Fluids flowing through pipes can generate enough vibration to make the pipes sing. I saw in an Emerson Exchange 365 community post, a great Valve Magazine article, Vibration Analysis Pinpoints Valve Noise Source, by Emerson’s Daniel Eilers. Daniel is a research engineer for the Fisher valve and instrument business unit.

He shares a story of a Southern California refinery located next to a residential area that had issues with a whining sound emanating from the process piping. Daniel describes the situation:

It [the refinery] has a capacity of over 300,000 barrels per day, but operates around the clock so the processing units contribute ambient noise to the surrounding neighborhoods. This noise is particularly troubling to residents who live on that southern border.

Specific to the noise issue [hyperlink added]:

…very loud harmonic noises (over 113 dBA…) were generated somewhere in the ISOMAX process unit near the hydrogen compressors and hydrogen quench control valves. Although the refinery hired an outside consulting firm to determine the exact source of the process unit noise, a problem that had increased over several years, the tests by the consultant were inconclusive.

This ISOMAX unit began generating noise that could be heard beyond the refinery’s boundary, and they:

…received complaints from nearby residents about a continued, high-pitched whine.

The refinery’s engineering team connected with the Emerson local business partner, Caltrol, who brought in the Fisher Severe Service group, which:

…recommended using vibration-analysis-based, noise measurement equipment and processes.

Since the traditional way of acoustic sound pressure measurement tried earlier by the consulting team did not resolve the issue, the Severe Service team began with:

…a survey of the quench valve area to determine where to begin testing.

The testing process involved the use of vibration accelerometers upstream, downstream, and on the valve stems of the control valves in the piping. From this methodical approach, Daniel highlighted their discovery:

The highest piping vibration levels were found next to the quench valves, with the highest overall reading being taken on the valve stems. This finding indicated that the source or cause of the noise was most likely the valve trim components.

Stroking the quench valves was shown to impact the tone of the noise. Depending upon the travel, the tones would disappear, increase or change frequency.

These quench valves had a quarter century of operation and had gaps that developed between the plug and valve body, causing vibration in the plug/stem assembly.

After identifying the cause of the high-pitched whine, the refinery engineers worked with the Caltrol team, for replacement valves that could meet the performance requirements and eliminate surrounding community noise concerns. Daniel highlighted the solution [hyperlinks added]:

A cage-guided valve design for high-pressure control requirements was chosen for its more stable operating capability. Also, a digital valve controller was added to each valve to allow optimizing control of the reactor temperature as well as to gain the ability to perform online valve diagnostics. All eight quench valves that were in the ISOMAX unit were replaced with this new valve configuration.

It sounds like the refinery, Caltrol, and Fisher Severe Service team members performed great detective work to solve this noise issue for the surrounding community. You can read the article to get the full story.