Stainless steel - a material particularly resistant to corrosion. Pipes made of it, can last for decades, even when exposed to an aggressive environment. Besides, products of stainless steel an attractive appearance. But to take full advantage of these benefits, you need to know all kinds of stainless steel pipes, their main dimensions and characteristics.
Properties of pipes made of stainless steel
The basic requirement for all steel grades in this category is a high chromium content in it. Regulated minimum content of the metal in the 12%. It creates on the surface of the product a particular film material protecting against external influences. It also contributes to the fact that the medium is pumped through the pipeline, and is not subject to change. This is particularly important for mains drinking water and food.
Cheap steel grades are limited only by the presence of chromium. They are characterized by ductility and resistance to deformation. To impart specific strength and corrosion resistance of the added molybdenum, nickel, titanium and other alloying additives.
In addition to chromium, it is regulated in the steel and the presence of sulfur and its compounds. It is believed that their maximum content must not exceed 0.02%.
The surface of stainless steel profiles amenable to polishing on special machines to a mirror. This not only lends an attractive appearance, but also provides additional protection against corrosion sources. Despite the increased price of polished, they are in demand as a design element.
Classification pipe rolling of stainless metal
The shape of the internal section of distinction:
- round
- elliptical,
- square and rectangular.
Considered as a separate class of corrugated options. They are characterized by a special ductility and ability to repeated cycles of compression and tension in both the longitudinal and transverse directions.
With different manufacturing methods of stainless steel may be different by the presence or absence of a seam in the finished product. pipe distinguished by this parameter:
- seamless,
- welded,
- spiral.
seamless technology
Production of continuous profiles is carried out without using welding, by rolling on special blanks. Such products have high tensile strength and can withstand heavy loads. Therefore, they are used on high-pressure pipelines or where need special reliability.
Method of manufacturing a seam without the formation leads to higher outputs. Use these products in the domestic sphere is unprofitable.
Production and various seamless stainless steel pipe is regulated by GOST 9940-81 and 9941-81.
welded welding
Blanks for this technology are steel sheets. Their special presses to bend into a circle of the desired diameter. The joint between the edges of the sheets are welded together to form a seam, walking over the entire length.
welding methods may be different, but the core is electric welding.
Parameters and requirements in the manufacture longitudinally welded stainless steel pipes presented in GOST 11068-81.
spiral technology
Manufacture is also based on welding curved steel sheet. But docking edges is not a straight line but a spiral, covering the whole length.
Such a seam is thought to be more durable because it eliminates the formation of longitudinal cracks. But its total length is greater than the longitudinal welded version. It also leads to an increase in the cost of welding.
Production spiral pipe regulated GOST 8696-74.
heating degree
By thermal treatment methods during manufacture of stainless steel products are distinguished:
- Cold-method. Manufactured without heating. a heat treatment of the finished product, if necessary.
- Teplodeformirovany. When forming the profile blank undergoes a slight heating.
- Hot. The tube is formed of steel, is heated to red-hot state.
The cold method is more complicated, but it gives the finished products more durable. Therefore, the cold-tubes are produced with a smaller wall thickness than that produced by hot technologies.
Differences standards governing the production of seamless pipes, lies precisely in the temperature regime during fabrication. GOST 9940-81 for the method of hot-and GOST 9941-81 - for cold and teplodeformirovannogo production.
Wall thickness
Except for the values of this parameter exists showing the ratio of the diameter to the wall thickness. The higher it is, the more thin-walled product is considered. This option is indicated by the SDR.
There are the following categories:
- particularly thin-walled - SDR> 40;
- Thin - SDR = 13 - 40;
- Thick - SDR = 6 - 13;
- very thick - SDR <6.
Appearance
Depending on the additional surface treatment after manufacture are three types of pipes:
- Matt. Removed only bumps and burrs.
- Ground. The material undergoes only an initial polishing using fine abrasives.
- Polished (mirror). Lapping the surface after polishing to a final gloss. Distinguish methods of mechanical, chemical and electrolytic polishing.
Applications stainless tubes
The corrosion resistance of such products causes their application in the pumping of corrosive environments and in particularly critical areas of conventional pipelines. A lack of contact with the pumpable substance allows their use in the food industry.
Beautiful appearance of the polished surface is used in the design registration of residential and industrial premises.
You can create profiles of stainless steel street structures.
Determination of weight per meter
For larger parties the price of tubular products indicated by weight - a ton. It is more convenient, because the range of pipes is reduced. The price of one metal quality does not depend on the diameter and wall thickness. Only in the retail trade and for domestic purposes value is calculated based on the length in meters.
For recalculation of prices is necessary to know the weight of 1 meter of the pipe with the desired characteristics. The necessary data for the calculations:
- density of the material,
- diameter (as for rectangular cross sections - length and width)
- wall thickness.
For sanitary products often denoted diameter in inches. Compliance with something like this:
- 1/2 = 15 mm
- 3/4 = 20 mm
- 1 inch = 25 mm
Specific density of the most common steel grades are given in Table below:
It turns out that the difference between the minimum and maximum values of less than 3%. Therefore, the exact value of the density is only required in the calculations for large parties. Under ordinary calculations enough to substitute the average number of - 7850 kg / m3.
Weight per meter stainless circular pipe is calculated according to the formula R = S * h * T, where:
- S - surface area = 3,142 * the outer diameter of the pipe;
- h - thickness of the wall;
- T - Specific gravity.
