D&H Sécheron Electrodes Pvt. Ltd. – Providing Sustainable Welding Solutions to the Nuclear Power Plants
Introduction
When electric bulbs were invented in 1800, coal was considered as the fuel source for generating electricity and in the 21st century, it is still a major source for us. Thermal power plants pollute the environment, which is why we humans are shifting towards nuclear as well as other forms of renewable energy sources. The lifestyle of mankind is now dependent on electricity whether he is a farmer or a manufacturer. It won’t be wrong to say that electricity is the fourth basic requirement for humans after food, clothing & shelter.
It is noticed that developed economies around the world are generally power sufficient & the nations who are developing or underdeveloped are usually in deficit. It showcases that when the demand for electricity meets its supply the chances of growth doubles.
Energy plays a vital role in the development of any nation and talking about India we see that it acts as a necessary element for fulfilling domestic needs, from running a steel plant to sugar mills.
India faces many challenges in power generation and the growing population makes it tough. The requirement of electricity is majorly fulfilled by thermal power plants, but due to global warming, we are trying to reduce the dependency on fossil fuels by taking the initiative of setting up nuclear power plants.
Since the beginning of the nuclear age in India, many indigenous nuclear reactors have been installed. India has seven working nuclear power plants which have a combined capacity of generating up to 7,480 MW of electricity, whereas five nuclear power plants are under construction & many are in the planning phase.
Why is Welding Essential for Nuclear Power Plants?
Nuclear power plants generate electricity in a similar way to any thermal power plant but the only difference is the type of fuel used. We are mentioning this because power plants produce heat that turns water into steam, which drives a turbine, connected to a generator and subsequently produce electricity. The process of power generation happens continuously which can create wear & tear issues and interrupt the process of electricity generation.
To avoid these scenarios repair & maintenance should be done on time with quality welding consumables. There are several applications & components in a nuclear power plant that require timely maintenance such as reactor, calandria, steam generators, heat exchangers, cooling towers, etc.
D&H Sécheron Manufactures Quality Welding Consumables for Nuclear Power Plants
D&H Sécheron Electrodes Pvt. Ltd. offers a wide range of welding consumables that are approved by the Nuclear Power Corporation of India Limited (NPCIL). Let’s discuss various equipment which are operational at nuclear power plants & how our exclusive welding consumable range can help in extending its service period.
The nuclear power plant consists of numerous buildings in which, the first is a containment tower where the nuclear reactor is housed, this building is generally made of 2 meters thick concrete walls in order to protect the radioactive leakages. Here the nuclear reactor is placed where the calandria is considered as its heart.
Calandria: It is a very crucial part of the nuclear reactor as it houses the nuclear fuel inside the calandria tube (Uranium: U-235). In the tube, a series of chain reactions of atom-splitting takes place, when the fission of radioactive fuel happens in a controlled manner it produces heat within the reactor.
The calandria tube also contains heavy water as moderator and coolant in the shell. Therefore special care must be taken while welding its various parts. The material of the calandria tube is zircaloy-2 and that of the shell is stainless steel (generally SS304L).
Welding consumables that can provide the best quality weld over calandria:
- Botox-B (https://www.dnhsecheron.com/products/conventional-welding-consumables/stainless-steel-electrodes/batox-b) an E308L-15 basic coated electrode that deposits low carbon 19Cr – 10Ni stainless steel weld metal & it has excellent resistance to intergranular corrosion.
- Rutox-D (https://www.dnhsecheron.com/products/conventional-welding-consumables/stainless-steel-electrodes/rutox-d ) is an E316L-16 stainless steel electrode that deposits an extra-low carbon 18Cr – 12Ni – 2.3Mo stainless steel weld metal.
Steam Generators {Heat Exchangers}: Heat transferred to heavy water from the nuclear reaction is further transferred to the steam via means of heat exchangers. The material used for this part has excellent thermal conductivity, hot strength, creep resistance, high-temperature corrosion resistance, low coefficient of expansion, etc
The materials used for the heat exchangers are low alloy steels (Cr-Mo), Austenitic stainless steel & Ni-based alloys (e.g., Inconel 617, Alloy 600 & Alloy 800 for steam-generating tubes).
Welding consumables that are developed to fabricate the heat exchanger are as follows:
- Supratherme (https://www.dnhsecheron.com/products/conventional-welding-consumables/medium-and-high-tensile-steel/supratherme ) an E7018 welding rod which is a heavy coated low hydrogen, iron powder type electrode.
- Supratherme (SPL) (https://www.dnhsecheron.com/products/conventional-welding-consumables/electrodes-for-low-temperature-service/supratherme-spl ) an E7018-1 iron powder, low hydrogen type electrode which produces a tough & ductile weld metal.
