A 9500Nm pneumatic torque wrench has been used on a new natural gas pipeline being built from Mozambique to South Africa

Gas is one of the most underutilised energy carriers in Southern Africa. Compared with the international average of 20 per cent of energy usage, South Africa’s gas consumption forms only 2 per cent of the energy grid. While this can be attributed to abundant reserves of cheap coal, long-term technological and environmental trends indicate a shift towards the convenience of a cleaner-burning energy source.

In response to this trend, a new natural gas pipeline is being built, running from Mozambique to South Africa.

The pipeline is the result of close collaboration between the Mozambique Government, Mozambique’s national oil company Empresa Nacional de Hidrocarbonetos de Moçambique (ENH), and Sasol, a global player in chemicals and fuels with commercial experience in coal-to-liquids and gas-to-liquids technology.

The 865km, 26-in, high-pressure steel pipeline will be buried 1m below the ground. The 531km Mozambican portion starts at the Temane field’s gathering point near Vilanculos and crosses the border near Ressano Garcia. The 334km South African portion continues from Komatipoort to Sasol’s Secunda site where it links to the Sasol Gas network.

Torque Tool (Pty) Ltd, the Southern African representative for Norbar, was asked by GLMC, a joint venture between Grinaker-LTA, McConnell Dowell and CCIC, to supply a 9500Nm pneumatic torque wrench – which was also capable of recording the readings – to tighten mainline valve assemblies and valve off-take assemblies along the pipeline.

“I was involved with the Mozambique side of the gas pipeline from Temane to Rassano Garcia,” recalls David Poerner, managing director of Torque Tool. “The requirement was for a pneumatic torque multiplier to cover 9500Nm and was capable of recording the readings to tighten mainline valve assemblies and valve off-take assemblies.

David Poerner explains: “Sasol was already a user of Norbar torque tools in South Africa. GLMC sent a table of requirements including bolt size and torque specifications.

“After delivering the equipment to GLMC, I flew up to Vilanculos in Mozambique, where I demonstrated how to operate the PT9 Pneutorque, fitted with an annular torque transducer, and how to record the readings, which would be stored on the Pro-Log digital display and downloaded to PC back at the base camp.”

A month later GLMC requested that Poerner should provide on-site training to ensure that the job was done correctly. In one instance he and his team arrived in torrential rain at the first of four scraper stations near Chokwe. Undeterred, the next day, they started the process of loosening all the bolts holding the valve to the pipe and the end plate with the PT9, and cleaned and lubricated the bolts.

“We started with the pipe valve side and re-fitted the bolts. It then rained again,” continues David Poerner. “We carried on just long enough to fit the end plate to seal the valve before the hole filled with water.”

However, the valves were eventually completely covered with water. This took four days to pump out. When they got started again, they managed to complete the both sides of the valve, using the PT9 fitted with the annular torque transducer and the Pro-log, recording all the readings. All this time they were draining the other hole with the other valve in it.

Norbar Torque Tools is no stranger to arduous field conditions. The company is also well known for its transducers, gearboxes and display units for use in harsh environments and even sub-sea. For many years Norbar gearboxes and transducers have been going ‘sub-sea’. Normally the gearbox will be driven by a hydraulic motor mounted on a remote operated vehicle (ROV). The common application of these tools is the actuation of valves on sub-sea pipelines. The gearbox and transducer will be mounted in an oil bath and Norbar have developed specific modifications to the products to allow for this and to counter the possibility of salt water contamination.

Despite the trials and tribulations endured by the people on the job, Norbar demonstrated that its tools are up to the job, regardless of weather conditions, in Mozambique, under the sea or anywhere else in the world.

Norbar Torque Tools Ltd is based in Banbury, Oxon, UK. Norbar Torque Tools Ltd