The Top 5 Things Mechanical Seal Users Need to Know

I recently attended the Turbomachinery and Pump Symposium, produced by the Texas A&M Turbomachinery Lab. I&#;ve been attending this conference off and on for 25 years and always sit in on the discussion groups for pump users and mechanical seal users. The same topics come up year after year. Those topics are new for some of the people in the room, but those with decades of experience have heard them all before. There are two reasons why this happens:

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• Centrifugal pumps were designed more than 100 years ago, mechanical seals about 80 years ago, and their basic design has not changed.
• New people are entering the industry and need to learn from those with decades of experience. If mechanical seal users keep my &#;top 5&#; in mind, they will avoid many of the problems I have been hearing about for 25 years.

1. Mechanical Seals Need Lubrication and Parallel Faces.

A mechanical seal is mysterious to most users, but its design is very simple. It consists of two parallel faces sliding past each other. Image 1 is an example of a 90-year old mechanical seal patent (USPTO#2,100,220, issued 23 Nov ). Image 1. Two sealing rings with flat/parallel faces (Images courtesy of Carbide Derivative Technologies)

Image 1. Two sealing rings with flat/parallel faces (Images courtesy of Carbide Derivative Technologies)

2. Seals Naturally Leak and Wear.

The hydrodynamic lubricating film will separate and the sealing faces, which provides a leakage path. This is natural, normal and held to a minimum with proper design. The film&#;s separation and lubrication also prevents wear in normal operation. Theoretically, the seal would last forever in normal operation. Wear occurs in stop/start conditions when the film collapses and the faces come into contact. Abrasives between the sealing faces can also cause accelerated wear, so seal support systems are used to minimize this. Wear also occurs in process upset conditions.

3. Seal Failure Is Usually An Indication of Problems Other Than The Mechanical Seal.

If all conditions of No. 1 and No. 2 are met, a mechanical seal will not fail but will only need to be replaced due to normal wear. If a seal fails prematurely, it is because it was robbed of lubrication or the face parallelism was upset. The seal cannot do this on its own, so a seal failure is usually an indication of something else in other parts of the fluid loop that robbed the lubrication or upset temperature or pressure. Dry running due to a lack of pumpage in the pump is a typical failure mechanism. Excess pressure against the seal due to process upset causes mechanical deformation and is a typical cause of the faces going out of parallel. Image 2 shows such deformation, which causes the out-of-parallel condition and the outer diameter (OD) edge of the rotating face to come into contact with the stationary face. Image 2. Faces out of parallel

Image 2. Faces out of parallel

4. Seal Features Can Mitigate Failures, But Not Prevent Them.

Since the basic design of the mechanical seal has done well and withstood the test of time, its design has not changed&#;and nothing on the horizon indicates that it will any time soon. Rather, seal performance has been enhanced through ring material and running surface improvements (See my articles on this topic in Pumps & Systems, August ,

5. Operate Your Pump and Seal Within Design Limits.

The root causes in No. 3 usually occur when the pump is operated outside of its design envelope. The issues raised year after year in the pump and seal user discussion groups can usually be traced to operating the pump outside of its limits. Every pump and seal application is unique. There is no way to document them all. Because of this, new users should seek out experienced users in their company to access the institutional knowledge those senior engineers have gained. They should also seek out noted industry experts such as Heinz Bloch, Lev Nelik and Jim Elsey. These guys have decades of experience and are prolific writers (including in this publication) whose articles are valuable to avoid typical pitfalls. The mysteries surrounding mechanical seals have caused a lot of misunderstanding and misinformation. So all users, especially new ones, should also seek out and read the writings of mechanical sealing authorities such as Alan Lebeck, Richard Salant, the Fluid Sealing Association and its technical director Henri Azibert. Build a network by attending conferences along with meeting other users and industry experts and listening to their experience.

