Production • Processing • Handling
The use and application of composite repairs
Andrew J Patrick provides case study information of specific repairs which have been completed using composite technology, the repair structure utilised and the overall benefits the use of a composite system provided for the specific repair solution.
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omposite repairs have now been utilised within the transmission pipeline, offshore, refinery and petrochemical industries for over the past 20 years for both the temporary
and permanent repair to reinforce sections of the pipe wall which have been weakened due to internal/external corrosion, mechanical damage and third party interference. As such most E & P, transmission and down
stream operators are familiar with composite repairs and the health, safety, technical and commercial benefits the utilisation of a composite repair provide.
What is a composite repair? Composite repairs can be classified into two types of architecture: composite repair sleeves – which utilise a factory manufactured and quality controlled full cure laminate repair sleeve which is sized for the particular pipe diameter and composite wraps which are a wet lay up system where the wetted fabric is hand applied around the substrate at site. In both instances the composite itself is a synergistic combination of two elements the strength member which is typically in fibre form (the most common fibre form being ‘e’ glass) which is then held within a resin matrix.
When applied to a non-leaking defect the composite repair works by sharing the loop load in the pipe wall and controlling the rate at which the steel substrate yields. In this particular instance a high compressive strength filler material is applied to the defect, this is then overwrapped with the composite repair sleeve and the complete repair is bonded and held in place using an applied adhesive.
Approval and regulatory acceptance Full cured composite sleeve repairs have been thoroughly tested (over 10 years starting in the 1980s) by third party industry organisations for long term permanent repair performance for which they have been proven and accordingly are accepted and recognised in various repair codes such as
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ASME B31.4, B31.8, API 1160. In addition many national regulatory authorities as well as operating companies have reviewed, tested and approved the use of composite repair sleeves as a form of permanent repair.
In addition industry guidelines based on shorter term testing and in documents such as ASME PCC-2 and ISO TS24817 can be applied for the design and manufacture of both composite sleeve and wrap repairs.
28-in main gas transmission pipeline During a routine excavation an excavator accidentally hit a 28-in main gas transmission pipeline causing significant mechanical damage of an 8 metre continuous section of the pipeline. As the pipeline is the main supply to a local
power station and also part of the gas supply system to Singapore it was critical the pipeline remained in operation. In addition the damaged occurred in mid-summer with temperatures in excess of 39°C and accordingly a period of peak demand for electricity supply. In choosing the repair option the client determined the line could not be shut down and hot work was also not possible and therefore a
Fig. 1. An example of a full cured composite sleeve repair.
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