I am not going to write about what is an electron beam welding machine about which anyone can read in a standard welding text book. I am going to write how students were trained in Moscow Power Institute.
There were two electron beam welding (EBW) machines in the Department of Technology of metals where I joined for my Ph.D program under Prof. N.A.Olshanskii. One was operating at high voltage and the other was operating at a low voltage. The one operating at a high voltage was built by Prof. Olshanskii and the other was a factory built machine. New students were asked to start with the machine built by Prof.Olshanskii and after mastering the principles of operation of EBW they were allowed to go on the factory built machine. There was a reason behind this exercise. The machine with which we started to learn operation of EBW used to go out of order often as it was very old. The cathode which was a filament made of
tungsten used to burn up fast either due to our wrong handling of the machine or due to its life being over. When that happened we were supposed to take out the electron gun and replace the tungsten filament. During this process we learnt how the electron gun looks, how to make the tungsten filament, how to mount the filament and how to align the filament properly etc. All EBW machines are connected to a fore vacuum pump which is a mechanical pump and an oil diffusion pump. Whenever these pumps went out of order we were supposed to strip them open, rectify the mistakes and put them back in to operation. These exercises gave the new entrants enough confidence to handle any EBW machine. When you made mistake no one asked any questions but you were only required to set the mistake alright.This was totally different from the approach of Indian institutions.After my quota of mistakes, when Prof. had the confidence that I can handle factory built machine he allowed me to go on that machine.
There is a particular procedure for opening and closing of various valves to create vacuum. In today's machines everything is automated. In 1968 all these operation were manual. Fist you have to switch on the electric heater to heat the oil in the diffusion pump and after some time you switch on the fore vacuum pump and when the fore vacuum has reached a predetermined level you close the valves of fore vacuum pump and open the valves connected to the diffusion pump. If valves connected to the diffusion pump is opened when the valves connected to the fore vacuum pump is not closed air enters diffusion pump and oil burns and vacuum is lost.Then you have to switch off the machine, clean up the mess and put the machine back in to operation.
I will write in next blog what happened when I burnt the oil in diffusion pump.
Monday, March 29, 2010
Sunday, January 3, 2010
Moscow Power Engineering Institute
I was selected by Government of India in 1968 on a USSR scholarship to do my Ph.D in Moscow. After reaching Moscow I was admitted to Moscow Power Engineering Institute.
Moscow Power Engineering Institute was set up in in 1930 to solve technological problems associated with power generation, distribution, control etc. The Institute was so huge that in 1970's the student strength was around 24000. The institute was training students from undergraduate level to post graduate level including Ph.D's and D.Sc's. There are 70 Departments in MPEI, 550 laboratories for students and more than 100 research laboratories. More than 500 Ph.D students out of which 100 foreign students are studying at any given moment. The faculty consists of over 1700 professors, assistants professors and lecturers. Many of the professors are Academicians.Selection to Undergraduate programme was similar to our IIT entrance exams. Very tough and students from all over USSR wrote the exams. If the students are not selected they used to cry their heart out. The admission to Postgraduation depended upon the performance in the Undergraduate programme and the the desire of the Professor to accept a Graduate student. All Postgraduate student got a scholarship of old 200 Roubles. In addition students are allowed to coach undergraduate students for which they were paid another 100 Roubles per month.
My Professor was Alexander Nikiolaevich Olshanskii.
All welding processes are based on heating the metal to be joined to its melting temperature and prevent the molten metal from contamination by oxygen and nitrogen in the atmosphere. For example, in manual metal arc welding, heat is generated by striking an arc between the base metal and the stick electrode. To prevent contamination the stick electrode is coated with chemicals which produce enough gas such as carbon di oxide, carbonmonoxide and other reducing gases. In addition a slag is deposited to blanket the molten metal to prevent contamination from atmospheric air. Some times alloying elements are added in the coating to improve the mechanical properties of the weld metal. Similarly in TIG welding and MIG welding Argon is used to shield the molten metal. The whole idea of using the gas is to displace the Air in the vicinity of weld. Thus whatever may be the heat source it is essential to ensure that weld metal is not contaminated by the atmospheric air.
