A reliable fastening solution for Oil, Gas and Mining

As the price of oil falls from highs of well over US$100 per barrel, profits are beginning to fall for oil and gas companies – unfortunately the costs remain the same.

Much of this cost is not being borne in the boardroom, but rather on the rigs themselves.

According to Baker Hughes the average oil rig count is expected to fall around 15 per cent in the first quarter of 2015, compared to the last quarter of 2014, as operators look to focus on their highest performing wells instead of those with lower output.[1]

But even with this, rig costs still remain high, with an average daily rate for floating drillships ranging between US$257,000 to US$520,000, while semisubmersible rates range between US$288,000 through to US$441,000[2], or approximately $13,000 an hour.

In light of these costs companies are looking to ways to make their remaining operating rigs more efficient and productive, with maximum uptime or productivity.

One of the major ways they are doing this is by looking at how they can obtain more efficiencies out of their existing equipment, using minor tweaks; getting more out of what you have by being smarter in how you use it.

But this is made difficult for the industry by the fact that all rigs, whether downhole or topside, onshore or offshore, face the most arduous operational requirements.

So cutting downtime is crucial in maintaining constant operations and making the rig profitable.

According to global technology and fastening company, STANLEY Engineered Fastening: “Their critical joints must be maintained and production downtime minimised, despite ever more extreme operational shock, vibration and temperature demands”.

One of the underrated issues for many rigs is shock and vibration, however it is an unavoidable, ever present issue on rigs.

In lockstep

When it comes to rigs, the vibration of all the operating equipment – working in unison –causes enormous stress on a rig’s superstructure and its additional equipment, putting machinery and equipment at risk of shearing away from the rig if it is not properly fastened or joined to it at best, and in a worst case scenario, falling off of offshore rigs in the ocean, creating a high one-off unexpected cost to recover the item or suffering permanent loss and in turn replacement costs.

Ensuring that this doesn’t happen to your equipment comes down to making sure you have the right fasteners and joints in place.

“From measurements while drilling (MWD) chassis, top drives, and set screws to high pressure compressor valves, vertical pumps, and beyond, the tapped holes and fasteners holding vital equipment together must operate with virtual 100 per cent reliability,” STANLEY explained

“Otherwise the cost of production downtime and unscheduled service can be astronomically high, particularly when million-dollar equipment is thousands of feet below ground or sea level in the wellbore.”

While engineers have traditionally used a range of fastening systems such as lock nuts, lock washer, lock wires, or adhesives to prevent loosening , the effectiveness of these methods can be questionable in oil rig applications. For example adhesive usage being ineffective or inconsistent in high or low temperatures, such as those found around Australian oil fields, and can have relatively high total cost when ongoing maintenance and production is taken into account.

When it comes to locknuts, the last few threads typically deform, making the product a single-use one and negating their ability to safely be used again.

Vibration may also deform these locknuts, forcing maintenance crews to cut them from the bolt, meaning both the locknut and the bolt need to be replaced – yet another cost from a single-use product.

But there is an alternative to these single-use, vibration affected fasteners that are not all able to operate in wide ranging temperature, contracting and expanding  and causing further loosening and warping of the hole.

A Tighter Solution

STANLEY offers a fastening solution that addresses the basic issue that arises from gaps that arise from vibration induced thread loosening: Spiralock®.

The innovative development is a self-locking thread designed for use in a range of different oil and gas applications from MWD chassis, reamers, top drives, through to high pressure compressor valves.

“The re-engineered thread form differs from traditional fasteners as it adds a unique 30 degree wedge ramp at the root of the female thread which mates with standard 60 degree male thread fasteners,” STANLEY states.

“The wedge ramp of the self-locking threaded fasteners allows the bolt to spin freely relative to female threads until tension is created.

“The crests of the standard male thread form are then drawn up and tightly against the wedge ramp, eliminating radial clearances and creating a continuous spiral line contact along the entire length of the thread engagement.

“This continuous line contact spreads the clamp force more evenly over all engaged threads, improving resistance to vibrational loosening, axial-torsional loading, joint fatigue, and temperature extremes.”

Also, as its locking mechanism comes from the interference between the thread forms there is no need for any additional chemical adhesives or secondary locking features, providing further cost savings as well as less downtime during maintenance activities.

Importantly, unlike the single-use locknuts it helps cut operator costs due to its multi-use capability.

“The thread form is not only self-locking but also reusable without damaging the locknut or bolt,” Ryan Bostick, STANLEY Engineered Fastening, oil and gas technical sales specialist explained.

“Full contact along the entire engaged length of the thread reduces thread galling and enables fastener reusability up to 40 times or more, reducing the need for replacement parts. 

“The locknuts are actually free spinning until they’re torqued down and locked in place, easing maintenance.”

In fact recent tests have shown the Spiralock threaded fasteners actually provide 50 uses without any loss of clamp load.

Added to this is another boon for the offshore oil and gas industry, with the fasteners being resistant to corrosive salt water environments.

As operators search for cost and production efficiencies in their operation, a simple change to smarter fastening solutions can help them keep a tighter rein not only on their equipment but also their bottom line.

Click here to watch STANLEY Engineered Fastening's accompanying video

[1] http://www.abc.net.au/news/2015-01-21/bhp-billiton-cuts-oil-rigs-in-the-us/6031534
[2][2] http://www.rigzone.com/data/dayrates/

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