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Andrew MathiasMike Huebner

Mechanical Seal & System Reliability Through Specification

Calgary Pump Symposium 8-9th November 2007

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Agenda

• Common Areas of Misspecification• Dual Seal Arrangements FTB, BTB, FTF• What Plan / Arrangement Suits What

Product.• Seal Selection Process• Questions?

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Common Areas of Misspecification

• Seal Types (A, B, C)• Single or Dual (Safety, Reliability)• Piping Plan vs Product• Site Philosophy • Elastomer Selection

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API 682 Type A Seal

• Rotating flexible element, multiple springs, O-ring secondaries• Silicon Carbide versus premium grade blister resistant Carbon• Fluoroelastomer O-rings (FKM)• Alloy C276 springs (316 for single spring option)• Type 316 SS sleeve, gland, and other metal parts• Throttle bushing in gland• -40C – 176C Operating Range

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API 682 Type A Seal

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API 682 Type B Seal

• Rotating bellows, O-ring secondaries• Silicon Carbide versus premium grade blister resistant Carbon• Fluoroelastomer O-rings (FKM)• Alloy C-276 bellows• Type 316 SS sleeve, gland, and other metal parts• Throttle bushing in gland• -40C – 176C Operating Range

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API 682 Type B Seal

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API 682 Type C Seal

• Stationary bellows, flexible graphite secondaries• Silicon Carbide versus premium grade blister resistant Carbon• Alloy 718 bellows• Type 316 SS sleeve, gland, and other metal parts• Premium carbon floating bushing in gland• Bronze anti-coke device• -40C – 400C

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API 682 Type C Seal

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Dual Seal Arrangements

• Face to Back (FTB)

• Back to Back (BTB)

• Face to Face (FTF)

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Dual Un-Pressurised Seal FTB

2CW-CW Type A

122CW-CW Type B

Dual Un-Pressurised Seal FTB

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Plan 52

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Plan 52 Reservoir

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API Plan 52 Considerations

• Primary Seal Runs on Product• Piping to Safe Disposal Point• More Suitable for Products Leaking as a

Vapour Such as a light Hydro-Carbon• Selection of Buffer Fluid• Liquid Leakage SG vs Buffer SG• Contamination of Buffer Fluid (H2S)• Thermal Degradation of Buffer Fluid• Piping Practices – Vessel Placement

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Dual Pressurized Seal FTB

3CW-FB Type A

173CW-FB Type C

Dual Pressurized Seal FTB

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Plan 53 A

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Plan 53A Reservoir

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API Plan 53A Considerations

• Primary Seal Runs on Barrier Fluid

• Reliable N2 Supply of Sufficient Pressure• Pressurised System Refill

• Solubility of N2 in Barrier Fluid• Selection of Barrier Fluid

• More Suitable for Products that Would Leak as a Liquid

• Operates on Liquid Level

• Thermal Degradation of Barrier Fluid• Piping Practices – Vessel Placement

213CW-BB Type A

Dual Pressurized Seal BTB

223CW-BB Type C

Dual Pressurized Seal BTB

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Plan 53B

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Plan 53B System

Natural Convection

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Plan 53B System

Water Cooled

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Plan 53B System

Forced Draft

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API Plan 53B Considerations

• Primary Seal Runs on Barrier Fluid• Pressurised System Refill• Selection of Barrier Fluid• More Suitable for Products that Would

Leak as a Liquid• Accumulator Bladder Material• Operates on Pressure• Thermal Degradation of Barrier Fluid• Piping Practices – Cooler Placement

283CW-FF Type A

Dual Pressurized Seal FTF

293CW-FF Type C

Dual Pressurized Seal FTF

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API 682 Plan 53C

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Plan 53C Pressure Transmitter

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API Plan 53C Considerations

• Primary Seal Runs on Barrier Fluid• Pressurised System Refill• Selection of Barrier Fluid• Impulse Line Clogging / Contamination• Compatibility of System with Process Fluid• Piston Hang Up• Thermal Degradation of Barrier Fluid• Piping Practices – System Placement• Small Working Volume

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Seal Selection Process

What we need to know and Why we need to know it.

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Process Conditions

• Process Fluid• Fluid Temperature (normal / max)• Suction Pressure (normal / max)• Discharge Pressure• Seal Chamber Pressure• Vapor Pressure• Percent Solids (and nature of the solids)• Viscosity• Specific Gravity• Hazardous / Flammable / Anything Else?

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Other Considerations

• End-User recommends seal type currently in use at plant or per the customer’s own Seal Selection Guideline.

• Verify new plant requirements for safety and emissions.

• Piping Plan Preference• Cooling Water Available?

• N2 Available?• Flare / Safe Disposal Facility

• Where is it Going?

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Any Questions ?