Which Rotary Shaft Seal is Right for the Pulp and Paper Industry?

Pulp and Paper Industry Rotary Shaft Seals

Americans consume roughly 504 lbs. of paper products per person per year. These products range from corrugated cardboard to packing paper, toilet tissue and many other items most people would consider indispensable in their lives. This dependence on paper helps drive an industry that, in 2015 alone, generated more than $96 billion in revenue.

Rotary shaft seals play an important role in the success of the paper and pulp industry, serving in a variety of equipment applications, including:

• Side-entry agitators
• Wood fiber screws
• Pulpers
• Chip washers
• Rotary air locks
• Wash press augers

Without properly functioning seals, this equipment is subject to expensive, time-consuming breakdowns that can mean the difference between staying in the black and sinking into the red.

High performance in a tough environment

The pulp and paper industry puts equipment to the test. The machinery deals with harsh and corrosive lime, ash and liquor sludge, for example, and the equipment’s seals must be able to stand up to the challenge.

It’s important to note here that not all seals are created equal. Simply put, some seals are designed and built to handle the toughest environments and others are not. CinchSeal rotary shaft seals, for instance, are designed to significantly reduce or eliminate the three leading seal problems:

• Leakage and contamination
• O-ring failure
• Damage from rubbing

Leakage and contamination

Commonly, leakage occurs at the interface between the shaft and the seal. CinchSeal has increased the size of the shaft/seal interface surface and uses durable, long-lasting polished stainless steel-plated PTFE rotor cups to prevent leakage.

O-ring failure

CinchSeal rotary seals get rid of this common cause of seal failure by simply eliminating O-rings. Instead, CinchSeal seals use:

• Purging that creates an air barrier to prevent product from entering the seal

• Cooling of the rotating seal faces by reducing friction-generated heat that shortens seal life


The CinchSeal design eliminates friction damage by employing an elastomer that spins with the shaft. This innovation greatly extends the seal’s service life.

These CinchSeal advantages should be enough to demonstrate the value they bring to the pulp and paper industry. But a closer look reveals other important distinctions.

More reasons to opt for CinchSeal

CinchSeal rotary shaft seals are available in both solid and split models. The split model is particularly suited to challenging environments that might require more frequent maintenance and change-out. Both CinchSeal versions will extend service life and reduce maintenance. However, the split design allows for much easier and faster maintenance and replacement.

The extended life and easier maintenance and replacement that CinchSeal rotary seals bring to difficult production environments explains, at least in part, why they are preferable to other seal alternatives. The relatively low expense associated with these alternatives—lip seals, for example—might be tempting initially, but the luster of low cost rapidly loses its appeal on the job.

Compared to CinchSeal seals, lip seals have some important drawbacks. For instance, lip seals:

• Use a rather small surface to “grab” the rotating shaft, increasing the probability of leakage
• Can’t hold high pressure very well, thus reducing their usefulness
• Wear out faster than CinchSeal rotary seals, particularly in harsh environments, severely reducing their cost-effectiveness
• Can damage rotating shafts because they are stationary

Other kinds of seals have as many or more faults, compared with CinchSeal seals, than do lip seals. The deeper the examination goes, the clearer it becomes that CinchSeal is the better choice.

CinchSeal: Better for the bottom line

For an industry such as pulp and paper that must keep its eye on the bottom line, the CinchSeal bottom line makes sense. To sum it up, CinchSeal rotary shaft seals:

• Feature innovative design features, such as elastomer that spins with the shaft, that reduce wear and tear, ensure a better seal, make maintenance and replacement easier and add to the seal’s useful life

• Reduce maintenance and replacement time and cost, thus more than making up for the apparent savings possible with the alternatives

• Provide the ideal seal solution throughout the pulp and paper production process

Since 1994, CinchSeal has been a major manufacturer of rotary shaft seals for screw conveyors, ribbon blenders and all kinds of bulk handling equipment. CinchSeal products serve as replacements and major upgrades that make the need for machine replacement less likely.

More information is available by contacting CinchSeal. Quotes and drawings are guaranteed to be available in 24 hours. Custom engineering usually takes 10 days.

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Rotary Shaft Seals