Tag Archives: failure analysis

API 682, end face mechanical seal, mechanical seal

What Do You Want from Your Seal Supplier?

In the early 1970s, I was part of a centrifugal pump inspection team whose goal was to increase pump reliability.  At the same time, we were converting many pumps from packing to mechanical seals.  We were also converting some pumps with single seals to tandem seals.  We were a busy group and I was on a very steep learning curve.

Even though I was new to pumps and seals (well, bearings, lubrication, — ok, everything!) our group leader made no bones about what he wanted and expected from our seal suppliers:  SEALS.  That was just about it.  He expected our suppliers to have lots of spare parts on hand for essentially immediate delivery.

Of course, we also wanted to be kept informed of the latest developments in the world of seals.  We wanted to see lab tests, technical papers, advances in materials such as perfluoroelastomer and silicon carbide, etc.  Finite element analysis was beginning to be used to study seal design and performance.  This was an exciting time to be learning about mechanical seals.

In those days, we did our own failure analysis and we had plenty of failures to examine.  By our rules, Mean Time Between Repairs (MTBR) was only about a year (some would have called it 2 years or more).   Improvements in reliability through failure analysis was one of the main functions of the inspection group.  We used failure analysis to point towards specific and general methods of improving reliability.  We did not want to be simply “parts changers”. 

We also did our own seal repairs, including lapping, and rebuilt our own seals.  Training was done by our group leader.  I actually heard him say, somewhat arrogantly, to a seal salesman:  “What can you teach me about seals?”  But then, he enjoyed challenging people – including our own group members.  We actually did go to a few outside, independent seals training courses and sometimes even asked a seal OEM for a detailed failure analysis report.  But, for the most part, we did not rely on the seal OEMs.

Of course, we had our own inventory of critical pump and seal parts in addition to the seal supplier’s inventory.  The relative proportions of these inventories were always a bone of contention.  I have to laugh when someone says that, long ago, inventory did not matter.  Of course inventory mattered – the “optimum” was simply a different amount than it is today.

We even had an equipment records system that used a computerized database (yes, even in the ‘70s!) of equipment, services and repairs.  Querying this database provided statistical evidence of problem pumps and problem components.  Yes, mechanical seals were the main component causing pump repairs.  In addition to the computer databases, we also had good old paper files for each pump which included the original specifications and datasheets, notes on repairs and, occasionally, a photograph but more often a sketch.

I realize that every process plant was not so well staffed, directed and equipped but mine was and I have greatly benefitted from that experience.

Fast forward some five decades and the relationship between seal supplier and end user is vastly different.  Most end users do not do failure analysis and do not rebuild their own seals.  They may not have their own equipment databases and failure records.  They even may not have an inventory of seal parts.  Instead, most end users seem to rely on their seal suppliers to provide not only goods but also services.

As a result of the changes in this relationship, it is the seal supplier who gains the experience and the knowledge that I received as an end user.  The seal supplier typically provides a technician or engineer, very nearly a contract employee, to his customer, the end user.  This person collects data, examines seal failures, makes recommendations (and gets to see the effect of those recommendations!) and builds up an equipment and failure database.  The loss of experience for the end user is definitely a gain in experience for the seal supplier.

So, what do you want from your seal supplier?

mechanical seal

Learning to Draw

I haven’t abandoned SealFAQs or even neglected it.  I’ve been busy learning to draw using Adobe Illustrator.  Here’s an example of a mating ring that I recently drew.

Mating Ring with Good Wear Track
Mating Ring with Good Wear Track

Hope this looks like a mating ring to you!  It’s a shame that I can’t draw.  I’ve had engineering drafting and can make simple 2D drawings but not 3D.

I thought that, by using Adobe Illustrator, I could make simple 2D shapes and extrude them to 3D,  Perhaps that can be done but I can’t seem to get it to work.  Instead, I’m drawing the 2D shape/face and projecting it back for 3D.   Next I have to learn to use gradients and shading.

All this to create illustrations of seal face wear patterns and damage.

Photography

Macro Lenses for Cell Phone Photography

Strictly speaking, the lenses I’m about to show and discuss are not true “macro” lenses.  In macro photography, the subject is projected in full size or larger on the negative or sensor.  Cell phone camera sensors are tiny — about 6mm diagonally – which means that only tiny subjects could be photographed as true macros.  In modern usage, “macro” has come to mean an extreme close-up such that the final image is the same size or larger than the subject.

I was able to do quick tests for the following lenses:

Macro lenses for cell phone cameras.

The Zoetouch and Xenvo are simple clip-on lenses that also include a wide angle lenses.  With my iPhone 7+, I had to be careful getting the lens over the 1x or 2x lens of the phone camera.

The Olloclip is a kit that includes 7x, 14x and 21x lenses.  The 14x macro is obtained by screwing a second lens onto the 7x lens.  The lenses are screwed into a holder which then snaps onto the clip.  The kit includes two translucent lens hoods which are a great help in obtaining a steady focus. The holder and clip for the iPhone 7+ can be configured to fit either the 1x or 2x lens of the phone camera.  The Olloclip works fairly well except that the Camera+ or ProCamera app are required in order to use the 2x lens of the iPhone 7+ with it.

