Every third week, a dropped object incident caused by bolt failures occurs on Oil & Gas installations on the Norwegian Continental Shelf. A review of 3,300 incidents registered at oljefakta.no confirms this statistic. Nord-Lock has reviewed the unwanted incidents registered at oljefakta.no from August 2008 to May 2013.

Surprised by the findings Petter Viken from Nord-Lock considers the findings rather unexpected. “I must admit that this is surprising to me. It is a well-known fact by most people in the industry that incidents with dropped objects do occur from time to time, but I did not know that so many of these incidents are caused by bolt failures. This is especially surprising considering the comprehensive safety routines the industry has established when it comes to inspection and re-tightening of bolted connections, as well as the amount of resources spent on this kind of work,” says Viken.

A well known safety issue The classification society DNV (Det Norske Veritas) states that 25% of all bolted connections on Oil & Gas installations must be re-tightened every year. However; dropped objects represent a major safety issue and therefore Nord-Lock believes that it is time for the entire industry to change their view on bolt security. “The Oil & Gas industry is innovative and under constant development, and we know that oil companies, operators and suppliers are extremely safety conscious. The statistics, however, show that the safety requirements on bolt security have not kept up with the overall development. The industry can therefore benefit greatly by focusing on improving bolt security,” says Viken.

A solution is available Wedge-locking washers from Nord-Lock are the only bolt security solution on the market today that has been certified by both DNV and ABS (American Bureau of Shipping). “Our washers secure the bolted connections, and keep them from loosening. A bolt secured with Nord-Lock washers becomes self-locking, which means that it cannot loosen by itself even if it is subjected to vibrations and dynamic loads. This contributes to saving lives and ensuring continued operations. Additionally, it can save a great deal of resources when it comes to maintenance,” says Viken.

Towards improved security and reduced cost Nord-Lock’s solution increases the level of safety and is already successfully used in the industry. However, other practical factors such as re-tightening and control routines remain costly for the operators. “Nord-Lock is working closely with DNV to find a solution which will replace the annual retightening requirements of 25% with a control every fifth year instead,” says Andrzej Serednicki, Principal Engineer, Technical Advisory Ship and Offshore at DNV.

“We have conducted our own laboratory tests of the system, and it shows that the bolt connections secured by Nord-lock washers hold up much better against vibrations and dynamic load,” added Serednicki.

“This will reduce maintenance expenses greatly, and minimize costly production stops related to maintenance and unwanted incidents,” says Viken. Re-tightening every fifth year would be applied if the following criteria are met: the bolts and nuts used are certified, bolt securing from Nord-Lock is used and finally that the professional conducting the installation has received specific training.

The Nord-Lock training is already implemented in a number of companies in the offshore sector. Technical Director John Einar Jorgenvåg at Transocean demands that all staff working on their platforms complete Nord-Locks training course for tightening bolts. “Our offshore environment is greatly exposed to vibrations and dynamic loads. Proper securing of components, especially those high up, is crucial. We started using Nord-Lock on some of our installations in 2005, and saw early on that this was an efficient way of securing our equipment,” says Jorgenvåg.