A good description & comparison of mechanical seal vs gland packing.

1. Mechanical Seal By Mr. Om Pratap Singh

2. Parts of centrifugal pump

3. Why sealing required ! Key component of the pump is its mechanical seal. This spring loaded component consists of two faces, one stationary and another rotating, and is located on the Pump shaft between the impeller and the rear casing (see figure below). It is designed to prevent fluid from seeping outside of pump casing towards motor. Pumps designed for work in harsh environments require a seal that is more abrasion resistant than pumps designed for regular use.

5. Mechanical Seal Vs Gland Packings Loss of Material A basic comparison with the leakage rate for the compression packings and mechanical seal yields the followings: (25 drop/minx60x24)+45 drops/day=800 a leakage ratio of packings to seals of 800:1 Power saving: 50% Less power consumption in Mechanical seal.

6. Cross-sectional view of mechanical seal

8. Gland packing

9. How Mechanical Seal Works !

11. Secondary Sealing Elements

12. Need of API Flushing Plan To lubricate and cool the pumps mechanical seal. To remove foreign particles to minimize abrasion. To remove carbon deposition on compression unit. To dilute ingresses material between Seal faces. It could provide safety to the seal from dry running to the some extent. To maintain the operational parameters of mechanical seal for which it is designed.

13. PLANT 11 Plan 11. A line is connected from the discharge side of the pump and recirculated through an orifice into the gland flush connection. Orifices are hard to size and since many pumping fluids contain solids orifices are easy to clog

15. To cool the product we are sealing

16. To dilute any leakage that might migrate across the seal faces.

17. To introduce low-pressure steam behind the seal to put out a fire.

18. The Quench connection is labeled (Q). A close fitting bushing (DB) in the end of the gland directs the quench fluid down a drain hole on the opposite side of the seal gland

20. API PLAN 13

21. Operational and Maintenance Errors Operation error is the single most cause in seal failure in throughout industry today. Some are mentioned below : Dry running. Suction chocking. Foreign material. Material Incompatibility. Abnormal process parameters. Flushing Plan Off. Maintenance fitting errors are also affects the mechanical seal Life : Misalignment < 0.02 mm Stuffing Box Concentricity or gland register <0.1 MM Shaft Run Out < 0.07 MM Stuffing Box To shaft Perpendicularity < 0.07 MM End Play (Hold b/w 0.02 MM – 0.1 MM) Radial Deflection < 0.07 MM Failed Bearings Unavailability of Flushing Plan Required

22. Stuffing Box Concentricity or gland register <0.1 MM

23. Stuffing Box To shaft Perpendicularity < 0.07 MM

24. Shaft Run Out < 0.07 MM

25. End Play (Hold b/w 0.02 MM – 0.1 MM)

26. Radial Deflection < 0.07 MM

27. Thank You