Major accident hazard (MAH) pipelines: Notification

This page summarises the information required on MAH pipeline Notifications. It tells you what Notification is and when it is required. Further details are given in HSE's Guidance A guide to the Pipelines Safety Regulations 1996.


TheĀ Pipeline Safety Regulations 1996 (PSR) place a duty on operators of MAH pipelines to provide certain information to HSE at various stages in the lifecycle of a MAH pipeline.

These duties are covered in the following Regulations:

  • Regulation 20: Notification before construction
  • Regulation 21: Notification before use
  • Regulation 22: Notification in other cases (eg. change of pipeline operator or major modifications to existing pipelines)

These requirements only apply to MAH pipelines.

Submission of Notifications

From the 3rd January 2012 you can send your notifications to HSE electronically using our online notification system.

Online form

If you have any questions or wish to send your notification/s by post or e-mail.

Our contact details

Regulation 20: New major accident hazard (MAH) Pipelines

Regulation 20 requires that the construction of a new MAH pipeline should not start until the operator has notified HSE at least six months prior to the start of construction. The Pipelines Safety Regulations (PSR) Schedule 4 lists the particulars required which includes the name and address of the operator. This notification may form the first contact between the pipeline operator and HSE for that pipeline. The intention is that this notification should be made at the 'end of the concept design' stage and hopefully before major expenditure has been committed to by the dutyholder. Operators often approach HSE in advance of regulation 20 requirements to discuss plans and designs; we welcome this early and productive dialogue.

If an operator is in any doubt as to whether HSE is aware of its identity and/or its MAH pipeline(s) it should contact us (see full Notification addresses).

Multiple Construction Sites: under regulation 20 if construction of a MAH pipeline occurs at more than one location (eg onshore, offshore or a combination of both) and in more than one stage, notification to HSE should occur at least six months before the first stage begins. An example is where a pipeline bundle intended for offshore use is constructed on land and is then taken for final assembly and connection to an offshore installation. Construction of the pipeline under these circumstances is deemed to start at the first stage on land, not at the subsequent phase offshore.

Regulation 21: Notification before use/re-use

Under regulation 21 HSE requires 14 days prior notification of the intention to bring a MAH pipeline into use so it has the opportunity of a final inspection before a dangerous fluid is first introduced into the pipeline.

This regulation also applies where a pipeline is to be brought back into use after it has been taken out of commission (other than where the circumstances were routine maintenance, planned or emergency repair).

PSR Regulation 22(1): Change of MAH Pipeline Operator

The operator of a MAH pipeline may change at any time throughout the life of a pipeline. Under regulation 22(1) any change of operator must be notified to HSE within 14 days of the change.

If a pipeline is transferred from one operator to another, there must be sufficient information passed to the new operator so that all the relevant duties can be complied with. The onus is on the new operator to ensure that it has sufficient information to comply with PSR and to enable proper decisions to be made about the integrity and safety of the pipeline.

Regulation 22(2): Other Cases

Regulation 22(2) requires notification in other cases. The notification period for this Regulation is at least three months. Regulation 22 concerns significant changes to the pipeline which can affect the level of risk. Examples include:

  • Major modifications/remedial work to the pipeline.
  • Changes in safe operating limits eg when changing from one pressure to another.
  • Changes in fluid composition or type. Pipelines may be designed to operate with dry gas but changes to the status of offshore installations may only be achieved if the gas can be transported in a wet state - this may have a significant effect on the integrity of those pipelines and downstream facilities.
  • End of use of a pipeline. This notification should set out the steps to be taken to decommission, dismantle or "abandon" a pipeline. It is envisaged that a notification will comprise a timetable indicating when the pipeline is to be taken out of service, how long the line was to remain decommissioned and a description of how the line is to be made permanently safe.
  • Changes in pipeline materials and equipment. This may comprise no more than a map or chart showing where the changes are to take place and a brief description of the material and/or dimensional changes.
  • Re-routing of pipelines eg. in close proximity to offshore installations which could have an effect on the safety of the installation.
  • Re-routing of pipeline risers on offshore installation which may then pass closer to living quarters or other vulnerable areas.
  • The repositioning of Emergency Shut Down Valves (ESDVs) on pipeline risers.

HSE Addresses

Please note that this e-mail should only be used for MAH Pipeline Notifications. Any other enquiries received will not be responded to via this e-mail account.

Scotland and Scottish waters

Health and Safety Executive
Gas and Pipelines Unit
Aberdeen International Business Park (AIBP)
Building 2, Level 1
Dyce Drive
AB21 0BR

E-mail: [email protected]

Rest of GB, territorial waters and UK continental shelf

Health and Safety Executive
Gas and Pipelines Unit
Rosebery Court
Central Avenue
St Andrews Business Park

E-mail: [email protected]

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Updated 2022-06-14