Weight of 1 meter square and rectangular profiles determined even easier. The perimeter of the cross section (the sum of twice the width and height) is multiplied by the wall thickness and specific gravity.
Diameters and wall stainless steel pipes size table. Part 1.
| D, mm | The wall thickness, mm | ||||||||||
| 1,5 | 2 | 2,5 | 3 | 3,5 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
| Weight 1 meter, kg | |||||||||||
| 15 | 0,55 | 0,74 | 0,92 | 1,11 | |||||||
| 20 | 0,74 | 0,99 | 1,23 | 1,48 | 1,73 | 1,97 | |||||
| 25 | 1,23 | 1,54 | 1,85 | 2,16 | 2,47 | 3,08 | 3,70 | ||||
| 32 | 1,58 | 1,97 | 2,37 | 2,76 | 3,16 | 3,95 | 4,74 | ||||
| 38 | 1,87 | 2,34 | 2,81 | 3,28 | 3,75 | 4,69 | 5,62 | 6,56 | 7,50 | 8,44 | 9,37 |
| 45 | 2,77 | 3,33 | 3,88 | 4,44 | 5,55 | 6,66 | 7,77 | 8,88 | 9,99 | 11,10 | |
| 50 | 3,08 | 3,70 | 4,32 | 4,93 | 6,17 | 7,40 | 8,63 | 9,87 | 11,10 | 12,33 | |
| 57 | 4,22 | 4,92 | 5,62 | 7,03 | 8,44 | 9,84 | 11,25 | 12,65 | 14,06 | ||
| 60 | 4,44 | 5,18 | 5,92 | 7,40 | 8,88 | 10,36 | 11,84 | 13,32 | 14,80 | ||
| 68 | 5,03 | 5,87 | 6,71 | 8,39 | 10,06 | 11,74 | 13,42 | 15,09 | 16,77 | ||
| 76 | 5,62 | 6,56 | 7,50 | 9,37 | 11,25 | 13,12 | 15,00 | 16,87 | 18,75 | ||
| 83 | 6,14 | 7,17 | 8,19 | 10,24 | 12,28 | 14,33 | 16,38 | 18,42 | 20,47 | ||
| 89 | 6,59 | 7,68 | 8,78 | 10,98 | 13,17 | 15,37 | 17,56 | 19,76 | 21,95 |
Table. Part 2
| 6 | 7 | 8 | 9 | 10 | 11 | 12 | 14 | 16 | 18 | 20 | 22 | |
| 102 | 15,09 | 17,61 | 20,13 | 22,64 | 25,16 | 27,67 | 30,19 | 35,22 | 40,25 | 45,28 | ||
| 108 | 15,98 | 18,65 | 21,31 | 23,97 | 26,64 | 29,30 | 31,97 | 37,29 | 42,62 | 47,95 | ||
| 114 | 16,87 | 19,68 | 22,49 | 25,31 | 28,12 | 30,93 | 33,74 | 39,36 | 44,99 | 50,61 | 56,24 | 61,86 |
| 121 | 17,91 | 20,89 | 23,88 | 26,86 | 29,84 | 32,83 | 35,81 | 41,78 | 47,75 | 53,72 | 59,69 | 65,66 |
| 133 | 19,68 | 22,96 | 26,24 | 29,52 | 32,80 | 36,08 | 39,36 | 45,93 | 52,49 | 59,05 | 65,61 | 72,17 |
| 145 | 25,03 | 28,61 | 32,19 | 35,76 | 39,34 | 42,92 | 50,07 | 57,22 | 64,37 | 71,53 | 78,68 | |
| 159 | 31,37 | 35,30 | 39,22 | 43,14 | 47,06 | 54,90 | 62,75 | 70,59 | 78,43 | 86,28 | ||
| 168 | 33,15 | 37,29 | 41,44 | 45,58 | 49,72 | 58,01 | 66,30 | 74,59 | 82,87 | 91,16 | ||
| 180 | 39,96 | 44,40 | 48,84 | 53,28 | 62,16 | 71,03 | 79,91 | 88,79 | 97,67 | |||
| 219 | 54,02 | 59,42 | 64,82 | 75,62 | 86,43 | 97,23 | 108,03 | 118,83 | ||||
| 245 | 60,43 | 66,47 | 72,51 | 84,60 | 96,69 | 108,77 | 120,86 | 132,94 | ||||
| 273 | 67,33 | 74,07 | 80,80 | 94,27 | 107,74 | 121,20 | 134,67 | 148,14 | ||||
| 325 | 80,16 | 88,18 | 96,19 | 112,22 | 128,26 | 144,29 | 160,32 | 176,35 |
Price formation
The cost of stainless steel tube depends on many parameters: the steel grade, presence or absence of a seam, the production method. For domestic pipe of small diameter and affects the quality of the surface grinding.
Therefore it is necessary to consider only some of the differences for individual characteristics.
Rates per kilogram per (ton) is weakly dependent on specific diameters and wall tubes. The difference is typically less than 10 - 20%.
A much stronger effect on the cost of steel grade from which the pipe is made. Under otherwise identical characteristics price varies greatly. Thus, 12H13 steel is 180 - 200 $ / kg, and the tube is exactly the same, but the brand of 08Cr18Ni10Ti 330 - 350 $ / kg.
A comparison of the methods of production:
- Seamless tube made of steel 08Cr18Ni10Ti made by cold-method is about 330 $ / kg.
- Price on Hot-production will be 90 - 120 € / kg.
