text: In the United Kingdom there are three principal regulations that mandate the marking of equipment and piping:
  * Classification, Labelling and Packaging of Chemicals (Amendments to Secondary Legislation) Regulations 2015,
  * Health and Safety (Safety Signs and Signals) Regulations 1996,
  * Provision and Use of Work Equipment Regulations 1998,
  The regulations require that vessels containing hazardous substances together with the pipes containing or transporting such substances must be labelled or marked with the relevant hazard pictograms or pipe marking. The labels used on pipes must be positioned visibly in the vicinity of the most hazardous points, such as valves and joints; at both sides of bulkheads and floor penetrations; and at reasonable intervals.
  The regulations do not specify a specific marking system, but BS EN ISO 1710 Graphical symbols — Safety colours and safety signs is often used.