EN 10216-2 TC2 16Mo3 Omega Seamless Tubes
 
Omega Seamless Tubes are heat exchanger tubes for nuclear power plants for nuclear power plants. The standard is EN 10216-2, the material is 16Mo3, the shape is shown in Figure 1, and the overall shape is π, Ω, etc.

EN 10216-2 16Mo3 Omega Seamless Tubes Quick Details
Manufacture:Seamless process
Wall thickness(WT): 3mm——12.7mm（According to customer's drawing requirements）.
Outer diameter (OD): 21 mm——114.3mm（According to customer's drawing requirements）.
Length: 6M or specified length as required.
Ends: Plain End, Beveled End, Treaded
 
Additional Info
Port of Shipment: Tianjin, China
Payment Terms:T / T, LC
Delivery: 30 days after payment,7 days for stock goods.
Surface: Tubes will be varnished (Outside only) to prevent rust.
Marking: Standard + Steel Grade + Size + Heat No + Lot No
Package: Bundles (hexagonal),Wooden Boxes,Crates (steel/wooden) or as required
 

MANUFACTURING PROCESS
(1)Steel making process
Steels shall be fully killed.
(2)Tube manufacture and delivery conditions
The tubes shall be manufactured by a seamless process.
The tubes shall be cold finished before heat treatment.
 
Heat Treatment EN 10216-2 16Mo3 Omega Seamless Tubes

TESTINGS
(1)Chemical analysis
(2)Tensile test(Tensile test at room temperature, Tensile test at elevated temperature)
(3)Flattening test
(4)Ring tensile test
(5)Drift expanding test
(6)Ring expanding test
(7)Impact test
(8)Leak tightness test(Hydrostatic test,  Electromagnetic test)
(9)Dimensional inspection
(10) Visual examination
(11) Non-destructive testing
 
 
MARKING
Marking to be applied
The marking shall be indelibly marked on each tube at least at one end. For tubes with outside diameter D ≤ 51 mm the marking on tubes may be replaced by the marking on a label attached to the bundle or box.



Brief summary of Omega Seamless Tubes processing technology:
1. Pre-processing of blanks
Use an intermediate frequency induction heater, and at the same time, it is equipped with an automatic temperature control device and an automatic discharge and delivery device. The heating temperature is controlled at 1160~1180℃, and the insulation time is 2~3 minutes.
 
2. Manufacturing of hot extrusion molds
The hot extrusion mold includes a mold cavity sleeve with an ω-shaped cavity, and a hot extrusion core rod is fixed in the middle of the mold cavity sleeve, and the mold cavity sleeve and the hot extrusion core rod form a mold cavity of the omega seamless steel pipe; an extrusion guide hole is directly above the center line of the mold cavity of the omega seamless steel pipe, and an extrusion guide 1 is provided inwardly at the edge of the mold cavity sleeve, and the introduction angle α is 30°.

3. Preparation of blank before extrusion.
15crmog of high-quality alloy structural steel is selected, the blank diameter is ≥182mm, and must be processed by an outer circular car to a diameter of 180mm, with a smooth appearance and no defects such as scale, slag, and pores. The holes are drilled in the center of the blank, and the diameter of the holes is 35mm.
 
4. Lubricate the surface of the blank and then heat extrude.
The glass powder is used, the blank is automatically rolled, and the core rod is lubricated with a mixture of oxidized paraffin and lime at a mass ratio of 1:3, and evenly applied, and then hot extrusion is performed to obtain an omega steel tube.
 
5. Check and grind the surface of the blank tube.
In order to facilitate the cold drawing process, straightness shaping must be performed, straightness ≤1mm/m.
 
6. Stress removal annealing.
The blank pipe must undergo hammer head, tube shrinkage, and drilling process, and then undergo stress annealing, heating and insulation temperature t=700~720℃, insulation time shall not be less than 2h, and slowly cool with the furnace to ensure sufficient mechanical properties, hrb≤85, and sufficient cold deformation performance.
 
7. Pickling.
The blank tube is subjected to the scaling process of removing the scale of the inner and outer surfaces of the blank tube, and is placed in a dilute sulfuric acid solution with a mass concentration of 20%. The content of ferrous ions is not higher than 80g/l, and the temperature is within the range of 40~50℃. After 40 minutes, check it every 5 minutes. The cylinder is determined according to the surface scale shedding and finish. Rinse it with clean water. After rinsing it clean, place it in a clean water tank for 5 minutes. After soaking in a phosphating cylinder, the temperature of the phosphating cylinder is controlled between 70~75℃, and appropriate free acid is dripped in. The blank tube reacts in the solution for 25 minutes. A layer of dense znhpo3 precipitation with a thickness of 0.15mm~0.2mm is formed on the surface of the steel tube, which is used as the basic carrier of soap lubricant to play a lubricating role, protect the steel tube and improve the life of the mold.
 
8. Design of cold-drawn mold.
From the blank tube to the finished product size, it is designed to be multiple cold drawing passes. Since this special-shaped steel pipe is unequal, the introduction angle and inner mold size of each set of mold determine the changes in the shape size and wall thickness. The best cold drawing deformation coefficient is controlled between δ=1.5-h.
 
9. Selection of cold drawing machine.
A 120t speed control and pulling machine is selected, with a linear pulling speed of ≤2.5m/min, which is conducive to the full deformation of the omega seamless tube in the horizontal and vertical directions. The steel tube will not be damaged during the deformation process and the mold will not be thermally broken.
 
10. Multiple production cycles.
Entering the second production cycle, stress annealing, reducing the surface hardness of the steel tube, and improving plasticity. After pickling and phosphating lubrication of the steel tube, the finished product is cold-drawn to the finished product size after multiple production cycles.
 
11. Normalization treatment.
The omega seamless tube is normalized in a continuous roller bottom normalizing furnace. The normalizing temperature is 920~940℃ and the insulation time is 6~8 minutes. The valve size of the air-fired triangle valve is adjusted through the computer program, and the temperature and speed are adjusted to control the heating and insulation time. After the oven is released, it is cooled by strong air to ensure that the cooling rate is ≤200℃/sec. After sampling and testing, the grain size must be greater than level 6, and the mechanical properties such as tensile yield, flaring, and flattening are required. After passing the inspection, enter the next process.
 
12. Straightening.
The straightness and twisting of the steel tubes are straightened on a 300t hydraulic straightening machine to ensure that the straightness is ≤0.5mm/m and the twisting is ≤0.5mm/m; then the head and tail are cut, and then the finished product size, surface eddy current flaw detection and water pressure bearing detection are carried out.
 
13. All inspections are completed, qualified, packaged and put into the warehouse.



Picture of EN 10216-2 TC2 16Mo3 Omega Seamless Tubes