Method for erecting support in water obstacle

FIELD: hydraulic engineering, particularly building bases and foundations, namely bridge piers, in water.

SUBSTANCE: method involves monitoring water obstacle in support building place, including investigating water parameters, recording water level in the course of year, determining floor shape, investigating floor ground, influence of outer disturbing forces and calculating weight and dimensions of support foundation case on the base of above parameters; producing hollow case with several cavities; moving case to installation place; submerging case in water; pacing thereof on floor; fixing case by piles and smoothing floor. Case submerging and placing operations are performed simultaneously with stabilizing vertical case position by performing control and filling of corresponding cavities. Bottom smoothing process is carried out by forcing artificial material, such as concrete layers with crushed stone interlayers, under case bottom. During case placing case is secured by blades built in case bottom and by piles inserted in cavities. Correspondence between case weight, number of blades, head resistance and side friction thereof for particular ground is determined to provide case stability on ground. Upper edge of submerged case is located above maximum possible water wave height. Rock fill is formed around underwater case part.

EFFECT: reduced time of support erection, increased reliability and stability, safety and service life, reduced labor inputs, possibility to erect supports in Arctic basin.

3 cl 1 ex

 

The invention relates to a method of construction of hydraulic structures, and in particular to methods of construction of bases and foundations in areas of water, and can be used, for example, in bridge engineering for the construction of the Foundation piers.

Well-known platforms (see US patent No. 4666341, CL E 02 In 17/00,1987) and similar platforms production in Russia, which were installed in the North sea. These platforms are connected with the bottom metal “skirt” and fixed at the four corners of the hollow pile. The height of this “skirt” corresponded to 4-5 m, and the diameter of the pile - 600-1250 mm and their length is equal to 6-7 m “Skirt” and hollow piles in this case is used for braking shell before landing at the bottom of the bed and to reduce its pull over in a horizontal direction from a specified landing site. In addition, the skirt is used additionally to control the position of the shell relative to the bottom.

The known gravitational platform, comprising a housing in the form of a shell, a base portion with a plate, which is placed at the bottom and which is equipped with anchors in the form of ribs-skirts, buried in the Foundation soil, and the space between the plate and bottom water barriers filled with cement mortar. This improved stability, to obtain a uniform contact stress and to refuse alignment Nam is before loading (see C-ku France No. 2335133, 1977).

However, the installation of this platform, as described above, accompanied by the need for considerable effort to push in the Foundation soil is flat passband edge skirts, mounted on the platform, limiting the depth of the push, to not achieving ribs-skirts durable layers of soil water barriers, to reduce the bearing capacity of the Foundation platform.

In A.S. SU # 1791528, 1990 reduce forces against nadavlivanii edge skirts in the Foundation soil while maintaining the stability of the gravitational platform to achieve the selection of such parameters ribs-skirts, as the distance between the crests of the skirts, the height of the ridges, the angle of internal friction of the soil, the angle of the “bulging”, depending on the angle of internal friction.

However, this method of installation of the platform leads to insufficient stability and bearing capacity, because it does not account its weight and such parameters of a knife, as the head resistance and side friction of the knife on the ground. In addition, when the calculation is not considered an external disturbance and does not provide for the alignment of the bottom of water hazards at the place of installation of the platform. This leads, as in previous decisions, the operational reliability of the sustainability of the vertical position of the platform on the ground. These circumstances lead to uneven draft platform of C the effects of underwater currents or pressure of the ice, a reduction in the reliability of fastening of a water barrier to the bottom.

Closer to the proposed invention should be considered as the method of construction of relying on water hazard, described in the patent RU №2057845, 1996, and includes the monitoring of water barriers in the place of installation support, including the study of properties of water, check the water level during the year, the definition of the bottom topography, the study of bottom soil, the influence of external disturbing factors and on the basis of this calculation the weight and dimensions of the shell, making a hollow shell with compartments, transport to place of installation, the boot shell to dive into the water and landing on the bottom, fixing piles, the alignment of the bottom.

