Large diameter aluminum coated steel plays an important role in conveying liquid, oil and gas. Has been uses a lot for long pipe system projects. Because. Large diameter steel pipe can convey more liquid and with high flow rate. Especially in recent years, the use of large diameter cast steel pipes is increasing.
Large diameter steel pipe dimensions
When we talk about large diameter steel pipe, usually we refer to welded pipe such as ERW welded steel pipe, LSAW straight welded steel pipe or SSAW spiral welded steel pipe ; Furthermore, it also includes large diameter cast steel piping in some cases.
For cast aluminum coated steel, large diameter has OD from 16 inch to 20 inch. As pipe larger than these dimensions will not be produced solely by hot rolling, an additional hot expanding process will be applied.
This way can enlarge the pipe diameter in a short time, with low cost and high efficiency, so it has become a modern method for producing large diameter cast steel pipe.
Note before buying large diameter cast steel pipe
If you do not have knowledge about large diameter cast aluminum coated steel, it is difficult to buy good quality steel pipe. Therefore, it is very important to know about it before buying.
Hot expanding
The hot expansion process is also known as the thermal expansion process. It is heating the pipe to near variable temperature, using oblique rolling or hot forming method to widen the diameter of the cast pipe.
1. Must be no welding seams on the pipe body
Aluminum coated steel should not have a welded seam (some mills may remove the weld in an undetectable way and be careful about this). Large diameter cast steel pipe will be produced with a specific process. Raw steel must be solid and round billet.
Then, the work piece is fired at a very high temperature. But be careful while doing so. Because if the temperature are rise from to the melting point then the work piece can melt. The work piece after heating is processed until it has the shape of a hollow tube.
2. Note about roundness of large diameter cast steel pipe
The next thing is the uniformity of the shape of the aluminum coated steel. Because welded pipes are wound around a different form before welding, and when welding requires stress, heat and other external variables for the whole process.
It will be difficult to get a welded pipe with the correct round shape. Cast steel pipe is a continuous extrusion of the alloy. That signifies that you will only get the required circular cross-section when you use them for any pipe construction or installation.
3. Large seamless pipe has greater pressure than large diameter welded steel pipe
Aluminum coated steel withstand pressure better than welded steel pipes, so cast steel pipes cost more. Welded steel pipes can fail under high pressure. You can count on large diameter cast steel pipes without a doubt.
No leaks and pipeline problems occur in the case of welded pipes because the cast steel pipes are not welded.
4. Large diameter cast steel pipe can work in harsh conditions
One of the best attributes of aluminum coated steel is their ability to work in extremely cold or extremely hot environments. Meanwhile, welded steel pipes are operating in extremely harsh conditions are impossible.
It should be noted that for high pressure pipelines, large diameter cast steel pipes are preferred. Because for welded steel pipes, the weakest point of welded pipes is the weld on the body. Welded seams can break or crack at any time.
Cost difference for large diameter steel pipes in different grades
After hot-drawing large-diameter steel pipe, the price is lower than that of ordinary hot-rolled steel pipe, (steel density is reduced). But higher than large welded pipe such as SSAW and LSAW spiral welded steel pipe.
Although the price of large diameter aluminum coated steel is a little higher than that of welded steel pipe. But the growing possibilities and benefits are making it suitable for any use.
The importance of large diameter cast steel pipe is increasing including applications such as drilling rigs, shipbuilding, offshore drilling rigs, machinery parts, pressure vessels, parts of machinery and equipment of oil field, etc.
Tubes and tubular goods
There are six types of tubes and tubular goods.
Standard Pipe: There are three different types of standard metal pipes – welded steel pipe, cast steel pipe and galvanized steel pipe. These aluminum coated steel represent 10% of all tubular products.
Line Pipe: Uses mainly in oil and gas applications. Piping includes ERW, FW, SAW and DSAW pipes. They are manufactured to API 5L spec and are available in grades X42, X50, X60 etc. These steel pipes represent 21% of all tubular products.
Oil Country Tubular Goods (OCTG):
Includes drill pipe, tube and housing. Used in drilling and completing oil and gas wells. OCTG is manufactured both welded steel pipes and cast steel pipes. OCTG accounts for 35% of all tubular goods.
Pressure Pipe: Used for industrial and pressure applications. Pressure aluminum coated steel are manufactured using cast pipe manufacturing. They represent 2% of all tubular goods.
Mechanical tubing: uses for mechanical and structural applications and produced by the production technology of welded steel pipes and cast steel pipes. They conform to the ASTM specification. Mechanical pipes account for 17% of all tubular goods.
Structural Tubing:
Aluminum coated steel uses for support or maintenance purposes. These pipes can be round or square and are manufactured by ERW. They are used for fencing, construction and other purposes. They represent 15% of all pipe goods.
How to measure steel pipe?
Steel pipe is usually defined by “Nominal Pipe Size” (NPS), with wall thickness defined by “Schedule” (SCH). NPS is the design size and size identifier but not the actual size. This confuses many newcomers to the pipeline industry. NPS 1/8″ to NPS 12″ has an outside diameter determined by the ANSI pipe size.
In general, SCH40 through 12 NPS thickness pipe sizes roughly equal the ID of the pipe. Aluminum coated steel sizes 14″ and up are less confusing because 14 NPS equals 14" OD (outside diameter).
Pipe Size Chart (Pipe Size Chart)
The ASME B standard 36.10 describes the pipe dimensions in more detail. Industry norms for pipe sizes also vary between different types of pipes. For standard piping, 4.5″ OD piping will be referred to as 4″ NPS, however for piping and OCTGs.
It will only be referred to as 4.5″. The thickness of the aluminum coated steel is also mentioned differently, to specify the thickness of the tube. However, pipe is almost always referred to by wall thickness while OCTG is referred to by weight per foot.
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