Industry Standard Update image

Industry Standard Update 103: Liquid Gas UK CoP 1 Part 4 – 2021

Date issued: 10 March 2021

This article appears in full in the May 2021 edition of Registered Gas Engineer.

This Industry Standard Update (ISU) provides an overview of the key areas of change arising from the revision of Liquid Gas UK Code of Practice 1 Part 4: 2021 – Bulk LPG Storage at Fixed Installations – Buried/Mounded LPG Storage Vessels.


During January 2021, Liquid Gas UK published a revised Code of Practice 1 Part 4 2021 Bulk LPG Storage at Fixed Installations – Buried Mounded LPG Storage Vessels(1). This supersedes the previous edition that was published in February 2008 (with amendment 2 (corrigendum) on 1 March 2013)(2).

The revision to this standard came into effect in January 2021. The following is a brief overview of the areas of significant change to the amended Standard, Liquid Gas UK CoP 1 Part 4.


Legislation, normative references and current standards have been updated throughout where necessary.


Liquid Gas UK CoP 1 Part 4 sets out the guidance for:
• Underground or mounded vessels with a capacity over 150 litres
• Vessel location and separation distances
• Vessel design and vapour withdrawal rates
• Valves, fittings and adjacent pipework
• Corrosion protection.

Section 2: Vessel location andseparation distances

This section has been extended toinclude additional guidance when considering reduced separation distances, with the need for high-level alarms and CCTV surveillance removed. The need to follow DSEAR has also been added to this section.

Table 2 has been altered, with group total nominal LPG capacity added, and vessels 0.05 tonnes to 4 tonnes being split into 0.05-1.1 tonnes and 1.1-4 tonnes. Clause states that, for buried vessels installed under overhead cables, a suitable and sufficient risk assessment shall be carried out to ensure plant and equipment can safely work in proximity to the cables.

For further guidance, refer to HSE Guidance Note GS6 (Avoiding danger from overhead power lines)(3)

Clause 2.3.3 gives advice on flooding, adding that in areas where flooding may occur, vessels shall be mounded or semi-mounded to a height where the top of the vessel is at least to the maximum flood level.

Mounded installations shall have safe access and egress provided for the purpose of filling, maintenance and the ability to close valves in the event of an emergency. If permanent safe access and egress is not provided to ensure the ability to close valves in an emergency, remotely operated valves shall be installed on the vessel outlet, with any controls positioned in an easily accessible position. These controls shall be clearly labelled. Only one dispersion wall would normally be installed. If two dispersion walls are being considered, 2.5.3 states they must be kept to as low as reasonably practicable, as required by Regulation 6 (1) of DSEAR(4). To be able to do this, a suitable and sufficient risk assessment must be carried out to identify those measures, in line with the hierarchy established in Regulation 6 of DSEAR, to ensure that, as far as practicable, risks are controlled and the natural ventilation of the installation not impaired. Any measure that the risk assessment identifies shall be implemented.

2.6.6 states that collision damage protection shall be provided for all above-ground equipment and fittings.

Section 3: Vessel design and vapour withdrawal rates

All new installations shall be fitted with cathodic protection unless the vessel is of the double-skinned type that incorporates a monitored interspace.

Section 4: Valves regulators, fittings and adjacent pipework

The maximum size of passageway through a maximum liquid level device has been increased from 1.4mm to 1.5mm, unless it is fitted with an excess flow valve. 4.8.1 gives further extended guidance on the use of Occasional Liquid Withdrawal Valves (OLW), commonly referred to as ‘checklock’ valves. New or refurbished underground vessels shall be fitted with an OLW valve with a male thread to BS EN 13175(5) only. OLW valves may incorporate a manual isolation valve that can be operated by a special removable type of key. A manual liquid service valve fitted with excessive flow valve complying with BS EN 13175 with a plugged outlet may be fitted as an alternative to an OLW valve.

Where this is not practicable, they shall only be fitted to the bottom of the vessel, and only where there is sufficient clearance beneath the vessel/valve to allow for the safe operation of the valve and for the safe connection of any transfer hoses.

4.10.1 states any valve regulator and their OPSO/UPSO devices shall be in accordance with BS EN 16129(6). Additionally, small pressure regulator installations should be located with the underground vessel valve box/chamber with a volume of no more than 0.5m3.

Section 5: Excavation, back filling and mounding gives advice that, when using ratchet straps to secure a vessel, care should be taken that the straps are not tightened any more than is required to take up any slack.

LGUK CoP 22(7) should be referenced for leak testing vapour off-take service connections after completion of backfilling or mounding.

When using sand as a backfill for mounded installations, advises that measures need to be taken to avoid sand migrating from the vessel area via the water drainage system.

Section 6: Flotation protection

Clause 6.2 gives the calculation for the residual flotation force (in tonnes) of a vessel. This formula is as follows:

1 x the volume of the vessel (in m3) minus the vessel tare weight (in tonnes).

The total mass of ballast and the strength of the anchoring arrangements should be sufficient to ensure the resistance of the maximum residual flotation force of the empty vessel when totally immersed in water.


Appendix A1 has the addition that LPG used for Autogas may now be classed as commercial propane.

Annex B has changed, with anode layout being replaced by ‘Safe Handling of LPG’.

Annex C has changed from Bibliography to Legal Requirements.

Annex D has been added, covering Standards and References.


As previously stated, this Industry Standard Update is only a brief overview of the information contained in the amended standard.

Registered businesses should be aware that they have a responsibility to ensure that they are fully apprised of all the requirements of the whole published standard and its practical application.


1. Liquid Gas UK Code of Practice 1 part 4: 2021 Bulk LPG Storage at Fixed Installations Buried/Mounded LPG Storage Vessels.
2. Liquid Gas UK Code of Practice 1 Bulk LPG Storage at Fixed Installations Part 4: 2008 Incorporating Amendment 1 March 2013.
3. HSE Guidance Note GS6 (Avoiding danger from overhead power lines)
4. DSEAR The Dangerous Substances and Explosive Atmospheres Regulations 2002
5. BS EN 13175 LPG Equipment and accessories
6. BS EN 16129 Pressure regulators. automatic change-over devices having a maximum regulated pressure of 4 bar, with a maximum capacity of 150kg/h, associated safety devices and adaptors for butane, propane and mixtures
7. LGUK CoP 22 Design, Installation and Testing of LPG piping systems