Regulation of Dangerous Goods

5.1.1.1

Pursuant to section 113(1) of Cap. 295G:

If a tank has been used for the storage of S2DG but is no longer so used, the person who owns or possesses the tank must—

(a) take necessary steps to decommission the tank; and
(b) inform the Director on completion of the decommissioning.

5.1.1.2

Pursuant to section 113(3) of Cap. 295G:

A person who without reasonable excuse contravenes subsection (1) commits an offence and is liable on conviction to a fine at level 4 and to imprisonment for 2 months.

5.1.2.1

5.1.2.2

5.1.2.3

5.1.3

5.1.3.1

Prior to the commencement of any decommissioning works, sufficient planning is needed to identify the hazards and decide a proper mode and safe method of decommissioning. The plan shall also be reviewed and revised from time to time and shall take, including but not limited to, the following factors into consideration:

(a) the types of the DG and/or hazardous gas/vapour involved;
(b) the method used to treat the DG and/or hazardous gas/vapour;
(c) the mode of decommissioning the tank as stipulated in 5.1.3.1.1;
(d) the hazards arisen from decommissioning works, e.g. treatment of DG, dismantling, cutting, lifting the tank;
(e) the hazards associated with the integrity and stability of the tank; and
(f) the disposal of chemical waste.

5.1.3.1.1

In deciding the mode of decommissioning, the tank and associated pipework shall normally be removed from the site permanently. It is reminded that the removal work might be considered as a demolition under the Buildings Ordinance (Cap. 123). However, if the tank and associated pipework had to be left in situ due to any constraints or various reasons, e.g. structural safety concerns, appropriate steps shall be taken to make the tank permanently or temporarily safe having considered the possibility of future reinstatement of the tank. The three modes of decommissioning the tank are summarised below:

(a) permanent decommission with the tank removed;
(b) permanent decommission with the tank left in situ; and
(c) temporary decommission with the tank left in situ.

5.1.3.1.2

In case the tank is to be left in situ, it is important to note that the completion of the procedures in this Part will not exempt any obligation to obtain any necessary approval from the other government departments, e.g. Buildings Department, Environmental Protection Department, Lands Department, nor act as a waiver of any terms in any lease, licence or etc. granted by the Government for leaving the tank. For example, the Petrol Filling Station (PFS) operator may also need a consent from the Environmental Protection Department, Lands Department and the other relevant government departments in order to leave the tank in situ subsequent to the closure of the PFS.

5.1.3.1.3

It is important to note that any decommissioning works shall only be carried out by persons specialising in that type of works. Advice from the DG manufacturer/supplier and tank manufacturer/supplier shall be sought in order to clear all the DG and decommission the tank safely. In addition, all the tests conducted shall be properly recorded and submitted to FSD upon completion of decommissioning.

Necessary Steps for Decommissioning a Tank

5.1.4.1

Decommission of Oil Storage Installation in Oil Terminal

5.1.4.1.1

The steps stipulated in 5.1.4.2 to 5.1.4.4 are not applicable to the decommissioning of oil storage installation (OSI)³¹ as defined in the Buildings Ordinance (Cap. 123), whether it is to be removed or left in situ, since the decommissioning of OSI is also regulated under the Buildings Ordinance (Cap. 123). Prior approval shall be sought from FSD in respect of the decommissioning methods on a case-by-case basis before the commencement of the decommissioning works. Reference could be made to API Standard 2610 3rd Edition (2018) or equivalent national or international standards. Moreover, it is important to note that FSD shall still be informed upon completion of the decommissioning as stipulated in 5.1.5.

³¹ Pursuant to section 2 of Cap. 123:
“oil storage installation” means any tank having a capacity of not less than 110 000 litres, or a group of tanks any one of which is a tank having a capacity of not less than 110 000 litres, constructed above ground level for the purpose of storing petroleum products.

5.1.4.2

Permanent Decommission with the Tank Removed

5.1.4.2.1

The tank and the associated pipework shall first be rendered safe in the following aspects before any removal works to be conducted:

5.1.4.2.1.1

All the remaining DG inside the tank and the associated pipework shall first be removed.  They shall be cleaned as far as reasonably practicable to remove the residual DG, or they shall be subject to a process in which their contents are neutralised, cured or chemically deactivated; and

5.1.4.2.1.2

The atmosphere inside the tank and the associated pipework shall be cleared of hazardous gas or vapour, e.g. flammable vapour.  Appropriate degassing or inerting methods shall be used having considered the type of gas or vapour present and the removal works to be conducted, e.g. cutting, dismantling, lifting.  If flammable gas or vapour is involved, Certification of Flammable Vapour Free shall be made by the person approved by FSD under section 105(2) of Cap. 295G.

