Gland packing is used for sealing and limiting leakage of the working fluid along the stem in valves, as well as the shafts of pumps. Gland packing can also be used for manhole cover sealing. Over time gland packing technology has developed to such an extent that various combinations of artificial fibres and innovative materials are used.
Gland packing applications
Gland packing is used in the following ways:
- Static applications like tanks hatch cover sealing
- Reducing leakage along the stem of valves like globe valves, gate valves, and ball valves
- Used for reducing leakage of the working fluid in reciprocating pumps.
- Limiting the leakage of working fluid in rotating pumps such as centrifugal pumps
- In propeller shaft sealing in life boats
The type of gland packing for these various applications differ significantly. Selection the appropriate gland packing depends on the temperature, pressure, corrosiveness, and suspended solids in the fluid, among a few considerations. An engineer will be asked to make the correct choice of gland packing.
Mechanical seals and gland packing
These days, almost all new ships have mechanical seals on rotating pumps as a result of very strict pollution laws. Gland packing is still used where a mechanical seal may not work properly, such as certain corrosive environments where a mechanical seal may corrode. In globe, gate, ball valves, and valve cocks gland packing is used since mechanical seals need a rotary motion for successful sealing action.
Gland packing advantages
Often gland packing is considered old and low-end technology. However, it offers some advantages over mechanical seals:
- It is an extremely reliable sealing method
- It is simple to install and maintain
- It can endure poor mechanical conditions such as off-centre shafts and worn-down anti-friction bearings
- It works better in abrasive and corrosive environments
- It requires very little time to change, making it very cost effective in downtime
- Gland packing is less expensive than mechanical seals
- With gland packing it is not necessary to open whole pump to changing the gland packing, unlike replacing a mechanical seal
Gland packing properties
Gland packing needs to have these properties to fulfil its purpose:
Anti-friction properties to prevent the gland packing from heating up and failing or even burning as a result of constant overheating.
Chemical resistance to the fluid being contained to prevent it from disintegrating and causing leakage. Temperature resistance.
Gland packing should be able to compress and conform to the shaft under the force and return to its original shape when the tension is released.
Gland packing is coated with lubricants and need to be able to retain this grease for anti-friction properties.
It should not contaminate the fluid being sealed.
Gland packing should be non-corrosive to avoid damage to the shaft and the housing.
Different material for gland packing
Depending on the application of gland packing, there are many different types of basic materials or combinations of materials used in its manufacture. Occasionally gland packing may also be reinforced with metal wires for extreme conditions.
- Jute
- Flax
- Hemp
- Cotton
- PTFE
- Aramid
- Wrapped metal foils
- Graphite fibre
- Carbon fibre
- Glass fibre
- Poly acryl nitrile fibre
Contact First Seal today
To learn more about the gland packing we have on offer, get in touch with our team of expert pump and seal specialists.
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