article 4.5.10.5., and
b) in the case of an aboveground storage tank, consist of
i) a visual examination of the tank shell, or
ii) if the bottom of the tank is not amenable to a visual examination, testing the bottom of the tank (see Appendix A).
9) Intent StatementA static liquid media leak detection test shall conform to Article 4.4.3.5.
10) Intent StatementThe precision leak detection test for underground storage tanks that is referred to in this Section shall
a) be capable of detecting a storage tank leak rate as small as 0.38 L/h within 24 h with a probability of detection of 0.95 or greater and a probability of false alarm of 0.05 or less (see Appendix A), and
b) be conducted by an individual who has been trained in the proper care and use of the test equipment and the operating procedures.
(See also Sentences 4.4.3.1.(2) and (3).)
11) Intent StatementPipe leak detection referred to in this Section shall conform to ULC/ORD-C107.12, “Line Leak Detection Devices for Flammable Liquid Piping.” (See also Articles 4.4.3.3. and 4.4.3.4.)
12) Intent StatementA single vertical check valve referred to in this Section shall
a) consist of a vertical check valve located immediately under the pump,
b) be installed with no other check valve between the suction pump and the storage tank, and
c) be part of an installation where lines must be sufficiently sloped so that any liquid in the line will drain back into the storage tank should a leak occur in the piping system.
(See Appendix A.)

