Category Archives: SealFAQs

SealFAQs, Uncategorized

A Rant

Fair warning: This is a rant.

I had to stop all comments because a certain person continually entered fake comments just to promote his own websites. I don’t understand how or why this person does this, but the only way I could prevent it was to not allow comments on any posts.

I’ll leave this post open to comments so I can test my latest options for preventing spam. If your website or email address uses words like ‘hairstyle’, ‘hair’, ‘style’, ‘hairstylevip’, etc. then you may not be able to comment – at least I hope so.

Of course, the spammer does not actually read my posts, so this message may go unnoticed, but I’ll leave this post up for a few days and see what happens.

API, mechanical seal, SealFAQs, Uncategorized, Wikipedia

Blogs about Mechanical Seals

A blog is a “weblog”, that is, an online journal or informational website.  Posts to a blog appear in reverse chronological order. A blog can be about anything. Many blogs are personal in nature and often are similar to a diary.  The first blogs began to show up about 1994 and were primarily text with a single author.  A blog is expected to be updated more frequently than a website and also to be somewhat less formal.  Blogs usually have a byline or author and the blog site includes the ability to find previous posts by author, date, category and tags.

A blogger is simply someone who operates a blog or blog site as opposed to someone who authors a post for a blog or website.

Blogs can generate money through sponsors and links to commercial sites; however, SealFAQs does not do this.

One problem with hosting a blog is the commitment to maintain it and to add new posts regularly.  Having neglected my own blog for several months, I’m well aware of this problem.  After a while, the newness and uniqueness of the blog sort of wears off and the blogger runs out of things to write about.  Fortunately, I have plans and topics for 2020.

Manufacturers Blogs

There are several different types of blogs.  Some seal OEMs operate a corporate blog to provide information and updates about their products.  Here are some links to OEM “blogs” that are specifically labelled blogs.

John Crane has a blog, https://resources.johncrane.com/blog/, attached to its main website, JohnCrane.com.  The Crane blog addresses a variety of subjects and appears to be somewhat irregularly updated.  The Crane blog appears to be a mix of technical articles, product announcements, news and field experience.  The author(s) name is not given.  The Crane blog began December 13, 2018.

Chesterton has a blog, https://blog.chesterton.com/, attached to its main website, Chesterton.com.  The current topic is part 4 of a series on double seals and barrier fluids; it dates to October 31, 2019.  Although good information, the overall feel is not that of a “blog”.  Apparently several authors contribute.  The Chesterton blog dates back to at least 2017.

Sepco has a blog, “Seal Connect”, at https://www.sepco.com/community/blog/, with posts by various authors dating back to July 23, 2019.

Flowserve does not appear to have a blog, as such. 

EagleBurgmann does not appear to have a blog, as such. 

Non-Manufacturers Blogs

SealFAQs is not a manufacturer sponsored blog.  There are a few other such blogs, but not many.

The Fluid Sealing Association (FSA), the International Trade Association for mechanical seals, has a blog, http://www.fluidsealing.com/mechanical-seals/mechanical-seals-blog/.  The FSA blog doesn’t feel like a conventional blog.  Posts tend to come from the various member companies of the FSA.  Many of the FSA posts were published in Pumps and Systems Magazine as part of the “Sealing Sense” series.  The most recent post was published in June 2019.

There is a relatively new blog at https://www.mechanicalseals.net/Mechanical-Seal-Blog/index.php?frontpage, with the title “Mechanical Seal Tips and Details”.  It has only three posts and has the feel of a project that was undertaken and then stopped.  However, it was off to a good start.

Seal Websites

Of course, there are other websites containing information about mechanical seals and a few use the word “blog” in their description but don’t really have the feel of a blog.

Wikipedia has a page for mechanical seals, https://en.wikipedia.org/wiki/End-face_mechanical_seal as well as a page for the seal standard, API 682, https://en.wikipedia.org/wiki/API_Standard_682.

If you are aware of other mechanical seals blogs and especially if you have a favorite mechanical seals blog, please leave a comment.

