First, an overview of dry gas seal Dry gas seal is a new type of non-contact seal developed from the foundation of gas dynamic pressure bearings in the late 1960s. The seal utilizes the principle of fluid dynamics to realize the non-contact operation of the sealing end surface by providing the dynamic pressure groove on the sealing end surface. After years of research, the British company John Crane took the lead in the late seventies to apply dry gas seals to gas delivery equipment on offshore platforms and achieved success. Dry gas seal was originally developed to solve the shaft seal problem of high-speed centrifugal compressors. Due to the non-contact operation of the seal, the friction material of the seal is basically not limited by the PV value and is particularly suitable as a shaft seal for high-speed and high-pressure equipment. With the increasingly mature dry gas sealing technology, its application is also more and more broad, at present, dry gas seal is gradually being applied in centrifugal pumps and blenders. In short, where the use of mechanical seals can be used dry gas seal occasions. Compared with the mechanical seal, dry gas seal has the following advantages: 1, long sealing life, stable and reliable operation; 2, the sealing power consumption is small, only about 5% of the contact mechanical seal; 3, compared with other non-contact seals, dry gas seal gas leakage is small; 4, can achieve zero escape of the medium, is an environmentally friendly seal; 5, seal auxiliary system is simple, reliable, use does not require maintenance; Second, the centrifugal pump with dry gas seal Centrifugal pump transport medium is liquid. According to different working conditions, the following types of seals can be used: 1, double-sided dry gas seal Double-sided dry gas seal can be used in the vast majority of centrifugal pump shaft seal, it has the following characteristics: 1) Replace the traditional "liquid blockage" principle with "gas blockage", that is, replace the pressured sealing liquid with pressurized sealing gas to ensure "zero escape" of the process medium; 2) The entire seal non-contact operation, the power consumption is only 5% of the traditional double-sided seal, the service life of more than 5 times longer than the traditional seal; 3) A simple auxiliary system to ensure that the process medium is not contaminated and the process medium does not leak to the atmosphere, completely get rid of the traditional dual-end mechanical seal on the oil system. Sealed gas using industrial nitrogen or industrial instrumentation, the pressure is higher than the medium 0.15-0.2MPa. Pump double-sided dry gas seal is inadequate is: 1) gas source that requires a certain pressure, gas pressure at least higher than the medium pressure 0.2MPa; 2) a trace of gas into the process. 2, series dry gas seal Pump series dry gas seal has the following characteristics: 1) dry gas seal and contact type mechanical seal used in tandem, the mechanical seal is the main seal, the dry gas seal is the secondary seal; 2) Dry gas seal and the main seal between the access to nitrogen, to ensure that the main seal has a certain back pressure, greatly extending the life of the main seal; 3) Leakage of the main seal of the process medium with sealing gas into the torch to ensure that the process medium does not leak to the atmosphere, is an environmentally friendly seal; 4) After the failure of the main seal, the dry gas seal plays a main role of sealing for a short period of time to prevent a large amount of leakage of the process medium to the atmosphere. 5) The life of this type of seal depends on the service life of the mechanical seal, which is usually about 2-3 years. 6) The seal is mainly used for volatile media occasions, such as liquid hydrocarbon media; less demanding on the seal gas pressure. The inadequacies of the seal are: 1) The seal is not yet a perfect dry gas seal, its overall performance is between the mechanical seal and dry gas seal. 2) The seal is suitable for volatile media occasions, the use of a narrow range
Flux Cored Wire:
Flux cored wire is also called powder-cored wire and tubular wire. It is divided into two categories: gas-entrained and non-gas-protected. The surface of the flux cored wire is the same as that of the Solid Wire and is made of materials such as low-carbon steel or low-alloy steel with good plasticity. The manufacturing method is to first roll the steel strip into a U-shaped section shape, then fill the U-shaped steel strip with solder powder prepared according to the dosage, roll it tightly with a rolling mill, and finally draw it into welding wires of different specifications.
Flux cored welding wire is a promising new welding material.
