We run a fleet of mobile units that allow us to offer pipeline recompression services across the network. We use them to depressurise a section of gas pipeline between two proven isolation points, usually block valves at either end of the section. This allows you to carry out remedial works safely on defective pipes that need a pressure reduction or complete evacuation of gas, purged to air. We can use the technique when the live section is operating at pressures up to 85 bar.
We connect the recompression unit (or units if needed) to the isolated section with high pressure temporary piping. Our on-site team operates the units, conducting hourly checks and adjustments of the equipment during operation, reducing the environmental and commercial impact of any vented gas.
If you need to conduct full-line intervention such as cut outs and re-welds, we can also complete a total pipeline depressurisation and gas evacuation, using a 200mm diameter, 12-metre-high vent stack, and direct air purging equipment.
How the operation works
Our recompression units are mounted on 12-metre trailers that we transport to the site along with associated pipework. We connect the units' suction and discharge points to the pipeline system either side of a main isolation valve, using a mobile crane. If full evacuation of the pipework system is required, we also pipe in vent and purge lines. Once all pipework is connected and joints correctly set, we follow a process to pressurise and commission the system, then bring the units online to recompress the gas.
We can calculate the time it will take to recompress gas based on pipeline length, diameter, starting and finishing pressures, and discharge pressure. It will also depend on how many units we use and whether we can run the system throughout 24 hours.
We supply all documentation to support the operation, including method statements, risk assessments, and hazardous area drawings and designs for the operation. We can also verify that we will have re-made - to the correct torque settings and standards - any joints broken to connect to the system.