Bridging the Operational-Environmental Gap With Upstream Pumping Seal Face Technology

Pumps are a driving force of operations for industries like oil and gas, pulp and paper, chemical processing, mining and power generation. However, mechanical seals, a trusted technology for sealing pumps in these industries, must be optimised — particularly around water usage.

John Crane's Upstream Pumping (USP) mechanical seal face technology tackles this challenge by providing reliable sealing while helping reduce water and energy consumption. By implementing USP technology, operators can raise the bar not only for reliability, but for efficiency and sustainability.

USP Seal Face Technology at a Glance

What is John Crane's USP Seal Face Technology?

Developed by John Crane, USP is a non-contacting liquid mechanical seal that uses spiral groove seal face technology to help enable reliable, high-pressure, contactless sealing for pumping applications.

Benefits of USP Seal Face Technology

USP can improve reliability relative to conventional mechanical options as it functions with near-zero friction, which extends a pump's mean time between repair (MTBR). With USP, an operator can save energy, reduce environmental impact and potentially eliminate the need for cooling flush water.

How USP Works

Upstream Pumping seals are akin to dual mechanical seals with the addition of John Crane's spiral groove technology. As the seal rotates, grooves on the wet, inboard seal face force a low-pressure barrier fluid — typically water — to the tips of the narrowing grooves. This creates a spike in pressure and causes the seal faces to lift off each other.

Unlike a traditional seal with a pressure flow from high to low, the pressure increases at the groove tips of an USP seal, forcing the release of a small amount of barrier fluid into the process side of the seal. This essentially “pumps” it “upstream” — hence the name, Upstream Pumping.

Operational Benefits

USP delivers tangible benefits for operators, including reductions in water usage, lower maintenance costs and broader operational flexibility.

Decreased Cooling Water Requirements

An USP seal requires scant — if any — cooling water flush. Due to its near-frictionless operation, very little heat is generated between the seal faces, which in turn minimises cooling requirements.

Replacing a standard seal with an USP seal may even render a cooling flush system unnecessary, making it an ideal sealing solution in areas where cooling water is potentially expensive and difficult to obtain.

Use John Crane's Water Savings Estimator to compare USP with several other sealing methods.

Increased MTBR

Seal repairs can interrupt operations and drive-up costs in terms of downtime, technician hours and replacement parts. The upkeep for traditional mechanical pump seals is frequent, as they have an MTBR of around three years, which may even be as short as months in the presence of abrasive or corrosive process fluids.

USP seals can operate continuously for five or more years, with many reaching seven, 10, 12 or even 15 years of service before requiring maintenance or repair. This reliability contributes to significant savings over the seal's lifetime and reduces overall operational costs.

Suitability with a Range of Process Fluids

The operation of an USP seal requires a small supply of clean barrier fluid, typically water, and consumes about 200 millilitres per hour of run time. This water is the only fluid that enters the seals, and because of the spiral groove technology, the seal forms a very high-pressure barrier. As no process fluid contacts the seal faces, USP can accommodate service fluids that would otherwise cause damage or shorten seal life.

These seals are ideal for slurries or fluids with abrasive, caustic, viscous or corrosive properties. For example, consider the challenges of processing crude oil or mining slurries and how USP seal faces do not encounter interference from the processing fluid.

• Crude oil refining: High sand content, scale and corrosives. Potential for sour (hydrogen sulphide) service and the inclusion of sulphurous and caustic compounds.
• Mining: Commonly uses abrasive, highly viscous slurries containing corrosive compounds.

Use of Water as Barrier Fluid

Even in water-scarce locations, water is cost-effective compared to barrier oil. An USP seal consumes significantly less water than a traditional seal that demands flushing and cooling. The low volume of water simplifies operations, as water trucks can periodically fill a small barrier fluid reservoir.

It's important to note that USP operates by pushing a trace amount of clean water (barrier fluid) into the process. This quantity is typically inconsequential, as water is already present in many process fluids.