There is another method of preventing contaminatin of the weld metal-by creating vacuum around the place where welding is going on.When you evacuate the place where welding is going on you have eliminated all gases from the vicinity of the weld. The part to be welded is kept in a chamber which is evacuated and welding is done as usual. This was in 1960's.When Prof. Olshanskii proposed this new process his peers laughed at him and asked him whether he plans to go to space to carry out welding. But undaunted he worked out the process of welding in vacuum for which he got his Ds.c. He had the last laugh when soviet astronauts did weld in space and brought back welded specimens for evaluation.
After successfully establishing welding in vacuum he conceived a new process of Electron Beam Welding about which I will write in the next blog.
Moscow Power Engineering Institute was set up in in 1930 to solve technological problems associated with power generation, distribution, control etc. The Institute was so huge that in 1970's the student strength was around 24000. The institute was training students from undergraduate level to post graduate level including Ph.D's and D.Sc's. There are 70 Departments in MPEI, 550 laboratories for students and more than 100 research laboratories. More than 500 Ph.D students out of which 100 foreign students are studying at any given moment. The faculty consists of over 1700 professors, assistants professors and lecturers. Many of the professors are Academicians.Selection to Undergraduate programme was similar to our IIT entrance exams. Very tough and students from all over USSR wrote the exams. If the students are not selected they used to cry their heart out. The admission to Postgraduation depended upon the performance in the Undergraduate programme and the the desire of the Professor to accept a Graduate student. All Postgraduate student got a scholarship of old 200 Roubles. In addition students are allowed to coach undergraduate students for which they were paid another 100 Roubles per month.
My Professor was Alexander Nikiolaevich Olshanskii.
All welding processes are based on heating the metal to be joined to its melting temperature and prevent the molten metal from contamination by oxygen and nitrogen in the atmosphere. For example, in manual metal arc welding, heat is generated by striking an arc between the base metal and the stick electrode. To prevent contamination the stick electrode is coated with chemicals which produce enough gas such as carbon di oxide, carbonmonoxide and other reducing gases. In addition a slag is deposited to blanket the molten metal to prevent contamination from atmospheric air. Some times alloying elements are added in the coating to improve the mechanical properties of the weld metal. Similarly in TIG welding and MIG welding Argon is used to shield the molten metal. The whole idea of using the gas is to displace the Air in the vicinity of weld. Thus whatever may be the heat source it is essential to ensure that weld metal is not contaminated by the atmospheric air.
There is another method of preventing contaminatin of the weld metal-by creating vacuum around the place where welding is going on.When you evacuate the place where welding is going on you have eliminated all gases from the vicinity of the weld. The part to be welded is kept in a chamber which is evacuated and welding is done as usual. This was in 1960's.When Prof. Olshanskii proposed this new process his peers laughed at him and asked him whether he plans to go to space to carry out welding. But undaunted he worked out the process of welding in vacuum for which he got his Ds.c. He had the last laugh when soviet astronauts did weld in space and brought back welded specimens for evaluation.
After successfully establishing welding in vacuum he conceived a new process of Electron Beam Welding about which I will write in the next blog.
Saturday, December 19, 2009
The biggest mistake I made in my life.
Yes it is true. I made the biggest mistake of my life. I was working in a company of 4000 people manufacturing hitech equipment for fertiliser, petroleum and petrochemicals, nuclear, power,defense and other industries. I was No.2 in the organisation. I was controlling about a dozen departments. I was running a well equipped R&D department which was developing missile components. In short I was working in a place which I was proud of. Suddenly I had an offer from a company in Chennai as Technical Director and I was recommended by one of my assistants who was working with me earlier and who has joined this company. At that time I was not aware of terms such as "Cost to the company". The salary offered appeared to be good but it was the "Cost to the Company. I later learnt that the salary included the rent for the flat, drivers salary etc. which effectively brought down my "Take home pay" which was not much higher from what I was getting from my previous job. For example, in my previous job I had an independent bungalow in half an acre of land with a garden, with subsidised electricity, water, a gardener, subsidised health benefits etc.By joining this the new company I lost all these benefits That was the first shock I got by joining the company. The next shock was my visit to the work shop which was located about 30 KM from Chennai. It was smaller than my R&D work shop in my previous organisation. There were some five or six welding machines which I learnt later was the property of the subcontractor. All the work was subcontracted hence there were no permanent workers. With such an arrangement quality was sacrificed. There was a GM who had no powers. His role was to beg for men and materials directly from MD. I was shattered and started wondering how long I will last in this Company. Incidentally, the turn over of the company was around Rupees twenty crores. The company I came from had a turn over of Rs.350 crores. Hence I was forced to think small.
