GAS LEAK CLASSIFICATION

(1)Introduction#

(a)In the use of the grade classifications for leakage that follow, consideration must be given to the fact that the analysis of a leak is not an exact science, but rather a judgment decision. Some of the individual grade classifications do not have precise limits because of the variable nature of the factors involved.#

(b)Grade classifications shall only be made by individuals who possess training, experience and knowledge gained through association with leakage work. The judgment of these individuals based upon information gained at the scene of the leak will form the basis for the classification.#

(c)Percentages of gas-in-air are based on natural gas. Where liquefied petroleum, manufactured or other gases are involved, appropriate adjustment shall be made as may be required consistent with the lower explosive limit (L.E.L.) of such gas or mixture of gases.#

(2)Definitions#

(a)Blowing Gas - A leak which can be heard, seen or felt.#

(b)Building - Any structure which is normally or occasionally occupied by humans for business, residential or other purposes.#

(c)Follow-up Inspection - An inspection performed after a repair procedure has been completed in order to determine the effectiveness of the repair.#

(d)Manhole or Vault - A subsurface structure that a man can enter.#

(e)Reading - Shall be construed to be the stabilized reading taken on a combustible gas indicator unit.#

(f)Tunnel - A subsurface passageway of a size large enough for a man to enter.#

(3)Leak Repair Records. A leak repair ticket shall be used for the entire history of a leak through the “follow-up” inspection. The document shall contain information as to corrective action taken and follow-up results when such follow-up is deemed necessary by the operator. Leaks may only be reclassified by responsible and suitably experienced individuals whose identification shall appear on the ticket.#

(4)General Statement. Any leak or odor call from the general public, police, fire or other authorities, or notification of damage to facilities by contractors or other outside sources shall constitute the need for prompt action.#

(5)Grade Classification.#

(a)Grade 1 Leak is a gas leak which due to its location and/or relative magnitude constitutes a potentially hazardous condition to the public or buildings. Grade 1 leaks include, but are not limited to:#

1.Any indication of gas entering buildings or tunnels.#

2.Any reading from a combustible gas indicator within five (5) feet of a foundation wall of a building which in the judgment of the operator is potentially dangerous.#

3.Any reading of at least four percent (4%) or greater gas-in-air on a sidewalk in a wall-to-wall paved area where the volume of the leak presents a potential hazard to persons or property.#

4.Blowing gas.#

5.A leak from a transmission line within Class 3 and 4 locations as specified in Part 192.5 of the OPS regulations.#

6.Four percent (4%) or greater gas-in-air reading in manholes, vaults, or catchbasins.#

7.Any leak which, in the judgment of the supervisor at the scene, is regarded as potentially hazardous.#

(b)Action Required:#

1.It shall require corrective action which shall consist of immediate effort to protect life and property and continuous action until the condition is no longer hazardous and scheduled for immediate daily repair activity.#

(c)Grade 2 Leak shall be a leak that does not constitute an immediate hazardous condition to the public or buildings, but shall be of a nature requiring scheduled repair. Grade 2 leaks include, but are not limited to:#

1.Transmission line leaks not classified as Grade 1 leaks.#

2.A leak on a valve or appurtenance which has migrated beyond the valve box which in the judgment of the operator requires scheduled repair.#

3.Reading between two percent (2%) and four percent (4%) gas-in-air on a sidewalk in a wall-to-wall paved area where the volume of the leak presents a potential hazard to persons or property.#

4.Any reading between two percent (2%) and four percent (4%) gas-in-air in a manhole, vault or catchbasin.#

5.Any Grade 3 leak which under frost conditions could migrate substantially.#

6.A high density of Grade 3 leaks in the street of a business or residential area.#

(d)Action Required:#

1.Grade 2 leaks shall be scheduled for repair within twelve (12) months or shall be rechecked during the next annual survey. Rechecked Grade 2 leaks that have not deteriorated may be rescheduled for repair if they are not in a hazardous location and the repair would be difficult or expensive.#

(e)Grade 3 Leak is any other leak not classified as either a Grade 1 or Grade 2 leak.#

(f)Action Required:#

1.Grade 3 leaks shall be re-evaluated at the next scheduled survey.#

Authority and Administrative HistoryAuthority: T.C.A. § 65-2-102. Administrative History: Original rule certified May 9, 1974. Administrative changes made to this chapter on April 27, 2018 pursuant to Public Chapter 94 of 2017; “Tennessee Regulatory Authority” references were changed to “Tennessee Public Utility Commission,” “Authority” references were changed to “Commission,” “Authority Director” references were changed to “Commissioner,” and “Chief” references were changed to “Director.”#