Adaptability to Pressure Changes

Spiral groove technology can accommodate pressure spikes or drops without affecting the seal's functionality.

A sudden pressure increase will cause the seal faces to push closer together, narrowing the water barrier between the faces while maintaining the seal. Conversely, USP is immune to reverse pressure damage that can occur with traditional sealing methods. If a process suddenly loses pressure, pulling a temporary vacuum in the pump, the seal maintains its barrier, albeit with a slight increase in water consumption.

Environmental Benefits

The operational advantages of using USP sealing go hand-in-hand with sustainability and energy efficiency to reduce an operation's overall impact.

Emissions Reduction

Similar to a dual-pressurised mechanical seal, USP seal face technology effectively prevents process fluid from leaking or escaping. This ability upholds safe operations and minimises a process' environmental influence.

Water Conservation

As part of our efforts to help customers strengthen their stewardship of water resources, John Crane has developed innovative water conservation solutions, including USP seal technology.

For a conventional solution, cooling water flush typically starts at 8 litres per minute (1.75 gallons per minute) and can potentially require a much larger volume flow. Thanks to their low-friction, low-heat operation, USP seals can reduce flush to just a few millilitres per hour, possibly eliminating the need for cooling altogether.

Energy Efficiency

As the energy transition progresses and net zero initiatives get underway, many industries are shifting their focus toward energy management. John Crane's USP technology supports decarbonisation through increased energy efficiency.

Near zero-friction operation reduces torque on the pump motor, saving several kilowatt-hours per pump over a year. The energy savings are significant if used throughout a plant where tens or even hundreds of pumps operate. Increased reliability also drives efficiency, with a reduction in energy-intensive downtime and fewer replacement resources required to maintain the seal.

USP Case Study

A Middle East oil and gas producer looking to decrease water and power consumption tested John Crane's USP technology by replacing the traditional mechanical double seal on one of nine pumps.

The pump equipped with USP consistently outperformed the others, and a cost analysis revealed that applying USP to all nine pumps would result in savings of more than 900K litres of water per year with an annual energy reduction of approximately 2 million kW.

Read the full case study here.

Installation of the USP and Support Systems

Physically, an USP seal is nearly identical to a traditional cartridge seal, yet its support system is very different. The reason is that API 682 piping plans assume that mechanical seals work from high to low pressure. However, because USP barrier fluids travel from low to high pressure, API 682 is primarily incompatible with the system.

John Crane engineers have created two standardised support system offerings to address USP's unique needs, basing designs on years of fluid control and industry and installation expertise.

• GS USP-R Seal Support System
• Uses a water reservoir to hold seal barrier fluid
• Holds an approximately 10-hour water supply
• Eliminates the risk of momentary loss of water supply
• Best for water-scarce areas

• GS USP-D Seal Support System
• Uses a direct water connection; no reservoir
• Smaller footprint than reservoir unit, increasing mounting choices
• Requires a low-pressure feed water
• Best for areas where water supply is ample and dependable

The USP support systems (USP-R and USP-D) are designed to be simple, robust and modular. Basic gauges and check valves can be added or upgraded as required. It is also possible to adapt the system to API standards with full transmitters, pressure relief and filtration.

In applications where barrier fluid particulates are a concern — using seawater, for example — there is an option to incorporate additional filtration using John Crane's standard filter cartridges. These cartridges can be cleaned and reinstalled for minimal waste and resource usage.

Engineering a Better Future With John Crane

As a mechanical sealing technology leader with a legacy of innovation, John Crane is committed to providing solutions that help customers achieve both operational excellence and environmental sustainability. Our USP seal face technology supports pumping applications for challenging industries, including oil and gas, mining, pulp and paper and power generation. Near-frictionless operation reduces or eliminates the need for cooling flush, decreases energy needs and increases reliability — potentially extending MTBR by years.

Explore how John Crane's USP seal face technology can help your company engineer a better future.