Service pipework

Looking after your service pipes

The pipe that carries the LPG vapour from the bulk storage tank to the building is called the service pipework. This is most likely to be owned by whoever owns the premises using the LPG – this could be the landlord if the premises are rented. It is normally not owned by the LPG supplier, even though it may have been installed by them. If you are not sure about ownership of the pipework, then you should check with your supplier and/or landlord if you do not own the property or land yourself.

The main concern with service pipework is that if it is damaged it is likely to release the LPG it is carrying. If the escaping LPG vapours were to ignite, the LPG could then cause a fire or explosion. Damage to the pipework could be caused by physical impact or through chemical means, for example corrosion of a metal service pipe.

The legal framework provides more information on the background to these responsibilities.

Installation route

Ideally, LPG service pipework should be run above ground using a route that minimises the possibility of physical damage, for example from vehicles, and away from excessive heat or cold. Where damage can be foreseen, protective barriers, bollards etc should be provided. If it is not possible to run the pipework above ground, then it can be buried underground and, in such cases, it is important to know its route and to mark it so that others are aware of it. Where traffic or other heavy loads pass over the pipe, protection should be provided, such as load-bearing slabs or covers.

For the majority of premises, it is likely that service pipework will already be installed. If this is the case then for buried pipework it is important to ensure that its route is known, recorded and, where possible, clearly marked. If the pipework is to be replaced, then think about replacing it with pipework that runs above ground if at all possible. If not then it should be replaced with non-corroding pipework made of material such as polyethylene (PE).

Materials of construction

The material the pipework is made from is very important, particularly if it is buried. In general, steel or copper can be used for pipework that runs above ground. Where pipework needs to be buried then it should be made of material, such as polyethylene, that is non-corroding. This is important because corrosion of buried metallic pipework can result in leaking of LPG and this could lead to a fire or explosion if it accumulates and is ignited.

Buried pipework installed within the last 15 years is likely to be made of non-corroding material, such as polyethylene. Older installations, though, may have buried metallic pipework. In these cases, the pipework is likely (but not always) to have some form of corrosion protection provided (for example it may have been wrapped in a special protective tape). This protection will not last indefinitely and the pipes will corrode over time. This may also happen more quickly in certain types of soil, for example waterlogged clay soil. If buried pipework is metallic then it will need to be replaced.  This should be done as part of a pipework replacement programme being developed by the UKLPG.

Pipe with Denso tape wrapped round its base

Polyethylene (PE) pipe enclosed in glass-reinforced plastic (GRP) sheath

Pressure

The LPG in the service pipework will be under pressure to drive the gas through the system.  Generally, the pressure may be low (less than 75 millibar) or medium (between 75 millibar and 2 bar gauge).  Pipework at medium pressure is of greater concern if leaks should develop as the amount of LPG that could be released is likely to be greater than at low pressure.

The pressure of the LPG in the pipework may be influenced by the rating of appliances in the premises that it is supplying. For example, factories using LPG in manufacturing processes may need a higher volume of LPG to run their appliances and so may require medium pressure to meet this need. In contrast, commercial premises, such as pubs, hotels and care homes may only be using the LPG to provide heating and cooking appliances and this can be met by low pressure.

You can tell if your pipework is under low or medium pressure by the type of regulators that are attached to the pipework.  If the pipework has only a single regulator on the tank and one near where it enters the building then it is probably under medium pressure.  If a second stage regulator is located at the tank then this indicates that the pipework is under low pressure. If you are not sure about the pressure in your pipework then you should consult someone who can help such as your supplier or an independent expert.

Pipework under medium pressure - second stage regulator at point of entry into building

Service pipework under low pressure - 2 regulators on the tank

• Combined valve & regulator
• Regulator and filling point
• Lockable valve cover

Inspection and maintenance

It is very important that service pipework is regularly inspected and maintained whether it is above or below ground. It is the responsibility of the owner of the pipework to ensure it is regularly inspected and maintained. This is likely to be the owner of the site, not the LPG supplier, even though it may have been installed by a supplier originally (check your supply contract).

A competent person should review the state of the pipework and establish the length of time for which it can be used safely before its next inspection, taking into account the time since it was last checked and any action taken at that time. For buried pipework, the only really effective inspection method currently available is to excavate the pipe for examination, particularly if it is metallic. Care should be taken when excavating pipe to prevent damage to the pipe or its corrosion protection. For metallic buried pipework that is likely to corrode, a specialised expert in corrosion of metal pipework would be required to assess its state on excavation.

Other tests are available for investigating the state of the pipework at the time of the test but these cannot give any assurances about its condition in the longer term.

Further, more detailed guidance on inspection and maintenance of pipework is available from UKLPG.

Replacement

It is known that buried metallic pipework, even if it was protected when it was first installed, will corrode over time. Corrosion can result in LPG leaking from the pipe and can lead to a fire or explosion if ignited. Buried metallic pipework will therefore need to be replaced with pipe made from non-corroding material such as polyethylene. The suppliers of LPG have developed a prioritised replacement programme for buried metallic pipes. If you are contacted by your supplier about replacing buried metallic pipework then you should discuss this with them and make the necessary arrangements to have the pipework replaced.

Entry into premises

Pipework should enter a building above ground and it should be contained in a sleeve sealed to the structure. This will protect the pipe and help to stop any passage of LPG vapour into the building should the pipe develop a leak. Within the building, any pipework should ideally not travel through any unventilated void (eg underfloor space, cellar or basement). Where it passes through a cavity wall it should be sleeved to prevent gas entering the cavity should it leak.

Where buried pipework leaves the ground to feed into the building (the so-called 'riser'), if it is made of polyethylene (the preferred material that is being used to replace underground metallic pipework) it should be protected with a glass-reinforced plastic sleeve. This protects the pipe from physical damage and from UV light which will make it brittle over time. Entry into the building from the riser should be above ground. This should be checked in case at some point in the past it was covered by other building work (for example raising the level of a yard or garden). If the buried pipe is made from polyethylene, then before it enters the building there should be a transition to steel or copper piping which then enters the building.

Pipework sleeving through wall

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