Pipeline Surge Pressure Relief

I use a service, WatchThatPage, to track changes to various pages around Emerson Process Management. It sends me an email when any page in a list of pages I have created has changed. I use this as one of my sources for the posts I create. This helps me keep track of changes in non-RSS enabled pages. For those who don’t use RSS (really simple syndication), here’s some resources on how it makes your information quest more efficient.

Late last week I received an email notifying me of a change to the Daniel liquid pipeline surge relief technical guide. I caught up with Dave Seiler to ask about this application and some of the challenges process manufacturers with high-pressure pipelines face. Pipeline operators and those with high-pressure pipelines are quite aware of the potential damage that can occur if a pressure surge occurs.

Dave noted that over-pressurization of a pipeline is commonly caused by sudden changes in liquid velocity. This may occur when a pump starts or stops or a valve opens or closes. When a pressure rise occurs above normal operating pressure, it’s very important to analyze the rate of the pressure rise to determine the proper size and type of valve required.

Dave described line blockage as the most serious pipeline issue. To mitigate this condition, pipeline design includes valve interlocking logic and clear operating procedures. As noted in the technical guide:

…pressure is contained must have some form of pressure relief, which is often mandated and regulated by local authorities. The design of such systems is dependent on a complex range of factors including, but not limited to, the potential for pressure increases, the volumes which must be passed by the pressure relief equipment in operation and the capacity of the system to contain pressures.

This guide describes applications you may have in your facility. On application is a pilot operated pressure relief valve used for pump protection duty and for similar applications where pressure relief is required to maintain pressure at a given set point. Another application might have exceptionally fast response times that require gas-loaded systems. These are described:

The basic valve is the balanced piston design. Nitrogen gas is used to pressurize the valve piston to keep it in the closed position. The valve incorporates an integral oil reservoir mounted on the external surface of the cylinder head, which upon installation is partially filled with a light oil. Gas under pressure is applied to the reservoir.

Other applications described include surge relief valve closed position and open position. I found the pictures like this one help make the text easily understandable.

Gas Tank and Instrumentation

If you have high-pressure pipelines in your process, take a look at this guide and see how it might help you.

Posted Thursday, April 3rd, 2008 under Abnormal Situation Prevention, Plant Equipment.

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