Pipe marking for ammonia

Anhydrous ammonia is widely used as a refrigerant in food and drink production sites around the world. To prevent accidents and reduce risk of worker exposure ammonia refrigeration systems are subject to a variety of environmental laws and regulations, including standards for the specific labelling of all pipes and ducts that contain ammonia. ammonia21.com presents an overview of labelling requirements in the US and EU.

Around the world, pipelines and pipe-work used for the conveyance of hazardous chemicals such as ammonia must be identified. To prevent confusion and misinterpretation ammonia pipe markers have been standardised, although the systems used in the US and the EU differ slightly.

US Guidelines for Identification of Ammonia Refrigeration Piping and System Components

Following the accepted standard created by the International Institute of Ammonia Refrigeration (IIAR) Bulletin 114, "Guidelines for Identification of Ammonia Refrigeration Piping and System Components,” all piping mains, headers and branches must identify the physical state of the ammonia based refrigerant (either vapour or liquid), its relative pressure level and the direction of its flow. All components of the refrigeration system, including receivers and heat exchangers, also need to be labelled.

The label should provide the name of the contents of the pipe in an abbreviated form, with arrows indicating the directional flow of the contents. Identification of additional details of the hazard such as temperature and pressure, should also be included.

Labels have to be applied on any differing segment of a piping system, including pipes that change direction or pass through walls and floors. Labels must also be placed at regular intervals on long runs of straight pipe, and close to valves.

In the US, ammonia pipe marking is divided into five sections, and has the following layout:

Arrows indicate the direction of ammonia flow in the pipe.
Components are indicated by abbreviations.
Whether the refrigerant is a liquid, vapour, or both is indicated.
AMMONIA is printed black letters on a yellow background.
Internal pipe pressure is indicated as high or low.

EU directive 67/548/EEC on dangerous substances

The Dangerous Substances Directive is one of the main European Union laws concerning chemical safety, and pipes that contain or transport dangerous or hazardous substances and formulations, must be labelled in accordance with this Directive.

Similar to US labelling, in the EU label colour choices are based on whether the substance is flammable, corrosive/toxic, combustible, fire quenching or compressed air. Arrows are also used to indicate the flow direction, placed before and after the text. However, pipes must also be clearly labelled with the following information:

Name of the substance
Danger symbols
Standard phrases
The European Commission number, a the seven-digit code that is assigned to chemical substances that are commercially available within the European Union; or equivalent.
For substances listed in Annex I, the words EEC label must be included.

This article is intended for general information purposes only and is not a substitute for review of applicable regulations and standards.