The new company was manufacturing Filter and cleaning systems for Power Plants. The Managing Director was a middle aged man and there were three people who was MD's Ears and Eyes. One was M supposed to be an "Expert" in design and "Installation", another was R supposed to be a financial wizard and another was RK who was supposed to be an expert in Corporate Affairs.All the three spied on their colleagues and reported on them to MD every evening. Whom ever they found to be a potential competitor to them he was massacred by filling the ears of the MD.(Incidentally I was one of the victims). MD never even cross cross checked the info given to him. Such was the mislaid confidence in the THREE. These were the not the only people who were spying on the others. Even the lowest peon can walk in to MD's room and tell him on any one whom he disliked. This was not so in the previous organisation. There was hierarchy and only those who were directly reporting to MD can meet him only after fixing an appointment. Here it was chaos. Every body was telling on every body and hence the whole atmosphere was one of distrust. Once I made a comment that MD should sit in a different place so that even a messenger will not have access to him. This was twisted out of shape and R reported to MD that I want MD to leave his place and hand it over to me!
Orders were not got on merit. Officers at the execution level in Power Plants had no confidence in the equipment supplied. Whenever such difference of opinion occurred, the higher ups stepped and a deal was struck and the order was secured. Those who were stubborn not to recommend the order were neutralized. The MD had stooped to such a low level that he asked my secretary to furnish him at the end of the day who all met me and at time I went to work and what time I left for home. Those who were spying on their colleagues were rewarded and those who refused were punished.Obviously M, R and RK were rewarded beyond their expectations.
In such a dirty atmosphere I knew I cannot survive for long. M felt I am a stumbling block to his progress. He poisoned the mind of MD and a day came that I decided to quit by giving the mandatory three months notice. On my last working day MD wanted to give me three months pay as gratis. I had the supreme satisfaction of telling him "GO to Hell". Of course the company is doing well and has expanded and I hope that with growth openness has come to the company. Of course, M and R have become Directors and if they have to change their jobs then at best they can be accommodated as Senior Managers in a new company. Any one wants to join a tiny family owned company must be ready to give up his dignity and self respect.
The new company was manufacturing Filter and cleaning systems for Power Plants. The Managing Director was a middle aged man and there were three people who was MD's Ears and Eyes. One was M supposed to be an "Expert" in design and "Installation", another was R supposed to be a financial wizard and another was RK who was supposed to be an expert in Corporate Affairs.All the three spied on their colleagues and reported on them to MD every evening. Whom ever they found to be a potential competitor to them he was massacred by filling the ears of the MD.(Incidentally I was one of the victims). MD never even cross cross checked the info given to him. Such was the mislaid confidence in the THREE. These were the not the only people who were spying on the others. Even the lowest peon can walk in to MD's room and tell him on any one whom he disliked. This was not so in the previous organisation. There was hierarchy and only those who were directly reporting to MD can meet him only after fixing an appointment. Here it was chaos. Every body was telling on every body and hence the whole atmosphere was one of distrust. Once I made a comment that MD should sit in a different place so that even a messenger will not have access to him. This was twisted out of shape and R reported to MD that I want MD to leave his place and hand it over to me!
Orders were not got on merit. Officers at the execution level in Power Plants had no confidence in the equipment supplied. Whenever such difference of opinion occurred, the higher ups stepped and a deal was struck and the order was secured. Those who were stubborn not to recommend the order were neutralized. The MD had stooped to such a low level that he asked my secretary to furnish him at the end of the day who all met me and at time I went to work and what time I left for home. Those who were spying on their colleagues were rewarded and those who refused were punished.Obviously M, R and RK were rewarded beyond their expectations.
In such a dirty atmosphere I knew I cannot survive for long. M felt I am a stumbling block to his progress. He poisoned the mind of MD and a day came that I decided to quit by giving the mandatory three months notice. On my last working day MD wanted to give me three months pay as gratis. I had the supreme satisfaction of telling him "GO to Hell". Of course the company is doing well and has expanded and I hope that with growth openness has come to the company. Of course, M and R have become Directors and if they have to change their jobs then at best they can be accommodated as Senior Managers in a new company. Any one wants to join a tiny family owned company must be ready to give up his dignity and self respect.
