Flange Protection

Heat Shrinkable Corrosion Protection for Flanges

     Flangeseals are a niche product that we manufacture and sell.  Though the volume isn't yet tremendous, this is a fantastic product with a long, successful use history.  Flange Protection is a fairly common need out in the world.  There can be plenty of confusion as well though, as flange protection sleeves very often are specified on different criteria than we see field joint coatings specified.  Coincidentally, I've recently been in a position to have a few different discussions about our specific flange protection solution.

     Being that these are separate projects, there is an interesting opportunity here to evaluate our product (Flange Seal) from a couple of different angles:  Technically and cost.  

     First let's look at coating thickness:

Flangeseal is supplied with a backing thickness of 51 mils.  It is supplied with an adhesive thickness of 47 mils.  So we have a total supplied thickness of 98 mils.  This is a product that will shrink 67% if allowed to shrink that much (unrestricted by a pipe diameter, etc).  In such a case where there was going to be a full unrestricted recovery, this product backing thickness would be 127 mils.  Just like the backing, the adhesive thickness will increase during the shrink process (volume of the adhesive does not change, while the area of sleeve backing is reduced, resulting in a thicker adhesive even with the consideration that some small amount of adhesive will flow at the edges of the sleeve by design to form a seal.

That would mean a total, full unrestricted recovery of something in the neighborhood of 180 mils.  This may answer the question as many spec writers would see a number like this on a data sheet - and would copy it over to a spec - not realizing that they may have made a mistake.  If they meant to include the "full unrestricted recovery" dimensions (which are certainly are directly tied to the installed dimensions) then they have succeeded.  If, on the other hand, they have included a number which is the 'full unrestricted recovery' dimension but what they really want is the installed thickness - they may have inadvertently caused themselves an issue. 

Determining installed thickness can very often be a difficult task (as evidenced by the fact that no shrink sleeve manufacturer anywhere in the world reports an installed thickness).  Why is it difficult?  Because there are a number of very important factors.  How much 'slack' was in the shrink sleeve prior to shrinking?  What was the exact temperature of the preheated steel?  How much longitudinal shrink occurred during the shrink process?  What were weather, humidity and wind conditions during the shrink process?  What was the exact thickness of the adhesive during the manufacturing process (this can vary a great deal for mastic products, though the plant is always certain to guarantee a minimum thickness). 

Looking at this through my own 15 years of experience, exclusively with this product line, here are my opinions.

This product would be ~180 mils with a full recovery.

This product is 98 mils supplied. 

I believe it is reasonable to assume that the shrink sleeve thickness at the pipe will reach the 130+ mil thickness. 

This raises another difficult aspect of trying to define 'installed thickness' (which your client may not have even intended to do).  Because the sleeve will shrink a great deal when it bonds to the pipe surface; while not shrinking nearly as much as it bonds to the Flange surface (which is much larger) - the installed sleeve will be thicker at the pipe surface than it is at the flange surface; because shrink sleeve recovery has such a significant bearing on installed product thickness.

I'm sorry I could answer that one with fewer words.  I'm sure that is more than you ever wanted to know about installed shrink sleeve thicknesses.

 Now, when considering specifically my product (FlangeSeal) against a competitors heat shrinkable option:

Competitors product: 

Backing thickness supplied:  31 mils

Backing fully recovered:  not reported

Flangeseal:

Backing thickness supplied: 51 mils

Backing thickness fully recovered:  128 mils

So right there - we are looking at ~62% thicker backing as supplied.  I expect there will be a similar disparity with fully recovered dimensions.  So 62% thicker backing.  That is pretty significant when considering the weight these sleeves will bear on larger flanges. 

An important note:  our backing is comprised of three layers:

1 layer of radiation cross linked polyolefin

1 layer of a fiber mesh material specifically designed to improve penetration resistance and abrasion resistance (critical for sealing a flange in my opinion)

a 2nd layer of radiation cross linked polyolefin

From all I can see - my competitors product is comprised of a single layer of polyethylene.

Looking at adhesive thicknesses (which aren't as important in my opinion) - Competitor is at 44 mils and our Flangeseal is at 47 mils. 

I really think the fiber mesh laminated in the backing of our product is the most important difference though.  Truly, I think it is the difference between a product that works...and a product that doesn't.