A mechanical seal is mysterious to most users, but its design is very simple. It consists of two parallel faces sliding past each other. Image 1 is an example of a 90-year old mechanical seal patent (USPTO#2,100,220, issued 23 Nov ).You will see two rings having flat sealing faces in parallel with each other. Take a look at any other mechanical seal design&#;including modern ones&#;and you will see the same thing. In normal operation, a hydrodynamic film will establish between the faces, which keeps them apart and provides lubrication. In most cases, this film will be the pumpage. If the pumpage does not provide sufficient lift or lubrication, a seal support system is used to supply a lubricating fluid. The parallelism between the sliding faces is essential for this lubricating film to establish itself (See &#;Solve Sealing Problems By Keeping Faces Close & Parallel,&#; Pumps & Systems, April ). If the faces go out of parallel due to face deformation from excess pressure or temperature, the film will collapse causing the faces to come into contact and wear excessively or fail catastrophically.The hydrodynamic lubricating film will separate and the sealing faces, which provides a leakage path. This is natural, normal and held to a minimum with proper design. The film&#;s separation and lubrication also prevents wear in normal operation. Theoretically, the seal would last forever in normal operation. Wear occurs in stop/start conditions when the film collapses and the faces come into contact. Abrasives between the sealing faces can also cause accelerated wear, so seal support systems are used to minimize this. Wear also occurs in process upset conditions.If all conditions of No. 1 and No. 2 are met, a mechanical seal will not fail but will only need to be replaced due to normal wear. If a seal fails prematurely, it is because it was robbed of lubrication or the face parallelism was upset. The seal cannot do this on its own, so a seal failure is usually an indication of something else in other parts of the fluid loop that robbed the lubrication or upset temperature or pressure. Dry running due to a lack of pumpage in the pump is a typical failure mechanism. Excess pressure against the seal due to process upset causes mechanical deformation and is a typical cause of the faces going out of parallel. Image 2 shows such deformation, which causes the out-of-parallel condition and the outer diameter (OD) edge of the rotating face to come into contact with the stationary face.The end results in that situation are temperature spikes, catastrophic wear and leakage. The bottom line of this point is that the root cause of a mechanical seal failure is often not the mechanical seal.Since the basic design of the mechanical seal has done well and withstood the test of time, its design has not changed&#;and nothing on the horizon indicates that it will any time soon. Rather, seal performance has been enhanced through ring material and running surface improvements (See my articles on this topic in Pumps & Systems, June August ). Many ring materials, coatings, surface features and surface treatments have all been invented and applied to mitigate &#;failures&#; and extend seal life. However, none of them will prevent the failure modes due to the root causes in No. 3. They will only buy the seal more time before it becomes damaged beyond usability.The root causes in No. 3 usually occur when the pump is operated outside of its design envelope. The issues raised year after year in the pump and seal user discussion groups can usually be traced to operating the pump outside of its limits. Every pump and seal application is unique. There is no way to document them all. Because of this, new users should seek out experienced users in their company to access the institutional knowledge those senior engineers have gained. They should also seek out noted industry experts such as Heinz Bloch, Lev Nelik and Jim Elsey. These guys have decades of experience and are prolific writers (including in this publication) whose articles are valuable to avoid typical pitfalls. The mysteries surrounding mechanical seals have caused a lot of misunderstanding and misinformation. So all users, especially new ones, should also seek out and read the writings of mechanical sealing authorities such as Alan Lebeck, Richard Salant, the Fluid Sealing Association and its technical director Henri Azibert. Build a network by attending conferences along with meeting other users and industry experts and listening to their experience.

If you have nightmares about stolen or damaged cargo, you need a good container seal. In this guide, we&#;ll run through the different container seal types, which ones are the safest, and how to make sure you fit them correctly to prevent theft and damage. 

You receive your container at the port only to find out your goods have been tampered with or stolen. To make things worse, you have no proof, so you can&#;t claim from insurance. The solution? Picking a quality seal, which protects your goods and acts as proof of tampering.

At xChange, we connect you with a wide network of container traders, freight forwarders, and shippers. It&#;s quick and easy to find the perfect box for your shipping needs, from the comfort of your office. Our platform helps you compare prices, negotiate terms, and manage all paperwork in one place.

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What is a container seal?

A container seal is a tag that secures the door lock of your box. They&#;re made to withstand harsh weather conditions and safeguard the container on its journey. Each seal has a unique identification number, and can only be broken once. After it&#;s been broken, it needs to be disposed of, as it can&#;t be used again.

There are many different types of container seal available. Choosing the right seal will depend on your container type, how long the route is, and what you&#;ll be shipping.

Why use a container seal?

