This section is from the book "Welding And Cutting Metals By Aid Of Gases Or Electricity", by L. A. Groth. Also available from Amazon: Welding and cutting metals by aid of gases or electricity.
The cost of the hydrogen plant is from £7 to £15.
The cost of the acetylene plant varies from £36 to £72, consequently four to five hydrogen plants could be obtained for the same expense ; besides, the acetylene generating plant cannot last for more than five years, representing an amortisation of nearly 1s. per day.
By using acetylene-dissous, however, the generating plant may be sound.
There is no additional expense ; the above price includes a complete hydrogen welding plant ready for immediate use.
To the above price must be added the cost of foundation and installation of the acetylene generator and washer, the laying of water-pipes for the maintenance of the generator, and a costly lead piping for the conveyance of the acetylene.
The hydrogen welding plant does not require any installation; furthermore, it may be placed anywhere.
The installation requires official authorisation and approval by insurance companies. The generator must be surrounded by sufficient air and protected against freezing and deterioration.
During a period of five years and with a registered number of more than 1,400 weldings, not one accident has been recorded.
Notwithstanding all precautions taken, more than ten fatal accidents have occurred during three years, besides those which have taken place in the use of acetylene for other purposes than welding.
It should not be forgotten that acetylene is the most explosive gas existing.
The hydrogen blowpipe is the most easy to handle.
The flame is not regulated according to its colour, to be judged by the welder, as is the case with the acetylene welding, but by a special indicator, which produces a saving of 15 to 20 per cent. as compared with previous arrangements.
The blowpipe is everlasting, that is to say, is replaced free of charge in case of being damaged.
A single blowpipe suffices for welding up to 20 mm.
The hydrogen blowpipe does not make any noise.
The acetylene blowpipe is difficult to regulate, and the welder never knows if the flame is of an oxidising or reducing nature, there being no indicator to guide him in this respect.
This explains why seventy reservoirs, delivered by an eminent French firm, were refused, sixty of them having split during the tests, although the welding appeared perfect on the surface.
It requires ten different blowpipes to weld the different thicknesses up to 20 mm., the total cost of the blowpipes alone amounting to about £50, besides the cost of their replacing when damaged.
The acetylene blowpipe makes a deafening noise.
Any mechanic can learn the handling of the hydrogen blowpipe in a few hours'
The mechanic seems to be sufficiently instructed as soon as he can make a weld, but time, by reason of the flame being mechanically regulated.
the weld is not perfect. It is only after a considerable time he can become a proper welder. M. Le Chatelier, in Marseilles, states that he never permits a welder to do the repair of a steam boiler unless he has had a previous practice in welding of at least eight months.
The hydrogen blowpipe gives off vapours of water only.
The acetylene blowpipe, during the welding, emanates a formidable quantity of carbonic oxide besides carbonic acid.
This is even admitted by inventors of acetylene blowpipes, who affirm that the quantity of oxygen in the blowpipe does not permit a transformation of this carbon but in carbonic oxide.
Each litre of acetylene gives one litre of carbonic oxide.
This has been repudiated, basing it upon analyses made at the laboratories under totally different conditions than those which take place at the welding of steel. On the other hand, it has been confirmed by the evidence of numerous welders, who complain, after one or two years' welding operations, of pains in stomach and great anguish in the chest, nausea, etc.
The hydrogen blowpipe, "Pyrox, 1907," is very economical by reason of -
(1) Its low price.
(2) Not requiring any cleaning, consequently no delay.
(3) The hydrogen blowpipe, being very portable, minimum of time is lost in replacing the welding pieces.
The acetylene blowpipe is not the most economical by reason of -
(1) Every time the welding has been finished the generator still continues to generate gas, which escapes into the atmosphere.
(2) Every morning it takes at least one hour to clean the acetylene apparatus and to remove the nauseous residues.
By using acetylene-dissous the generator can be abandoned.
(3) The acetylene blowpipe, being less portable, causes troubles and expense in its displacement. The generator lasts for three to five years only.
Hydrogen permits welding of iron, steel, brass, copper, bronze and aluminium, after a few hours' instruction.
The weight of the hydrogen blowpipe is 250 grammes.
Acetylene permits the welding of iron and steel only. The weld obtained is not malleable; it is hard to file and brittle, which explains why it should not be employed for pieces which haveto resist a certain tension. Copper, brass, bronze, or aluminium cannot be welded by acetylene by reason of the great temperature it produces.
The weight of the acetylene blowpipe varies from 1 to 1.5 kilogrammes.
To overcome the difficulties experienced by the forging process it has been suggested to employ the water-gas, which will enable the parts to be united to be heated locally even to the temperature of white heat. As soon as the temperature required has been reached the heating appliance is removed, and replaced by the hammer or press.
The application of water-gas is connected with complicated and expensive installations ; besides, the high percentage of carbonic oxide which the water-gas contains, and which is odourless, has caused a high death roll.
The water-gas welding has found application principally in large works for making steam boilers and tubes, as fully described in Chapter Y., page 1G8.
It is stated that it cannot weld plates with a thickness of less than one-fifth of an inch.