Saturday, November 7, 2009
LIFE IN RUSSIAN HOSTEL-2
HOT SHOWERS IN THE HOSTEL
We lived in a four storied building identified as Foreign Students Hostel.You must be wondering why I am writing about HOT Showers is in many undergraduate hostels there were no showers. Many of the Indian students living in such hostels used to come to our hostel regularly for a shower!
The showers were located in the ground floor. The showers were working round the clock. Three days were reserved for girls and the remaining days were for boys. Sunday was for girls when all the girls in the hostel used the shower. Many used the showers once a week.
We Indians used the showers all the seven days in a week. Russians used to ask us why there is necessity to take bath everyday when we don't sweat. With so many clothes we were wearing to protect ourselves from cold we were sweating inside. Moreover many Indians are accustomed to take bath every day. So we continued our daily routine. We invariably showered just before going to bed. There were about six showers and all of us showered in our birth day suit. Initially it was embarrassing but we got used. Just to mask their bad body odor they Russians used cheap scents which only enhanced their bad smell.
We lived in a four storied building identified as Foreign Students Hostel.You must be wondering why I am writing about HOT Showers is in many undergraduate hostels there were no showers. Many of the Indian students living in such hostels used to come to our hostel regularly for a shower!
The showers were located in the ground floor. The showers were working round the clock. Three days were reserved for girls and the remaining days were for boys. Sunday was for girls when all the girls in the hostel used the shower. Many used the showers once a week.
We Indians used the showers all the seven days in a week. Russians used to ask us why there is necessity to take bath everyday when we don't sweat. With so many clothes we were wearing to protect ourselves from cold we were sweating inside. Moreover many Indians are accustomed to take bath every day. So we continued our daily routine. We invariably showered just before going to bed. There were about six showers and all of us showered in our birth day suit. Initially it was embarrassing but we got used. Just to mask their bad body odor they Russians used cheap scents which only enhanced their bad smell.
Friday, November 6, 2009
LIFE IN A RUSSIAN HOSTEL-1
KGB IS WATCHING YOU
Last time I had written that we had to share a room with a Russian who did not know English. Invariably he was a member of the communist party. His main job was to keep a watch on who comes to meet us and how often we meet. In addition we used to visit Indian Embassy twice a week to collect our mail. His job was to inform KGB how often we visit the embassy and what type of mail we got. He always questioned about our attitude to Soviet way of life. Our standard answer was we like USSR. After we suffered his company for one or two years he was shifted to other new comers room.
Another ploy employed by KGB was to call us on telephone and accuse us of having an affair with a Russian girl and they have enough evidence to prove it. If we accept it then they will blackmail us that they report the Indian Embassy and ensure that we will be sent back. If we agree to cooperate with them when we go back to India, they will hush the whole thing up and we can continue as usual. When we faced such a situation our seniors had already warned us that we should abuse the caller and tell the caller that we are being harassed we are bringing this to the notice of our Embassy. Then such calls will stop. They did not want our Embassy to know that we are being watched.
Other than such minor incidents life in USSR was very interesting. We were free to roam freely in Moscow.
Last time I had written that we had to share a room with a Russian who did not know English. Invariably he was a member of the communist party. His main job was to keep a watch on who comes to meet us and how often we meet. In addition we used to visit Indian Embassy twice a week to collect our mail. His job was to inform KGB how often we visit the embassy and what type of mail we got. He always questioned about our attitude to Soviet way of life. Our standard answer was we like USSR. After we suffered his company for one or two years he was shifted to other new comers room.
Another ploy employed by KGB was to call us on telephone and accuse us of having an affair with a Russian girl and they have enough evidence to prove it. If we accept it then they will blackmail us that they report the Indian Embassy and ensure that we will be sent back. If we agree to cooperate with them when we go back to India, they will hush the whole thing up and we can continue as usual. When we faced such a situation our seniors had already warned us that we should abuse the caller and tell the caller that we are being harassed we are bringing this to the notice of our Embassy. Then such calls will stop. They did not want our Embassy to know that we are being watched.
Other than such minor incidents life in USSR was very interesting. We were free to roam freely in Moscow.