However, the method according to the description of the patent RU No. 2057845, 1996 complicated. In the method provided by the preliminary alignment of the bottom up approach of the shell to the dive sites. This leads to unnecessary increase in terms of construction of the support. In addition, the inappropriateness of such alignment is determined by the inability to accurately determine the phase of inhibition and withdrawal of the sheath from a place with aligned bottom. In addition, the presence of brake panels around the perimeter leads to disruption of the structure of the natural occurrence of soil, loosening the bottom. This, in turn, leads to non-uniform sediment platform and its low bearing capacity. Moreover, in str is both not provided for stabilizing the vertical position of the shell, which leads to insufficient reliability of the stable position on the ground. In addition, the nearest analogue, as above, install the shell is accompanied by a significant effort sadasivuni in the soil, and the attachment of the membrane to the bottom only piles limits of its carrying capacity.

The present invention solves the problem of simplifying the way, improve the reliability of saving vertical position of support, stability, support on the ground at any combination of adverse external disturbing factors with simultaneous increase of the bearing capacity, terms of construction and reduced cost of construction, in particular, the supports of the bridge on the water hazard.

To solve the problem in the proposed method of construction relying on water hazard, including monitoring water hazards at the place of installation support, including the study of properties of water, check the water level during the year, the definition of the bottom topography, the study of bottom soil, the influence of external disturbing factors and on the basis of this calculation the weight and dimensions of the shell Foundation support, manufacturing hollow shell with compartments, transport to place of installation, the boot shell to dive into the water and landing on the bottom, fixing piles, align bottom, according to the invention when loaded and landing the imp is alter the vertical the provisions of the membrane by controlling the current vertical position of each of the compartments and in case of deviation from the vertical optionally fill in the appropriate compartments to recovery the vertical position of the shell, the alignment of the bottom is performed by injection under the bottom of the vertically located sheath of synthetic materials, when planting shell fix built into the bottom of the blades, number of blades, their frontal resistance and side friction of the soil is determined based on the following conditions steady shell on the ground:

n ≤ F/(αqc+βfs),

where n is the number of blades;

F is the calculated weight of the shell;

qc- drag knife;

fs- side friction of the knife on the ground;

α, β - coefficients depending on the soil type,

while piles are passed through the compartments filled shell, and the top face of the submerged membranes have a higher maximum possible wave height on water hazard.

In addition, according to the invention in the particular case of the method as a synthetic material for alignment of the bottom can use concrete layers, interbedded with layers of gravel.

In addition, around the underwater part of the filled shell can build a stone filling.

The technical result of the proposed method lies in the ability to provide fast, reliable and minimal work organization setup channel bridge piers in the difficult conditions of the Arctic basin with raised is Oh reliability stable position while security and increase operating life.

The proposed method can be used as follows.

The shell on the proposed method is a reinforced concrete structure, divided into compartments, covered with a bottom and having a round, oval cross-section or cross-section of a polygon.

The method begins with monitoring water barriers, which are conducting a study of water parameters, including the definition and recording of water level during the year, the study of bottom soil. Study the parameters of the external disturbing factors, such as the force acting on the shell side of the wave in the disturbances and storms over the water hazard, study impact strong wind. To do this, hold the meteorological, hydrological and geological studies, study the topography and structure of bottom soil water barrier in the place of installation support, using known materials.

On the basis of the monitoring computer calculation of the parameters of the hollow shell, its weight, shape and dimensions. The calculation is conducted on the basis of the buoyancy of the collected construction, after construction, it was possible to tow it in the intended place of installation and filling bays, lowered directly to the bottom of the water obstacles with a minimum amount of work away from the shore, which is especially important for offshore areas to the s of the sea.

Further executes the computer calculation of immersion of the membrane at the bottom of water hazards and the calculation of the stabilization parameters vertical position when loading and landing. Based on the results of monitoring on the basis of conditions of stability of the shell on the ground and prevent horizontal movement of the shell calculate the parameters of the knife embedded in her bottom. Modeling dive and landing with stabilization of the vertical position of the shell will take into account all adverse external disturbance. This gives you the opportunity to clarify the obtained design parameters.

Based on these calculations, the shell is made in dry dock or on the outdoor construction site. Choice of steel or concrete for the manufacture of construction depends on economic factors. Transport to place of installation, perform the tug boats on the water.

Upon arrival at the place to make the loading compartments of the shell and its immersion. During the loading and landing are stabilizing the vertical position of the membrane by controlling the current provisions of each of the compartments of the shell and, in case of rejection of the compartment from the vertical position, controlled by additional filling in the corresponding compartment is proportional to the deviation to restore the vertical position of the shell. Alignment position on the shell is controlled by the signal level sensors, which are mounted on each compartment. This will improve the reliability of the stable positions of the shell.

