US2181361A - Pipe and method of forming same - Google Patents

Description

Patented Nov. 28, 1939 UNITED STATES PIPE AND METHOD OF FORMING SAME Albert 0. Bean, Kansas City, Mo., and Joseph B. Ray, Forth Worth, Tex.

No Drawing. Application March 23, 1936, Serial No. 70,448

2 Claims.

appears to be in excellent condition, only to find severe pitting underneath the same.

One object of our invention is to provide a I pipeline which will resist corrosion.

Another object of our invention is to provide a method of forming pipe-lines so as to render them corrosion resisting.

In general, our invention contemplates the provision of a coating in contact with the steel of the pipe comprising Portland cement suspended in a drying oil. This coating is in turn protected by a coating of a bituminous substance, such as coal tar pitch, which may have incorporated therein a suitable binder.

We have found that once rust begins, that the rusted spot will continue to corrode. The Portland cement in the priming coat changes ferric oxide (rust) into inert calcium ferrite, permitting the priming coat to form a perfect bond with the steel surface. The bituminous coating protects the priming coat.

Sections of the country in which corrosive brines are present in the sub-soil, and in which sections pipelines corrode severely andrapidly, are known as hot spots. The entire Mid-Continent oil field, the Gulf coast, the Roclw Mountains, and eastern State oil areas contain many hotspots.

We have made experiments on a test section of pipe in a west Texas hot spot, which was a low place which formed the drainage ground for a wet-weather lake. Pipe-lines running through this spot have had to be replaced on the average of every eighteen months. Each time the pipe was replaced it was coated with the best available coating which could be secured, and yet it was necessary to continually replace pipe-lines running through this area. A test section was coated with a suspension of Portland cement in boiled linseed oil. The linseed oil was kettle boiled at a temperature from 200 to 225 F. to insure that it was thoroughly dehydrated, and an emulsifying agent was incorporated. The emulsifying agent used was aluminium stearate. It is to be understood that any of the water insoluble metallic soaps may be used as the emulsifying or jellying agent, such as stearates,palmitates, oleates, resinates and the like. While we have used linseed oil, it is to be understood that any paint vehicle such as drying or semi-drying oils may be employed. The aluminium stearate is quickly taken up and is added in the amount of from 5 to 15 per cent by weight. The colloiding agent jellifies the boiled linseed oil and imparts to it an increased viscosity and enables it to hold Portland cement in suspension. One part by weight of the jel thus formed is then stirred into 10 to 12 parts by weight of a paint vehicle such as linseed oil. Commercial Portland cement 15 which has been reground to additional fineness so that it will pass through a 250 mesh screen, is then added to the above vehicle in an amount so that each gallon of the finished cement paint will contain from 5 to 8 lbs. by weight of Portland ce- 2o ment. The test section was thoroughly cleaned to obtain a clean metal surface, and an application of the suspension of Portland cement was then made. This was allowed to dry for fortyeight hours and a coating of coal tar pitch containing a minor proportion of a fibrous binder, in this instance asbestos binder, was applied. Several test sections were placed in the hot spot. After eighteen months one test section was inspected and the coating was found to be in as perfect condition, apparently, as when installed. The coating was hammered briskly with a ballpeen hammer. Most pipe-line coatings are brittle and this treatment would chip or crack ofi sections of the coating. No effect was had by the hammering. The test section was then hammered with the edge of a heavy trowel sufliciently hard to dent the metal beneath. The coating, however, did not chip 011. The finish coat and the primer remained intact at the bottom of the dent, and only broke at the edges where actually cut by the trowel. The coating could be removed only by a sharp knife. When out it became apparent that the finish and primer coats had bonded and the combination coat had united firmly with the pipe. Where the coating was removed by a sharp knife, the pipe was clean without a trace of corrosion or pitting.

Another test section was moved after two and one-half years, and showed the coating in perfect condition with no reaction on the outside coat or priming coat. The pipe was as clean as when the coating was applied.

Another test was made in the famous Spindletop hot spot", where corrosion eats up cast It was then covered with an ordinary asphalt,

wrapped with burlap and buried at pipe-line depth. It was left in the ground for three years and two months. When taken up the asphalt coating was found to be dry and brittle and in unsatisfactory condition, but the priming coat was intact. The rust had completely united with the Portland cement. The pipe surface was clean, free from pitting and corrosion and in generally satisfactory condition. As far as we know it is the only successful test on record in this Spindletop hot spot,

It will be seen that we have accomplished th objects of our invention. We have provided a corrosion resisting pipe and a method of forming same. In some cases it might be desirable to wrap the outside coat of bituminous material with fabric, though this is not necessary.

While the disclosure of the invention has been described in connection with longitudinally laid pipe lines, it is contemplated as well that the corrosion resisting coating may be used on oil well casing, solid rods, or any metallic surfaces subjected to underground corrosion.

Having thus described our invention, what we claim is:

1. Underground metal pipe having a coating of Portland cement incorporated in boiled linseed oil by aid of a water insoluble metallic soap of an organic acid, in contact with the metal of said pipe and a second coating of pitch containing a minor portion of a fibrous binder over said first coating. v

2. A method of coating underground metallic pipes including the steps of applying a coating of Portland cement incorporated in boiled linseed oil by the aid of a water insoluble metallic soap of an organic aciddirectly to the metal of the pipe, permitting said coating to set and then applying thereover a second coating comprising pitch containing a minor proportion of a fibrous binding.

ALBERT C. BEAN. JOSEPH B. RAY. I