5.1.4.2.2

Acceptable methods to render the tank and associated pipework safe include:

5.1.4.2.2.1

Hydrophobic foam fill for hydrocarbon fuel tank
In order to render a hydrocarbon fuel tank safe, all the residual fuel is firstly removed as far as reasonably practicable, and then, hydrophobic foam having a designed compressive strength of 8 tonnes/m² is generated on-site and pumped directly into the tank and associated pipework via the fill pipe. It shall be noted that foam of this density is appropriate for rendering the tank safe for a period not exceeding six months;

5.1.4.2.2.2

Nitrogen foam fill for hydrocarbon fuel tank

For a hydrocarbon fuel tank with all the residual fuel removed as far as reasonably practicable, high-expansion foam, produced in a generator using nitrogen, water and a detergent foam compound, is then introduced into the tank and the associated pipework via the fill pipe.  Unless the tank has been completely filled with nitrogen foam, the atmosphere inside the tank and the associated pipework shall be tested to ensure that the oxygen level has been reduced to below 5%.  An opening to the tank for testing can be created by disconnecting the vent pipe at the tank top after the theoretical quantity of foam required to fill the tank has been added.  Non-sparking tools or equipment shall be used for this operation.  Removing the vent pipe in this way will also allow the foam to overflow more readily from the vent opening.  The atmosphere will only remain safe for a limited period of time (e.g. 24 hours);

5.1.4.2.2.3

Nitrogen gas purging for hydrocarbon fuel tank

For a hydrocarbon fuel tank with all the residual fuel removed as far as reasonably practicable, all the openings shall be sealed except those required for the inlet of nitrogen and the exhaust outlet (usually the vent pipe outlet, flame trap outlet).  Nitrogen is introduced continuously into the tank at one point, causing the air and vapour to be purged from another opening, remote from the first opening, in a safe position.  The nitrogen shall then be introduced, and the mixture leaving the tank shall be vented so that the tank remains at the atmospheric pressure throughout the entire operation.  To ensure a constant pressure is maintained when carrying out this process, it is recommended that the nitrogen gas be introduced directly from an industrial gas supplier’s tank-vehicle, which is fitted with the necessary pressure reducing valves and measuring equipment.  The atmosphere in the tank and the associated pipework shall be tested and purging shall be continued until the oxygen level has been reduced to below 5%.  On completion of the purging, the openings of the tank shall be sealed.  The tank atmosphere will only remain safe for a limited period of time (e.g. 24 hours);

5.1.4.2.2.4

Water fill for hydrocarbon fuel tank

For a hydrocarbon fuel tank with all the residual fuel removed as far as reasonably practicable, the suction pipe(s) shall be disconnected and the tank connecting points sealed.  The tank shall then be filled completely with water, with care being taken to ensure that any water or residual fuel does not overflow from the fill point.  Surplus water or residual fuel shall, if necessary, be removed from the fill pipe to avoid an outflow when the vent pipe is disconnected from the tank.  The vent pipe shall then be disconnected and the tank connection point and fill point sealed.  Extreme care has to be taken when using a mechanical plant to avoid puncturing the tank and causing an escape of contaminated water.  It is, therefore, important that periodic checks are made to ensure that no water has leaked out of the tank during the course of tank removal works.  This method is not suitable if it is suspected that there is a leak in the tank;

5.1.4.2.2.5

Dry ice (solid carbon dioxide) fill for hydrocarbon fuel tank

For a hydrocarbon fuel tank with all residual fuel removed as far as reasonably practicable, the vent pipes shall be removed, and all the openings sealed except the one required for insertion of dry ice.  At least 2 kg of dry ice for each cubic metre of tank volume shall be allowed.  The dry ice shall be used in pellet form or blocks broken down into pieces no larger than 3 cm in diameter.  The tank shall be left for 12 hours and then the atmosphere tested, taking readings from the top, middle and bottom levels.  When oxygen contents have been reduced to below 5% at all levels, the openings shall be sealed.  The tank atmosphere will only remain safe for a limited period of time (e.g. 24 hours);