Once loaded, the shell touches the bottom knives, perform further loading compartments breed and artificial material mode push the knife into the ground. Calculation of parameters of knives can be made when designing based on the results of monitoring, based on the following conditions steady shell on the ground

n ≤ F/(αqc+βfs),

where n is the number of blades;

F is the calculated weight of the shell;

qc- drag knife;

fs- side friction of the knife on the ground;

α, β - coefficients depending on the soil type, its characteristics.

Align the bottom of water hazards carry out simultaneously with immersion into the soil by injection under the bottom of the vertically located sheath of synthetic material. This will improve the reliability of the stable position on the ground and to reduce the time of construction support. As a synthetic material for alignment of the bottom use concrete layers, interbedded with layers of gravel. This can further increase the stability of the shell on the ground.

After this, the membrane is fixed by piles. While piles are passed through the compartments filled shell.

Fiksirovany the shell simultaneously with knives and piles will increase the reliability of the stable positions of the bearings during operation taking into account the effect of any adverse external factors, such as static effects: own weight all items loaded shell, the weight of technological and other equipment of the bridge, as well as dynamic effects of moving on the bridge of interest, the impact of strong wind and sea disturbance.

When this calculated height of the shell assumes its installation on the bottom and the location of the top edge above the maximum wave height during the storm water hazards that will allow to extend the possibilities of support in the operation of the bridge.

To improve the seismic stability of the supports of a bridge span bridge underwater part of each support may be surrounded by a stone dumping on all or part of the water depth.

Example

A method for the construction of the bridge across the Bering Strait, the length of which is 52 km

Monitoring was conducted water hazards at the place of installation support, which studies properties of water, including identified and registered that the maximum water depth in areas of erecting the pillars of the bridge was changed during the year within 20-25 m Studied the topography and structure of bottom soil water barrier in the areas of construction of the bridge.

According to preliminary data on climatic, hydrological, geological and seismological parameters conditions of the area of the bridge solved the issue of vozmozhnosti effective implementation of the construction project of the bridge, including about the possibility of erecting the most part supports the proposed method. These data are shown in the article Silina HP, Kosarev ALEXANDER, Fridkin V.M. “may be unique bridges?” anniversary collection “works of the Department “Bridges” MGEUPS (MIIT), Moscow, Izd. MGRPS, 1998, S. 251, 187-194.

On the basis of monitoring data found that the Foundation of the bridge bearing the desired hollow shell, which can be made in the form of a circular (or oval) design of reinforced concrete with a diameter of 18 to 30 m (with a diameter of 27 m its weight 24000 kN). Involves the separation membrane into 12 compartments. The calculated height of the shell exceeds the maximum possible wave height, including the height of the waves on the water hazard at the storm that will ensure its safe operation in the climatic conditions of the waters of the Bering Strait.

Discusses the production of a hollow shell in dry dock mode with favorable natural conditions, followed by sea transport in the alignment of the bridge.

On the basis of the obtained data was also estimated models in the form of a shell attached to the bottom of the knives. Refined parameters of the shell and knives for a particular soil. According to the results of the calculation of derived parameters knives, based on the following conditions are stable position of the shell on which runte:

n≤F/(αqc+βfs),

where n is the number of blades;

F is the calculated weight of the shell;

qc- drag knife;

fs- side friction of the knife on the ground;

α, β- coefficients depending on the soil type, its characteristics.

Presumably for steady support with an estimated weight of hollow shell 24000 kN, with a diameter of 27 m and a height of 25 m need 12 embedded in the bottom of the knives with frontal resistance 320 kN and lateral friction of one of the knife on the ground, equal to 150 kN, when the coefficients α=1,2 and β=1,3 (for bottom soil in the form of Sands and loams).

When checking dive modes were considered possible for the Bering Strait environmental conditions. Take into account that when you install shell wave height can be 0.6-0.8 m and wind speed to 10 m/s Were taken into account other monitoring data and previously in empirical data, the actual static and dynamic disturbance on the shell. It is established that the mode of immersion of the membrane must be made with regard to uniform loading compartments of the shell. Checked immersive mode in case of deviations of the shell from the vertical position, and picked up the necessary program download. It is revealed that a necessary condition is to control the vertical position of the compartments, which can be implemented with additional the second loading of the compartments, alignment of the shell and its installation in a vertical position.

