Ensuring long-term integrity for high-pressure pipelines
The design standard for high pressure pipelines in the UK is IGE/TD/1 and the latter standard provides guidance on sleeve design. In relation to nitrogen filled sleeves it was standard practice in earlier times prior to about 1985 to install the carrier pipe within a sleeve at road or rail crossings. Once the carrier pipe was in a sleeve the pipeline is then shielded from the pipeline electrical corrosion protection (or Cathodic Protection (CP) system) and could suffer corrosion. To ensure that the pipeline within the sleeve was protected from corrosion the sleeve was filled with nitrogen to exclude air and since no oxygen was present corrosion could not take place.
A number of these nitrogen sleeves have now failed to retain the nitrogen pressure and are leaking. Thus, as a result air can enter the sleeve, and atmospheric corrosion can occur on the gas carrier pipe.
It is often difficult to repair failed nitrogen sleeves, and the UK gas industry has been looking at ways to overcome the problem. If there is ongoing corrosion on the carrier pipeline within a sleeve, then that can be a significant threat to the pipeline integrity.
Carr Civil Engineering (Grouting) Ltd have researched and invested in a long-term solution to overcome these issues and now have a fully tested and approved product to grout N2 Nitrogen Sleeves. Also, if considering the abandonment of pipelines, we can grout up to 3km in length. This process has full technical support and has been fully tested under laboratory conditions at Aachen University.
Our team have been fully trained to operate our grout pumps and to produce the required data on our bespoke software system.
This is an exciting new innovation, and we would be happy to discuss any HP grouting requirements you may have.