Monday, November 2, 2009
Government of India Scholarship
LEARNING RUSSIAN LANGUAGE
I was a Research Scholar in Indian Institute of Science working for my M.Sc degree in Mechanical Engineering. I had applied for a scholarship to do Ph.D from a Canadian University. I was offered a scholarship with a condition that I must produce a letter from my professor that I have submitted my Thesis for M.Sc. Unfortunately I could not get such a letter and for no fault of mine I lost the opportunity to study in Canada.
After completing my degree I got a job in CSIR and left for Durgapur in West Bengal.CSIR encouraged us to apply for Government of India Scholarships to study abroad. Countries such as U.K, Canada, West Germany, USSR were offering scholarships to Indian Scholars to pursue Ph.D programs in their country. Children of influential people cornered scholarships to study in the West but people like me had to be contented with scholarships offered by USSR and other countries. By the time I finished my Ph.D I was glad that I went to study in Moscow.
When I went to Moscow I did not know one word of Russian Language. We were assigned to various professors depending upon what topic we wanted to specialise for Ph.D programme. Since we did not know Russian language we were asked to learn for six Month's Russian language. Hence we were directed to the Russian language faculty. One young and beautiful Russian girl was assigned to teach six students. Perhaps assigning a young and beautiful teacher was sort of incentive for us not to bunk classes. The teacher knew English well.She used to talk to us in English for few weeks and once we learnt to recognise alphabets she stopped talking to us in English and switched over to Russian. We had tutorials lasting for about six hours a day for five days in a week. Further we were loaded with enough home work to last for another four to five hours. We were put up in a hostel and your room mate is a Russian who could not speak one word of English.Hence we were forced to communicate with him in our broken Russian which also helped us to learn Russian faster.Later we learnt that he was put up with us more for spying on us than to help us to learn Russian.
We went to buy daily necessities such as bread, butter jam etc. We will pick up the article and ask the sales girl its name and write down and in this way we learnt names of commodities which were not taught to us in class room.
My Professor insisted that I must come to the faculty after Russian classes. He introduced me to the fellow scholars and workers. The workers taught me the names of tools such as wrenches. screw driver, file etc. which were not taught in the Russian class room. In addition they taught me slang language without teaching the meaning which I used in one of my Russian classes. The teacher was shocked and asked me to repeat the word which I repeated without being aware of the meaning.She asked me who taught this slang and I told her the workers in the lab. She asked me whether I knew the meaning. I said no. She let it go at that but complained to my Professor that in the company of workers I am learning vulgar language. The professor warned the workers not to teach me vulgar language. When I fully learnt the language I understood what I had uttered and was ashamed of it. But I was not to be blamed.
Russian grammar is similar to Sanskrit grammar. In Sanskrit grammar we have "ekavachana, dwivachana, and bahuvachana". In Russian Language also we have "ekavachana, dwiavchana and bahuvachana" In Sanskrit the verb changes with number and gender. Same in Russian also. Hence Indians had no difficulty in accepting that the verb changes with gender and number. But students from Vietnam, France and even U.K had a lot of difficulty to accept that verb changes with number and gender.
There are a number of words in Russian which are similar to Sanskrit words, For example, OGON in Russian is AGNI in Sanskrit, VADA in Russian is UDAKA in Sanskrit, SYESTRA in Russain is SAHODARY in Sanaskrit etc. Hence it was not difficult for Indians to accept that verb changes with gender and number.
In addition to teaching Russian, our teacher took us to Museums, Ballets and plays. Next day she would ask us to narrate in our own words what we saw. We were asked to read the news paper and narrate in our own words what we have understood.
With such rigorous training in Russian for six months we were ready to enter our faculties. But learning Russian never ended. The technical language we have to master was a different kettle of fish. Here the colleagues and professors helped us a lot and we can never forget their love and affection.
I was a Research Scholar in Indian Institute of Science working for my M.Sc degree in Mechanical Engineering. I had applied for a scholarship to do Ph.D from a Canadian University. I was offered a scholarship with a condition that I must produce a letter from my professor that I have submitted my Thesis for M.Sc. Unfortunately I could not get such a letter and for no fault of mine I lost the opportunity to study in Canada.
After completing my degree I got a job in CSIR and left for Durgapur in West Bengal.CSIR encouraged us to apply for Government of India Scholarships to study abroad. Countries such as U.K, Canada, West Germany, USSR were offering scholarships to Indian Scholars to pursue Ph.D programs in their country. Children of influential people cornered scholarships to study in the West but people like me had to be contented with scholarships offered by USSR and other countries. By the time I finished my Ph.D I was glad that I went to study in Moscow.
