Maintenance & Reliability · SOP

Centrifugal Pump Mechanical Seal Inspection & Greasing

Comprehensive standard operating procedure for inspecting stationary and rotating faces of mechanical seals, measuring shaft runout, servicing the seal chamber, and re-greasing flush lines on ANSI/ASME B73.1 industrial centrifugal pumps.

Estimated Time

45 min

Difficulty

Advanced

Regulation

API 682 / ISO 21049

Version

2.1

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Purpose

Define the mandatory inspection regime and greasing protocol for mechanical seals installed on ANSI/ASME B73.1 horizontal end-suction centrifugal pumps. This procedure ensures compliance with API 682 (2nd/3rd edition) seal flush plans, guarantees maximum mean time between planned maintenance (MTPM) of the seal assembly, and prevents catastrophic fluid leakage leading to environmental fines or bearing housing contamination.

Scope

Applicable to all single and dual (tandem/back-to-back) mechanical seals operating in Process Plant Zones 1 & 2. Includes seals with Plan 11, 21, 62, and 53A flush systems. Excludes submersible pumps, high-pressure boiler feed pumps (> 600 psi), and magnetic drive pumps (sealless). This revision applies to all Frame 3 & 5 pump models within the facility.

Safety Precautions

LOTOLockout/Tagout Mandatory: Isolate the pump driver at the motor control center (MCC). Depressurize the seal chamber to 0 psig. Bleed the flush plan piping. Verify zero energy state using a qualified electrician before proceeding.
PPEChemical-Resistant PPE Required: Wear Viton/butyl rubber gloves, full-face splash shield, and Tychem coveralls if handling hydrocarbon or caustic services. Have an eyewash station available within 10 seconds.
HOTHot Work Permit: If torqueing seal gland bolts or seal press fitment requires grinding, obtain a hot work permit per NFPA 51B. Ensure fire watch is present.

Required Tools & Materials

Dial indicator with 0.0001" resolution (0.002 mm) mounted on a magnetic base.
Mechanical seal puller / installation tool (specific to seal OEM, e.g., John Crane, EagleBurgmann).
Grease: Lithium complex EP2 (NLGI #2) or per flush plan specification (e.g., Krytox GPL 205 for high temp / oxygen service).
Precision torque wrench (calibrated within the last 6 months, 10–80 ft-lb range).
Micrometer (0–1" / 25 mm) for measuring shaft OD and seal bore.
Service manual for pump make/model (e.g., Goulds 3196, Flowserve 4100).
Non-abrasive pad (Scotch-Brite) and clean, lint-free wipes.

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Procedure: Step-by-Step

1 Isolation & Depressurization: Verify pump suction and discharge valves are closed and locked. Open the seal flush plan valve (e.g., Plan 11 orifice) to atmospheric pressure. Confirm seal chamber pressure is 0 psig on the local gauge.

2 Dial Indicator Setup & Shaft Runout Check: Mount the magnetic base on the pump bearing housing (do not mount on the stuffing box). Set the dial indicator plunger perpendicular to the pump shaft. Rotate the shaft by hand to record total indicated runout (TIR). Maximum allowable TIR is 0.002" (0.05 mm). If TIR > 0.002", inspect bearings before proceeding.

3 Seal Disassembly & Face Inspection: Remove the seal gland bolts. Using the seal puller, carefully disengage the rotating face from the shaft. Place the stationary seat and rotating assembly on a clean, oil-free paper towel. Inspect both faces for scoring, heat checking, or pitting. Cracks or wear tracks wider than 0.010" (0.25 mm) require seal replacement.

4 Seal Chamber & Shaft Inspection: Clean the stuffing box bore with a non-abrasive pad (Scotch-Brite). Check the seal bore for grooving or corrosion. Measure shaft diameter with a micrometer at the seal contact area. Worn shafts (more than 0.005" under nominal) require a wear sleeve.

5 Greasing of Flush Ports & Quench Connections: Using a manual grease gun, charge the seal flush ports (Plan 62 quench connection) with 5 pumps of approved grease. Ensure grease exits the opposite quench port to verify no blockage. Wipe away excess grease. For Plan 53A buffer fluid reservoirs, top off to the correct level with the specified barrier fluid.

6 Seal Re-installation: Lubricate the shaft / sleeve with a thin film of clean water or compatible assembly lubricant (DO NOT use oil). Slide the rotating face assembly onto the shaft. Install the stationary seat and gland. Tighten gland bolts evenly in a star pattern to the torque specified in the OEM manual (e.g., 30 ft-lb for 3/8" bolts). Re-check shaft TIR.

7 Post-Maintenance Verification: Open the suction valve and slowly pressurize the seal chamber (max 25 psig). Perform a static leak check (wait 5 minutes). Zero leak is expected across the stationary seat. Place the pump into service and record amp draw, discharge pressure, and seal chamber temperature every 15 minutes for the first hour.

Centrifugal Pump Mechanical Seal Inspection & Greasing

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