Container seals keep your goods safe and secure inside. Not only this, but they also prevent criminals from planting contraband or illegal substances into your box, which can get you into a lot of trouble.

If your seal is broken upon arrival, this is a sure sign that your container has been fiddled with. It&#;s also possible that goods may have been removed or damaged. The container seal acts as proof that your box has been handled by someone else. With this broken seal as proof, you can claim for damages and theft, or report that items have been added to your container illegally.

They also protect your goods from harsh weather conditions, as they make sure the doors are closed tightly, preventing the elements from getting in. This is especially important with perishable goods such as food items and medicine.

Different types of container seal

Container seals come in many shapes and sizes, and are made from various materials. Some commonly used container seals include:

The plastic seal

These come in various colors and sizes. Plastic seals are perfect for short journeys and provide clear evidence of tampering. They can vary slightly depending on the manufacturer. As with all seals, a closed plastic seal can&#;t be opened without being cut. This seal is best for short journeys, as it&#;s not very strong, and is easy to break.

The bolt seal

These are sturdier than plastic seals, so &#; you guessed it &#; they&#;re harder to break. Bolt seals are made of metal (usually steel) with a plastic casing. You need a bolt cutter to break open a bolt seal. Because they&#;re made of metal, these seals are strong and provide excellent security for your boxes.

The e-seal

An e-seal looks just like a bolt seal, but with the added benefit of RFID (Radio Frequency Identification) technology. It has a unique ID that can be scanned through a mobile reader. This seal speeds up the customs clearance process, because it can be verified automatically. Now isn&#;t that convenient?

The cable seal

These seals have a steel cable and are self-locking. Cable seals are heavy-duty and, like bolt seals, can only be opened with a bolt cutter. They&#;re flexible and last longer than other seal types, even in unfavorable weather conditions. Cable seals are the most popular container seals in the shipping industry.

The metal strip seal

These seals have a ball-shaped end and are self-locking. They&#;re made of metal that&#;s highly resistant to corrosion and damage. Metal seals can endure long journeys in all types of weather conditions, and are used to secure a variety of container types.

Placing a container seal correctly: How and where to place it

A standard container has two doors, each with a lock rod for security. The lock rods have handles with holes through which a seal is attached to the container door.

The left door of the container is generally closed first, followed by the right door. So, you&#;re going to want to put the seal around any lock rod on the right door.

Fixing a container seal

A bolt seal is made up of two parts:

• The bolt
• The barrel (both with the same unique ID)

To place the seal correctly, start by snapping the two pieces apart. Slide the seal through the hole in the lock rod, and close it with the barrel cap. You&#;ll hear a faint &#;click&#; sound as the bolt fixes itself into the barrel.

Check the lock again by trying to pull apart the two pieces. Once it&#;s locked firmly, you can only open it again with a bolt cutter. Self-locking cables and metal seals are locked in the same way.

Container seal standards

Container seals are standardized by ISO , which is recognized worldwide. These standards include the following regulations:

• A container seal must be a single-use device that is easy to inspect.
• Each seal must be unique, difficult to copy, and be marked with basic information, such as the logo of the company and a unique identification number.
• Security bolt seals must be at least 18 mm in diameter.
• The tensile strength of a container seal must be greater than kg.
• The cutting strength of a container seal must be greater than 340 kg.

Port and customs requirements for container seals

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You must have at least one seal per shipping container, in order to pass through customs. As the shipper, you&#;re free to add more seals if you want your box to be extra secure.

The maximum number of seals you may have on your container is 6. This is because there are only 6 door lock holes on each box.

The customs department can pick your container for a random inspection at any time. During an inspection, your seal is broken, so that your container and it&#;s contents can be checked. Once the inspection is finished, a customs seal will be placed on your box to keep your goods safe. If you see a customs seal, you know that your box has been checked by customs, and has not been tampered with &#; so don&#;t panic!

What is a customs container seal?

A customs container seal, commonly known as a customs seal, is a specific type of security seal applied to shipping containers to indicate that the container has been officially inspected and cleared by customs authorities. These seals are a critical component of international trade and shipping, helping to ensure the security and integrity of cargo during transit across borders.

Here are some key features and functions of a customs container seal:

Official Inspection Indicator: Customs container seals serve as an official indicator that customs authorities have inspected the container and verified its contents.