It is established that the use of knives, the estimated parameters are given above, will give the opportunity to prevent horizontal movement of the casing during installation, improve reliability sustainability of the shell on the ground during long-term exploitation, regardless of any external influences on the shell.

Checked the alignment mode of the bottom. This mode is supposed to perform when installing by injection under the bottom of the vertically located sheath of synthetic material, for example concrete layers, interbedded with layers of gravel. This will increase the strength of the erected support of the Foundation of the proposed bridge and to increase its bearing capacity.

The proposed shell optional locking 6 piles with a diameter up to 2000 mm and a length of 60 m, which should pass through the filled compartments of the shell. According to this calculation will give an opportunity to further improve the reliability of the stable position of support on the ground to ensure its long-term operation.

For the construction of the bridge across the Bering Strait spans 500-550 m around the underwater part of each filled shell proposed to make a stone dumping on all or part of the water depth. This can be achieved by increasing the seismic supports.

1. The method of construction of relying on water hazard, including monitoring water hazards at the place of installation support, including the study of properties of water, check the water level during the year, the definition of the bottom topography, the study of bottom soil, the influence of external disturbing factors and on the basis of this calculation the weight and dimensions of the shell Foundation support, manufacturing hollow shell with compartments, transport to place of installation, the boot shell to dive into the water and landing on the bottom, fixing piles, align bottom, characterized in that the loading and landing perform the vertical position of the membrane by controlling the current vertical the position of each of the compartments and in case of deviation from the vertical optionally fill in the appropriate compartments to restore the vertical position of the shell, the alignment of the bottom is performed by injection under the bottom of the vertically located sheath of synthetic materials, when planting shell fix built into the bottom of the blades, number of blades, their frontal resistance and b is the lateral friction of the soil is determined, based on the following conditions steady shell on the ground:

n ≤ F/(αqc+βfs),

where n is the number of blades;

F is the calculated weight of the shell;

qc- drag knife;

fs- side friction of the knife on the ground;

α, β - coefficients depending on the soil type,

while piles are passed through the compartments filled shell, and the top face of the submerged membranes have a higher maximum possible wave height on water hazard.

2. The method according to p. 1, characterized in that when the alignment of the bottom as an artificial material used concrete layers, interbedded with layers of gravel.

3. The method according to p. 1 or 2, characterized in that around the underwater part of the submerged membrane constructing stone filling.



 

Same patents:

The invention relates to the development of underwater mineral deposits, namely for the construction of technological systems, which provide carrying out maintenance work on the shelf of the open sea

The invention relates to the field of drilling offshore, in particular to methods of installation drilling monoatomic reason, stabilize them on the bottom and dismantling

The invention relates to the development of underwater mineral deposits, mainly of liquid and gas, the construction of technological systems that provide on the continental shelf the high seas with the ability against ice, and seismic loads

Drilling platform // 2231594
The invention relates to a device for carrying out engineering-geological surveys on the shelf and can be used for drilling operations in shallow water, open water areas

The invention relates to the development of underwater mineral deposits, mainly of liquid and gas, the construction of technological systems, which provide mainly operational, works on the deep shelf seas

The invention relates to the development of underwater mineral deposits, mainly of liquid and gas, the construction of technological systems that provide on the continental shelf the high seas

The invention relates to the field of hydraulic engineering construction and can be used during the construction of long-term hydraulic structures during the development and construction of shallow sites, for example in the extraction and deep processing of hydrocarbon raw materials, during the construction of the hatchery industrial complexes, in particular, during the construction of artificial Islands

The invention relates to the field of construction of offshore marine structures designed for drilling and/or production of oil or gas in the deepwater areas of the ice period

The invention relates to hydraulic construction and is intended for development and offshore shelf

The invention relates to the development of underwater mineral deposits, construction of technological systems that provide on the continental shelf the high seas

FIELD: hydraulic engineering, particularly building bases and foundations, namely bridge piers, in water.

