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Wednesday, December 9, 2015

DIRAX Set Up Time

How Fast is the DIRAX Set Up Time

     Most road bore field joint coatings require serious cure times after application before the field joints can see any type of forces or stresses.  DIRAX is a product with the shortest (by far) set up time of any other product on the market approved for use on road bores or directional drilling applications.  Today in Houston (December 9th) it is 73 degrees F outside.  Looking at just one of the more popular two part epoxies on the market:  Denso 7200.  Denso 7200 (per the data sheet at 70F) can be tack free in  60-90 minutes.  Has a recoat window of 1-3 hours.  Can hit shore D 70-75 in 3-4 hours.  Can hit shore D 80-85 in 4-6 hours.    At 50F, those times all basically double. 

     Looking at DIRAX though, we don't see such significant wait times while the field joint coating sets up and cures in place.  Why is that?  There are two very important and significant reasons. 

1.  While it isn't generally possible to control or impact ambient temperatures on a pipeline spread (sure you could utilize some kind of controlled temperature structure or tent to impact the temperature of the coating environment), that problem doesn't exist as much with DIRAX.  One of the most important steps of the DIRAX installation process (after pipe cleaning, but before applying the epoxy) is the preheating of the pipe surface (bare steel and adjacent FBE).  This is important for many reasons; but the reason I will focus on here is that it brings a controlled heat source (the large steel pipe) to the equation; conrolling and quickening the cure / set up time of the S1301M Epoxy Primer


2.  After the DIRAX shrink sleeve is wrapped around the still wet and uncured epoxy; that shrink sleeve is shrunk with a bushy flamed propane torch.  The shrink sleeve itself will shrink as the backing reaches a temperature of 267F (the crystalline melt point of this polyolefin modified material).  This now introduces an exterior heat source that further controls and heightens the temperature at the S1301M / Pipe Surface interface.  As we all know; higher heat (within reason) leads to faster cure times. 

     So between those two:  preheated steel and external heat during the shrinking process; even though the ambient temperatures might be 70F (or significantly lower as our products have been installed everywhere from Alaska to Canada to the Soviet Union), the installation procedure introduces heat in a controlled manner to improve cure times without sacrificing coating integrity or bonds.

     As a result, in most cases, we find that DIRAX shrink sleeves are ready for exposure to stresses and forces just about as soon as the sleeve has cooled down from install.  This normally (but not always) means something in the thirty minute range.  No more overnight waits. 

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