ASME A13.1
Scheme for the Identification of Piping Systems
ASME A13.1 is a standard issued by American Society of Mechanical Engineers covering colour, legend, and placement for pipe markers carrying identified contents.
Read it at American Society of Mechanical Engineers
Affixure supplies artifacts and hosts records. We do not interpret this standard on your behalf and we do not certify compliance with it. The link above goes to the issuing authority so you can read the text yourself.
Who enforces this, and how it reaches you
Voluntary in itself, adopted by reference into many state and local codes and commonly required by insurers and by facility standards. Fire departments also rely on it during response.
How this differs from the neighbouring standards
Voluntary in itself, but adopted by reference into many state and local codes and routinely required by insurers. The colour and legend scheme is the part that gets audited.
What you have to be able to show
ASME A13.1 governs the identification of piping systems: the colour scheme tied to the hazard of the contents, the legend naming those contents, the direction of flow, the letter height relative to pipe diameter, and where markers are placed along a run. Like the ANSI format standard it is discharged by the artifact being correct rather than by a recurring activity, but unlike it there is an ongoing condition - markers have to remain present and legible along the run, and pipe runs get painted, insulated, cut into and extended. What has to be provable is that the identification currently on the pipe matches what is currently in it.
What the record adds that the tag cannot
The dangerous failure with pipe marking is not an absent marker, it is a stale one. A line that was repurposed and never re-marked is worse than an unmarked line, because an unmarked line prompts someone to ask and a wrongly marked line does not. Nothing about a physical marker communicates when it was applied or whether the contents have changed since. Binding markers to a record means a repurposed line is a record that can be updated and a marker set that can be identified for replacement, rather than a floor walk of every run in the building. For a standard where the harm comes from confident misinformation, dating the assertion is the useful property.
The mechanics are the same for every standard, and they are set out on how inspection records work.
Why this is a different purchase from ordering the same item printed
Pipe markers are sold from a catalogue by legend and pipe diameter, and any supplier will get the colour scheme right because it is table lookup. What no supplier does is track which marker went on which run. The same order here produces markers that are individually identified, so when a line changes service you can locate the specific markers that are now wrong instead of surveying the plant. The colour scheme is table lookup. Knowing where the wrong ones are is not.
Choosing a substrate for this environment
Pipe markers are specified by pipe diameter as much as by material, because the standard ties letter height to the size of the pipe and a marker sized for a small line is unreadable on a large one. Physically the decision is between adhesive markers and snap-on or strap-on carriers. Adhesive suits clean, dry, accessible pipe. Insulated, dirty or hot lines take carriers, because adhesive on lagging fails and adhesive on a hot line fails faster. Outdoor runs need UV stable stock, since the colour is doing the communicating and a faded marker misidentifies rather than merely fading.
Substrate and rating are stated on every product page. If you are not sure, compare the options or order the hundred unit minimum and see how it survives before committing a fleet to it.
Equipment this applies to
Consumables used under this standard
| Product | Substrate | From |
|---|---|---|
| Valve and equipment tag, anodised aluminium | Anodised aluminium | $1.70 |
| Pipe marker, ASME A13.1 colour | Vinyl, outdoor grade | $1.90 |
Questions people ask about ASME A13.1
Does the colour scheme depend on the contents?
Yes. A13.1 assigns colour combinations by the hazard characteristics of the contents - flammable, combustible, toxic, and so on - and specifies legend text, flow direction and letter height relative to pipe diameter. The scheme is deterministic once the contents are known. Identifying the contents is yours; producing the conforming marker is ours.
What happens when a line changes service?
This is the failure worth designing for. A repurposed line carrying an old marker is more hazardous than an unmarked one, because a wrong marker suppresses the question an unmarked pipe would prompt. Serialised markers let you identify precisely which markers are now incorrect and replace that set, instead of surveying every run and hoping to notice.
Is there an inspection interval for pipe markers?
A13.1 does not set one. The practical obligation is that identification remains present and legible, and the events that defeat it are painting, insulation and modification rather than the passage of time. A record of when markers were applied is what makes it possible to review runs that have since been worked on rather than reviewing all of them.