5.1.4.2.2.6

Cleaning and degassing for hydrocarbon fuel tank
For a hydrocarbon fuel tank, all the residual fuel and sludge are removed and the tank surfaces are cleaned. Then, forced ventilation is applied until the tank can be certified flammable vapour free (gas free) and the openings shall be sealed. The tank atmosphere will only remain safe for a limited period of time (e.g. 24 hours); or

5.1.4.2.2.7

Inert gas purging for Class 2 DG tank
A Class 2 DG tank shall be isolated and depressurised. It shall be purged with an inert gas at a suitable pressure for the tank design conditions and does not give rise to danger. Typical purge pressure shall be 0.5 bar or 10% of the design pressure, whichever is lower. The tank shall be pierced or cut to prevent any possible repair and pressurisation.

5.1.4.2.3

In case the methods provided in 5.1.4.2.2.1 to 5.1.4.2.2.7 are not adopted or not applicable, other methods could be adopted, provided that prior approval from FSD is obtained before commencement of the decommissioning works.

5.1.4.2.4

After rendering the tank and the associated pipework safe, they shall be removed properly and safely from the site, taken into consideration the period that the tank remains safe, the further precautions or testing required, the structure and configuration of the tank and the associated pipework, the hazards arising from the removal work, the transportation and disposal of the wreckage, etc. Precautions during the removal of a tank include:

5.1.4.2.4.1

If there is any possible flammable gas or vapour, lifting of a tank by chains or wire ropes shall not be used unless they are protected to prevent contact with the tank to reduce the risk of any sparks or sources of ignition;

5.1.4.2.4.2

A tank shall not be lifted by placing chains or ropes around the tank lid as it is possible to rip the neck from the tank;

5.1.4.2.4.3

All the openings to the tank, including any pipework remaining attached to it, shall be sealed and any holes caused by corrosion or damage during removal shall, as far as reasonably practicable, be sealed to prevent the loss of the inert atmosphere or liquid, if any;

5.1.4.2.4.4

A suitable pressure relief valve shall be fitted, if necessary;

5.1.4.2.4.5

The removal of pipework shall be carried out until it has been drained, flushed for any flammable atmosphere or residual DG and isolated from sources of DG and the site earth bonding arrangements; and

5.1.4.2.4.6

Inform the person who receives the tank of the previous use of the tank and its possible hazard.

5.1.4.2.5    

For the purpose of ensuring that the necessary steps are properly taken in the course of decommissioning, relevant documents, test reports or records against the adopted methods, including but not limited to those listed below, shall be properly maintained and submitted to FSD upon completion of decommissioning:

Filling with sand and cement slurry for hydrocarbon fuel tank

Hydrophobic foam fill for hydrocarbon fuel tank

Filling with foamed concrete for hydrocarbon fuel tank

Inert gas purging for Class 2 DG tank

• Relevant documents as mentioned in 5.1.4.2.5
• Record for sand/cement slurry ratio

• Certification of Flammable Vapour Free

• Certification of purging

•  Relevant documents, testing reports and records

Water fill for hydrocarbon fuel tank

Hydrophobic foam fill for hydrocarbon fuel tank

Inert gas purging for Class 2 DG tank

• Safety control plan
• Record for water level

• Safety control plan
• Record for compressive strength of hydrophobic foam

• Safety control plan
• Record for positive pressure maintained in the tank
• Certification of purging

•  Relevant documents, testing reports and records

After completion of decommissioning, the person who owns or possesses the tank shall inform the Dangerous Goods Division of FSD in writing by fax, email or letter, as soon as practicable, with the following details:

(a) date of completion;

(b) decommissioning method(s) adopted; and

(c) relevant documents against the adopted method as mentioned in 5.1.4.

Upon receipt of the report of completion, FSD will consider whether all necessary steps to decommission the tank have already been properly taken to remove or eliminate the hazard associated with the unused tank.  For the purpose of section 113 of Cap. 295G, FSD will either:

(a) issue a certificate of completion of decommissioning once all necessary steps are satisfactorily completed; or

(b) issue a letter requiring further necessary steps, remedial actions or further testing to be taken within a reasonable period if all necessary steps are not satisfactorily completed.  The subject person shall comply with the letter within the period specified in it and inform FSD after compliance.  If the letter is not complied with, the subject person may contravene section 113 of Cap. 295G.