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Editor’s note: This post was originally published on 3/27/18 and has been updated for accuracy and comprehension.
ASME Safety Relief Valves.
A possibly dry topic to be sure, but it’s one piece of equipment in your facility that should not be installed and forgotten.
Well, a picture really is worth a thousand words.
Relief valves are the last line of defense against accidents like this one.
They’re an important part of your facility’s safety equipment and they can prevent lost revenue, downtime AND – most importantly – injury to people.
There are three main things you should do to keep the ASME safety relief valve ready to do its job should it become necessary.
The primary role of a safety relief valve is to prevent over-pressure situations in pressurized vessels or systems. If the tank’s relief valve fails, it can lead to an accident that destroys property, life, or landscape.
The National Board of Boiler and Pressure Vessel Inspectors is one of the governing bodies for the testing and/or repair of ASME Safety Relief Valves.
Within their Code, they recommend a written procedure be created for testing these type valves.
We recommend that the test is performed by an authorized testing facility. A list of these facilities can be found on the National Board’s website.
You can also find other companies that perform this service by typing “relief valve repair” into your favorite internet search engine.
Based on the National Board Code, which bases their inspection intervals on what type of service the valve is used for, the following intervals are suggested:
It should be at least as large in diameter as the valve’s outlet.
If not, the piping could form back-pressure on the valve’s outlet, causing the valve not to open properly.
Also, keep in mind that this piping should be oriented so that no liquid relieved through this piping can flow back and rest on the ASME safety relief valve’s outlet port.
Doing so could allow corrosion to occur within the valve’s internal components and prevent the valve from opening.
Set your tanks’ maximum operating pressure to at least 10% below the valve’s set pressure.
This will prevent the valve from “creeping” open.
The ASME relief valves are set to fully open at its “set” pressure but will begin to partially open before then – normally at 10% below its set pressure.
If your valve is allowed to do this, trash and/or corrosion can set in over time which could prevent the valve from either closing completely or from fully opening, either of which is not a favorable solution.
Pressure relief valves are an often neglected and overlooked safety feature in your facility.
Take some time to inspect them.
You never know when they may be called on to save your life.