Stuffing box, pump

Modifications Requited, Temperature Range 250-350°F. Pumps for operation in this range shall he provided with a water-jacketed stuffing box. 

Cast Iron—316 SS Fitted. IS" only pump shall have cast iron casing and stuffing box cover. 316 SS metal impeller shaft shall he 1045 steel with 316 SS sleeve. 

Permit the pump and paeking to leak generously for about 15 minutes to allow the packings to absorb the pumped fluid,. swell, seat and adjust to the stuffing box wall and the shah. 

Products with dissolved gas must be properly vented. In most cases, vent the stuffing box back to pump action. 

Part Purpose Shaft sleeve Protects the shaft where it passes through the stuffing box. Usually used in pumps with packing but often eliminated if mechanical seals are employed. 

Figure 3-16. Stuffing box details lined pump with porcelain or teflon shaft sleeve. (Courtesy Dorr-Oliver, Inc.)...

Lantern Gland Stuffing Box Gland Figure 3-17. Packed stuffing box. (Courtesy Dean Brothers Pumps, Inc.)... 

Figure 3-18. Typical single mechanical seal inside pump stuffing box. (Courtesy Borg-Warner Co.)...

Forced circulation Viscous and solid-containing liquids can be circulated. Enables an erosion-fouling balance. Circulation rate can be controlled. Relatively expensive due to extra shell volume. Cost of pump and pumping. Leakage of material at stuffing box. 

Static seals are standard provision from many suppliers therefore seals for the moving elements in pumps will be discussed. For centrifugal pumps, both stuffing box and mechanical seals will be considered and the discussion will be extended to reciprocating and rotary machines. 

Shaft seal requirements and two common types of seals, packed stuffing boxes and simple mechanical seals, are described and discussed in this section. A packed box typically is used on slow- to moderate-speed machinery where a slight amount of leakage is permissible. A mechanical seal is used on centrifugal pumps or other type of fluid handling equipment where shaft sealing is critical. 

Having discussed how a simple mechanical seal is assembled in the stuffing box, we must now consider how the pumped fluid is stopped from leaking out to the atmosphere. 

This procedure provides detailed instructions on how to repack centrifugal pump packed stuffing boxes or glands. The methodology described here is applicable to other gland sealed units such as valves and reciprocating machinery. 

Contact operations to start the pump and allow the stuffing box to leak freely. Tighten the gland bolts one flat at a time until the desired leakage is obtained and the pump runs cool. 

With the pump stuffing box cover bolted down, clamp the dial indicator to the shaft with the stem against the face of the stuffing box. The total indicator runout should not exceed 0.003 inches. 

The stuffing box of the equipment, especially centrifugal pumps, should always be vented before startup. Even though the pump has a flooded suction, it is still possible that air may be trapped in the top of the stuffing box after the initial liquid purge of the pump. 

The simplest, and oldest, form of seal is the packed gland, or stuffing box, Figure 5.12. Its applications range from sealing the stems of the water taps in every home, to proving the seal on industrial pumps, agitator and valve shafts. 

For open system sump pump service, the pressure containing components Types VS4 and VS5 pumps are the volute casing, suction cover, and discharge fine. For closed system pressurized or vacuum tank service, the outer stuffing box or seal housing, pump cover plate, and tank cover also become pressure containing components. 

Where process equipment is provided with fixed-temperature detectors, these should be located as near as possible to the potential fire source for example, above flammable liquid pump seals, immediately over a solvent draw-off point, or mounted above a crude tank mixer stuffing box. As a general rule, fixed-temperature detectors directed at a potential hazard should be considered only for process equipment where specific fire problems are anticipated. 

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