- Medio (https://www.dnhsecheron.com/products/conventional-welding-consumables/mild-steel-electrodes/medio ) is an E6013 medium coated rutile type MS welding electrode designed to operate even with 45 OCV.
- F 70S-2 (https://www.dnhsecheron.com/products/conventional-welding-consumables/mild-steel/f-70s-2 ) is an ER70S-2 triple deoxidized copper-coated mild steel wire for GTAW which gives smooth flow, stable arc and spatter free under optimum welding conditions.
- D&H 1212 (NS) (https://www.dnhsecheron.com/products/conventional-welding-consumables/electrodes-for-nickel-and-its-alloys/dh-1212ns ) an ENiCrFe-3 non-synthetic electrode that deposits homogeneous Ni-Cr-Fe alloy composition.
- D&H 1250 (https://www.dnhsecheron.com/products/conventional-welding-consumables/electrodes-for-nickel-and-its-alloys/dh-1250 ) an ENiCu-7 basic coated electrode depositing monel weld metal.
Condenser Tube: The steam surface condenser provides a barrier between the relatively impure cooling water and the high-grade condensate, which becomes feedwater for the nuclear or fossil steam generator. This part requires a material having corrosion resistance, where the choices of materials are Titanium, SS 304 & SS 316.
The electrodes to weld these grades are as follows:
- Botox-B (https://www.dnhsecheron.com/products/conventional-welding-consumables/stainless-steel-electrodes/batox-b) a stainless steel welding electrode that is an ideal choice to weld stainless steels of similar composition like 304L and equivalents, for overlays, surfacing, and repairing castings of similar materials.
- Rutox-D (https://www.dnhsecheron.com/products/conventional-welding-consumables/stainless-steel-electrodes/rutox-d ) has excellent resistance to intergranular corrosion even at elevated temperatures & it is an ideal suit for welding stainless steels of similar composition.
- Rutox-Mo (https://www.dnhsecheron.com/products/conventional-welding-consumables/stainless-steel-electrodes/rutox-mo ) is an E316-16 stainless steel electrode depositing a weld metal containing 18Cr – 11Ni – 2.3Mo.
Steam Turbine: It is considered as one of the major parts of the power plant because, the steam which is produced gets released with pressure on the turbine, due to which the turbine starts to rotate and generates electricity. The generated electricity is further transferred to the main transformer & then to the transmission line. The material used in steam turbines possesses properties such as high creep resistance, erosion-corrosion resistance, fatigue resistance, and also the resistance from steam oxidation.
The rotors of steam turbines are usually made of low-alloy steel. The role of the alloying elements is to increase hardenability in order to optimize mechanical properties and toughness after heat treatment. The rotors are required to handle the highest steam conditions therefore the alloy most commonly used is Cr-Mo-V steel.
The suitable welding consumables as per material specifications for turbines are as follows:
- Supratherme (https://www.dnhsecheron.com/products/conventional-welding-consumables/medium-and-high-tensile-steel/supratherme ) is a medium & high tensile steel welding rod, which has a metal recovery of about 115%.
- Molytherme (https://www.dnhsecheron.com/products/conventional-welding-consumables/electrodes-for-creep-resisting-steels/molytherme )an E7018-A1 low hydrogen iron powder type electrode yielding a weld deposit containing 0.5%Mo.
- Medio (https://www.dnhsecheron.com/products/conventional-welding-consumables/mild-steel-electrodes/medio ) welding rod is suitable for all types of mild steel structures, plant machinery, pipes, dredgers, trawlers, etc.
As the vapor starts to cool down, it turns back into a liquid state. Further, the water is discharged into a cooling tower, the steam seen rising from a cooling tower is this heat being released into the environment in the form of steam.
D&H Sécheron’s consumable range for various applications & components of Nuclear Power Plant (Table: 1)
Table: 1
Conclusion
D&H Sécheron is expanding its horizons day by day by manufacturing 800 plus products that cater to many organizations of various industries. As our nation is moving towards renewable/sustainable energy sources we feel that it is our duty to innovate products accordingly. For nuclear power plants, we have a wide range of products that are approved by prestigious agencies such as NPCIL & IGCAR.
Our domestic dealer network & the team of sales engineers work with full responsibility to ensure that our end customers receive quality welding consumables. If you are looking for the best quality welding consumables that can provide lasting solutions feel free to drop us an email at info@dnhsecheron.net or call/Whatsapp us at +91-98335 50505 or visit our website www.dnhsecheron.com we will answer all your queries & provide complete support for your welding needs.
