Reimagining Seal Gas Filtration for API 692 Standards
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Reimagining Seal Gas Filtration for API 692 Standards

John Crane redefines the seal gas filtration system standard

April 16, 2020 | 5 minute read

 

After nearly 10 years in the making, comprising input from both equipment manufacturers and end-users, API 692 was released in June 2018. API 692 is the first API standard dedicated to best practices for dry gas seals and systems and provides a significantly more detailed set of operating and maintenance requirements. If we were to consider just dry gas seals requirements prior to API 692, this amounted to just 10 pages in API617 and 35 pages AP I614.

Coming in at just over 500 pages, you might think API 692 requires huge changes, and inevitably there are many, but there are no surprises regarding dry gas seals themselves.

However, this can’t be said about dry gas seal systems, and especially seal gas filtration. 

  

 

John Crane has published a guide to describe the main changes between the API 614 and API 692 design standard for seal gas filters and separators, and the interpretation of those requirements.

While API 692 was being compiled, John Crane identified the need to develop a completely new seal gas filtration system. From the outset, it was clear the improvements in seal gas filtration would place an extra burden on the seal gas filtration equipment available, and while it was possible to specify tighter size limits on particle size and efficiency, it would unavoidably reduce the mean time between replacement (MTBR) of filter elements, decreasing percentage uptime and incurring more OPEX.

Design rule

Filter Type

Fineness

Efficiency

API 614 5th Edition

Separation/Buffer Gas

4 μm

β 85 = 98.8%

API 692 1st Edition

Separation/Buffer Gas

10 μm

β 1000 = 99.9%

API 614 5th Edition

Seal Gas Filter

4 μm

β 85 = 98.8%

API 692 1st Edition

Seal Gas Filter

1 μm

β 1000 = 99.9%

 

In tandem with this realization, John Crane was busy acquiring its second specialist filtration company. 

Seebach joined John Crane with many years of experience in a wide variety of industrial filtration applications which enabled them to develop both precision manufacturing practices and custom software tools to determine the scientific characteristics of the fluids to be filtered and the filter media used. The insight gained has enabled the development and manufacturing of the radical new filter element design at the heart of the new FCF seal gas filtration system, complete with optimized diameter / length ratio and built-in flow straightener.

 

 

The result is the new FCF seal gas filtration system. Complying with the API 692 filtration requirements for contaminants of one micron and smaller, at efficiencies of 99.9%, the new seal gas filtration system boasts a more efficient and compact design to save space and energy. 

Our development engineers discovered that to reach optimal performance, the flow through the filter system needed to be streamlined. Conditioning the flow is particularly important when used in combination with three-way valves or 90-degree pipe bends, where the efficiency of the filtration process is adversely affected by consequential flow vorticity. Such inefficiencies are affecting gas seal reliability and are the cause of unplanned downtime, requiring more maintenance and increased OPEX.

In the FCF series a combination of new flow conditioning technologies has been incorporated to deliver reduced size filter systems with increased filtration capacity. This new system delivers significantly reduced pressure loss and optimized process flow, with a 50 percent lower pressure drop both at start up and in operation; an additional flow capacity up to 60 percent; and coalescing performance boosted to 0.005 ppm for improved centrifugal compressor reliability and crucial operational efficiencies.

Contact us to discuss next generation seal gas filtration with our team of experts, and find out how we have redefined the seal gas filtration standard.