The Key Things To Know About ASME U Stamp Vessels

The Key Things To Know About ASME U Stamp Vessels

There’s a lot to know and understand about ASME. What exactly does this certification body do? How it started? What does it mean? Etc. Let us look at these questions one-by-one.

The ASME Story

Quite often, we hear about Heat Exchanger offering “Code” units. But are these truly the ASME Code Stamped with a full U-1 data report or is it or is it merely “Designed to” or “Tested in accordance”? This article seeks to provide relevant information that would you understand the ASME Code issue.

What Is The ASME Code Vessel?

ASME simply stands for American Society of Mechanical Engineers. They are responsible for establishing and maintaining design, construction, and maintenance as well as inspection standards to ensure maximum protection of life as well as property.

Before a vessel can be fabricated, an ASME vessel manufacturer must apply for and obtain a Certificate of Authorization from the Boiler & Pressure Vessel Committee of ASME. After this is received, in compliance with certificate of Authorization, an ASME Code vessel would then be designed fabricated and inspected in conformance with the ASME Code rules.

How Do I Identify An ASME Code Vessel?

In order to identify the ASME Code vessel, the symbols “U” or “UM” are used. These symbols are either stamped on the body of the vessel itself or the data plate attached to the vessel of the manufacturer. If the vessel is stamped with symbol “U”, a manufacturer’s data report for pressure vessels (Form U-1 according to ASME Code) will be provided on request. If the symbol “UM” is used, a Form U-3 certificate would also be provided on request.

What is a “U” symbol?

When “U” symbol is used, it is an indication that the vessel manufacturer has satisfied all the ASME Code requirements for pressure vessels. It also means that the vessel has passed inspection by an authorized third party inspector that was commissioned by National Board of Boiler and Pressure Vessel Inspectors or that the ASME U-stamped vessel manufacturer has satisfied the ASME UG 90(c)(2).

This ASME UG 90(c)(2) mandates the vessel manufacturer to have an authorized inspector on its site for a period no less than 40 hours per week and would be audited by ASME more rigorously.

What Does “UM” Mean?

The symbol “UM” limits the construction of pressure vessels to 5 cubic feet in volume and 250 psi design pressure or 1 cubic feet in volume and 600 psi pressure. These kinds of vessels are not inspected by authorized inspectors from the National Board. They may also be exempted from inspection by the local inspectors. Form U-3 would be provided on request is just a manufacturer’s certification indicating that the vessel is in compliance with ASME Code for “UM” symbol vessels.

Why are these important to users of pressure Vessels?

ASME Code “U” is required of a pressure vessel if it is going to be installed in a public building constructed for human occupancy. Also, the “U” symbol construction is required by insurance companies before insurance would be issued to the owner of such public building. Code requirement is becoming more relevant to users of pressure vessels for these reasons:

If a non-code vessel is accepted and even installed in an area that requires code construction, it would be rejected during an inspection or insurance. A non-code vessel cannot be converted to a coded vessel after it had left the manufacturer as a non-code vessel. A new vessel would have to be brought to the code construction standard, thus making it an expensive change.

If in case a non-code vessel is installed in an area which did not initially require code construction but later requires code construction, a new container would have to be brought to comply with local and insurance requirements making the change quite costly.

If a vessel is accepted and installed as “UM” but the jurisdiction does not accept this symbol, it would have to be changed to the “U” symbol. Once again, a very costly change.

Why Is A Manufacturer Required To Be Registered With The National Board?

One of the benefits an ASME U-stamped vessel manufacturer would enjoy is that he gets a permanent record of this data report. Any manufacturer not registered with the National Board is only required to keep their records for five years.

Since the life of a pressure vessel is more than five years, it is possible that pressure vessels that are older than five years may not have any proofs of ever been certified. Also, the data report contains very vital design information in case there is need to repair or modify the pressure vessel.

How Can A Specification Be Written To Indicate ASME Construction?

The following wordings written on a vessel indicate an ASME Code vessel:

“A manufacturer’s data report for pressure vessels, Form U-1 as required for the ASME Code Rules” is to be furnished to the owner. The form must be signed by a qualified inspector, holding a National Board Commission, certifying that the construction conforms to the latest ASME Code Section VIII Div 1 for pressure vessels. The ASME symbol “U” must also be stamped on the Heat Exchanger. Also, it must be stated, “The Manufacturer must be registered with the National Board”.

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