Tuesday, November 18, 2014
This one comes up fairly often. What is the difference between wax tape and shrink sleeves? or Are shrink sleeves better than wax tape? or Technical comparison of shrink sleeves and wax tape? And many other variations of that same phrase.
First of all, let me disclose that I do not sell very many wax tapes. We do occasionally sell some petrolatum tapes, but not often. I'd also like to be clear - there are some applications where a wax tape would be clearly the right choice. Wax tapes (because they are so malleable) are very good for coating highly irregular substrates. They do a good job on well heads and on some fittings where the simple physics of a heat shrinkable sleeve will simply not work. But which is technically superior?
Rather than try to convince you, I think I'd rather simply share the data here as reported on product data sheets. I will not leave anything off. I will not skip anything.
Thickness: 70-90 mils
Weight: 4lbs/sq yd
Dielectric Strength: 170 volts/mil
Application Temperature: 0F to 110F
Operating Temperature: -50F to 120F
Saturant Pour Point: 115F to 125F
Thickness: 46 mils
Weight: .295 lbs/ft2
Breaking Strength: 22.5 lb/in
Water Vapor Transmission: .006 perms avg
Elongation @ Break: 10% avg
Breakdown Voltage (55% overlap): 16 kV min.
Resistance to Cathodic Disbondment: .28" avg
Resistance to Acids, Alkalies and Salts: Excellent
Maximum Service Temperature: 158F
So there you have it. All of the data I could find from two different wax tape manufacturers. Not a whole lot there, really. I find it particularly strange that there is no mention of peel values, shear values, penetration resistance or impact resistance.
So lets look at one of our products: WPC100M
Tensile Strength @ 23C and 80C (2200 psi min / 200 psi min)
Elongation to Break @ 23C and 80C (400% min / 500% min)
Heat Aging Followed by Elongation to Break @ 150C / 23C (200% minimum)
Volume Resistivity @ 23C (10-14 ohm-cm min)
Shore D Hardness @ 23C (50 min)
Shrink Force @ 150C (35 psi min)
Toughness @ 23C (30,000 psi min)
Lap Shear Strength @ 23C and 80C (30 psi min / 3 psi min)
Softening Point 135 + or - 10 C
Cathodic Disbondment @ 80C (25mm max)
Peel Strength to Steel @ 23C and 80C (30 pli min / 1 pli min)
Impact Resistance @ 23C (40 in-lbs)
Penetration Resistance @ 80C (no holiday with 12kV detector)
Moisture Vapor Transmission @ 38C (.08 max)
Low Temp Flex -40C max
Effect of Temperature on Installed Sleeve @ 100C (no swelling, wrinkling or lift up from pipe surface).
Total Thickness Fully Recovered (111 mils)
I think the question: "is there a technical difference between shrink sleeves and wax tape is clear after a simple look at the different data sheets.
Monday, November 17, 2014
Installing Two Part Epoxies on Pipelines in Cold WeatherTwo part epoxies, by their very nature, require heat in order to properly cure. In some scenarios, the chemical reaction that occurs as the two epoxy components mix actually causes heat to be generated, resulting in a naturally occurring faster cure time. At the same time however, at certain temperatures, many epoxies will not begin the curing process (at least in any significant way) no matter how long you wait. Two part epoxies that are not curing are very similar to honey or wet tree sap. They are very thick, but you certainly wouldn't expect them to withstand soil stresses, pipe racks, directional drills or even someone bumping up against them. All would result in a nasty sticky mess.
Even though everything I've said here is general public knowledge, every single winter we still see cases where people are planning and attempting to install two part epoxy pipeline coatings in the winter. What the heck?!? I don't get it. So let's take a little closer look at some of the common options out there.
SPC has a specially designed epoxy that is formulated exactly for lower temperature conditions. This material is called SP-2831 Low Temperature Cure Coating. The data sheet that is readily available online says very specifically that this epoxy has "the ability to cure down to 0C (32F)." Based on that, I'm confident it is safe to assume that this material will not be recommended (or likely even usable) when ambient temperatures are in the 20's and below. Yet there are still folks out there trying to require that this material is used in sub-freezing temperatures!
Likewise we can look at a product like Powercrete R-65/F1. This product is sold as "extreme fast curing." The folks at Seal for Life are very open and honest in the data sheets (which is one of the reasons that they are my most trusted partner in the industry). Their data sheet says very clearly "Minimum Ambient Application Temperature - 35F (2C)." Very clear. Very honest. I don't think there is any question. Based on the data sheet for Powercrete R-65/F1 - if your ambient temperatures are going to be in the 20's (F) or less - you must use a different product. Yet still, there are jobs out there right now requiring the this product be used in sub freezing temperatures.
Then there is a product like DIRAX. Because of the heat applied at different steps of the installation process; DIRAX has no issue with cold weather. DIRAX utilizes a two part epoxy (S1301M) so it does incorporate all of the strengths of an epoxy coating system (CD Disbondment, Shear, etc) but also incorporates all of the strengths of a dual layer, fiber reinforced, high density, radiation crosslinked backing. It won't be hours before you can move the pipe. It won't be days before you can bore the pipe. Based on install and cure times, your crews probably won't even notice that it is cold outside!
Friday, November 14, 2014
Pipeline Coating on a Direct Pipe Application
First let's talk about what Direct Pipe is....I think this video explains it pretty well:
Isn't that fascinating?? Amazing technology. Drill the hole and drag the pipe all in one fell sweep. My understanding after having a conversation with one of the engineers out there who has specified that this technology be used is that with Direct Pipe, the hole is much smaller. It is still a big larger than the pipe itself, but the extra 'space' in the hole is nowhere near what it is when pulling through a bore hole. He told me that the hole will still be filled with mud which will act as a lubrication. In addition, the pipe is pushed into the hole rather than being pulled through the hole.
I couldn't say what the cost different is between Direct Pipe and standard directional drilling applications.
So, just like any directional drilling or road bore application, when selecting your field joint material, you really need to be sure you are choosing the correct product. For the project I'm talking about, the engineer has elected to use DIRAX to coat the field joints on this line. It will be about a 3000 foot section of 48" pipe when all is said and done and I have absolutely no doubt that the DIRAX will perform perfectly. How can I know? I know because DIRAX has performed perfectly every other time it has been installed -- yes -- even on 48 inch pipe!
Utilizing a fiber reinforced, heat shrinkable, high density, radiation crosslinked polyethylene backing, the DIRAX is practically impenetrable. Installed on top of a thin, wet layer of S1301M epoxy primer, DIRAX also exhibits incredible peel and shear resistance. Without requiring any special equipment -- and with incredibly short cure times (thanks to the way DIRAX is installed), your life has never been simpler. Give us a call so we can discuss or schedule a demonstration for you.