Mechanical Seals


It is widely known that a significant amount of water leaks into the process from older packing boxes and worn single cartridge mechanical seals. It is crucial that there is as little water leaking to the process as possible since any water that leaks into the process must also be evaporated there. It is expensive to evaporate water that is not necessary.

The Valmet double cartridge mechanical seal type BA, which replaces older mechanical seals and packing boxes was created to reduce the amount of water and eliminate the need for seal maintenance.

Valmet’s new mechanical seals is available for the preheater agitator shaft, discharge screw as well as the Defibrator feeder screw. They require no further machine adaptation during installation and fits flawlessly.

Cost of water to process

In addition to a fresh water costs of 500 euro/per year, each liter/min of sealing water that leaks in to the process costs 5,500 euros per year in water to evaporate in the dryer and 2,000 euros per year in additional steam consumption in preheater.

Each liter/min of sealing water that leaks in to the preheater costs approximately 8000 Euro per year.

New mechanical seals - Zero water to process

The following table shows typical figures for older packing boxes and mechanical seals compared to Valmets new double cartridge mechanical seal. With Valmet’s new mechanical seal the water to process is reduced to 0. Upgrading to Valmets new mechanical seals will reduce water and energy consumption as well as costs for spare parts.

Traditional packing box
In (new) 8-10
Out 5
To process (new) 1
To process (worn) 8-10
Single cartridge mechanical seal
In 6
Out 4-6
To process (new) 0-2
To Process (worn) 4-6
Valmet double cartridge mechanical seal
In 8
Out 8
To process (new) 0
To Process (worn) 0

Spare parts costs

Mechanical Seal reduces spare parts costs by approximately €9,500/year, if the stuffing box packings are changed three times per year, and each change costs approximately €1,500, and if the wear sleeve has to be changed once.


The time it takes to install a Valmet Mechanical Seal is the same as it takes to change a wear sleeve in an existing packing box, approximately 10 hours. The existing water system used for the packing boxes can be used again for the mechanical seals. An additional water filter may be necessary, depending on the quality of the water.

Exchange system

Valmet offers an exchange system for our mechanical seals which means easier handling and reduced costs. By using the exchange system the customer always receives a complete unit reconditioned and upgraded to the latest design. The trade-in unit is disassembled and inspected. Worn parts are reconditioned or replaced. The fixed price presumes that all vital parts of the trade-in unit can be reconditioned. If main parts must be replaced with new parts then the price is adjusted accordingly. The reconditioned trade-in unit become the property of Valmet and stored for the next customer.

Our expertise is at your service

Our expertise is at your service

Our focus is to bring your performance forward utilizing our extensive experience and in-depth knowledge of pulp process technology. Get in touch with our experts through your local Valmet office, or the link below.

Contact us