4.4.3. Leak Detection Testing of Storage Tanks, Piping Systems and Sumps

4.4.3.1. Leak Detection Tests
1) Intent StatementWhere field test methods are included in the storage tank construction standards referred to in Articles 4.3.1.2. and 4.3.1.3., such tests shall be permitted for storage tanks conforming to those standards.
2) Intent StatementIf a precision leak detection test referred to in Sentence 4.4.2.1.(10) detects a leak rate exceeding 0.38 L/h on an underground storage tank, the tank shall be considered to be leaking.
3) Intent StatementDuring a leak detection test on a storage tank, the pressure at the bottom of the tank shall not exceed the tank manufacturer's specifications.
4.4.3.2. Pneumatic Leak Detection Tests
1) Intent StatementPneumatic leak detection tests using compressed air shall not be performed on storage tanks and piping systems having once contained flammable liquids or combustible liquids.
2) Intent StatementExcept as provided in Sentence (1), pneumatic leak detection tests using compressed air or an inert gas shall include the application of soap and water to the storage tank and piping surface, fittings, joints and connections to help in the detection of leaks.
3) Intent StatementIn the case of underground storage tanks or piping, the test referred to in Sentence (2) shall be conducted prior to covering the tank or piping system.
4) Intent StatementWhere a pneumatic leak detection test is conducted before an underground storage tank is backfilled, in the case of a new tank, or after the tank is uncovered, in the case of a previously installed tank, the test pressure shall be in conformance with the production testing requirements of
a) ULC-S603, “Steel Underground Tanks for Flammable and Combustible Liquids,” or
b) ULC-S615, “Reinforced Plastic Underground Tanks for Flammable and Combustible Liquids.”
5) Intent StatementPneumatic leak detection tests shall not be performed on field-erected aboveground storage tanks.
6) Intent StatementMeasures shall be taken to guard against the hazards associated with pneumatic leak detection testing in areas where explosive mixtures of flammable liquid or combustible liquid vapours and air may be present in the vicinity of a storage tank that has been in use.
4.4.3.3. Protocols for Pneumatic Leak Detection Testing of Piping Systems
1) Intent StatementA pressure decline test using an inert gas is permitted to be used as a leak detection test for piping systems that
a) are new or in use, and
b) convey a volume of less than 1 000 L.
2) Intent StatementA pressure decline test performed on a piping system shall conform to Sentences (3) to (9).
3) Intent StatementThe design and installation of the piping system permitting, the piping system's contents shall be drained prior to conducting the pressure decline test procedure.
4) Intent StatementPumps, dispensers and other auxiliary equipment that are connected to the piping system and cannot withstand the pressure of the test shall be isolated from the test procedure to prevent damage to the equipment.
5) Intent StatementA stabilization period of up to 30 min is required after pressurization.
6) Intent StatementPipe volumes of 500 L or less shall be pressurized for at least 60 min after stabilization.
7) Intent StatementPipe volumes greater than 500 L but less than 1 000 L shall be pressurized for at least 2 h after stabilization.
8) Intent StatementTest pressures shall
a) be the greater of 350 kPa (gauge) or 1.5 times the maximum operating pressure, and
b) not exceed the piping manufacturer's test specifications.
9) Intent StatementThe piping system shall be considered to be leaking if any pressure decline is detected within the time periods stated.
4.4.3.4. Protocols for Liquid Media Leak Detection Testing of Piping Systems
1) Intent StatementLiquid media leak detection testing of piping systems shall conform to Sentences (2) to (9).
2) Intent StatementTest devices and methods shall conform to the performance requirements of ULC/ORD-C107.12, “Line Leak Detection Devices for Flammable Liquid Piping.”
3) Intent StatementTests shall be conducted by an individual who has been trained in the proper use of the test device and the operating procedures.
4) Intent StatementA sufficient amount of time shall be allocated to stabilize the temperature of the liquid throughout the volume of the piping during the test.
5) Intent StatementExcept as provided in Sentences (6) and (7), test pressure shall
a) be the greater of 350 kPa (gauge) or 1.5 times the maximum operating pressure, and
b) not exceed the piping manufacturer's test specifications.
6) Intent StatementTest pressures exceeding 700 kPa (gauge) shall not be permitted unless the piping system is designed for such pressures.
7) Intent StatementWhere test pressures exceed the design pressures for pumps or similar components connected to the piping system being tested, such pumps or components shall be isolated from the test procedure.
8) Intent StatementClass I liquids shall not be used for pressure testing piping systems, except that pressure piping normally containing Class I liquids is permitted to be tested with such liquids at pressures not exceeding their maximum operating pressures.
9) Intent StatementThe piping system shall be considered to be leaking if the leak rate exceeds 0.38 L/h.
4.4.3.5. Protocols for Leak Detection Testing of Sumps
1) Intent StatementStatic liquid media leak detection testing of turbine, transition, dispenser and pump sumps shall conform to Sentences (2) to (4).
2) Intent Statementchange beginStatic liquid media testing of sumps shall be performed at the installation stage after all electrical and mechanical work passing through the sump wall has been completed but before any backfilling around the exterior of the sump is completed.change end
3) Intent StatementThe liquid used for the test shall
a) exceed the elevation of the piping and other points of entry into the sump change beginby at least 50 mmchange end, and
b) not be a flammable liquid or a combustible liquid.
4) Intent StatementThe minimum duration of the test shall be 1 h change beginwith no visual or measured evidence of leakagechange end.

4.4.4. Leak Detection Monitoring of Storage Tanks and Piping Systems

4.4.4.1. Inventory Reconciliation
(See Appendix A.)
1) Intent StatementWhere inventory reconciliation is required by this Section, the liquid level in any storage tank shall be measured at intervals not greater than 7 days in conformance with Sentences (2) to (4), except that at fuel-dispensing stations the measurements shall be taken each day the station is in operation.
2) Intent StatementThe level of water at the bottom of an underground storage tank shall be measured at intervals not greater than 7 days, except that at fuel-dispensing stations the measurements shall be taken each day the station is in operation.
3) Intent Statementchange beginInvestigative action shall be undertaken if the inventory reconciliation described in Sentence 4.4.2.1.(2) indicates the following inexplicable conditions:
a) a monthly loss of
i) 0.5 percent or more of the throughput from an underground storage tank, or
ii) 1.0 percent or more of the throughput from an aboveground storage tank,
b) three consecutive losses greater than 200 L/day, and
c) a water level greater than 50 mm.change end
4) Intent StatementA record of the measurements for each storage tank and of the computations described in Sentence (3) shall be retained, in conformance with Article 2.2.1.2. of Division C.
4.4.4.2. Leakage Detection
1) Intent StatementWhere continuous leak detection is provided on an underground piping system, it shall conform to ULC/ORD-C107.12, “Line Leak Detection Devices for Flammable Liquid Piping.”