The Moment macro lens is a 10x lens.  Apparently, the original version of the lens used a clip mount whereas Version 2 requires a special case from Moment.  Optics are identical for Version 1 and Version 2.  I got Version 2 and the Moment case ($30).  The Moment case is very thin and easily fit inside my iPhone holster.  The Moment lens is easily attached to the case and fits over either the 1x or 2x lens of the iPhone 7+.  Like the Olloclip, the Camera+ or ProCamera app are required in order to use the 2x lens of the iPhone 7+; however, Moment offers a free app that is very simple to use and works well with the Moment macro lens.  I really like the Moment system and have ordered their telephoto and wide angle lenses as well.

Here are images obtained from photographing a penny using the various macro lenses.   I tried to make each image as large as possible by placing the iPhone 7+ as close as possible to the penny.  Each individual  image was then copied to a blank Photoshop page so the combination below is approximately to scale.

Macro photos of a penny using add-on macro lenses with an iPhone 7+.(click for larger view).

As noted previously, there is a space of only an inch or so between the lens and subject so lighting is not easy.  For these images, I placed a small LED video light to the right of the penny and a sheet of white paper on the left side.

I’m not going to comment on every image but a few observations are in order:

  • The Zoetouch and Xenvo lenses were difficult to hold steady and obtain focus.
  • The Moment system obviously missed the white balance when only the penny was in view.
  • The Moment lens seemed to have the best optics.
  • The Olloclip 21x lens mounted over the iPhone 7+ 2x lens provided the most enlargement and was also the most difficult to use.
  • Simple enlargement and cropping can give good results.

My preference?  I’ll be using the Moment system but also having the Olloclip kit available.  I’m still tinkering with lighting though.

 

 

mechanical seal, Photography, pusher seal

Accessories for Cell Phone Cameras

iPhone 7+ and LED light on Joby Gorillapods
iPhone 7+ and LED light on Joby Gorillapods

We photographers certainly love our accessories!  Here are some suggestions for accessories to help get the image you want with your cell phone.

Tripod

Although many people prefer not having to deal with a tripod, it is still one of the first and best accessories for photography.   In this discussion, since the subject is cell phone photography, it is implied that the tripod be small and lightweight.  Also needed is a means of attaching the cell phone to the tripod.

One of the Joby Gorillapods seems ideal for cell phone photography.  I’m currently using this one with my iPhone 7+.  To use the cell phone with a more conventional tripod, you’ll need a cell phone mount .

When using the cell phone mounted on a tripod, I prefer to use a 2 second delay to trip the shutter.  This helps to prevent camera/tripod vibration from my touch.  For my iPhone, setting the shutter delay also automatically switches the camera to a 10 shot burst mode – which is not always desirable.  Unfortunately, there is no way to turn off this burst mode; however, a workaround is to turn on the “HDR” mode as well.  With HDR mode, only two shots are taken:  one shot is normal, the other HDR.  Actually, the HDR image is often a good one.

Diffuser and Reflector

A diffuser can soften the light and prevent hot spots when the subject is in bright sunlight.   You can make one with a translucent trash bag taped to a cardboard frame.

A reflector placed on the opposite side of the light source helps distribute the light and reduce shadows.  The reflector can be a piece of copy paper (or bring along a large sheet of foamboard).

Diffusers and reflectors can be difficult to handle – another reason to free up your hands by placing the camera on a tripod.

Backdrop

A backdrop can hide that unwanted background clutter but can be difficult to set up.  A painter’s drop cloth and a few spring clamps can be useful.  For small subjects, the backdrop and reflector can be a sheet of paper.

Lights

A small, inexpensive, battery powered LED light is probably the best way to add light to the scene.    I use one like this with a rechargeable battery (separate purchase); similar ones can be purchased for about $30. With the camera on a tripod, move the light around to find the best angle and distance to light the scene.  Unfortunately, a battery lasts only about an hour.  Add a reflector on the opposite side of the light to balance the lighting.

The original Joby Gorillapod is useful for holding the LED light.

Macro lens

There are a number of macro lenses available for cell phone close-up photography.  Some of these lenses are very powerful; however, getting good lighting can be a problem.  When using a macro lens on a cell phone, the lens will probably be only about an inch from the subject area.  As far as I’m concerned, if you buy a macro lens, you might as well buy a light or two while you’re at it.

Here are some macro lenses that are popular and appear useful:

I recently got the Olloclip kit of macro lenses and am trying to decide whether I like them or not.  I’ll probably get one or two of the less expensive lenses and compare them in a separate blog post.

Coming up

The next post will be about cell phone camera apps.

bellows seal, mechanical seal

Using Your Cell Phone Camera

A cartridge seal.

Your cell phone can be useful when documenting equipment failures, repairs, etc.  In fact, most readers have probably already used their cell phones to do so.  With the cell phone, you can dictate notes, record video or take still photographs.  This post is about improving those still photographs.

