Fluid Power Hoists Prove Ideal for Marine Applications

Equipment used in the marine industry faces tough operating conditions, including temperature and weather extremes, hostile environments, and demanding duty cycles. Offshore locations that are far from service and parts sources require a high level of dependability. Hoists and cranes powered by compressed air provide greater safety than electrically powered hoists in potentially explosive atmospheres. Hydraulic hoists are a practical alternative wherever hydraulic lines, central hydraulic systems or hydraulic power units are available. Both types are more compact than electrically operated products, and because they have fewer components, they offer extended service life and simplified maintenance. Here are some typical applications where air or hydraulically-powered hoists are standing up to these requirements.

Low-headroom hoist used in BOP handling operations provides lifting power and control where installation space is limited.

On the Maersk offshore rig, Guardian, four J.D. Neuhaus (JDN) type EH50 air-operated monorail hoists are incorporated into a blowout preventer (BOP) handling unit that provides synchronized lifting and handling during pre- and post-drilling operations. Two hoists are mounted on each of the unit’s twin parallel overhead rails, with each hoist providing 50 metric ton load and 20-m lift capacities for between-deck operations. Operating together, the two sets of hoists provide a combined lift capacity of 200 metric tons. Whether all four hoists are used together, individually or in pairs, synchronized operation of all linear movement and lifting operations is handled by multi-function controllers that incorporate a main-air emergency stop as well as load monitoring.

A large offshore crane system was constructed by J D Neuhaus to comply with offshore duties that include operating at temperatures down to –20° C in turbulent weather conditions and at inclines of 3 deg. from the horizontal with the crane loaded or 27 deg. when unloaded. The semi portal, A-frame design supports twin overhead horizontal track beams, each fitted with a single hydraulic EH 40-H hoist unit. The hoists can be operated individually or simultaneously from one controller. Working together, they provide a total lift of 80 metric tons, with a 12-m lift height over a 7.5-m span. To cover additional operational and service requirements, the company also supplied a JDN 6 TI-H hydraulic hoist with six metric ton lift capacity.

Low-headroom hoist used in BOP handling operations provides lifting power and control where installation space is limited.

All Profi TI hoists incorporate top-hook suspension mounting and pendant pushbutton controllers. When used with overhead rail mounting, these handheld controllers provide sensitive, infinitely variable or single-speed control of the load lift, lower, and powered-trolley traverse movements. Trolley mounting options include manual, reel chain, and motorized variations. All hoists are also fully ATEX-rated for operation in hazardous or potentially explosive atmospheres to a standard classification of Ex II 2 GD IIA T4/II 3 GD IIB T4. For operation on offshore rigs or ocean-going vessels, the equipment includes extra corrosion protection for rough, salty weather conditions.

Standard hoist safety features include integrated adjustable overload protection for load ratings of one metric ton and above. They incorporate a self-adjusting fail-safe braking mechanism, together with trolley anti-climb, anti-drop devices and an emergency stop switch integrated into the main power supply. An emergency lowering device also is available. It includes a separate air tank, with two additional buttons incorporated into the hand controllers.

Shown here are two of four EH50 air-operated hoists for between-deck handling of blowout preventers on the Maersk offshore rig Guardian.

This air reservoir is maintained automatically at full working air pressure and acts as a positive emergency braking system when required. The device becomes operable in the event of a severe reduction or total loss of main air pressure. Two-handed control operation prevents unintentional lowering. One button controls selection between normal hoist operation and emergency lowering, while a second button provides braking to ensure controlled lowering and safe grounding of the suspended load under its own weight.

For more information, call J.D. Neuhaus LP, Sparks, Md, at (410) 472-0500, e-mail the company, or visit its website.