Lokring: No More Hot Work

Saving money is just a bonus for engineers using new carbon-steel connections in their piping systems. Other benefits include a safer work environment and shorter project schedules.

But what really matters to engineers is the fact that Lokring makes their job significantly easier by allowing them to make connections without associated hot-work issues.

In the past, engineers in charge of repairing or installing permanent piping systems were limited to using hot work — work that involves burning and welding that might lead to fire or explosions. In addition to the obvious safety issues, welding is a source of high costs and often lost productivity for the oil and gas companies & contractors that rely on it.

"For offshore facilities and other upstream sites that use it, hot work is a major issue, and they prefer not to do it," said Martin Parker, international sales & operations director, Lokring Europe Ltd., which pioneered the LTCS-333 Process Fitting product in Aberdeen. "First and foremost, the concept gives them a 'cold work' solution."

Lokring's stainless and carbon steel connections aren't new; they have been prevalent in utilities, steam, process services and a number of process applications since the early 1990s. Relying on Lokring's elastic strain preload (ESP) technology, Lokring fittings eradicate the need for welding by sealing pipes during an installation without the use of heat.

The technology works like this: During a piping installation, the axial movement of the Lokring driver over the fitting body swages the body onto the pipe surface, compressing the pipe wall first elastically and then plastically. When the pipe wall resists this swaging action, it generates high unit compressive loads at the contact points. These contact stresses are high enough to plastically yield the pipe surface under the multiple sealing lands, forming a 360-degree circumferential, permanent, metal-to-metal seal between the pipe and fitting body. Finally, the installation process causes the Lokring driver to grow slightly in diameter — an "elastic strain" — so that it exerts an elastic, radial preload on the metallic seals. This secures the fitting for the life of the connection.

Several years ago, Lokring saw the opportunity to better serve the marketplace by developing a product that achieves the same integrity as welding but removes many of the challenges and long-term costs of hot work. In January 2010, the company introduced a new LTCS-333 Process Fitting, based on its tested ESP technology. Using the same design, LTCS-333 Fittings incorporated a new material — low temp 4130 carbon steel — that provided a new scope of capabilities for users.

Prior to use, the new fittings undergo extensive mechanical testing to verify the mechanical and sealing integrity of the connection. This includes burst, tensile, torsion, flexural fatigue, impulse & vibration, corrosion & fire testing. The carbon steel material that is used for LTCS-333 Process Fittings is impact tested thus can be used on low carbon steel applications and also complies to NACE.

"Testing has been comprehensive," Parker said. "It has enabled the fitting to be used on piping systems with an increased corrosion allowance of one-eighth of an inch from what was one-sixteenth of an inch on the standard design."

The result is a superior quality, leak-free fitting that is extremely reliable, easy to install and requires no heat for installation in a far wider scope of applications.

"Safety is the clearly the biggest thing," Parker said. "But to be honest, key engineers know it's also a no-brainer in terms of cost. So they also know automatically that it will reduce their time and produce real savings."

The addition of LTCS-333 Process Fittings also enables engineers to use Lokring Technology in applications that they couldn't before, specifically, in cases where hot work poses a high risk — i.e. open and closed hazardous drains and vents, gas-lift, flare gas, propane, butane, LPG, hydrocarbon, sour water and sour gas, diesel and chemical injection.

Furthermore, with Lokring, fabrications can be made onsite and systems and can be fully field-routed, significantly reducing design, fabrication and off-site costs while still enhancing safety.

"You don't have to necessarily fabricate onshore and ship pipework offshore," Parker said. "So it's superior to a weld because you can avoid post-weld heat treatment (PWHT). You also have no decontamination, no flushing, no purging, no hot-work permits and no enclosures or fire tents, no atmospheric tests and possibly a reduction in scaffolding. You also have a much lower rework rate whilst eliminating heat affected zone (HAZ) issues and also nondestructive testing (NDT) costs."

"Welding can be an expensive process, and it's not just about the actual weld," Parker said. "There are numerous challenges associated with the process & they all add up to time and cost."

As well as the benefits in Maintenance, Repair & Operations – Lokring is used on Projects & Turnarounds providing more efficiency & reducing schedules. Training is provided to non-skilled personnel, so that coded welders can focus on large-bore or critical path piping. This means multiple trades can be stacked during Lokring installation, contributing to higher productivity and quicker turnaround times.

"Lokring installations have been proven to make significant cost savings over welded pipe, documented at between 25 and 62 percent," Parker said.

Although utilizing piping connection technology that eliminates hot work and saves money may seem like a formality on paper, but winning over engineers isn't as simple as you'd expect.

Since launching the LTCS-333 in January 2010, Lokring has helped many global oil and gas companies, and their contractors and fabricators operating in upstream sectors, replace their welded systems with Lokring's pipeline solutions. Yet while many engineers have eagerly embraced the new technology, other groups are hesitant to move away from traditional ways of doing things, even if it makes their jobs easier.

"Welding is an industry steeped in tradition, accountability and documentation," Parker said. "So sticking with the status quo is perceived as less of a risk to the decision-maker than going down a route of change. In other words, sometimes welding is the "easier" option for those away from the plant.

"We're asking engineers to make a paradigm shift and go away from something that's the norm. While in many ways it's an improvement — it's safer and more productive & equivalent integrity— there's a hesitancy of some engineers to change."

Switching from welding to the Lokring system for piping applications also requires a lot of upfront administration from engineers, who must write specifications and produce required documentation to change. According to Parker, swaying engineers has not simply been a matter of showing them that this technology offers increased benefits over welding, we must show that there is no compromise in quality or integrity. We have also developed similar protocols that provide the same accountability & "insurance policy" that installations are safe & appropriately selected.

"So it offers the same integrity of the weld with a number of performance benefits, from increased productivity to lower overall cost. The technology is significantly easier to use and it addresses almost everything in regard to the challenges that engineers have right now."

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