The contents of ISO/TS and ASME PCC-2 includes details on;. • Qualification; tests repair suppliers are required to perform to conform to the standard. Composite material repairs for metallic pipes from three different suppliers were evaluated according to ISO Technical Specification TS The intended. ISO TS Petroleum, petrochemical and natural gas industries Composite repairs for pipework Qualification and design, installation, testing and.
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Composite repair offers an affordable alternative to the costly replacement of piping and pressurized equipment that have been severely damaged by corrosion or years of use. We jso display the email address publicly, but this page will go to the organization’s information tss we have on file.
In recent years, composite repairs have been gaining greater acceptance among asset owners and equipment operators—not only because these repairs provide an engineered, durable and affordable alternative to replacement, but also because they comply with international engineering standards.
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Two-part component composite repair systems typically comprise 2417 resin material and a reinforcement sheet that can be tailored for application onto pipeline, pipework and vessels in pressurized services. Suitable applications for this type of repair include large-diameter pipelines and components such as bends, flangesvalves, and reducers among others.
Others include piping above or below ground, joints, valves, gaskets, fittings, etc. Because the composite repair system must form a bond with the damaged substrate, it relies on the adhesive quality of the resin for some of its strength.
Epoxy-based resins can be used as base material for two-component composite repairs due to their isk adhesion, mechanical properties and erosion corrosion resistance.
In this regard, epoxies are superior to other non-metallic resins such as polyurethanemethacrylate, alkydvinyl, and polyester-based resins. Alkyd resins are examined in the article An Overview of Alkyd Resins. The reinforcement sheet provides strength to the repair and hoop strength where required. These sheets are typically made of carbon, glass fibers or a combination of both. Carbon reinforcement sheets are costly, more rigid, and difficult to cut, design and apply in comparison with glass fiber reinforcement.
However, a combination of glass fiber and carbon reinforcement provides mechanical strength 244817 delivering a certain degree of flexibility for better long-term thermal cycling performance. As mentioned before, the growth in acceptance and usage of composite repair systems is inherently ieo to the availability of standardizing documentation. We would love to hear your thoughts or feedback to help us improve. While both standards supply extensive information and guidance on how to design, apply, test and inspect composite repairs systems, there are certain differences in calculation engines and considerations.
On te other hand, the ASME standard does not explicitly consider the repair expected lifetime in the design equations.
Such a combination provided superior adhesion and mechanical strength when compared to other functional polymeric ys such as polyurethane, methacrylate, alkyd, vinyl and polyesters.
Designing & Testing a New ISO/ASTM-Compliant Composite Repair Solution
Epoxy phenol Novolac resins 24871 form highly cross-linked matrices that display high temperature and chemical resistance. Because epoxy-based resins tend to cure slowly or very quickly at low and high temperature levels respectively, two types of resins were designed, as shown in Table 1.
The use of two types of isoo facilitates application of the composite system in different environmental conditions:. The selection of appropriate reinforcement sheet material was based on mechanical strength, degree of elasticity and ease of use wetting, cutting, wrapping. Polyester was found to be very flexible and of low density, but it had the lowest tensile strength and modulus of all the aforementioned fibers. Kevlar is a registered trademark for a specific type of aramid synthetic fibers.
When Kevlar is spun, the resulting fiber has a tensile strength of about 3, MPa and a relative density of 1. However, Kevlar requires special cutting tools and it was not found to be as strong as carbon fibers. Dyneema has yield strengths as high as 2. Carbon has the highest tensile modulus of all the above fabric types Kop, D. Glass, on the ys hand, is easy to cut, transparent and fairly inexpensive. Tx transparency of glass fibers would allow the applicator to readily identify areas with insufficient resin, but glass was found to have the lowest tensile strength and modulus when compared to Kevlar fibers.
After carefully oso the benefits and drawbacks of each fabric, it was decided to use a hybrid of carbon and glass reinforcement fibers woven together. Furthermore, the reinforcement sheet would be available in three different sizes to facilitate the application for the repair of piping elements exhibiting complex geometries such as tees, flanges and reducers among others.
By using this hybrid reinforcement sheet in conjunction with HLT and HT resins, the two-component system was expected to yield an optimized balance of mechanical strength, optimum adhesion and flexibility.
Qualification of such systems is required for compliant application onto pipework. For some tests, composite slabs were prepared using LT and HT resins reinforced with three wraps of resin-wetted reinforcement.
For others, actual carbon steel spools of known dimensions and specific defects were repaired in accordance to ISO requirements. Testing details are summarized below. Several results worth mentioning are displayed as follows. Learn about various ways to measure strength in the article 6 Tests to Measure a Material’s Strength. Internally generated circumferential stresses tend to cause the pipe to slightly increase in diameter while becoming shorter.
Hence, any composite repair used to restore mechanical strength to a pressurized pipe system must be able to cope with these stresses in similar ways to the pipe itself. This means that such a composite repair will react similarly to the carbon steel substrate onto which it is applied upon compression or tension loads.
Also, experience has shown that an elastic modulus of at least 6, MPa is a good benchmark for predicting the in-situ performance of a composite repair Alex. Thermal expansion coefficient in solid materials describes how the size of a material changes with a change in temperature while the pressure is held constant. Thermal stresses cause metals to expand and contract when exposed to high and low temperature levels respectively.
Hence, any composite repair used to restore mechanical strength to metallic substrates must be able to cope with thermal stresses in the same or a similar way to the substrate itself. This value is then used to characterize the adhesion between the composite repair and the substrate. Mathematically, the value is also utilized for determining the minimum composite repair thickness required for applications onto through-walled substrates.
During short-term pressure survival testing, carbon steel spools with a defect of known dimensions were rebuilt by using a composite repair designed to provide the original yield strength. The yield pressure of the undamaged spool was calculated to be A repair was then engineered to restore the pipe to this original pressure.
The repair was applied to specification and the pipe was pressurized up to This demonstrated that the two-part composite repair had performed as designed. Pressure was then increased to determine where a yielding would occur, whether in the repair or in the original pipe. At around 42 MPa, the pipe clearly yielded, outside of the repair area. This is factual evidence that not only had the composite repair returned the pipe to its original strength, but it had also made the defect area stronger than the original pipe section.
All the above properties and survival testing results must be quantitatively provided for the composite systems to be in compliance with ISO and ASTM standards.
Composite repair system compliant with ISO/TS
These compliant composite repairs rely not only on a pre-qualified material and pre-defined mathematical design, but also on competent application craftsmanship.
In a second articlewe’ll address how to provide compliant application of a two-part composite repair system, such as the one described here. In his role as Oil and Gas Manager, he works with Belzona colleagues, asset owners, engineering firms, contractors, and fabricators in the oil and gas industry across all of the Americas. He has authored several 2417 articles and conference presentations.
For info on how we work with industry partners click here. Written by Osmay Oharriz, Ch.
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