When I went to Moscow I did not know one word of Russian Language. We were assigned to various professors depending upon what topic we wanted to specialise for Ph.D programme. Since we did not know Russian language we were asked to learn for six Month's Russian language. Hence we were directed to the Russian language faculty. One young and beautiful Russian girl was assigned to teach six students. Perhaps assigning a young and beautiful teacher was sort of incentive for us not to bunk classes. The teacher knew English well.She used to talk to us in English for few weeks and once we learnt to recognise alphabets she stopped talking to us in English and switched over to Russian. We had tutorials lasting for about six hours a day for five days in a week. Further we were loaded with enough home work to last for another four to five hours. We were put up in a hostel and your room mate is a Russian who could not speak one word of English.Hence we were forced to communicate with him in our broken Russian which also helped us to learn Russian faster.Later we learnt that he was put up with us more for spying on us than to help us to learn Russian.
We went to buy daily necessities such as bread, butter jam etc. We will pick up the article and ask the sales girl its name and write down and in this way we learnt names of commodities which were not taught to us in class room.
My Professor insisted that I must come to the faculty after Russian classes. He introduced me to the fellow scholars and workers. The workers taught me the names of tools such as wrenches. screw driver, file etc. which were not taught in the Russian class room. In addition they taught me slang language without teaching the meaning which I used in one of my Russian classes. The teacher was shocked and asked me to repeat the word which I repeated without being aware of the meaning.She asked me who taught this slang and I told her the workers in the lab. She asked me whether I knew the meaning. I said no. She let it go at that but complained to my Professor that in the company of workers I am learning vulgar language. The professor warned the workers not to teach me vulgar language. When I fully learnt the language I understood what I had uttered and was ashamed of it. But I was not to be blamed.
Russian grammar is similar to Sanskrit grammar. In Sanskrit grammar we have "ekavachana, dwivachana, and bahuvachana". In Russian Language also we have "ekavachana, dwiavchana and bahuvachana" In Sanskrit the verb changes with number and gender. Same in Russian also. Hence Indians had no difficulty in accepting that the verb changes with gender and number. But students from Vietnam, France and even U.K had a lot of difficulty to accept that verb changes with number and gender.
There are a number of words in Russian which are similar to Sanskrit words, For example, OGON in Russian is AGNI in Sanskrit, VADA in Russian is UDAKA in Sanskrit, SYESTRA in Russain is SAHODARY in Sanaskrit etc. Hence it was not difficult for Indians to accept that verb changes with gender and number.
In addition to teaching Russian, our teacher took us to Museums, Ballets and plays. Next day she would ask us to narrate in our own words what we saw. We were asked to read the news paper and narrate in our own words what we have understood.
With such rigorous training in Russian for six months we were ready to enter our faculties. But learning Russian never ended. The technical language we have to master was a different kettle of fish. Here the colleagues and professors helped us a lot and we can never forget their love and affection.
Tuesday, October 27, 2009
Hastelloy-G welding
In late 1970's the emission from existing power plants and chemical plants came under Governments scrutiny and laws were enacted to control emission of sulphur di oxide phosphoric acids and other harmful emissions. Flue gas desulpharisation was insisted upon and there was a need to look in to the material which can withstand corrosive products emitted by the stack. We looked in to the problem from material angle and decided that we need to study Hastelloy-G as a candidate material.
Hastelloy-G is a columbium stabilised nickel based alloy with additions of chromium,molybdenum and iron as major constituents in the alloy. The chemical composition of this alloy
is chosen to resist both acidic and alkaline media. It can also resist both oxdising and reducing media. This alloy is eminently suited to handle sulphuric acid which changes from oxidising to reducing depending upon concentration and temperature. Hastelloy-G has outstanding resistance to mixed acids,flurosilisic acid, sulphate compounds,contaminated nitric acid,flue gases and hydrofluoric acid. The alloy resists pitting, crevice corrosion and also stress corrosion cracking.
Hastelloy-G is welded either by manual metal arc or by TIG process.In manual metal arc welding electrode confirming to ENiCrMo-1 which deposits a weld metal whose composition is close to plate material is used.Some minor problems are encountered during welding. Hastelloy-G being a nickel rich material flowability is poor which makes it difficult to place the weld where it is required. But this problem can be over come by training of welders.
