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heat up the girth weld to 150°F (65°C) after blasting and prior to hand-applying liquid epoxy would not contaminate the blasted surface, and would not damage or weaken the coating, the engineer did not agree with me, the chief inspector, or the pipeline contractor. From The Field To The Lab I decided to have testing performed at a certified laboratory to prove or disprove this propane contamination theory for future pipeline projects. The pipeline contractor supplied me with some 16-inch (40.64cm) diameter pipe coupons that had been used for weld testing for the pipeline. These weld testing coupons were sent to Partech Consulting and Testing Services. I also sent Partech two coating procedures for the two sets of coating tests that I wanted them to perform at their laboratory. I explained in the two coating procedures what type of testing I wanted performed on the coating. Two sets of tests were performed at Partech's Laboratory in Pearland, Texas. One set of tests was performed using a propane torch to heat up the girth weld to 150°F (65°C) after blasting and prior to hand-applying liquid epoxy. The other set of tests was performed at an ambient temperature, which was 75° (23°C) without heating up the girth weld after blasting and prior to hand-applying liquid epoxy. As far as I know, there are no papers written on this subject nor is there any testing to prove or disprove this theory. A thorough search through NACE and SSPC archives revealed that no papers or articles had been written on this subject. The results — Partech Lab Report #848 1-R03 prepared by Karl Kelso Lab Manager for Partech — are available at www.coatingspromag.com. Conclusion: The Results Test results overall for both sets of tests, heated and unheated, were very close. The test ing concludes that using a propane torch after blasting to heat the steel to 150°F (65°C) prior to coating does not weaken or damage the epoxy coating in any way. Preheating the steel to 150° (65°C) with propane prior to hand-applying liquid epoxy will reduce the cure time. Propane does not damage the coating. Chemical analysis reveals that propane contains less than 3 percent impurities. The temperature of a propane torch is 3,623°F (1,995°C). In compari- son, the surface of the sun is believed to be 10,000°F (5,537°C). Any impurities that came out of the propane torch tip would be incinerated by the extreme temperature. Further, the Environmental Protection Agency (EPA) has classified propane as a clean-burning fuel. Coating manufacturers recommend applying heat if the steel temperature falls below 150°F (65°C) and not to apply coating above 150°F (65°C). Hopefully, this will put the propane myth to rest. CP Coating Thickness Gages Now smarter, faster and more powerful than ever before and still... Simple. Durable. Accurate. ■ Rugged, weatherproof, ergonomic design ■ All models include memory, statistics, HiLo alarm and a USB port ■ Simplified paperless QA – no software required ■ NEW PosiTector body accepts all PosiTector 6000, SPG, and DPM probes easily converting from a coating thickness gage to a surface profile gage or dew point meter TM For a demo visit www.PosiTector.net 1-800-448-3835 www.defelsko.com 45 Years of Quality DeFelsko Corporation • Ogdensburg, New York +1 (315) 393-4450 • techsale@defelsko.com Write in Reader Inquiry #34 May 2012 J www.coatingspromag.com 29 Made in U.S.A. Advanced model New