API 682, pusher seal, SealFAQs

Thrust Load from Seals

The pressure surrounding the mechanical seal and its shaft sleeve imposes an axial force – a thrust – on the shaft.  This thrust load and direction can be determined by summing the products of the various pressures and areas of the seal and sleeve.  Fortunately, many of these products cancel each other out and the thrust load can be computed in a simple manner. 

The method shown below for calculating thrust load is taken from Chapter 17, “Seal Thrust Loads on Pump Shafts”, of Mechanical Seals for Pumps:  Application Guidelines from the Hydraulic Institute and Fluid Sealing Association.   Only the thrust load for single pusher seals is shown in this post but the book includes dual seals and bellows seals.

The general idea is that there is a hydraulic area between the balance diameter of the seal and the shaft upon which the seal chamber pressure acts to produce an axial thrust.  This hydraulic area is given by

where

    • A is the hydraulic “thrust” area, inch2
    • Db is the balance diameter of the seal, inch
    • Ds is the OD of the shaft, inch.

The thrust force is the product of the seal chamber pressure and thrust area.

The location of the balance diameter is illustrated below.

For many seals, the balance diameter can be estimated from the shaft size as follows:

  • Classic rotating seal:  shaft diameter plus 1/2” to 5/8”
  • Inverted rotating seal (made into stationary seal):  shaft diameter plus 5/8” to 1”
  • Stationary seal:  shaft diameter plus 5/8” to 1”.

These approximations to the balance diameter can be made because, typically, radial thicknesses, radial steps and even O-ring cross sections are based on 1/8” increments.  Radial clearances are often based on 1/16”; seals with large radial clearances may also have larger balance diameters.  Another variation comes from the shaft diameter not being an exact 1/8” increment and the sleeve may be used as an “adapter”.  Of course, the exact balance diameter depends on the seal design, thicknesses, clearances, etc. and the seal manufacturer should be consulted.

So, how much thrust is produced by the seal?  Sometimes, quite a lot – especially for large seals at high pressures.  The graph below is based on a classic rotating seal with balance diameter 1/2” larger than the shaft and a stationary seal with balance diameter 3/4” larger than the shaft.

Obviously, the thrust load estimated here for a stationary seal exceeds that of a rotating seal but this may not always be the case.  Again, the details of the seal design must be checked.  However, it is often the case that the thrust load from a stationary seal is larger than that from a rotating seal; therefore, it is best to consider a stationary seal configuration when making general assumptions about thrust loads.

This thrust load is transmitted to the shaft – typically by set screws – but devices such as pins, slots, grooves, split rings, etc. are sometimes used.  Therefore this thrust load is added to the thrust load imposed on the pump bearings.  Note that if the pump uses two seals (one on the driven end and one on the non-driven end) then the net thrust load from the seals that is imposed on the bearings may be zero.

Eventually, this blog post will make its way into the design pages of SealFAQs.  In a later post, we’ll take a look at the thrust capacity of set screws.

API 682, mechanical seal, SealFAQs

Back-to-Back, Face-to-Face, Face-to-Back Orientations

The definitions for seal orientations have been tweaked a bit in order to make those definitions more general.  At first glance, this revision might seem to make the SealFAQs definitions differ from the API 682 definitions however, there really is no conflict.  Note that although SealFAQs includes much information about API 682, SealFAQs is much more general.  To save you a click or two, the revised definitions read

Back-to-back = Dual seal in which both of the seal rings are mounted between the mating rings.

Face-to-face = Dual seal in which both of the mating rings are mounted between the seal rings.

Face-to-back = Dual seal in which one mating ring is mounted between the two seal rings and one seal ring is mounted between the two mating rings.

FF FB BB Illustration
FF FB BB Illustration

Although rotating springs are shown in the illustration above, the same definitions apply to seals having stationary springs or even to configurations mixing rotating and stationary springs.

The revised SealFAQs definitions now consider only the physical orientation of the seal rings and mating rings and not how the resulting configuration might be applied.  This is a much more general approach than is used in API 682 but is not in conflict with API 682.  In API 682:

The back-to-back configuration is used for Arrangement 3 and has the barrier fluid on the OD of both the inner and outer seals.

The face-to-face configuration is used for Arrangement 3 and has the barrier fluid on the OD of both the inner and outer seals.

