In recent years new technologies, novel products, improved services and better contracting procedures are emerging and showing great potential for increased performance and safety. This is increasingly evident for applications in sectors like offshore, petrochemical and refining, ship and submarine building, nuclear power, hydropower, oil and gas transfer lines where failures are can lead to hazards to life. One such technology is a non-gasketed pipe connection and is recognised by the authors as representative of an ‘emerging technology’. It is based on several un-orthodox principles and does consist not only of a pair of welding neck flanges, but of an all-inclusive entire system, comprising bolts, washers, nuts, wrenches, procedures and training.
This paper is based on two years of experimental and finite element studies [Ref 1,2] of both standard/conventional ANSI (gasketed) and modern non-gasketed flanged joints. This has led to a deeper understanding of the requirements for a successful assembly and long term usage. ANSI and VCF joints have been subject to internal pressure, axial and lateral forces, with these loads having been applied both singly and in combinations. Mode of load acting in the joint i.e. static or dynamic has been studied for both kinds of joints. Experimental and analytical results have been compared.
Some practical considerations on the use of important emerging technology i.e. non-gasketed pipe joints in comparison to conventional gasketed systems are presented. Of fundamental importance is an insight into the mechanism of the bolted joint showing the effect from an external load on a preloaded bolt. It is found that it can be made near zero hence, in a properly built, non-gasketed bolted joint a static mode rules, and therefore the stamina of such a joint is unlimited.
Other practical issues of fabrication, handling, surface damage and assembly, have been examined in the lab and on site and a summary of results is presented. In addition a probability risk assessment has been undertaken and results compared with the standard (conventional) ANSI type joints. In addition this paper demonstrates that the novel system is an efficient and well -engineered alternative to traditionally designed joints.