Hastelloy-G plates are supplied in solution treated condition. Solution treatment consists of heating to 1175 degC, holding at this temperature for sufficient length of time and rapid air cooling or water quench.
Hastelloy- G being high nickel alloy the flowability of molten metal is poor. It is necessary to place the weld metal where it is required. Large bevel angles and small root face is necessary. Side wall fusion is another problem with welding of Hastelloy-G- It is difficult to obtain full penetration. In such cases back chipping and placing sealing weld is necessary to ensure good radiography quality welds. Magnetic arc blow which is problem with all high nickel alloy is also experienced by Hastelloy-G. But the problem can be overcome by suitably locating ground clamps. Porosity is another problem which is encountered often. By using short arc and proper cleaning of base metal and baking the electrode porosity can be eliminated. A large number of trials were carried out by varying heat in put over a wide range. Mechanical tests were carried out to establish the strength and ductility of welds. From these results we established the optimum heat input for welding Hastelloy-G.
In TIG welding the filler wire used is ERNiCrMo-1. Similar problems which we experienced with manual welding were also experienced with TIG welding.
The test specimens from both the methods of welding were subjected to corrosion tests in sulphuric acid with concentration ranging from 10% to 70%. At 70% concentration the acid becomes oxidizing and the corrosion rate is extremely high.
Weldments showed excellent corrosion resistance in entire range of concentration in phosphoric acid.
Weldments were subjected to stress corrosion cracking tests in 42% boiling Magnesium Chloride solution. Hastelloy-G did not show any signs of cracking even after hundreds of hours of test.
We passed on these results to the manufacturing section of BHPV for fabricating equipment with Hastelloy-G.
Hastelloy-G is a columbium stabilised nickel based alloy with additions of chromium,molybdenum and iron as major constituents in the alloy. The chemical composition of this alloy
is chosen to resist both acidic and alkaline media. It can also resist both oxdising and reducing media. This alloy is eminently suited to handle sulphuric acid which changes from oxidising to reducing depending upon concentration and temperature. Hastelloy-G has outstanding resistance to mixed acids,flurosilisic acid, sulphate compounds,contaminated nitric acid,flue gases and hydrofluoric acid. The alloy resists pitting, crevice corrosion and also stress corrosion cracking.
Hastelloy-G is welded either by manual metal arc or by TIG process.In manual metal arc welding electrode confirming to ENiCrMo-1 which deposits a weld metal whose composition is close to plate material is used.Some minor problems are encountered during welding. Hastelloy-G being a nickel rich material flowability is poor which makes it difficult to place the weld where it is required. But this problem can be over come by training of welders.
Hastelloy-G plates are supplied in solution treated condition. Solution treatment consists of heating to 1175 degC, holding at this temperature for sufficient length of time and rapid air cooling or water quench.
Hastelloy- G being high nickel alloy the flowability of molten metal is poor. It is necessary to place the weld metal where it is required. Large bevel angles and small root face is necessary. Side wall fusion is another problem with welding of Hastelloy-G- It is difficult to obtain full penetration. In such cases back chipping and placing sealing weld is necessary to ensure good radiography quality welds. Magnetic arc blow which is problem with all high nickel alloy is also experienced by Hastelloy-G. But the problem can be overcome by suitably locating ground clamps. Porosity is another problem which is encountered often. By using short arc and proper cleaning of base metal and baking the electrode porosity can be eliminated. A large number of trials were carried out by varying heat in put over a wide range. Mechanical tests were carried out to establish the strength and ductility of welds. From these results we established the optimum heat input for welding Hastelloy-G.
In TIG welding the filler wire used is ERNiCrMo-1. Similar problems which we experienced with manual welding were also experienced with TIG welding.
The test specimens from both the methods of welding were subjected to corrosion tests in sulphuric acid with concentration ranging from 10% to 70%. At 70% concentration the acid becomes oxidizing and the corrosion rate is extremely high.
Weldments showed excellent corrosion resistance in entire range of concentration in phosphoric acid.
Weldments were subjected to stress corrosion cracking tests in 42% boiling Magnesium Chloride solution. Hastelloy-G did not show any signs of cracking even after hundreds of hours of test.
We passed on these results to the manufacturing section of BHPV for fabricating equipment with Hastelloy-G.
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