Since its launch in December 2015, the DNV GL certification scheme for offshore gangways for personnel transfer has provided a basis for various designs focusing on safety and efficiency. The “Walk2work” class notation supporting this certification standard is part of the rules published in January 2017.
With a rapidly expanding offshore wind energy sector and growing numbers of unmanned wellhead platforms, the call for flexible walk-to-work solutions is increasing. These operations include high-frequency personnel transfer operations often performed under challenging environmental conditions with high wind speeds and harsh seas. Offshore gangways provide a safe and cost-effective alternative to personnel transfer by helicopter, basket transfer or boat landing. They form a bridge between two vessels or between a fixed object and a floating installation to transfer people, cargo or equipment. Gangways can take many forms, ranging from permanently installed links between accommodation units and production assets to temporary transfer between service vessels and unmanned installations such as offshore wind turbines and offshore fish farms.
Since its launch in December 2015, the DNV GL certification scheme for offshore gangways “DNVGL-ST-0358 – Certification of Offshore Gangways for Personnel Transfer” has been received very well by the industry. “By addressing a complete set of requirements for materials, strength, safety and functionality as well as testing and recommended in-service follow-up, we have created a specific and dedicated standard to make gangway operation safer and more efficient,” says Per Arild Åland, Business Development, Offshore Classification, DNV GL – Maritime.
The Dutch manufacturer Barge Master was the first supplier to receive approval for their gangway system. DNV GL has been working closely with Barge Master to define the scope of certification for one of their newest and most innovative offshore gangway concepts featuring a secondary offshore crane function. The challenge of combining the standards for personnel transfer and lifting appliances was mastered successfully and the system received approval for both uses according to DNVGL-ST-0358 as well as the DNV Standard for Certification 2.22.
Rob Das, Service Responsible at DNV GL – Maritime, reports: “We worked with Barge Master on this project from the draft version of the new code until the DNVGL-ST-0358 was released and applied to their product. Their input during the external hearing process contributed to the improvement of the standard.”
“I am very happy about our collaboration with DNV GL, and extremely proud the Barge Master Gangway is the first to receive the DNV GL approval in principle,” says Jorrit van Dommelen, R&D Engineer at Barge Master.
Ensuring equipment reliability
The Barge Master gangway is equipped with a high-performance motion compensation system that enables safe transfer of personnel from a floating vessel to a fixed structure in waves up to 4.5 metres HS. Its modular design allows it to be configured for the given purpose. Modules range from a height-adjustable pedestal to an integrated motion-compensated lifting winch.
Ten gangway systems have been certified since the launch of the new DNV GL standard, among them the Telescopic Access Bridge (TAB) M series by the Dutch manufacturer SMST, which incorporates the safety and design principles of the DNVGLST- 0358 – Certification standard. The M series is one of SMST’s four types of access bridge systems which vary in length from four metres up to 58 metres and can be equipped with active or passive motion compensation. The S, M and L sizes were primarily developed for walk-to-work applications whereas some of the L as well as the XL sizes can serve as long-term links between offshore structures and accommodation vessels. The modular M series TAB is suitable for a variety of vessels and operational situations. Compact and transportable by container truck, it can be installed quickly and has a large operating window. It is controlled by the vessel‘s own crew, doesn’t need large generators and is inexpensive to operate.
After the successful launch of the TAB M series, the Access & Cargo Tower, based on proven components and designs, is the second SMST system certified to DNVGL-ST-0358. Its modular design featuring variable height adjustment enables safe, efficient, stepless transfer of both cargo and personnel from multiple deck levels to the turbine platform. To ensure comfortable crossing and maximum workability, the height of the access bridge can be adjusted to match the platform landing height. The integrated elevator with capacity for personnel and cargo pallets can stop at several levels to optimize logistic performance.
“Our continued collaboration with DNV GL for certification of our cranes and, more recently, our offshore gangways has proven fruitful yet again. The next step would be obtaining DNV GL Type Approval for our complete range of offshore gangways,” says Pieter de Bos, Project Manager at SMST. “We are very happy that we are number one in the world with a mobile, actively motioncompensated gangway in operation built under the new DNV GL standard. Series production of the first 20 pieces is in full swing,” SMST CEO Erik Hessels adds.
“DNV GL‘s efforts in 2015 to issue the new standard have been rewarded in 2016 by a lot of positive feedback. Our customers have been working hard, and with each new design we see the industry benchmark set higher. We are proud to support ongoing efforts to improve the safety of offshore personnel transfer,” says Aldo Matteucci, Head of the DNV GL Lifting Appliances section. The launch of the class notation “Walk2work” is another step towards ensuring transparency and predictability in the marine offshore industry. With “Walk2work” in their string of notations, ship and rig owners can easily communicate and document the ability of their fleets to take part in safe and efficient walk-to-work operations. To qualify for the notation the offshore gangway must be certified in accordance with the requirements of the DNVGL-ST-0358 standard. The certified gangway system and related equipment are subject to periodical in-operation surveys to ensure walk-to-work equipment reliability, and to contribute to the general operational excellence. With this service for offshore gangway systems DNV GL contributes to a cost-efficient and robust maintenance scheme on board as the in-operation survey scheme carried by the “Walk2work” notation is integrated into the general ship management routine.
DNV GL believes that continuous development and improvement of its rules and standards is an essential activity. An improved scheme for the qualification of offshore gangway control systems will be introduced shortly. The main focus of this extended system certification will be software integrity assurance based on simulator testing.
Barge Master gangway equipped with a high-performance motion compensation system.