WP-25 Help with Best Practice for Purging

Advanced Training Courses - Safety Critical Welding

nuclearWelding skills and the introduction of new technologies are focus areas behind a series of recommendations set out in the "2012 Nuclear Construction Lessons Learned" study report.

The report, published by the Royal Academy of Engineering, notes the need for advanced training in some welding practices*.

'Welding is recognised as an area at high risk of skills shortage, with an ageing and retiring demographic'

A guidance document includes a recommended approach to Quality Assurance, referencing ASME and RCC/ETC codes/standards with detailed discussion of the relevance of the ISO 3834 framework welding-specific Quality Assurance. 

Whilst this significant study is nuclear-specific it highlights the urgent need for specialist training in all sectors where safety critical welds are produced.  Such industries include the petrochemical, pharmaceutical, food and beverage sectors and indeed the power generation industry generally.

One area in particular where training has been recognised as important is Weld Purging.

The International Significance of Advanced Weld Purging

A nuclear power station such as the Olkiluoto Nuclear Power Plant in Finland, where a European Pressurised Reactor is under construction, might have up to 200 km of piping and 30,000 welds.

A $6m monoethylene glycol plant is planned for 2016 in the industrial city of Ras Laffan, Qatar. The design calls for the fabrication of an extensive pipework network.

Norwegian Cambi has announced that it has been awarded a $65m biogas plant to treat 50,000 ton of food waste annually.  The output will include 27,000 ton of bio fertilizer for farm use.

Because of the overriding importance of weld quality during construction in these and many other major international projects, higher quality inert gas purging will be necessary to prevent oxidation, contamination and risk of weld imperfections.

The Royal Academy of Engineering report pulls no punches in highlighting the urgent need for attention to be paid to welder training.  In responding to this report it is important that advanced welding skills and the continuous introduction of new techniques should include 21st century advanced weld purge techniques.

The last decade has witnessed major advances in weld purging equipment and instrumentation.  An advanced engineering design approach has been introduced by the suppliers and in particular by Huntingdon Fusion Techniques (HFT), the global leader and manufacturer in this sector.

 

The most effective purge systems for use where weld quality, cost and speed of the purge process all need to be considered are those based on the inflatable dam concept. HFT designs incorporate advanced materials to give high temperature resistance coupled with low outgassing rates, durability with flexibility and abra-sion resistance. HFT has also developed a family of Weld Purge Monitors® capable of accurate measurement of oxygen content down to 10 ppm 

The most effective purge systems for use where weld quality, cost and speed of the purge process all need to be considered are those based on the inflatable dam concept.  HFT designs, incorporate advanced materials to give high temperature resistance coupled with low outgassing rates, durability with flexibility and abrasion resistance.  HFT has also developed a family of Weld Purge Monitors® capable of accurate measurement of oxygen content down to 10 ppm

HFT has a specialist team of engineers dedicated to exploiting technical advances in materials and components and applying their skills to manufacturing advanced weld purging systems designed for use on many hundreds of similar circumferential joints.

The portfolio of inflatable weld purge systems covers the diameter range from 25 to 2000 mm (1 to 80").  These specialised products provide opportunities to maintain very low oxygen content in the purge zone, typically 0.01%, whilst also reducing inert gas consumption and total purge time dramatically.

Tube, pipe and vessel fabrication encompasses a wide range of dimensions and the HFT portfolio of purge systems is the widest available internationally with proven systems covering diameters from 25 to 2000 mm (1 to 80").

12W-InflatableStoppers 03W-InflatableStoppers

In larger LNG projects for example, the Argweld® Quick Purge® Systems have been shown by contractors using them, to save many tens of thousands of dollars in Argon costs alone, while labour charges have been reduced by an even greater value because of the much shorter purging times to reach the lower oxygen values.

In response to the clearly defined need for advanced welder training to meet the requirements of the safety critical sectors of manufacturing industry, Huntingdon Fusion Techniques has used its extensive knowledge of weld purging to develop a comprehensive training programme.  This is available to all welding engineers and associated disciplines and can be undertaken at HFT's headquarters in the UK where conference facilities and workshops are on-hand or on site where the practices can also be demonstrated and put into immediate use.

The programme is based on the basic aspects of purging shown below but is of modular nature and can be modified to suit specific requirements of clients.

Training Programme

  • Weld purging concept
  • Understanding of basic terms and principles
  • Poorly purged welds and the significances of extra costs involved
  • Good versus bad techniques
  • Cost effectiveness
  • Selection of technique
  • Commercial attractions of inflatable systems
  • The need for proper oxygen measurement
  • Workshop activity: use of systems
  • Issue of certificate of competency

* www.raeng.org.uk/ncllwelding

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