Shaft Sealing and Water Reduction Strategies in Water & Wastewater Treatment

Who We Are… A leading global manufacturer of industrial fluid sealing systems, advanced polymer composites, cleaners, lubricants, metalworking fluids and industrial specialty products A company with a strong commitment to innovation, helping our customers with products and programs that help them operate more reliably, efficiently and economically

The World of Chesterton Founded 1884 Headquartered in Woburn, Massachusetts, US Global Manufacturing Worldwide distribution and service centers Revenues of $235 million 1200 people North America 160 Sales and Service Locations South America 42 Sales and Service Locations Europe, Middle East & Africa 234 Sales and Service Locations Asia Pacific 66 Sales and Service Locations

Mechanical Seals The leader in split seal technology with split seal solutions from 25mm to 900mm that cover the widest range of applications, including pumps, screw feeders, boiler feed pumps and Kaplan turbines. Only split seal with NSF61-certification. The innovator in sealing technology bringing cassette seal technology that helps lower costs of sealing for the process industries Innovative and patented SpiralTrac® environmental control technology to increase reliability in slurry handling and contaminated process streams.

Mechanical Packing & Gaskets SuperSet® pump sealing solutions using patented SpiralTrac® technology for increased reliability with minimized flushwater requirements Valve Sealing Program that offers high performance sealing solutions for all types of valves and offers leak free service for a guaranteed period of 5 years Chesterton is the market leader in engineered sealing solutions for critical flanges, reactor vessels and tubular heat exchangers with a multi-year low emissions guarantee

Focus for Today Sealing Strategies …think about the following: Seals represent 2 – 5% in the overall acquisition cost of a pump. 70 – 80 % of unscheduled pump shutdowns are seal/packing related. So it’s critical to understand what sealing system is needed and how you ask for it. The art is SPECIFYING the best sealing system…without overkill! ENHANCE operation & MAXIMIZE Value 6

Common Sealing Strategies Mechanical Packing Single Component Seals Cartridge Seals Split Seals Zero Flush Sealing System

Common Sealing Strategies Mechanical Packing

Mechanical Packing Resilient material formed around the shaft to create a long axial seal An adjustable gland is used to compress the packing between the stuffing box bore and the shaft Tightening the gland reduces the clearance As the shaft rotates, it wears additional clearance into the packing. This necessitates further gland tightening

Mechanical Packing Friction between the shaft and packing generates heat and wear leading to swift deterioration of the shaft/sleeve. Also solids or abrasives in the pumped fluid imbed into the packing and wear at the shaft/sleeve Flush water must be introduced via a lantern ring to lubricate the packing arrangement. This flush must leak to the environment.

FLUSH WATER WASTEWATER

FLUSH WATER WASTEWATER

EXCESSIVE WEAR ON PUMP SHAFT SLEEVES

EXCESSIVE WEAR ON PUMP SHAFT SLEEVES

Packing Summary ADVANTAGES Inexpensive acquisition cost Don’t have to dismantle the pump

Packing Summary DISADVANTAGES Designed to leak Requires excessive flush water for lubrication and cooling Shaft/sleeve damage and replacement Requires frequent adjustment Housekeeping costs from leakage Leakage impact: bearing failure; corrosion Added power consumption (like driving your car with the brake on)

Packing Summary Perceptions Easy to install Easy to replace packing

Common Sealing Strategies Mechanical Seals

Mechanical Seals Consists of two extremely flat surfaces, called faces Held together by product pressure and spring force to prevent product from escaping to the environment. Visible leakage that comes from compression packing is usually eliminated

Mechanical Seals All seals have common basic elements Primary seal (rotary and stationary faces) Spring mechanism (single spring, multi-spring, bellows) Secondary Seals (o-ring, bellows, v-rings) Metal components

Types of Mechanical Seals In Water and Wastewater: Component Seals Single Cartridge seals Split Seals

Component Seals Most of your low cost seals typically are component seals Can vary somewhat in cost and widely in performance. OEM’s offer cheapest seal to get them out of warranty.

Component Seals O Rotating face Primary seal Springs Stationary face Secondary seal O Consists of the four key components of a seal: Primary seal (Faces), Secondary Seal (Teflon Wedge), spring element and metal parts) All these elements are installed at the pump manufacturer Requires precise measurements for proper installation

Component Seals Seal faces must remain clean and undamaged during handling and installation. Incorrect installation can occur resulting in premature seal failure The majority of seal failures for component seals come from mis-installation or mis-application. 

