Smart innovation: recent developments in stainless steel tubes and pipes

Sellers’ market

Inflation is back, with the pandemic exacerbating a problem that may have occurred anyway. Supply chains stretched to the limit, congested ports, and labour shortages are factors that suggest inflation is not going away any time soon. This is reflected in recent rises of all commodity prices, including stainless steel, and in the sellers’ market that currently prevails in the field of tubes and pipes.
Covid 19 affected producers in different ways; some were compelled to close down facilities, while others have carried on (almost) as normal. The sector as a whole was badly hit at the start of the pandemic (2020) but has bounced back as restrictions are lifted. The fundamentals were always good: growth in the stainless steel pipes and tubes market is expected to be +4.1% per year from 2021 to 2027( ref 1). Seamless tubes and pipes are growing 3-5% annually(ref 2). Moreover, the sector is bristling with innovation and is learning to harness smart technology to lower production costs and streamline inspection, monitoring and maintenance.

Markets

Oil and gas

Demand is high in all the process industries, especially oil and gas and power generation. The oil price plunged dramatically during the early stages of the pandemic but has soared recently, while the rise in natural gas prices has been even more dramatic. The high pressures and often sour conditions of modern offshore developments is boosting demand for speciality alloys of all kinds, especially duplex, super duplex and hyper duplex stainless steel tube and pipe.

Power Generation

But the really dramatic developments are occurring across the whole range of power generation. One striking feature of the COP26 talks in Glasgow is the reappraisal of nuclear power as a means to combat global warming, with the International Energy Agency pointing out that targets will be difficult to meet without the contribution of nuclear fission. According to Fine Tubes, global demand is not slowing and comes mainly from China, Canada, the USA and India. The demand is for tubular products in titanium, zirconium, nickel alloy as well as stainless (ref 3). Other power generation sectors likely to consume more stainless steel and CRAs include concentrated solar power, which requires heat-resistant nickel alloy tubing, ultra-supercritical (USC) coal-fired stations and biomass and waste-to-energy facilities. USC plants have benefited from the recent development of A625 weld overlay on austenitic stainless, a technology that brings high corrosion resistance and the ability to withstand hot steam. Austenitic stainless-steel base tubes are expected to see greater use in biomass and waste-to-energy plants, where operating temperatures are increasing.

Auto

Another market seeing innovation in tubular products is that of electric cars. Here the considerable weight of the batteries makes it imperative to save weight in other areas. Thyssenkrupp Precision Steel is exploring highstrength, ultra-light steel, manganeseboron steel for tube stabilisers and hybrid aluminium-steel tubes using an internal high-pressure forming process. Another company offering tubular solutions for the auto and energy industries is the recently formed Vallourec Tubos para Indústria (VTI), a collaboration between Vallourec’s Drawn and Profiled Tubes Unit and the Açotubo Group’s Cold Drawn Tubes Division. Also, Centravis has developed lean-duplex (2304) cold-worked pipes for use in the auto industry.

Technology

One of the most important innovations in manufacturing is additive manufacturing (AM or 3D printing), which is likely to have a profound effect on process tubing. The Savannah River National Laboratory is researching the use of type 316L in a powder bed fusion laser process to fabricate a hydrogen isotope separation unit for a thermal cycling absorption process. Vallourec is studying the application of wire arc additive manufacturing (WAAM) to its products. Already, carbon steel components are qualified with pressure up to 22,500 psi, and the company has indicated that some CRAs will be available soon.
Of more immediate impact, however, are recent improvements in the design of welded tubes, which could lead to encroachment of the applications usually reserved for seamless tubes. Seamless tubes are considered the safer option in critical applications in heat exchangers and pressure boilers in the nuclear, oil & gas, petrochemical and chemical industries, where the absence of welds reduces risk. Welded tubes are generally restricted to less critical applications in architecture, auto, food & drink and pharmaceutical. However, seamless tubes are more costly than welded, so manufacturers are beginning to specify welded tubing where previously seamless would have been preferred. Posco won a prize for its laser welded duplex stainless (329J4L) tube for gas heaters in upgraded thermal power plants in South Korea. Plate heat exchangers using seamless tubes are being replaced by tube heat exchangers using welded tubing in order to avoid flue gas leakage. The LBW welding process was selected, and the welding and heat treatment conditions were optimised to improve the corrosion resistance of the weld. Costs and lead times were both reduced.

Smart maintenance

Another field where innovation is taking place is that of maintenance, inspection and monitoring. Robotic inspection has existed in the oil and gas industry since about 2017, with Equinox, Total and Chevron leading the way. Covid 19, with its travel restrictions, has accelerated a turn towards their use in dangerous or inaccessible areas. During the lockdown, Vallourec proposed its VAM® Field Service (VFS) remote offer to a larger number of customers. By means of an app technicians can access VFS, which provides a remote service.

Where access is difficult it is desirable to have “eyes inside the well” using “intelligent pipes”. This is the idea behind Vallourec’s solution for well monitoring, its Intelligent Pipe technology. Since 2018, Vallourec and OpenField Technology have been collaborating on a monitoring solution involving sensors directly embedded in the pipes which monitor the entire wellbore. These Intelligent Pipes can also provide information on the well environment, such as characterising moving salt formations or determining the efficiency of the injection process. This technology can also be used in other applications such as CO2 storage wells and hydrogen wells.
Another example is the use of robots to take measurements inside gas pipes. The UK gas transmission system is aging, increasing the risk of corrosion and leaks. To avoid the need for timeconsuming and costly excavation, the UK National Grid worked with Premtech, Pipeline Integrity Engineers and Synthotech to develop GRAID (Gas Robotic Agile Inspection Device). This robot inspects the most inaccessible pipelines from the inside, saving hundreds of hours of work. The robot is tracked underground via GPS and transmits data on wall thicknesses which is then turned into easily understood images. Thus a pipe’s condition can be assessed before a rupture occurs, significantly improving safety. This is the first time a robot has been used in an environment with pressures of up to 100 barg, with live gas inside the pipes. During testing super duplex grade 2507 was used and performed as expected.