Boilers are used in applications ranging from manufacturing processes to power generation. When dealing with these devices, safety is of utmost importance.

A large vessel containing heated water under high pressure is a recipe for disaster if not maintained properly. Boilers must be used properly and inspected regularly to ensure safe operation.

Boiler placards provide crucial information to for operators and inspectors servicing boilers.


Boilers are subject to a fair amount of scrutiny from regulators. Industry-wide authorities have developed agreed upon standards. While there are widespread guidelines, each state sets forth their own legislation as well. Make sure your boilers match up with all pertinent requirements.


The American Society of Mechanical Engineers (ASME) has set forth their own rulesets for the operation and identification of boilers and other pressure vessels.

One of the fundamental elements of ASME certification is the use of a metal placard. This plate must be permanently attached to the boiler vessel.

Organizations which comply with these standards typically include an ASME certification stamp on the placard itself. This mark indicates the equipment is compliant with all relevant ASME standards.

National Board

The National Board of Boiler and Pressure Vessel Inspectors was created in the early 20th century to help create a standardized set of guidelines for the operation and safety of boilers and other pressure vessels.

National Board guidelines state that the boiler placard must be kept original. If the plate needs to be replaced, there is protocol to follow. This includes prominently distinguishing “replacement” on the new placard, as well as filling out the proper paperwork (form NB-136).

In addition, if the vessel is registered with the National Board, the number must be included on the placard.

What Information is Included?

While the specific information on the plate may vary by industry or organization, there are some items found on most plates.

The main elements commonly included on boiler placards include:

  • Serial Number
  • Manufacturer Information
  • Maximum Allowable Working Pressure (MAWP) (Measured in PSI)
  • Minimum Design Metal Temperature (MDMT) (Measured in Degrees)
  • ASME Symbol
  • National Board Seal
  • National Board Registration Number
  • Date(s) Tested
  • Year of Installation

How Are They Attached?

Identification placards are typically attached to the front of the boiler vessel. They must be prominently shown in an easily accessible and visible area.

Boiler safety relief valves are also often labeled with their own placard containing pertinent information.

Regulations state the placard must be attached in a very secure manner so it doesn’t become dislodged or lost.

In order to accommodate this type of secure hold, many organizations choose to directly weld their plates to the boiler vessel in some capacity. This must be done without compromising any structural integrity of the pressure retaining vessel itself.

Placards can also be attached via industrial grade adhesive backing or bolted on with hardware.

Marking Processes

Photo Anodization

One of the most versatile placard marking solutions, photo anodization is used for a wide range of applications.

Photo anodization embeds a custom design beneath a sealed layer of anodized aluminum. This provides incredibly high durability, even in industrial type environments. This process offers 20+ years of longevity, with corrosion resistant properties.

In many of the guidelines for these identification plates, stamping is called out as a permanent marking solution for the information. Elements such as dates and certification approvals are meant to be stamped into the metal substrate.

Photo anodized placards can be produced with blank spaces to later stamp information into. This means information for a large quantity of these plates can remain the same.


The etching process utilizes a chemical process to produce the impression of a custom design on a metal plate.

Similarly to photo anodizing, etched placards often include spaces to mark future information and approvals. Etching often incorporates a color fill into the indentations.

Etch plates can be very thick, enabling them to weld easily to a pressure vessel.

While this process is effective, it is not quite as durable. The etched design will only be slightly indented in the material. Any color fill is highly susceptible to fading and wear.


Boiler placards provide an effective method for providing information to operators and inspectors regarding the usage and maintenance of pressure vessels.

Organizations which use these vessels are required to utilize custom identification plates to meet ASME and National Board guidelines.