Regulatory Compliance: The presence of a customs seal on a container helps demonstrate compliance with customs regulations and facilitates the smooth movement of goods across borders.

Unique Identification: Customs seals typically have unique identification numbers or codes. This allows customs authorities to track and verify containers easily. The identification information is often recorded in shipping documentsWhat are shipping documents? In shipping, shipping documents are documents that provide information about the goods being shipped. They may include information such as the origin and destination of th... More and may be cross-referenced during inspections.

Tamper Evidence: Customs seals are designed to be tamper-evident. Any attempt to break or tamper with the seal should be immediately noticeable. This feature helps prevent unauthorized access to the container during transit.

Now that you&#;re up to speed on the customs container seal, let&#;s get into how you can apply and remove them as safely and accurately as possible:

How to seal a container

Sealing a container with a container seal typically involves using a device or mechanism to secure the container in a way that prevents unauthorized access or tampering. Here are general steps on how to seal a container using a container seal:

Choose the Right Seal

Select a container seal that meets the security requirements of your shipment.

Inspect the Container

Before sealing the container, inspect it for any signs of damage or tampering. Ensure that the container is in good condition and that the doors and access points are secure.

Prepare the Seal

If your seal requires assembly, follow the manufacturer&#;s instructions to prepare the seal for use. For example, if it&#;s a bolt seal, insert the bolt through the locking mechanism.

Place the Seal

Position the seal over the points where the container doors meet or any other designated sealing points.

Secure the Seal

Use the provided tools or mechanisms to secure the seal.

Record Seal Information

Keep a record of the seal number and any other relevant information. This is crucial for tracking and verifying the integrity of the shipment.

Document the Sealing Process

It&#;s often a good practice to document the sealing process, especially if it involves a chain of custody. 

Verify Seal Integrity

After sealing the container, visually inspect the seal to ensure it is securely in place. Verify that the seal has not been tampered with and that it shows no signs of damage.

Note: Specific steps may vary based on the type of container seal you are using, so it&#;s essential to refer to the manufacturer&#;s instructions for the seal model you have.

Removing a container seal correctly

To remove a container seal successfully, it needs to be cut with a bolt cutter along the length of the pin. Depending on the strength of the seal, it might take you a few tries to cut through it.

When removing a container seal, take note of the following:

• Before removing the seal, check it for wear and tear, or signs of damage.
• The seal number should match the bill of lading number and other shipping documents

  What are shipping documents? In shipping, shipping documents are documents that provide information about the goods being shipped. They may include information such as the origin and destination of th... More

• If you see a customs seal on your container, you know that it&#;s been opened by customs representatives at the port.

Get quality containers and container seals on xChange

Now that you know all about container seals, it&#;s time to get yourself some good quality boxes, with strong, sturdy container seals.

xChange connects you with more than vetted logistics partners in + locations worldwide. We&#;re a neutral, transparent marketplace for buying, selling and leasing shipping containers.

It&#;s never been easier to find and buy the perfect boxes for your needs. Once you&#;re a member on xChange, it&#;s simple to get started. All you need to do is type in the container type you&#;re after, as well as your location, and press &#;search&#;. You&#;ll have access to hundreds of containers in your area, available at competitive prices.

Every aspect of your workflow process can be managed on our platform, from searching and striking a deal, to payments, invoices and container tracking. And what&#;s more, all negotiations can be done directly with your partners, no middle men, no hidden fees!

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How do you use a container seal?

A container seal is used by securing it around the door locks. It can only be unlocked once by the recipient. Often, a bolt cutter must be used to open a container seal. Once a container seal has been opened, it can't be reused, and must be disposed of

How do you seal a container?

You seal a container by sliding it through the holes in the lock rod handles on the door. The seal is locked either with a barrel, or has a self-locking system. The seal can only be opened again once.

What happens if a container seal is broken?

If a container seal is broken, this acts as proof that the goods inside have been tampered with. If your box arrives with an open seal, you should immediately contact the shipping line and their insurance company to claim compensation for loss or damages.

Why do containers get a plastic seal?

Containers get a plastic seal to protect them against tampering or theft. This also ensures that goods are protected from external weather conditions, and acts as proof that the shipment is safe inside the container.

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