Any proposed crossing of a National Transmission System (NTS) pipeline by road, railway, runway or buildings may result in the pipeline needing to be diverted. This page outlines the process for diverting the NTS and directs you to who to contact. 

Reasons for diversions

Pipelines are the safest way to move large quantities of liquids and gases over distances, but work will always need to be carried out nearby, which can become a hazard. Gas marker posts can be accidentally moved; pipelines change can direction and may not always run in straight lines between posts. A gas leak from a damaged pipeline has the potential to ignite.

You will need to contact us before starting work near a gas pipeline. Depending on the nature of the work, it may be necessary for the pipeline to be diverted. No work can be carried out in the vicinity of a pipeline without our written consent

No mechanical excavators should be used within three metres of a high-pressure gas pipeline.

Written approval from us is required before any planting on the easement strip above a gas pipeline. No trees are permitted usually within six metres of a pipeline, and only shallow rooted hedge species directly above.

Finding out if you need a diversion

The first step is to ask about proposed work near pipelines by contacting the Plant Protection team.

You will need to supply a clearly identifiable plan, site grid reference or postcode, a works start date, your contact details, and details of the planned work.

You should contact us at least seven days in advance of any works.

The team will check the location of any assets in the vicinity of the proposed works, and say if the work is of high, moderate or low risk. It may be necessary to divert the pipeline before work can start. You will be sent a map showing the location of the asset, together with advice on 'avoiding danger from underground services' (HSG47) and specific guidance on working near the asset or assets found.

Additionally, Linesearch is a free online enquiry service that provides instant results from a grid reference, postcode, or street name.  If your result is within a National Gas zone of interest, you can click directly through to the Plant Protection team to request plant location details.

Diversion process

Several National Gas departments are involved when a gas transmission pipeline needs to be diverted. If Plant Protection, after your initial contact, identify a gas transmission pipeline they will put you in touch with the Asset Protection Team. They will discuss the diversion process with you, as well as the safety aspects, and the timescales. All diversion work is customer-funded.

The Gas Commercial Team is responsible for managing the contractual issues. They will arrange any studies required, pre-works agreements if needed, and the diversion agreement. National Gas Construction employees and contractors undertake the physical works. Following completion of the diversion works the Gas Commercial Team will reconcile the costs.

We allow a minimum of three years from initial enquiry to the completion of the works.

National Gas is, in principle, willing to divert its gas pipelines, if the terms on which the diversion will be undertaken can be agreed with the developer.

When National Gas agrees to divert its gas pipeline:

It passes through its costs of doing so to the person seeking the diversion and makes no profit from the works.

The capability of its gas national transmission system will remain the same and without enhancement.

In other words, there is no upside for National Gas but there is significant potential downside for it (and its customers). As a consequence, our terms are designed to:

Keep National Gas whole.

Leave it with minimal risk.

Shield it and its customers/shippers from constraint costs.

The terms will not reflect the risk profile which might be expected if National Gas were engaged by you as your contractor to build part of your development.

Please contact the Connections team within our Commercial department here  for further information on the commercial contracts for diversions of the NTS.