The Seamless steel pipe for ship building usage are mainly used for Level 1& Level 2 pressure pipe in piping system, boiler and super-heated unit of shipbuilding.
Shipbuilding involves the assembly of various structural elements, and tubes play a crucial role in this process.
Seamless tubes are approved by classification societies such as CCS, LR, GL, DNV, and ABS .
Shipbuilding tubes find applications in various systems and components, including:
Seamless steel tubes for ship-building refer to the ship building steel pipes which are designed and manufactured for boilers,super heaters and pressure systems of ship. The ship building steel pipes can be expansively used in various kinds of ships such as CCS,DNV,LR,GL,ABS,BV,RINA,NK as well as China national standards.
Two systems of ship and marine engineering demand roughly in three types of steel pipe:
Different ship and marine engineering, both conventional systems have a dedicated system.
Ship service life of 20 years. Many of the conventional system, bilge water, ballast, dewater sewage, air, measurement, injection, domestic water, fire, cargo oil stripping, breathable, inert gas, heating, washing, foam extinguishing sprinkler, vapor, liquid level telemetry, valve remote control systems, special ships also include a dedicated system for the transportation of liquefied petroleum gas (LPG), liquefied natural gas (LNG). Marine engineering service life of up to 30 years, or even longer. Marine engineering in addition to the conventional system, special drilling equipment systems, crude oil / LPG / LNG processing workflow system, special mooring system, flare system, and so on. It has been statistics, ship pipe annual consumption of 450 million tons, about 440,000, its standards are GB, YB, CB, 70% of the steel pipe connection. Only a 30-ton very large crude oil pipes for the amount of up to tens of kilometers, only steel pipe usage (including), there are about 1,500 tons, of course, the amount of 40,000 tons relative to the hull structure or limited. In addition, taking into account the same ship, to the construction of ships, as well as many other ships, so the cumulative dosage is also a lot of. And a 300,000 tons-class number of large FPSO pipe over 30,000, more than 90 km in length, which is the same tonnage level 2 to 3 times. Therefore, the shipbuilding industry has become a big user of steel pipe market.
Steel tube marine engineering applications, in addition to the above conventional system with a dedicated system, many constructed a large number of steel pipes, such as jacket, underwater steel piles, Casing, mooring bracket, helicopter platform, torch tower. Type of steel pipe, material specifications, with the same diameter, reducers, different wall thickness, as well as a large number of Y, K, T-managed nodes. Such as jacket, steel piles, wellhead impermeable sleeve, mostly large diameter steel pipe sizes, are generally made of rolled steel. Their material for E36-Z35, D36-Z35, E36, D36. Such steel pipe standards have not with YB, CB, and mainly is GB712-2000. The production of steel pipe structure steel pipe manufacturing practice SY/T10002-2000 developed by China’s Petroleum Industry Standards and Technology Commission (CPSC). Since China does not have the specialized enterprises, are usually the purchase of steel plate from construction units, self-molding process.
|Designed Pressure(Mpa)||Designed Temperature (℃)||Designed Pressure (Mpa)||Designed Temperature (℃)||Designed Pressure (Mpa)||Designed Temperature (℃)|
|Steam and Hot Oil||1.6||300||0.7-1.6||170-300||0.7||170|
When the designed pressure and temperature reach the ones in the above Class I, this steel pipe belongs to Class I pipe. If it meets the pressure and temperature of Class II, it is defined to be the Class II pipe.
Other media refer to air, water, lubricating oil and hydraulic oil.
Class III seamless steel tubes can be manufactured in accordance with the national standards approved by the ship inspection department.
1) As for the seamless steel pipe for boiler and super heater purpose, the working temperature of wall thickness does not exceed 450℃.
2) The dimension of marine seamless steel pipe should firstly select the general steel pipe size in the first group of GB/T7395-1998 table one. The outside diameter of steel tube should choose the standard outside diameter size in the first series of GB/T7395-1998. We can also produce pipes with other specifications not appear in the GB/T7395-1998 table one.
Special purpose steel special steel pipe used in the specific working environment and the working medium. Undersea pipeline is typical specialty steel pipe, the demand for larger, high strength, small tolerances, good corrosion resistance. Currently, the pipeline production is only in its infancy, because the welding materials, corrosion resistance or less Specifications (diameter and wall thickness), expensive, etc. China’s offshore crude oil need insulation transport. The past, using the double pipe insulation structure, safe and reliable. But as a protective pipe steel pipe is very economical, and offshore pipe laying ago, have to carry out internal and external pipe welding, greatly reducing the efficiency of the pipe laying, to cause installation costs increase exponentially. Into the 21st century, it has launched a concrete counterweight steel pipe.
