Recently we received a call from a customer. He was attempting to install a mechanical seal and had broken two of them. After a short discussion with one of our service technicians, it became clear that the customer was demonstrating a classic example of how to kill a mechanical seal, not using the correct lubricant.
When I heard about this, I asked the service technician to tell me more. I asked him to share with me the top 5 ways he has seen mechanical seals go down due to installation. He did not disappoint.
1. Not following the installation instructions
Mechanical seals are easily damaged during installation. That’s why it’s imperative to read the installation instructions carefully before attempting to install the seal. See photo here. The installation instructions stated to remove the spacers before starting the unit. The spacer became lodged in the seal, damaging internal components.
2. Install on a misaligned pump
Pump misalignment is caused by pipe strain, deflection during a hard start, shaft run out, or a myriad of other scenarios. Misalignment puts undue stress on mechanical seal components, causing them to not function properly, wear prematurely, and potentially fail.
Be sure to follow proper installation guidelines and use laser alignment tools to ensure the pump (and ultimately the mechanical seal!) is set up for success.
3. Lack of or wrong lubrication on shaft
Lubrication is necessary for proper mechanical seal installation. Lack thereof can damage o-rings or rubber bellows on the seal, causing them to tear, or roll. There are many options available, from petroleum jelly, to silicon grease, to special lubricants. Always check the installation instructions to ensure the lubrication you choose is compatible with seal components and the product pumped.
4. Dirty work surface/hands
Dirt on the seal face, even oil from finger prints, can set a mechanical seal up to fail. Tiny particles can create wear and destroy seal faces, causing leakage.
Ensure proper handling during installation by following these tips:
- Don’t unpack the seal until ready to install
- Wash hands
- Avoid touching or handling lapped seal faces
- Use clean tissue paper on workbench to prevent contamination
- Don’t set the seal down on its face
- Clean faces with soft tissue and approved solvent before putting them together on the equipment
5. Uneven or over-tightening of fasteners
This is probably one of the most common mistakes. Over-tightening fasteners can cause seal components to become distorted and leak. Oftentimes when a seal starts to leak, the natural reaction is to tighten even further! Unfortunately this just exacerbates the problem. Instead, try loosening a bit, the problem may correct itself, if the internals haven’t broken already from mechanical shock.
After reviewing this list of 5 ways to kill a mechanical seal, the service technician I worked with on this said he could come up with many more ways. Maybe that will be a follow up post. How have you seen a mechanical seal go down? Let me know in the comments!
Not sure why your mechanical seal is failing? Ask us about it! We gladly provide technical assistance to businesses and municipalities in Wisconsin and upper Michigan.