Giàn tự nâng phục vụ thi công tháp gió (liftboat)

Gửi ae tham khảo một số hình ảnh và thông tin về một loại Công Trình Biển di động.

A liftboat is a self-propelled, self-elevating vessel with a relatively large open deck capable of carrying equipment and supplies in support of various offshore mineral exploration and production or offshore construction activities. A liftboat also has the capability of rapidly raising its hull clear of the water on its own legs so as to provide a stable platform from which maintenance and construction work may be conducted.

 

Một trong những dạng công trình hứa hẹn trong tương lai. Khi dầu và khí hết thì năng lượng gió, sóng, thủy triều sẽ được phát huy tối đa. Và liftboat sẽ là giàn khoan phục vụ công tác thi công, bảo dưỡng các tháp gió.

Loại này thường có chân tròn hoặc chân dạng thanh giàn. Hệ thống nâng hạ và cẩu bao lấy chân.

Việc thiết kế liftboat cũng giống như thiết kế giàn khoan tự nâng (áp dụng tiêu chuẩn IMO MODU hoặc ABS MODU) nhưng nó thuộc dạng "self-propelled" do có Thrusters ở đuôi và lái, một số giàn thiết kế hiện đại hợn thì có thêm hệ thống DP1.

 

Mình thấy chỗ này chưa đúng nên chưa "Cảm ơn", bạn SteelMan nếu thấy mình nói đúng thì "thông cảm" nhé.

Trong hàng hải thì cả 2 từ AFT và STERN dân trong nghề thường gọi là lái, phía lái; dân ngoại đạo thì gọi là đuôi tàu, đít tàu. Ở đây tôi mạn phép bổ sung thêm "Self-Propelled" có nghĩa là "tự hành" và hệ thống DP1 (Dynamic Positioning - Class 1) hiện nay đã khá lạc hậu, các tàu đóng mới trong mấy năm gần đây nếu có trang bị DP thì họ thường dùng Class 2.

---------- Post added at 08:50 AM ---------- Previous post was at 08:11 AM ----------

WHAT IS A LIFTBOAT?

A liftboat is a self-propelled, self-elevating vessel with a relatively large open deck capable of carrying equipment and supplies in support of various offshore mineral exploration and production or offshore construction activities. A liftboat also has the capability of rapidly raising its hull clear of the water on its own legs so as to provide a stable platform from which maintenance and construction work may be conducted.

The first liftboat was designed in 1955 by brothers Lynn and Orin Dean in Violet, Louisiana. In 1950 the Dean brothers owned a repair service for automobiles, marine, and farm equipment called Universal Repair Service which is now known as EBI, Elevating Boats LLC. EBI, Elevating Boats LLC, operates 30 liftboats that service the shallow water Oil & Gas industry in the Gulf of Mexico from their liftboat dock in Houma, Louisiana.

If registered to the United States, liftboats structures and their machinery are covered under Title 46 of the Code of Federal Regulations. Liftboats are usually outfitted with at least one crane; marine cranes are usually designed to API specification 2C or the equivalent classification society guidelines.

Liftboats are commonly used to perform maintenance on oil and gas well platforms. The liftboat usually moves on location on a side of the platform where no obstructions or pipelines are observed, lowers its legs and jacks up out of the water. Because the pads of the liftboat are setting on a muddy, unstable seafloor, most liftboats practice a safety measure called a preload, where the boat jacks up a few feet out of the water, fills its holds with water for weight and allows the boat to settle in the mud for several hours before dumping the water and jacking up to work height.

If the mud of the seafloor gives way under the liftboat, it can fall into the water and put the lives of the crew in danger. A complete site survey prior to moving on location is an important safety measure to ensure that all seafloor features (canholes, pipelines, etc.) are known before choosing a final location.

L/B Robert
Montco Offshore's MiNO Marine, LLC designed L/B Robert is the world's largest liftboat with a working water depth of 270 feet (82 m), 15,400 square feet (1,430 m[SUP]2[/SUP]) of deck area and a 500-ton crane. The legs are 335' long and it has 3 additional cranes in addition to the main crane. The vessel uses electro-hydraulic jacking systems and cranes all driven from the segregated machinery spaces.

What is a Liftboat?
Liftboats are the preferred vessel for most shallow water jobs in the United States Gulf of Mexico (GOM) where there are about 200 such vessels. So, outside the US-GOM, why are they virtually unknown? This article will address the overall features of a liftboat, uses, and address the questions – why have they been unknown outside the US-GOM.

A liftboat is a self-propelled, multi-purpose, self-elevating vessel. Some have referred to liftboats as jack-up barges, lift barges, jack-boats. We will examine the distinguishing features of a liftboat as compared to its closest cousin, the jack-up drilling rig. Since, a liftboat spends most of its working life out of the water, it is felt it better to address what it does during its working life. Further, lets look at how it gets to the job site.

The overall liftboat design optimizes the interrelationship of the key features, i.e., one would not desire a big deck area without a comparable deck load, etc. Looking at the liftboat, there are certain key elements to focus on (1) Legs and pads, (2) Jacking System, (3) Working Water Depth, (4) Open Deck Area, (5) Net Deck Load, (6) Crane Capacity, (7) Personnel Accommodations, (8) Propulsion and (9) Classification Considerations.

Legs
Proven to be a cost effective design, the vast number of liftboats have three columnar legs (pipe legs). Columnar legs and pads provide added buoyancy for the liftboat as the legs are lowered to the sea floor. This buoyancy in both the legs and pads (spud cans) helps reduce the bottom bearing pressure on the pads. In combination with the buoyancy, larger liftboat pads are designed to reduce bottom bearing pressure. This has the effect of less penetration for the typical liftboat.

