Coating processes – Interior of hollow article coating – Spraying
Reexamination Certificate
1999-09-28
2001-01-16
Meeks, Timothy (Department: 1762)
Coating processes
Interior of hollow article coating
Spraying
C427S235000, C427S238000, C427S239000, C427S327000, C427S348000, C427S421100
Reexamination Certificate
active
06174566
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a method for applying a protective film of, for example, oil to the interior of a metal pipe for preservation purposes. The invention furthermore relates to apparatus for applying a protective film of, for example, oil to the interior of a metal pipe for preservation purposes, at least comprising a storage vessel for, for example, oil.
Metal pipes are commonly known semi-finished products, which are manufactured in various lengths, wall thicknesses and diameters. In the process industry and in the installation industry, for example, it is very desirable that the interior of such semi-finished pipes are clean and non-corroded. Usually such pipes are provided with a protective film of oil for interim storage and transport to the end user, which oil film, due to its preserving action, prevents corrosion on the inside of the pipe. A known method for applying an oil film to the interior of a metal pipe is to submerge such a pipe in an oil bath. This method requires a great deal of time and space, however, whilst it is furthermore characterized by excessive oil consumption, which burdens the environment, and said method is not very efficient and functional when pipes of considerable length are to be preserved. In addition, said method is not suitable for use with pipes having a small diameter, since the oil cannot penetrate into the pipe sufficiently well upon submersion. Moreover, it is practically impossible to remove the (excess) oil after the treatment.
A prior arrangement consists of moving an oil-soaked wad through the pipe, which wad is connected to a rod which is moved forward and backward through the pipe. Moving the rod with the oil-soaked wad through the pipe is a laborious and time-consuming activity, which makes the apparatus unsuitable for preserving pipes having a considerable length or a small diameter. In addition, there is a risk of the wad remaining behind in the pipe after the treatment and obstructing said pipe, as a result of which the pipe will be unusable.
Further drawbacks of the known methods and apparatus are the fact that they can only be used with straight pipes and that it is difficult to ascertain after each treatment whether the interior of the pipe is fully coated with an oil film.
SUMMARY OF THE INVENTION
The object of the invention is to obviate the above drawbacks and to provide a method and apparatus by means of which the complete interior of metal pipes having a relatively random length, cross-sectional shape and diameter can be coated with an oil film in a quick and efficient manner, using a small amount of oil.
In order to accomplish that objective, the method according to the invention is characterized by the steps of placing one end of the pipe to be preserved against a pipe member, siphoning over a particular amount of oil from an oil storage vessel into a bent pipe section of said pipe member, generating and leading a compressed air pulse through the pipe member and the pipe to be preserved by quickly opening and closing a valve which is disposed in said pipe member between said bent pipe section and a pressure vessel for compressed air which is connected to the other end of said pipe member.
With this method a particular amount of oil proportional to the metal pipe to be preserved is used at all times, as a result of which the oil consumption is kept well in hand and the burden to the environment is reduced to the smallest possible degree. Above all, the invention makes use of the insight that it is possible to obtain an optimum control of the oil distribution over the interior of said metal pipe by quickly opening and closing a valve and leading the compressed air pulse that is thus generated through the pipe. In contrast to the methods and apparatus that have been used at this moment, the entire interior of the pipe is provided with an oil film, as a result of which no impurities can deposit directly on the interior of the pipe and no corrosion will occur.
According to the invention, a further improved preservation is obtained in that the distribution of the film over the interior of the pipe is partially determined by the speed and the duration of opening and closing the valve and by the initial pressure of the compressed air pulse.
The method according to the invention can furthermore be characterized in that, following the step of quickly opening and closing the valve, the compressed air pulse which is led through the pipe is collected, the air is cleared of residual oil, which residual oil is returned to the oil storage vessel. In contrast to the methods which are already known, this leads to a further reduction of the oil consumption, which benefits the environment.
An improved treatment of a pipe can be obtained in that prior to the application of the oil film to the interior of the pipe, the pipe is cleaned by means of a compressed air pulse not containing any oil.
The invention furthermore relates to apparatus for applying a protective film of, for example, oil to the interior of a metal pipe for preservation purposes, which apparatus comprises a storage vessel for, for example, oil. The apparatus is according to the invention characterized in that it comprises a pipe member, which is connected to said oil storage vessel via a pipe, as well as a bent pipe section for containing a particular amount of oil, wherein the pipe to be preserved can be placed on a first end of said pipe member and wherein the other end is connected to a pressure vessel for compressed air, and wherein a valve is disposed in said pipe member between said pressure vessel and said bent pipe section, which valve functions to quickly pass a compressed air pulse for a short period of time. Thus it is possible to preserve metal pipes of relatively random length and diameter in a quick and efficient manner, while using a small amount of oil, by applying a protective oil film to the interior thereof. By opening the valve for a brief period of time, an “explosive ” pressure pulse of compressed air through the pipe member is generated, which “shoots ” the amount of oil through the metal pipe to be preserved, and a more or less uniform film distribution over the complete interior of the pipe is provided. Thus, the number of pipes to be rejected due to a contaminated and corroded interior is reduced to a minimum.
Preferably, the bent pipe section is a U-shaped or spiral-shaped section or constructed as a siphon.
In another embodiment, the apparatus according to the invention is characterized in that said valve is a quick-acting pneumatic valve, which is preferably actuated by means of an electric pulse. Depending on the valve dimensions, the type of valve and the opening and closing characteristic, the use of such a quick-acting pneumatic valve enables proper control of the final film distribution over the interior of a pipe, which distribution partially depends on the length and the shape of the electrical pulse. The selection, adjustability and actuation of the quick-acting pneumatic valve makes it possible to adapt the preservation treatment completely to metal pipes having a particular length and diameter.
According to another aspect of the invention, the first end of the pipe member is fitted with a spray nozzle.
Thereby, the spray nozzle may extend conically in the direction of its free end. Another embodiment of the invention is characterized in that the bore of the spray nozzle diverges in the direction of the free end of the spray nozzle. These different constructions of the spray nozzle make the apparatus suitable for a wide range of pipe diameters. In addition, such spray nozzles are self-aligning and they also seal the pipe to be preserved.
Another embodiment of the apparatus is according to the invention characterized in that said apparatus is provided near the free end of the pipe to be preserved with means for collecting the compressed air pulse passed through the pipe, clearing said air from residual oil and returning the residual oil to the oil storage vessel. This contribut
Barr Michael
Brubek B.V.
Jacobson Price Holman & Stern PLLC
Meeks Timothy
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