Cartridge Seals Advantages: Self contained assembly of all components No special skills required for installation Hydraulically balanced Will not fret or damage shaft A cartridge mechanical seal is a completely self-contained assembly that includes all four elements of a mechanical seal; the primary seal, secondary seals, the spring mechanism and all metal parts. The cartridge seal is fully pre-assembled on a sleeve and enclosed in a gland. The seal faces remain in contact during handling and installation limiting damage and contamination. Measurements required for installing, while significant, are relatively easy to accomplish. Cartridge seals usually require no assembly prior to installation.    There is one item that most distinguishes a cartridge seal from a component seal. It is the location of the drive mechanism (usually set screws). On most component seals, the drive mechanism is inside the stuffing box. This requires tightening before assembly of the equipment. On a cartridge seal, the drive mechanism is outside the stuffing box and seal. This allows for assembly of the equipment before tightening. If the cartridge seal is installed on a pump, the impeller can also be adjusted before the set screws are tightened.

Cartridge Seals Disadvantages: A cartridge mechanical seal is a completely self-contained assembly that includes all four sections of a mechanical seal; the primary seal, secondary seals, the spring mechanism and all metal parts. The cartridge seal is fully pre-assembled on a sleeve and enclosed in a gland. The seal faces remain in contact during handling and installation limiting damage and contamination. Measurements required for installing, while significant, are relatively easy to accomplish. Cartridge seals usually require no assembly prior to installation.    There is one item that most distinguishes a cartridge seal from a component seal. It is the location of the drive mechanism (usually set screws). On most component seals, the drive mechanism is inside the stuffing box. This requires tightening before assembly of the equipment. On a cartridge seal, the drive mechanism is outside the stuffing box and seal. This allows for assembly of the equipment before tightening. If the cartridge seal is installed on a pump, the impeller can also be adjusted before the set screws are tightened. Disadvantages: Initial Acquisition Cost higher than Component Seal Must disassemble pump to remove the seal

Cartridge Seals – Desired Features Hydraulically Balanced Stationary seal Stationary face shall be spring loaded to provide self-alignment due to stuffing box misalignment Dynamic o-ring moves towards clean surface as face wears Spring should be Hast C and located outside of the pumped fluid

Split Seals The Best of Both Worlds Split mechanical seals

Split Seals No Equipment Disassembly No Coupling Re-Alignment Multiple trades sometimes required for component or cartridge seals (electrician, pipe fitter, rigger, mechanic) No Coupling Re-Alignment Easiest Field Reparability

Split Seal Advantages MOST PRACTICAL SEAL TO INSTALL ON LARGE SHAFT DIAMETERS (Greater than 2.5”) (Multiple trades issue) When it is too difficult to change the packing sleeve or non-split seal When down-time is expensive or critical/unacceptable Comparable in cost to cartridge seal Spare parts kits are relatively inexpensive No re-alignment of pumps required Newest designs very easy to install.

Split Seal Features Both pressure and vacuum Capability Secondary seal will not damage shaft or sleeve Springs out of the process fluid Hydraulically balanced seal Minimal number of components Field repairable

Seal Selection Criteria

Seal Selection Criteria Fluid Properties Operating Conditions Equipment to be sealed Seal Design Chosen Material Compatibility / Suitability Environmental Controls Selected

Seal Selection Considerations Shaft Size < 2.50”: Cartridge Seal Easiest seal type to install Due to relatively small pump size, pump dismantling not overly difficult or time consuming. Shaft Size > 2.50: Split Seal removal required – not easy to repair on site.

Materials of Construction Water with varying degrees of Solid / Abrasives: Face materials: HARD FACES = Silicon Carbide vs. Silicon Carbide Secondary Seals: FKM, EPR or Aflas* Springs: Hastelloy C** or Elgiloy*** Misc. Metal Parts 316 SS * Registered TM of Asahii Glass Co. ** Registered TM of Hayes Int’l *** Registered TM of Elgiloy Ltd. Partnership

Environmental Controls

Environmental Controls Strategies utilized to control the temperature, pressure and the fluid inside the stuffing box. The controls ARE the life support system for the seal

Environmental Controls From a major pump manufacturer, “SEAL ENVIRONMENT IS CRITICAL FOR EXTENDED SEAL LIFE. The number one cause of pump downtime is failure of the shaft seal. These failures are normally the result of an unfavorable seal environment such as improper heat dissipation(cooling) and poor lubrication of the seal faces or seals operating in liquids containing solids, air or vapors.”