The advantages of using your cell phone camera to record damaged part information are

  • Always with you
  • More than adequate quality
  • Easy to use
  • Easy to send images to others.

I’m currently using an iPhone 7+ and really appreciate the quality and new features of its camera.  I especially like the telephoto (2x) lens.  Learn to use the features of your cell phone camera.   Here are some tips for getting good images from a cell phone camera without using additional auxiliary equipment:

  • Set focus point yourself, don’t rely on the camera autofocus
  • Zoom in (use 2x dual lens if available)
  • White Balance (color balance for the light source)
  • Adjust exposure manually, don’t rely on camera to set exposure
  • 2 second delay will help to avoid camera movement.

For more detailed information, especially with the iPhone, check out https://iphonephotographyschool.com/iphone-camera-controls/.

Remember that pictures you take will be used to tell the story of the failure or repair.  Be sure to establish the scene with the “big picture”.  Include some shots of components or areas before going too far with extreme close-ups or macros.  For example, in the report, you’ll want to be able to write things like:

  • Here’s the complete cartridge seal when first removed from the pump (the big picture)
  • Here’s the retainer (a component)
  • Notice the fretting inside the retainer (close-up of damage).

Clean up the background.

Remember the saying “90% of photography is moving furniture!” and apply this thought to removing the junk and clutter from the background of your photo.  Use cardboard, shop rags or copy paper for a background or to hide the clutter.

Fill the Frame

Move the camera in close and/or use the dual lens so that the screen is filled with the subject image.  This will save editing/cropping time and also produce a better image.  By filling the frame, you also allow for extracting a “macro” during editing.

Macros

Although macro lenses are available for cell phone cameras, those will be discussed in the next blog.  Most of the necessary documentation photos will not be macros or even close-ups but the camera can be moved very close to the subject to record details.   In post processing (editing) you can crop and zoom in for a “macro” image of details.

Don’t use the flash

The cell phone flash will produce hot spots on the image; turn the flash off and try to find good lighting.   Indirect light near a door or window can be very helpful.  If possible, move the parts outdoors on a cloudy day.

Select the best images

Get many pictures from different angles and distances, then select and use only the best ones.

Coming up

So far, the discussion has not included auxiliary equipment such as tripods, lenses and lighting.  Auxiliary equipment will be discussed in the next blog.

 

 

mechanical seal

Documenting Repairs with a Cell Phone

iPhone for documentatio
Simple setup using cell phone for documentation

Photography has been a hobby of mine for many years.  My first engineering job was at Texas Eastman Company in Longview, Texas in 1970.  Texas Eastman was in the chemicals division of Eastman Kodak and the company sponsored a photography club.  The club had cameras for rent, studios, and darkrooms for making prints.  The more experienced club members taught classes in photography.  I quickly became hooked and bought a 35mm single lens reflex camera to replace my little point and shoot Instamatic.

In those days, getting a photo of a mechanical part meant using the company photographer.  Typically, the photo would be a black and white print or perhaps a color slide.  There really was no good way to attach a photo to a report.  One or two people might get a copy of the print and another print went into a file.

The first photo of a broken part that I personally requested was of a broken shaft.  The camera used was a Hasselblad – a medium format camera.  This camera was primarily used to get publicity photos of people and events for the company newsletter.  Although the print of the broken shaft came out quite well, getting it was a very big deal.  I couldn’t help but think that I could have got the same photo with my 35mm camera and the process would have been much simpler.

As the years passed, for purposes of making presentations (which meant 35mm slides in those days), I began to take pictures of products and failures.  This was not an easy task.  Getting the lighting right was not simple.  My personal 35mm camera would not focus close enough so I got a simple “extender”.  There was no “editing” of the 35mm slides so I bracketed exposures.  The results were not very good.

More years passed and I tried a very basic digital camera having ¾ megapixel resolution.  Although it was OK for snapshots of friends, it was not very good for recording the condition of broken parts.

The next camera upgrade was very significant.  We (meaning the company) bought a 3 megapixel Nikon 990 digital camera.  At first, I thought it was wonderful.  I could even attach it to a microscope.  But after a couple of years, I had to admit that the quality (meaning resolution) just wasn’t very good.  On the other hand, the entire technology of writing a report had changed and it was relatively simple to add a digital image to a report and print it – or simply email the report.

I needed/wanted a better camera so I personally bought a Canon Powershot and used it (and a few upgrades) for many years to get images of products, new parts and broken parts.  I had learned a bit about lighting along the way so my images had improved.

Before too long, cameras were incorporated into cell phones and salesmen as well as end users began to send me digital images.  Frankly, most of these early cell phone images were terrible; however, I greatly appreciated the additional information at the time.   Fortunately, cell phone cameras have improved tremendously and that is the real reason for this blog.

Today, you can provide more than adequate information about a broken part by just using your cell phone camera.  In fact, there are many advantages to using your cell phone camera for this task.  But this post is already long so I’ll expound a bit more in the next blog.