Bulkheads

Application example: Bulkhead seal for a pump drive shaft

Issue and challenge:

Oil re­sources in the deep sea cannot be ex­ploited with drilling plat­forms. Here, FPSO oil supply ships (FPSO = Floating Pro­duc­tion, Storage and Of­fload­ing Vessel) come into play. Through pipelines, which are flexibly anchored to ex­trac­tion heads at the bottom of the sea, the crude oil is pumped on to the FPSO ship, where it un­der­goes a variety of refining stages. Gas, water and solids are sep­a­rated from the crude oil, and stored until being trans­ported away. The con­vey­ing pumps, along with other pumps for ex­plo­sive ma­te­ri­als, are located in a com­part­ment between bulk­heads. The elec­tri­cal drive for the con­vey­ing pump is located in the adjacent com­part­ment, with a drive shaft passing through the bulkhead. The Aus­tralian operator wanted a seal for this shaft feed-through which, due to the small avail­able space, needed to be compact, easily mounted, able to prevent ex­plo­sive gases from getting into the machine room, and which, in the event of an emer­gency, would also function under water.

Solution from EagleBurgmann Espey:

The com­peti­tor's seals pre­vi­ously used for this ap­pli­ca­tion had an average service life of three months. The operator of the oil supply ship asked EagleBurgmann Espey to offer a seal solution that would run for at least a year. To meet the op­er­a­tors needs, Espey chose an Espey® WDKS with a con­nec­tion for barrier gas, a length of only 50 mm (1.97 “), and an easily as­sem­bled split housing. It is designed for a pressure of 2.1 bar (30.46 PSI), a tem­per­a­ture of 50 °C (122 °F), and a rotation speed of 3550 rpm, and is also able to operate un­der­wa­ter. The ambient air is used as the barrier gas, in order to minimize the costs that an ad­di­tional barrier gas supply would entail. The im­ple­mented seal has a long service life, is main­te­nance-free, and com­pen­sates for shaft move­ments. The seal was in­stalled in Sep­tem­ber of 2008 and is still running without having needed any repairs.

Application example: Bulkhead seal for a shut-off valve

Process description:

Ships with drive shafts that run through one or more bulk­heads require bulkhead seals to prevent any pos­si­bil­ity of water from rushing into adjacent sections of the ship – and there­fore provide a high level of pro­tec­tion against flushing. The work and ob­ser­vance vessel We­ser­plate with a length of 27.1 m (1,066.93”), a width of 6.7 m (263.78”) and 1.19 m (46.85”) depth of flota­tion requires a bulkhead seal to protect the engine room against flushing.

Problem and challenge:

The shaft feed through in the bulkhead of work and ob­ser­vance vessel We­ser­plate requires a bulkhead seal. The entire drive system needs to be highly reliable in order to ensure that the ship offers year-round service without ever being laid up for repairs – and call for a minimum of main­te­nance at the same time. The shaft runs with 1,800 min-1 rev­o­lu­tions. The diameter in the sealing area is 98 mm (3.86"). The seal op­er­at­ing tem­per­a­ture in the engine room is maximum 45 °C (113 °F) ac­cord­ing to the spec­i­fi­ca­tions of German Lloyd. The op­er­at­ing pressure in case of damage will not exceed 1.5 bar (21.76 PSI). The in­stal­la­tion length should be as short as possible. The seal should guar­an­tee an easy assembly.

EagleBurgmann Espey solution:

To fulfill the ap­pli­ca­tion re­quire­ments Espey designed the bulkhead seal Espey®  WDK-BHS with two seg­mented seal rings made of a PTFE-car­bon compound and split housing for easy assembly. A barrier gas port is not needed. The seal width’ of only 30 mm (1.18") meets the cus­tomers’ re­quire­ments. The seal guar­an­tees a long-term op­er­a­tion time without any main­te­nance.