Its structure is (from inside to outside):
anti-corrosion layer of steel, epoxy powder (FBE), polyurethane insulation, polyethylene (PE) jacket tube, reinforced concrete counterweight layer (the internal configuration of the steel mesh). This type of special steel, China has imported from abroad, such as the Bohai Penglai 19-3 oil field, a project using Malaysian BREDEROPRICE company products. China after research and testing, and in 2002 built in Tanggu, China’s first concrete with heavy steel pipe production line, has thousands of kilometers of pipelines for offshore oilfield products. It is reported that, using this steel per kilometer subsea pipeline to reduce the cost of 50 million to 100 million, and greatly reduce the cost of offshore oilfield development, so that a number of marginal oil fields to be cost-effective to develop.
Specifications of Marine Seamless Steel Pipe Table 1 Grade of Seamless Steel Pipe (Pressure Tubing)
|Society||Standard or usage||Steel grade||C||Si||Mn||P||S||Cr||Ni||Cu||Al||Mo||V||P+S|
|GLR||Non alloly||GL-R 410||≤0.21||≤0.35||≤1.4||≤0.025||≤0.02||-||-||-||≥0.020||-||-||-|
|DNV||for pressure ASTM A53/A53M||A53B||≤0.3||-||≤1.2||≤0.05||≤0.045||≤0.4||≤0.4||≤0.4||-||≤||≤||-|
|ABS||for pressure||Grade 3||≤0.3||-||≤1.2||≤0.05||≤0.045||≤0.4||≤0.4||≤0.4||-||≤0.15||≤0.08||-|
|NK||for pressure||grade 1 No3/ KSTPG 42||≤0.3||≤0.35||0.3~1.00||≤0.04||≤0.04||-||-||-||-||-||-||-|
residual elements:Cr≤0.25％, Mo≤0.10％, Ni≤0.30％, Cu≤0.30％aggregate≤0.70％
The production equipment consists of punching machine, automatic pipe rolling machine, coiling machine, sizing machine and reducing machine. The round tube is inserted into the hollow of the thick-walled tube, and the axes of the two rollers form an oblique angle with the rolling line. In recent years, the inclination angle has increased from 6° to 12° to 13° to 17°, increasing the speed of the punch. When producing structural seamless pipe with a diameter greater than 250mm, secondary perforation is used to reduce the thickness of the hollow billet wall. New technologies have also been developed to enhance the perforation process and improve the quality of the capillary.
The production equipment includes punching machine, continuous rolling mill, and tension reduction machine. The round billet is pierced into a hollow billet, then inserted into the mandrel, and continuously rolled by 7 to 9 two-roll mills. After rolling, the mandrel bar is taken out and reheated to reduce tension. In 2014, the annual output of 140mm continuous rolling mills is 0.4 to 600,000 tons, which is 2 to 4 times that of plug mills. The characteristics of this unit are suitable for the production of steel pipes with a diameter of 168mm or less. However, the equipment investment is large, the installed capacity is large, and the processing and manufacturing are complex.
Three-roll rolling production is mainly used to produce thick-walled seamless steel pipes with high dimensional accuracy. The wall thickness accuracy of the seamless steel pipe produced by this manufacturing process can reach plus or minus 5%, and the pipe accuracy is twice that of the seamless steel pipe produced by other methods. This manufacturing technique developed rapidly with the invention of the new three-high skew rolling mill in the 1960s. The new type of rolling mill is characterized by rapidly rotating the inlet rotary rack to change the expansion angle of the tail, thereby preventing the triangle from appearing at the tail, and expanding the ratio of the outer diameter to the wall thickness of the production varieties from 12 to 35, which can not only produce thin-walled seamless welded steel pipes , but also can improve production capacity.
The peeled round base is first perforated or expanded, then heated by induction heating or a salt bath, coated with lubricant, and loaded into the extruder. The metal is squeezed into the pipe through the circular gap between the mandrel and the tip of the pen. This manufacturing process is mainly used for the production of superalloy tubes, specialty tubes, composite tubes and non-ferrous metal tubes. It has a wide range of production but low volumes. The production of extruded tubes has also grown in recent years due to improvements in die materials, lubricants and extrusion speeds.
This manufacturing process is used to produce small-diameter precision-shaped thin-walled low-carbon steel pipes. It is characterized by the use of multi-stage cycle manufacturing technology. In the 1960s, it began to develop in the direction of high speed, multi-line, long stroke and long tube blank. In addition, small roller mills have also been developed, mainly for the production of precision tubes with a thickness of less than 1mm. The cold rolling equipment is complex, the tool processing is difficult, and the specification conversion is not flexible. And usually a combined process of cold rolling and cold drawing is used, that is, cold rolling is used to reduce the wall thickness to obtain larger deformation, and cold drawing technology is used to obtain various specifications.
Before cutting pipe and tubing
No matter the material, measure the diameter of the pipe or tube to be cut to ensure that you use the right-size tube cutter for the job. When determining how to make a straight cut, use a tape measure and a pencil or other writing instrument to mark on the surface where you want to cut. If possible, mark around the circumference of a pipe, especially when cutting with a handsaw. Ensure that a cut is as straight as possible by securing the pipe with a vise, clamp, miter box or even duct tape to keep the length from shifting out of place while cutting.
After cutting pipe and tubing