A gland is a type of stuffing box sealant that is used to seal a rotating shaft against a fluid. The most common is the head of a tap called the faucet where the gland is usually packed with string which has been soaked in similar grease. The gland nut allows the packing material to be compressed to form a watertight seal which prevents the water from leaking up the shaft when the tap is turned on.
The gland at the rotating shaft of a centrifugal (outward moving) pump may be packed in a similar way and the graphite grease is used to accommodate continuous operation. Linear seals around the piston rod of a double acting steam piston is also known as a gland and is particularly used and seen in marine applications the same as the shaft of a hand or wind pump is sealed with a gland where the shaft exits the borehole.
Other types of sealed connections are without moving parts but are still, depending on the components thereof, considered glands. Some really good examples include if a gland connects to a flexible electrical conduit to an enclosure, bulkhead or machine facilities assembly and prevents gas or liquid leakage.
Mechanical seals and gland packing are very important components of pumps and shafts. There are countless engineering applications that rely on these devices to function properly. Even though packaging and pumps have similar functions by using either depending on the budget or personal preferences and most importantly they must meet the application requirements.
Gland packing can also be known as a conventional shaft seal. Many engineers do not recommend packing for a lot of applications due to the requirements and high costs of maintenance. The sealing of gases and liquid are not that effective either because packing is prone to leakage and therefore there is a need to regularly adjust so that the seal is well lubricated.
However, there is also a problem of abrasive liquids that causes corrosion and this would usually take a toll on the lifespan of gland packing, thus, forcing to spend more on repairs and replacements. On the positive side, there are such cases where packing can outperform seals. This means that they are good at handling aggressive fluids. Some manufacturing companies, like First Seal, have set industry standards to manufacture gland packing and seals so that there are always more advantages!