SUBSTANCE: method involves monitoring water obstacle in support building place, including investigating water parameters, recording water level in the course of year, determining floor shape, investigating floor ground, influence of outer disturbing forces and calculating weight and dimensions of support foundation case on the base of above parameters; producing hollow case with several cavities; moving case to installation place; submerging case in water; pacing thereof on floor; fixing case by piles and smoothing floor. Case submerging and placing operations are performed simultaneously with stabilizing vertical case position by performing control and filling of corresponding cavities. Bottom smoothing process is carried out by forcing artificial material, such as concrete layers with crushed stone interlayers, under case bottom. During case placing case is secured by blades built in case bottom and by piles inserted in cavities. Correspondence between case weight, number of blades, head resistance and side friction thereof for particular ground is determined to provide case stability on ground. Upper edge of submerged case is located above maximum possible water wave height. Rock fill is formed around underwater case part.

EFFECT: reduced time of support erection, increased reliability and stability, safety and service life, reduced labor inputs, possibility to erect supports in Arctic basin.

3 cl 1 ex

FIELD: stationary sea oil platforms.

SUBSTANCE: block has underwater support, made in form of two-level bench, formed by vertical beam cases and horizontal links, and also has support columns, connected to support. Horizontal links of bench are made in form of floating tanks, while links, placed along perimeter of lower level of bench, are separated by water-impenetrable walls on sections, provided with ballasting means. Method for mounting support block at the bottom of continental shelf includes transporting, ballasting of floating tanks and fixing support block at the bottom of water body. Support block is transported into wells drilling zone in planned position, sections of floating tanks are ballasted until lower level of support lowers into bottom of water body for 0.3-0.7 of its height, different and slants are evened and holding beams are inserted into cases of support with their following forcing into hard bottom portion and fixing in cases. Ballasting of sections of floating tanks and forcing of holding beams can be performed in pairs in diagonal planes relatively to center of lower level of support.

EFFECT: simplified assemblage, higher reliability.

2 cl, 12 dwg

FIELD: hydraulic engineering, particularly for forming temporary structures for enclosing closed in plane water area bottom part and space above the bottom part through the full water thickness.

SUBSTANCE: method of shallow tunnel construction involves forming structure enclosing closed in plane bottom part; removing water from the structure; performing works in dry structure and demounting above structure. Method of enclosing structure forming involves producing bottomless hydraulic enclosure with controlled floatability; transporting and moving thereof to tunnel path; immersing the enclosure in water up to reaching water area bottom by reducing floatability thereof and fixing enclosure with fastening means and anchor system; leveling upper enclosure part with horizon line and arranging cranage and platforms for building material storage on upper enclosure part; erecting cutoff walls inside space defined by enclosure; removing water from the enclosure; developing bottom ground by trench digging; constructing pile tunnel base; building foundation grill on pile tunnel base; locating composite or precast reinforced concrete tunnel sections on foundation grill; recovering initial floatability of the enclosure. Enclosure structure has movable fastening means formed as blades along vertical walls thereof.

EFFECT: increased tunnel reliability, reduced time of erection thereof.

4 cl, 4 dwg

FIELD: production of ice.

SUBSTANCE: method comprises producing a hollow near the ship's side, delivering air under the ice cover, the air volume does not exceeding the volume of the space defined by ice covering from the top, water from the bottom, and ice walls from the sides over the contour of the future hollow. The walls are frozen from top to bottom by means of direct nonseparable heat exchangers mounted in advance into the covering immediately behind the contour up to the bottom of the future hollow. The delivery stops and the bottom of the future hollow is frozen with the use of L-shaped nonseparable heat exchangers set into the covering simultaneously with the direct heat exchangers. As a result, a closed space is defined, which is stripped, and ice blocks are removed.

EFFECT: enhanced efficiency.

FIELD: hydraulic engineering, particularly underwater structures adapted for oil and gas well operation, preferably on shallow continental shelf having bottom covered with thick silt layer and in ice-covered period.

SUBSTANCE: platform comprises base, vertical pile holders connected with the base and positioning unit for drilling string and well-control equipment fixation. Base is formed as a structure with cavities filled with ballast. The structure is composed of hollow members and functionally divided into two areas. Positioning unit is arranged in the first area, another area including catching opening. Platform is additionally provided with removable mounting frame with production equipment installed on the frame. Arranged in lower frame part are inclined guiding means to provide access into catching opening during mounting frame connection with support platform base in underwater position.

EFFECT: reduced labor inputs for production equipment mounting and maintenance, increased reliability.

7 dwg

FIELD: offshore oil-field hydraulic structures, namely for building fixed platforms.

