Maintaining mechanical seals – a guide & expert tips

Mechanical seals are characterised by their long service life. However, the seals will only achieve a long service life without serious damage if you maintain the mechanical seal regularly. By maintaining mechanical seals, you not only protect your seals but also your plant from sudden stoppages and costly downtime. 

In the long term, regular maintenance of mechanical seals also reduces your operating costs.

When should a mechanical seal be serviced?

Mechanical seals should be serviced regularly to detect age-related wear at an early stage. Ideally, this should be a routine preventive check. In addition, you should service the mechanical seal if you notice anything unusual, for example: 

- Increasing leakage / changes in leakage rates 
- Temperature changes 
- Unusual noises 
- Development of (unusual) odours 
If the seals are not maintained regularly, maintenance of mechanical seals is necessary at the latest when you notice deviations from normal operation. Whether the service life of the seals can still be extended depends on the damage the mechanical seal has already sustained. 

Not sure whether your mechanical seal is still operational? We’re happy to help! Contact our team: 
- By phone: 09090 - 705880 
- By email: mail@billi-seals.de 
- Via WhatsApp

What should be checked when maintaining mechanical seals?

The maintenance of mechanical seals can be divided into two areas. Firstly, a visual inspection is carried out, and secondly, you measure and check various parameters when maintaining your mechanical seal.

The visual inspection includes: 
- Checking the seal for wear, leaks and damage of any kind 
- Checking the sealing surfaces for pits, grooves, etc. 
- Checking whether the sealing surfaces are sufficiently lubricated. 
- Checking the shaft and shaft sleeve for damage 
- Checking the seal chamber for cleanliness 
- Checking the alignment of the motor and pump 
- Checking for signs of imbalance or unusual vibrations 
- Check elastomer components (such as O-rings) for cracks, hardening or swelling

Parameters to be measured during mechanical seal maintenance: 
- Temperature / cooling, to prevent thermal damage caused by overheating 
- Operating pressure / pressure test - Leak rate measurement

Guide to the proper maintenance of mechanical seals

To avoid any unpleasant surprises with your mechanical seal, you should include routine maintenance of the seal in your maintenance schedules.

Alignment and balance of the surrounding area

- Thoroughly remove deposits, dirt and corrosion from the pump and the seal cavity
- Use a soft brush and a suitable cleaning agent

Mechanical cover

- Is the mechanical cover running normally? 
- If you notice any scratches or obvious wear, you should replace the mechanical cover.

Seal housing

- Are there any signs of leakage in the area of the seal housing?

Seal chamber

• Rinse the cleaned seal components with clean (distilled) water and/or a suitable solvent
• Remove all residues, including those from the cleaning agents, completely

Seal surfaces

• Are there any scratches or signs of wear on the seal surfaces?
• Determine the condition of the sealing surfaces by checking the surface finish and flatness of the surfaces.
• If the surfaces show damage or excessive wear, you should replace the sealing surfaces.

Shaft sleeve / shaft

• Is any damage visible when inspecting the shaft or the shaft sleeve?

Elastomer components

• Are there any signs of damage, such as hardening, cracks or swelling, on the O-rings or other elastomer components?
• If so, you should replace the damaged components immediately.

Lubrication, flushing and cooling 

• Are the sealing surfaces properly lubricated?
• What is the quality of the lubricant?
• Does it need topping up?
• Does it need replacing?
• Are all flushing and cooling systems working properly?

Checking pressure and temperature against design limits

• Is the operating temperature monitored?
• Is the operating pressure monitored?

Our expert tip: When servicing the mechanical seal, document all maintenance results as well as all measures carried out and planned. This will help you keep track of everything. Furthermore, your records can be useful when searching for the cause of faults, which is often a difficult task.

How often should a mechanical seal be serviced?

How often you should service your mechanical seal depends on the system or pump. You should also follow the manufacturer’s instructions. For guidance, you will find general information on maintenance intervals below:

Check daily

· Pumped medium: temperature / discharge pressure

Check weekly

· Motor temperature 
· Pump tightness and vibrations

Check quarterly

· Tight and correct fit of detachable screw connections 
· Wear / damage to the mechanical seal 
· Shaft sleeve: Contamination, damage, correct concentricity 
· Impeller: Contamination, damage 
· Casing seal: Damage

Our expert tip: If the medium contains solid particles, it is advisable to shorten the maintenance intervals to extend the service life of the seals. You should also have the motor inspected if necessary.

When should the mechanical seal be replaced?

Maintaining the mechanical seal extends the service life of the seals. Nevertheless, there are situations that require the mechanical seal to be replaced. Replacement of the seal may be due to age or environmental factors. Typical causes include, for example: 

- Excessive or persistent leakage from the mechanical seal 
- Worn or damaged seal surfaces, O-rings or other elastomeric parts: Cracks, grooves or spalling 
- Wear of the mechanical seal due to dry running 
- Wear due to contamination of the seal chamber 
- Wear of the seal because it is unsuitable for the system (seal compatibility) 
- Wear of the mechanical seal due to installation errors / incorrect tools used during installation 
- Chemical degradation of seal materials 
- High operating temperatures may indicate misalignment of the seal, poor lubrication or friction, causing the mechanical seal to fail. 
- Unusual noises or increased vibrations in the pump indicate internal wear of your seal. 
- Constant readjustment or retightening of the mechanical seal indicates that it is nearing the end of its service life. 

Our expert tip: Depending on the cause of the seal wear, you should consider replacing individual components. If the seal can be repaired, you will save money and, in many cases, valuable time.