The face-to-back configuration can be used for either Arrangement 2 or Arrangement 3 and has the barrier or buffer fluid on the ID of the inner seal and OD of the outer seal.

Outside of API 682, other schemes for pressurization and operation are sometimes used – although I must say that I don’t like some of them!

SealFAQs

SealFAQs Statistics for December 2018

I almost forgot to publish statistics for December 2018!  The SealFAQs site is doing well but in 2019 I won’t be publishing statistics every month.  January 2019 views are at record highs so far.

SealFAQs statistics for December 2018.  December was a good month although not as good as November and October.  I blame the holiday season for the drop in viewers.

SealFAQs has been officially launched for a full year now.  In December, unique visitors dropped quite a bit from November and October.  Here are the statistics according to Awstats (Advanced Web Statistics).

SealFAQs had 2269 unique visitors during December and a total of 3970 visits (1.73 visits/visitor).  Visitors averaged looking at 2.2 pages per visit.  Bandwidth was 2.0 GB.  So the visits per visitor increased but pages per visit dropped a little.

Visits per day during December averaged 128; the most visits in a day was 196.   As usual, most people visit during the week and the middle part of the day.  There has always been a drop off in visits on the weekends and this drop off also occurred during the holiday season.

By far, the most visitors are from the United States and distantly followed by Thailand, India and Russia.

The average time of a visit decreased to 272 seconds in duration but 84% of all visits are still for less than 30 seconds.  It does appear that some people are logging in and staying on the site an hour or more – forgetting to log out or reading/studying?

Access to SealFAQs via search engines was based on 8 different keyphrases having 17 different words.  As in the past, piping plans were the most common search words.

I check SealFAQs for comments every day.  Almost no one has submitted a real comment but several bits of spam or faked comments show up daily.  The lack of comments and discussion continues to be troublesome to me.

SealFAQs

SealFAQs Statistics for November 2018

SealFAQs statistics for November 2018.  November was the best month, so far, of 2018 although realistically, only fractionally better than October.

SealFAQs has been officially launched for eleven months now.  In November, unique visitors increased quite a bit from previous months.  Here are the statistics according to Awstats (Advanced Web Statistics).

SealFAQs had 2675 unique visitors during November and a total of 3980 visits (1.48 visits/visitor).  Visitors averaged looking at 2.4 pages per visit.  Bandwidth was 2.4GB.  So the visits per visitor and pages per visit has remained about the same for several months. This means that many visitors do not make a return visit and also look at only a few pages.

Visits per day during November averaged 132; the most visits in a day was 199 – twice!.   As usual, most people visit during the week and the middle part of the day.  There has always been a drop off in visits on the weekends.

By far, the most visitors are from the United States and distantly followed by India and China.

The average time of a visit decreased to 283 seconds in duration but 82% of all visits are still for less than 30 seconds.  It does appear that some people are logging in and staying on the site an hour or more – forgetting to log out or reading/studying?

Access to SealFAQs via search engines was based on 9 different keyphrases having 23 different words.

I check SealFAQs for comments every day.  Almost no one has submitted a real comment but several bits of spam or faked comments show up daily.  The lack of comments and discussion continues to be troublesome to me.

SealFAQs

SealFAQs statistics for October 2018

October was the best month, so far, of 2018.

SealFAQs has been officially launched for ten months now.  In October, unique visitors increased quite a bit from previous months.  Here are the statistics according to Awstats (Advanced Web Statistics).

SealFAQs had 2634 unique visitors during October and a total of 3769 visits (1.43 visits/visitor).  Visitors averaged looking at 2.3 pages per visit.  Bandwidth was up to 2.4GB.  So the visits per visitor and pages per visit has remained about the same for several months. This means that many visitors do not make a return visit and also look at only a few pages.

Visits per day during October averaged 121; the most visits in a day was 166.   As usual, most people visit during the week and the middle part of the day.  There has always been a drop off in visits on the weekends.

By far, the most visitors are from the United States and distantly followed by India and China.

The average time of a visit decreased to 304 seconds in duration but 80% of all visits are still for less than 30 seconds.  It does appear that some people are logging in and staying on the site an hour or more – forgetting to log out or reading/studying?

Access to SealFAQs via search engines was based on 16 different keyphrases including, as usual, several searches for information on piping plans.