SUBSTANCE: support substructure comprises three-dimensional latticed structure having prismatic shape and composed of tubular members. The structure has vertical panels with posts, cross-pieces, struts and horizontal diaphragms connected one to another. Horizontal diaphragms have guiding nets for marine risers. The structure is secured to ground by main piles arranged in vertical posts and by foundation having additional piles, which is rigidly connected to tubular members of side edges of above structure. The structure is provided with ice-protection means formed as two truncated prisms of sheet steel and having beveled side ribs rigidly connected one to another by major bases. Marine risers are arranged inside prisms. Each prism of ice-protection means is rigidly connected with tubular members of corresponding diaphragms of three-dimensional latticed structure.

EFFECT: increased resistance to wave, seismic and ice loads, improved manufacturability and, as a result, reduced cost of permanent offshore structure building.

3 cl, 2 dwg

FIELD: offshore oil-field hydraulic structures, namely for building fixed platforms.

SUBSTANCE: method for forming support substructure by welding large blocks involves producing and serially connecting precast members to create flat units, namely panels and diaphragms; connecting flat units by tubular inserts and tubular links to create three-dimensional latticed structure. All operations are divided into four stages in accordance with technological order. The first stage includes forming tubular links and tubular inserts, pile sections and marine riser sections. The second stage includes assemblage of flat panels and diaphragms in horizontal position on corresponding mats. The third and the forth stages include simultaneous installation of flat panels and diaphragms and rigid connection thereof.

EFFECT: reduced labor inputs, time and cost for assembly work performing due to elimination of complicated tubular joints used as assembly units.

3 cl, 7 dwg

FIELD: ground hydraulic structure erection, particularly to decontaminate silt or bottom sediments in water bodies.

SUBSTANCE: method involves building protective dam along perimeter of silt and/or bottom sediment area to be protected; laying waterproofing layer along inner dam perimeter, wherein waterproofing layer height is 2 times as much as silt and/or bottom sediment layer; forming artificial ground massif of watertight ecologically friendly natural ground in water area inside the dam, wherein artificial ground massif thickness is equal to at least three thicknesses of silt and/or bottom sediment layer; forming above-water relief area having 2.5 m height over water surface; forming surface flow discharge system and planting greenery in artificial ground massif.

EFFECT: increased reliability, reduced contamination concentration, prevention of hazardous substances ingress in ambient space and improved ecological safety.

2 cl, 1 dwg

FIELD: marine hydraulic structures, particularly fixed marine oil and gas production platforms.

SUBSTANCE: method for pile installation with the use of handling machine involves driving each pile in conical hole made in guiding means fixedly secured to marine platform base; installing pile and guiding means in coaxial position by guiding device having body installed on guiding members of the base so that the body may be displaced and fixed in predetermined position; lowering pile to working position; installing guiding device above water level on guiding members of platform base in predetermined position, wherein the guiding device is made as cylindrical body part and cylindrical part of guiding member secured one to another and having crossing axes so that cylindrical part of guiding means and cylindrical part of guiding member of guiding device are brought into coaxial state by corresponding linear and angular guiding member displacement; securing guiding device body with guiding members of platform base.

EFFECT: extended technological capabilities and simplified method of pile installation in working position.

5 cl, 4 dwg

FIELD: marine oil production hydraulic structure building, particularly marine platform assemblage.

SUBSTANCE: method involves forming assembly units, namely support unit, load-bearing deck and block units of upper structure, at subassembly site; docking floating vehicle to subassembly site; serially installing assembling units on stockpile carts; moving assembly units from subassembly site to floating vehicle with the use of above stockpile carts; transporting thereof to assemblage site and performing successive mounting thereof with the use of crane-and-mounting ships. The successive mounting operation involves installing support unit on previously prepared ground; installing piles in corresponding bell-shaped guiders of the support unit; driving the piles and cementing thereof to create pile foundation; arranging load-bearing deck on struts and installation guiding bars having different heights and previously formed on support unit, wherein the load-bearing deck has seats for struts and bars receiving and connection thereof is carried out by successive alignment of above bars and seats.

EFFECT: increased efficiency of building equipment and floating vehicle usage; reduced building time, decreased number of operations to be performed at sea, reduced labor inputs and decreased costs of marine fixed platform building.

7 cl, 17 dwg

Up!