Working water depth also affects the type of leg. After about 220 feet (67 meters) of water, then lattice legs are the norm. The vast majority of liftboats are three-legged. The four-legged liftboat will cost more than the cost of simply adding the cost of another leg, i.e., the jacking system to support two legs loaded diagonally is greater and the hull structure is different/heavier. But operationally, the setup time savings of a four-legged equates to money, so, one has to weigh the costs and benefits of three vs. four legs.

Jacking System
The jacking system for a liftboat is very different than the jacking system for a jack-up drilling rig. The two major differences center around speed and cycles.

Speed of the liftboat jacking system is essential. While a typical jack-up drilling rig elevates at two feet per minute a liftboat could elevate at four to six feet per minute and lower the legs at 14-18 feet per minute. This gives the liftboat the ability to get on and off location significantly faster.

The jacking system for a liftboat encounters a very different operational cycle. It would not be uncommon for a liftboat to jack up and down in one year the same number of times that a jack-up drilling rig would encounter in its entire lifetime. So, the wear factors, redundancy, material grades and shock loads are different between jack-ups and liftboats.

Working Water Depth
The expected wind, wave and current (environmental conditions) in the maximum working water depth needs to be determined. Although, other variables will go into the liftboat design, such as, net deck load, the starting point is still working water depth. An area with moderate environmental conditions vs. harsh environmental conditions will be a significantly different liftboat design in all aspects, i.e., legs, jacking system and hull.

Deck Area
The deck area is the unobstructed, open area. The liftboat crane is used to move equipment and materials around and on to and off the platform/offshore location. There is a relationship among these variables – open deck area, net deck load and crane capacity. Further, you need a crane capacity that is commensurate with the expected deck loads and area.

Deck Load
The net deck load for a liftboat is what you have on your deck in transit and can then jack up with on the deck. Consumables (such as water, fuel, hydraulic fluid, etc.) are in addition to the net deck load.
There is a definite relationship among deck area, deck load and crane capacity. Liftboats are designed as multi-purpose vessels. Also, one needs to consider the type of equipment and components that will be on the deck, so that, various areas can be designed to accommodate the various loadings, i.e., an area near the bow may have higher point loading than other areas.

Crane Capacity
There are a variety of cranes for liftboats. Cranes for liftboats are designed by crane manufacturers specifically for liftboats. Weight is a key consideration in liftboat design, so, every consideration needs to be made in the overall design including the crane. Therefore, cranes for liftboats are typically structurally lighter than a comparable offshore crane. Regarding types of liftboat cranes, there are lattice boom, box boom, telescopic boom, pedestal mounted, and leg encircling cranes. The main things to consider in crane selection is reach, load capacities and affect on deck area.

Accommodations
The accommodations are another feature of liftboats. The personnel accommodations are generally divided into two areas – navigation crew and customer/operational personnel. As liftboats have gotten bigger with increased capacities, so, has the requirements for more personnel. For example, a 100-man accommodation block would typically have about 20 navigation crew and the remaining 80 for customer/operational personnel.
The type of job that the liftboat is performing will dictate the accommodation requirement, i.e., an offshore construction job would generally require more personnel than a well intervention job. The construction job may even require additional modular living quarters on the deck.

Propulsion
A standard and key feature of a liftboat is that it is self-propelled. This alleviates the need for tugs to move the liftboat or to set up on location. The liftboat can wait for a weather window and move. The larger liftboats have integrated propulsion and bow thrusters.

Classification Societies
Most of the major Classification Societies do not class liftboats which is considered a requirement for international operations.

Advantages of Liftboats
Liftboats have historically proven to be a cost effective offshore service vessel. Major advantages include lower down time, no need for tug assists, stable work platform in the elevated position, negates the need for jack-up drilling rigs in a lot of cases, and negates the need for derrick barges in a lot of cases. They can be used for all types of offshore construction and maintenance to well intervention services like wire-line, coiled tubing, and nitrogen. They have even been used to build high-rise bridges. So in answer to the question that was poised at the start of this article “why have they been unknown outside the US-GOM.” Liftboats that are designed for the US-GOM are generally not suited for international operations due to increased working water depths, increased environmental conditions, and need for a recognized Classification Society approval. It is simply not enough to have a United States Coast Guard (USCG) approved liftboat for the international market place. Liftboats have gotten bigger and more capable – capable of international markets.

(from Wikipedia, the free encyclopedia)

 

Thực tế DP hiện nay đã có đến DP3 rồi, tùy mục đích sử dụng, mức độ yêu cầu mà người ta dùng DP1, DP2 hay DP3, ví dụ như giàn bán chìm hoặc tàu khoan thì cần phải dùng DP3 mới làm việc an toàn.

Còn liftboat chỉ làm nhiệm vụ chức năng như accommodation barge phụ vụ các công tác thi công, khi đến vị trí chỉ cần hạ chân xuống là có thể làm việc vì vậy thực chất không cần phải dùng DP (giống như 6 cái 320E Levingstone của Saigon shipyard đóng) nếu dùng chỉ cần DP1 là đủ, dùng DP2 hay DP3 hơi phí, không phải phí do chi phí DP mà phí chi phí mua các thiết bị tương thích đồng bộ với hệ thống DP2,DP3.

 

Hey, đúng là bé cái nhầm.
Chính xác lại là Mũi/forward (đầu/phía trước) và lái stern/after(đuôi). Liftboat thường được trang bị chân vịt/Thrusters ở cả mũi và lái.

 

Dong y voi y kien cua ban.

 

Giàn Liftboat không những phục vụ thi công tháp gió mà còn phục vụ công tác thi công, sửa chữa, hiện đại hóa, hủy bỏ giàn. Khu vực và lĩnh vực hoạt động của Liftboat đã tăng rất nhanh trong những năm gần đây.