Environmental Controls In Water & Wastewater Treatment, controlling fluid properties and removing trapped air are the most significant concerns Preventing solids buildup, keeping abrasives from seal faces, & preventing heat generation at the seal faces

Environmental Controls Most common single seal control: FLUSH Clean, cool fluid with restrictor bushing in the stuffing box throat to create flow Strategy: Try to prevent solids build up in stuffing box (15 fps under bushing) Try to keep abrasives away from faces, Try to push air out of stuffing box and force liquid film lubrication across seal faces. Source of Flush water: City Water Plant Effluent

API Plan 32 – Clean Flush

Issues with Flush Water to Seals Capital cost of flush systems Reliability of flush water systems Loss of system causes seal failure Quality of Flush???? No Worries on quality… We use City Water We use Plant Effluent

Issues with Flush Water to Seals City Water: Typical Cost of flush: $.002/ Gal . Pump shaft size: 2.000” Typical Flush rate: 2 GPM per pump $.002 x 2GPM x 60 Min x 24 Hrs. x 365 = $2102.72 FYI…NYC = $.0049/gal., ($5151) Philly = $.005/gal. ($5256)

Issues with Flush Water to Seals Plant Effluent: Cost of retreating water that has been through the plant = $$$$

Vertical Pump (Flooding) BACK TO SUCTION 1/8”(3.18mm) ORFICE Abrasives Enter seal cavity as pump is flooded. Air Trapped around seal face must be vented off The fluid dynamics in the vertical position are the same as in the horizontal position.

Vertical Applications – API Plan 13

“State of the Art” Sealing Seal Design to Minimize Life Cycle Cost Split seals Effective Environmental Control Active Throat Bushings Reduce or Eliminate Flush Water Requirement Eliminate flush water system wherever possible Improve Pump/Seal Reliability Reduce Plant Operating Cost Satisfies KISS Principle: reliance on flush water can add unnecessary complexity

Active Throat Bushing Active Throat Bushing is used with Split Mechanical Seals to reduce or eliminate flush fluid required and further enhance seal reliability by driving seal cavity circulation and exchange

Zero / Reduced Flush Technology 442 Split Seal Active Throat Bushing

442C Split Cartridge Seal Eliminates Equipment Teardown Specifically designed to seal stuffing box pressure AND vacuum. Fast, economical and easy rebuild of seal in the field, increasing uptime on the pump. Adjustable gland fits  2, 3 or 4 bolt patterns

SpiralTrac Bushings

Trapped Air in Stuffing Box

Air Migrates to Seal Faces

Air Removed by Active Throat Bushing

Dirty Process Fluid in Stuffing Box

Active Throat Bushing Extracts Solids

Active Throat Bushing Technology From one municipal client… “…active throat bushings are both an economically and environmentally responsible upgrade for your pumping applications.”

Summary Common sealing strategies: Packing & Mechanical Seals: Design features Advantages & disadvantages Seal Selection & Criteria in Water & Wastewater Environmental Controls State of the Art Sealing in Water & Wastewater Split Seals & Active Bushing Technology

Parting Gift Flash Drive Copy of the M/S 101 presentation (Shaft Sealing Strategies…) Sample Specifications Seal Recommendations in Wastewater by application Product Brochures Installation Instructions Environmental Controls used In Water & Wastewater Videos Active Throat Bushing

442C Split Cartridge Seal Latest innovation in split seal technology Simple & Quick to Install Superior sealing reliability Simple Field Repair

442C Split Cartridge Seal

442C Split Single Cartridge Seal Simple & Quick to Install Superior sealing reliability Simple Field Repair Operating Conditions Materials Sizes 25 mm to 120 mm Faces CB, CR, SC* Pressure 711 mm Hg vacuum to 31 bar g Elastomers FKM, EPDM, FEPM, FFKM* Temperature 120°C Metals 1.4401 (316SS), SuperDuplex Speed 20 m/s Springs Elgiloytm * - RSC Standard, SSC Optional * - FFKM optional

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