Category
AWS standard
Chemical compostition of deposited metal(wt%)
C
Mn
Si
Cr
Ni
Mo
P
S
V
Cu
Fe
Carbon Steel and High Tensile Strength Steel Flux Cored Wire
CO2 Gas Shield
E71T-1C
0.12
1.75
0.9
0.2
0.5
0.3
0.03
0.03
0.08
0.35
-
Self-shielded
E71T-11
0.04
1.3
0.22
0.02
0.01
0.01
-
-
-
-
-
E71T-GS
0.035
0.5
0.11
0.01
0.01
0.01
-
-
-
-
-
Stainless Steel Flux Cored Wire
CO2 Gas Shield
E308LT1-1
0.04
0.5-2.5
1
18.0-21.0
9.0-11.0
0.75
0.04
0.03
-
0.75
-
E309LT1-1
0.04
0.5-2.5
1
22.0-25.0
12.0-14.0
0.75
0.04
0.03
-
0.75
-
E309LMoT1-1
0.04
0.5-2.5
1
21.0-25.0
12.0-16.0
2.0-3.0
0.04
0.03
-
0.75
-
E316LT1-1
0.04
0.5-2.5
1
17.0-20.0
11.0-14.0
2.0-3.0
0.04
0.03
-
0.75
-
Low-temperature Steel Flux CoredWire
Heat-resistant Steel CO2 Gas Shield
E81T1-K2C
0.15
0.5-1.75
0.8
0.15
1.0-2.0
0.35
0.03
0.03
0.05
-
-
Low-temperature Steel
E81T1-Ni1C
0.12
1.5
0.8
0.15
0.8-1.1
0.35
0.03
0.03
0.05
-
-
E91T1-Ni2C
0.12
1.5
0.8
-
1.75-2.75
-
0.03
0.03
-
-
-
Weathering Steel CO2 Gas Shield
E81T1-W2C
0.12
0.5-1.3
0.35-0.8
0.45-0.7
0.4-0.8
-
0.03
0.03
-
0.3-0.75
-
High-strength Steel CO2 Gas Shield
E101T1-K3C
0.15
0.75-2.25
0.8
0.15
1.25-2.60
0.25-0.65
0.03
0.03
0.05
-
-
Nickel-based Alloy Flux Cored Wire
Mixed Gas Shield
ENiCrMo3T0-4
0.1
0.5
0.5
20-23
≥58
8.0-10.0
0.02
0.15
-
-
5
ENiCrMo4T0-4
0.02
1
0.5
14.5-16.5
Rem
15.0-17.0
0.03
0.03
-
-
4.0-7.0
ENiCrMo10T0-4
0.02
1
0.5
20.0-22.5
Rem
12.5-14.5
0.03
0.015
0.35
0.5
2.0-6.0
Flux cored wire is a very widely used welding process. It is widely used in the welding of low carbon steel, low alloy steel and other alloy materials in heavy manufacturing, construction, shipbuilding, offshore facilities and other industries.
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Flux Cored Wire,Flux Core Welding,Flux Core Welding Wire,Stainless Steel Flux Core Wire JIANGSU FUERMU WELDING CORPORATION , https://www.fuermuwelding.com
(1) Advantages:
1) For the welding of various steel materials, it is very convenient and easy to adjust the composition and proportion of the flux (the general-purpose flux-cored wire is often called the additive as the flux core, and the term flux only appears in the specific flux-cored wire). Requested weld chemistry can be supplied.
2) The process performance is good, and the welding seam is beautifully formed. Combined protection with gas slag is used to obtain good forming. The arc stabilizer is added to stabilize the arc and the droplet transfer is uniform.
3) Fast deposition speed and high production efficiency Under the same welding current, the flux-cored wire has high current density and fast melting speed. The deposition rate is about 85%-90%, and the productivity is about 3-5 times higher than that of electrode arc welding.
4) Larger welding current can be used for all-position welding.
(2) Disadvantages
1) The welding wire manufacturing process is complicated
2) When welding, wire feeding is more difficult than solid welding wire
3) The appearance of the welding wire is easy to rust, and the powder is easy to absorb moisture, so the requirements for the storage and management of the flux-cored welding wire are more stringent
CO2 Gas Shield
