What is the purpose of the stuffing box?
A stuffing box or gland package is an assembly which is used to house a gland seal. It is used to prevent leakage of fluid, such as water or steam, between sliding or turning parts of machine elements.
What is the advantage of a gland packing over a mechanical seal?
Gland packing offers multiple benefits that make it an ideal choice for certain applications. Firstly, gland packing offers a low upfront cost and easier installation compared to mechanical seals as it does not require decoupling of drive shaft, resulting in a shorter turnaround time.
How do you maintain a stuffing box?
Water is required to lubricate conventional packing, so a properly adjusted stuffing box can be watertight when the shaft is stopped, but it must drip when the shaft is turning. Two or three drops per minute are adequate. It is not uncommon to see stuffing boxes leak at a much higher rate.
Which of the following statement about stuffing box is true?
5. Which of the following statement about stuffing box (in a reciprocating steam engine) is TRUE? Explanation: Piston rod passes through the crank end of the cylinder, at this end the piston rod must pass through a steam-tight hole, to prevent leakage of steam. Stuffing box does this job.
How do you check a stuffing box?
Check the Packing Start the engine and put it in gear. Let it run for two minutes to see if the box leaks. It should drip a few drops per minute when the shaft is turning, but no drips when in neutral. If it does, give the packing nut another half turn and check again.
How do you adjust a stuffing box?
If the stuffing box is above a deep bilge, tie a retaining line to the wrenches before you start. With your wrenches on both nuts, hold the adjusting nut and turn the locknut clockwise to release it. Back this nut off a couple of turns. Now turn the adjusting nut clockwise until the dripping just stops.
Why stuffing box is used in centrifugal pump?
A stuffing box of a pump houses a gland that compresses the packing used to seal the pumped fluid. It prevents leakage along the shaft that passes through a hole in the pump.
What is impeller clearance?
The impeller vanes must always be parallel to the surface of the bowl leaving a gap, which is known as the clearance. To operate efficiently, the impeller vanes need to comply with the clearance they were designed for.
What is the main difference between a stuffing box gland and a mechanical seal on a centrifugal pump?
Mechanical seal is required where zero tolerance for leakage for fluid to be sealed. Whereas the gland packing is used where leakage of fluid is used for lubrication of gland as well as no hazard or loss of fluid occur.
What is difference between gland packing and mechanical seal?
When considering gland packing vs mechanical seal solutions, mechanical seals are the best for minimizing sleeve damage. Packing seals are removed and replaced much more often than mechanical seals, which causes considerable wear and tear to the pumps as they are disassembled and reassembled.
How do you stop a stuffing box from leaking?
When a stuffing box starts to leak excessively, you should tighten the packing nut until the leak stops. This may be all that is required, but each time the nut is tightened, it squeezes and compresses the packing further, forcing it tighter around the shaft.
What is a stuffing box in oil and gas?
A stuffing box is used to maintain or seal the pressure of fluid during unit operation. The pumping unit moves around the rod to pull whatever you are trying to access — such as oil — to the surface. The stuffing box helps maintain the correct pressure inside the unit during use.
Why stuffing box is provided in centrifugal pump?
If a pump handles suction lift and the pressure at the stuffing box is below atmospheric, the stuffing box function is to prevent air leakage into the pump. If the pressure is above atmospheric, the function is to prevent liquid leakage out of the pump.
Which sealing method is best for high pressure pump systems?
For most of these high-pressure applications, dual mechanical seals provide a superior level of reliability and safety. A dual mechanical seal arrangement uses a barrier or buffer fluid between the two seals to counter the high pressure of the process fluid.
Why sleeve is used in shaft?
The basic function of a shaft sleeve is to protect the shaft from packing wear at the stuffing box. Shaft sleeves help protect the running surface of the shaft seal or the surfaces in contact from damage or abrasive wear.
What is wear ring in pump?
Pump wear rings are the contact zone between rotating and stationary parts. During start-up, shut down, and off-design operation, the rotating and stationary rings come into contact. This contact creates friction and wear. Under adverse conditions, the wear rings can seize causing severe damage.
Why do stuffing box applications require some leakage?
Most applications allow for a small amount of leakage between the shaft and packing, in order to lubricate and cool the packing material.
What is the purpose of a stuffing box in a pump?
Pump packing, contained in stuffing boxes, may be used in some applications to prevent extreme loss of fluid from the low-pressure side of the pump where the shaft penetrates the volute. If a pump handles suction lift and the pressure at the stuffing box is below atmospheric, the stuffing box function is to prevent air leakage into the pump.
What is stuffing box arrangement?
Stuffing Box Arrangement. In most of the pumps, and even in the ship’s propeller shaft , the stuffing box consists of a stack of packing rings or a short square cross sectional rope made of greased flax. The material is closely packed or wound tightly around the propeller or pump shaft with threaded nut or spacer compressing it in place.
What are the problems of stuffing box packing?
High temperatures or pressures complicate the problem of maintaining stuffing box packing. Pumps in these services are usually provided with jacketed, water-cooled stuffing boxes. The cooling water removes heat from the liquid leaking through the stuffing box and heat generated by friction in the box.
Can the stuffing box handle mechanical seals?
The stuffing box was designed to handle both mechanical seals and packing; however, through years of experience, it was found that the mechanical seal’s outside diameter had too small clearance between it and the bore of the box. This limited the amount of cooling that a seal could obtain, especially in double seals.