Composite Repairs in High Temperature Environments Whitepaper

One area of focus for composite repairs has been around temperature capabilities, specifically for the use of composites to be effective at elevated temperatures such as those experienced in refining and chemical processing plants. Learn more about how the boundaries for composite repairs continue to be pushed as a result of extensive testing and field validation.

By Matt Green, VP of Technical Services, CSNRI

As Engineered Composite Repair (ECR) Systems have gained more recognition and acceptance as a reliable and beneficial repair alternative within the refining and chemical processing industry, continued advancement in materials and capabilities have also allowed for a greater range of usage. This is thanks in part to the development and implementation of standards specifically developed for these repair materials, the ASME PCC-2 Articles 401-403, as well as the ISO 24817, both originally published in 2006 and which provide industry a great deal of guidance on the material testing, qualification, and design for composite repair systems. One area of focus for composite repairs has been in the area of temperature capabilities, specifically for the use of composites to be effective at elevated temperatures such as those experienced in refining and chemical processing plants. Led by industry demand, a push for qualified composite repair systems which could be used at elevated temperatures gave composites the opportunity to step up and deliver.

As of 2017, the number of operable oil refineries in the USA alone was 141 (U.S. Energy Information Administration, 2018). When you include the rest of the world, plus other industries also operating high temperature piping, which would outnumber the USA refineries significantly, it is clear that composite repairs of this caliber and capability would be beneficial to the industry at large. There are a variety of ECR Systems available on the market today, however, and it is important to understand the testing associated with the high temperature environment and recognize the special needs for this. Since composite repair systems are being used routinely in the oil and gas industry, it is only natural that the boundaries continue to be pushed.

 TESTING

Figure 1 - Sample DMA test for Glass Transition Temperature

As with any repair material, complete and thorough evaluation and qualification is key to success in the field.  Any ECR System produced by CSNRI has undergone rigorous testing, not just on the qualifications as set forth in the previously mentioned standards, but also additional performance testing deemed valuable to fully characterizing the material.  This includes a host of environmental checks, in addition to the specific material properties such as the Tg (Glass Transition Temperature).  As we look at use in elevated temperature, this becomes a very important factor to consider as in many of the standard qualification tests, there may be limited “real world” parallels without this additional testing. 

Without getting into many of the details, there are several important tests that can help to characterize the actual performance of a composite repair in various environments.  Some of the more critical performance needs include tensile and adhesive properties, specifically in how they react when exposed to these environments during operation.  With that in mind, testing conducted includes both long- and short-term tests in various conditioning parameters. Secondarily, it is one thing to condition a sample and then conduct a test in laboratory environments, but what we are really after is how the material performs in the operating environment.  Therefore, such testing for these temperature requirements include multiple parameters to fully explore all possible operating conditions and expectations of the material.  The performance of a material may be much different at 75°F (24°C) than it is at 500°F (260°C).

FROM THE LAB TO THE FIELD

Once a material has been tested and qualified, it doesn’t just stop there; now we have to successfully bring this material to the field.  Many systems may have some relatively standard curing profiles for much of the intended use, however, as we look at using composite repairs in higher temperature environments, in many instances there are additional needs to achieve the desired temperature rating.  In general, epoxies or other resin systems that are used in these conditions have a specific and elevated curing protocol in order to reach the temperatures desired.  This information is one of the characterizations that is completed in the qualification process for that material but curing the material in the field is not as simple as curing it in the laboratory.

Figure 2 - Installing a pre-impregnated, high temperature ECR System

Many of the systems which can successfully reach elevated temperatures of about 500°F (260°C) and above may likely come in a pre-impregnated form and require a specific heating procedure to properly cure.  Having and know the proper field equipment which can achieve this, as well as how to properly install and protect the composite during this, is critical to the success of the repair installation and subsequent operation of the composite repair system. Working with the manufacturer and the right equipment, or even a heat-treatment expert, can have a great effect on this process to ensure the safety of all involved and a successful outcome.

Figure 3 - Sample cure schedule for a high temperature ECR System

THE FUTURE IS HOT

Thousands of plants and other process piping industries are truly realizing the benefits of composite repair systems in their everyday repair and maintenance work, and as the industry continues to push the boundaries and acceptance, we see a bright future and new horizons for these materials.  Backed by the proper testing and qualifications, installed according to specification by qualified technicians, and operated within the design, we can truly make a difference in efficiency and safety in these aggressive environments.  CSNRI has designed and manufactured composite repairs for more than 40 years and have multiple systems across several temperature ranges to meet your needs.  For more information on any of our high temperature composite repair systems, or composite repairs in general, please reach out to us at any time. 

For further information on this topic, listen to our webinar online: The Influence of Temperature on Composite Repairs TEC talk.

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