Pipe plugs for the pipeline industry
The Pipestoppers Division of Huntingdon Fusion Techniques has launched a new range of aluminium pipe stopping plugs which are suitable for use in pipeline applications. Such plugs are used for sealing pipes, blocking them, testing for leaks and to prevent entry of unwanted foreign material.
This new range comprises half inch as well as full inch sizes to ensure that every pipe and tube diameter between 1.5 and 6 inches has a plug that will seal to full pressure and leak tightness.
They are equipped as standard with a natural rubber seal and can be delivered with Nitrile, Neoprene, Viton or other synthetic rubber seals to allow use with high temperatures, harmful or corrosive chemicals and fluids.
Another advantage of the new range of Pipestoppers Aluminium Plugs is the use of a tough wing nut with a friction free washer underneath to make plug tightening easy. Other mechanical plugs and inflatable stoppers for pipe sizes up to 2,000 mm diameter are also manufactured by the company.
High speed weld purging of pipeline welds
Stainless steel, titanium and other alloy pipes generally have to be filled with argon to purge out the air prior to welding.
With small tubes and pipes this work can be done relatively quickly by a number of different methods, but the larger the pipes become, the longer it takes to complete a purge and to ensure that the oxygen level is sufficiently low to start welding and achieve a good weld.
To speed up the purge process for large pipes, Huntingdon Fusion Techniques has designed and developed a range of quick purge systems.
Based on the technique of the successful Argweld® Inflatable Purge System, the new quick purge devices restrict the purge volume to about 75 mm either side of the weld.
As the surfaces of the Argweld Quick Purge System are nearer to the hot metal, they are protected with heat protecting material which has been tested up to 1,000°C. This material prevents any damage to the quick purge systems during welding and protects the systems in the event that hot metal droplets may fall on the system during welding.
The systems are built for all pipes ranging from 200 to 3,000 mm diameter. Welding on 750 and 900 mm stainless steel pipes have shown a purge time of
7 and 10 minutes respectively down to 500 parts per million of oxygen.
Huntingdon Fusion Techniques has also launched its MKV version in the range of Argweld Weld Purge Monitors for use in monitoring oxygen content during welding.
The new model is technically more advanced than its predecessors and is the most cost-effective in the global market.
The Argweld Weld Purge Monitor is robust but portable, weighing a mere 200 g. It has the ability to measure oxygen levels accurately down to 0.1 per cent and can indicate down to 0.01 per cent.
It is supplied with its support equipment in a custom-designed protective carrying case and features temperature compensation, continuous or sample reading and a self-calibrating function.
Whichever method of oxygen removal is used, however, there remains a need to monitor residual gas levels accurately before and during the welding operation. Some metals are more sensitive to becoming discoloured or contaminated due to the presence of oxygen: stainless steels and nickel alloys are particularly prone to this.
Case Study: low-cost accessory obviates power station shutdown
Derek Halsall – ECS Engineer, Slough Heat and Power, UK
A new compressor installation, to be completed within a short window of time, was going well until a problem was discovered. The design drawings failed to show that a cold-water valve extension handle clashed with the air inlet pipe of the compressor.
Critically, this was the only isolating valve from the cooling water main header and could not be moved without closing the cooling water system. This would have also meant shutting down the whole power station, which was not an option.
Potential solutions included re-routing the inlet pipework of the compressor and contracting in a specialist pipe freezing company to enable the valve to be moved.
All initial potential solutions would have taken time to organise, which could have affected the timely completion of the project.
Freezing was considered as the best option but this valve was welded into place and freezing would have to be made far enough up stream not to be adversely affected by the applied heat from the grinding and rewelding operations.
As the water pipe was 75 mm diameter, it was not possible to acquire one of the commonly available domestic or commercial plumbers’ freezing kits, as these only have a capacity up to 50 mm.
As time was of the essence, an Internet search discovered a Pipe Freezing Kit for 3 inch pipe available from the “Pipestoppers” Division of Huntingdon Fusion Techniques (HFT). The HFT Technical team were quickly able to reassure us that “Qwik Freeze” pipe freezing systems were a proven option for this size of pipe, and within 24 hours we had a kit in our possession.
Installation was easy and CO2 bottles were obtained from the local BOC gas supplier. The freeze worked well taking around an hour to freeze the pipe. This freeze allowed time to grind out the welded valve plus a length of pipe and re-weld a flange back on to the pipe at a new position and install a new valve. The job took around two hours to complete in total and at cost of around 25 per cent of a specialist contractor.