I check SealFAQs for comments every day.  Almost no one has submitted a real comment but several bits of spam or faked comments show up daily.  The lack of comments and discussion continues to be troublesome to me.

SealFAQs

SealFAQs statistics for September 2018.

Whatever happened in August or late July has had a continuing effect:  SealFAQs is being visited much more often than in the past.

SealFAQs has been officially launched for nine months now.  In September, unique visitors actually decreased from August by about one day’s worth of visitors.  Here are the statistics according to Awstats (Advanced Web Statistics).

SealFAQs had 2079 unique visitors during September and a total of 3013 visits (1.45 visits/visitor).  Visitors averaged looking at 2.3 pages per visit.  Bandwidth was up to 1.8GB.  This means that many visitors do not make a return visit and also look at only a few pages.

Visits per day during September again averaged 100; the most visits in a day was 144.   As usual, most people visit during the week and the middle part of the day.  There has always been a drop off in visits on the weekends.

By far, the most visitors are from the United States and distantly followed by India and Canada.

The average time of a visit increased to 350 seconds in duration but 80% of all visits are still for less than 30 seconds.  It does appear that some people are logging in and staying on the site an hour or more – forgetting to log out or reading/studying?

Access to SealFAQs via search engines was based on 19 different keyphrases including several searches for information on piping plans.

I check SealFAQs for comments every day.  Almost no one has submitted a real comment but several bits of spam or faked comments continue to show up daily.

October is shaping up to be another good month.

SealFAQs

SealFAQs statistics for August 2018

Something happened in August or late July and, whatever it was, SealFAQs has been visited much more often.  Here’s a chart showing SealFAQs statistics since being launched in January.

Monthly History to Aug 2018

SealFAQs has been officially launched for eight months now.  In August, unique visitors increased significantly – nearly doubling —  from July.  Here are the statistics according to Awstats (Advanced Web Statistics).

SealFAQs had 2196 unique visitors during August and a total of 3121 visits (1.42 visits/visitor).  Visitors averaged looking at 2.2 pages per visit.  Bandwidth was up to 1.7GB.  So although more people visited SealFAQs, many did not make a return visit and they also only looked at a few pages.

Visits per day during August increased to an average of 100;  the most visits in a day was 177 – both are new highs.   As usual, most people visit during the week and the middle part of the day.

By far, the most visitors are from the United States and distantly followed by India, Russia, China, Canada and others.

The average time of a visit decreased to 317 seconds in duration but 81% of all visits are still for less than 30 seconds.  It appears that some people are logging in and staying on the site an hour or more.

Access to SealFAQs via search engines was based on 15 different keyphrases including several searches for information on piping plans.

I check SealFAQs for comments every day.  Almost no one has submitted a real comment but several bits of spam or faked comments show up daily.

So August may mark a change in SealFAQs viewership.  It appears that someone or some organization has discovered SealFAQs.

SealFAQs

SealFAQs statistics for July 2018

SealFAQs has been officially launched for seven months now.  In July, unique visitors increased slightly from June.  Here are the statistics according to Awstats (Advanced Web Statistics).

SealFAQs had 1170 unique visitors during July and a total of 1912 visits (1.63 visits/visitor).  Visitors averaged looking at 4.7 pages per visit – the same as for June.  Bandwidth was up to 1.2GB.

Visits per day during July was the same as during June with an average of 61;  the most visits in a day was 90.   As usual, most people visit during the week and the middle part of the day.

By far, the most visitors are from the United States and distantly followed by Nigeria, India, Russia, South Korea, Poland, China, Canada and others.

The average time of a visit has increased to 460 seconds in duration but 75% of all visits are still for less than 30 seconds.  It appears that some people are logging in and staying on the site an hour or more.

Access to SealFAQs via search keyphrases was 6 different keyphrases including “fundamentals of bellows design” – that’s a good project for the future.  Also, it seems that someone was searching for information on piping plans.

I check SealFAQs for comments every day.  Almost no one has submitted a real comment but several bits of spam or faked comments show up daily.

So July was about the same as June for SealFAQs.  Interestingly, August already shows a large increase in viewers so someone or some organization has discovered SealFAQs.