US2301165A - Machine for coating pipe - Google Patents

Description

3, A. w. MACHINE FOR COATINGv PIPE Filed July 13, i940 INVENTOR Hlw'n Neal Y Nw Mmmm

Qgwp/nauu ATTORNEY Patented' Nov. 3,1942

NT OFFICE MACHINE FOR COATING PIPE Alvin W. Neal, Mount Lebanon, Pa., assignorfto Gardiner Coating Machine Company, Inc., a

corporationk of New York Application July 13, 1940, Serial No. 345,267

Claims.

This invention relates to a machine for coating a pipe and more particularly tothe formation upon the pipe of a thick thermoplastic coating that has a satisfactorily smooth exterior surface and that is substantially free from pinholes and other flaws including those commonly known as holidays In the 'art of the coating pipe, such as that to be used in underground pipe lines, it is customary to employ a machine which is supported by rollers resting upon the pipe and which, as the machine moves along the pipe, supplies the coating materialat a position behind the supporting rollers. As the coating ordinarily a thermoplastic material including as the base asphalt, pitch, tar, or the like, the coating sometimes including fillers, plasticizing agents, or other admixtures.

Y When such material is applied, imperfections appear in the layer of coating' material. Thus, numerous pin-holes, air bubbles, or thin spots are frequently found in the coating layer. In fact, these imperfections are so common that there has been recommended the electrical testing of coated pipes, to show the positions of the imperfections by arcing through weak spots in the coating. 'I'here has long been need of a convenient method oi' applying a two-layer coating, without the need of an intermediate layer of felt or other means to protect the coating first applied from injury by the supports for the machine, as the machine is again moved over the pipe in supplying the second coating.

Also, there has been need of a simple manner of` smoothing the exterior of the material, to eliminate striations, grooves, or other irregularities of surface introduced during the application of the coating composition.

The present invention provides a'machine for overcoming these difficulties,4 and disadvantages in a machine for coating pipes with compositions of the kind described.

The invention makes possible flowing and spreading heated coating` composition before it hardens over a previously applied layer of the composition and into flaws therein.r In the preferred embodiment, the invention provides means material, there is used -4 i and 4scribed in the said patent to of the first layer before the -additional material is applied.-

The additional material readily wets the surface of the layer first applied and is quickly drawn thereover by the forced of surface tension and gravity. The layer of material rst applied, having been cooled somewhat by the cold pipe, cools in turn the additional materialand thus decreases the flowability before an excessive amount of the additional materiall drains away. As a resultthere is obtained not only penetratignpf the additional. material within or spreading"ver the aws of the originalcoating but also a relatively smooth exterior surface of the final layer of coating material. A.

The invention will be in connection withthe attached drawing.

Fig. lis a side elevation of` my machine partlyin section; Fig, 2 is rig. 3 is" aside elevation partly broken away for clearness ot Aillustration of a pipe coated in accordance with the invention.

The present machine represents an improvement upon the machine described in U. S. Patent ,L

No. 2,194,268 issued toJames D.`Cummings on Y i Pipe coating de-1.y thesame'as de-v March 19, 1940, and vice.

entitled Parts and details are Cummings, except as noted herein. The present machine differs for applying heated coating composition over a portion of an unheated pipe, spreading the resulting layer'of applied material mechanically over at least the lower portion of the pipe,` and then applying additional flowable coating composition, at a position removed from the place of applicafrom the machine of Cummingsparticularly in K :u the provision of supplementary means, to the v right in Fig. 1, for applying additional coating@l collecting the drip-VY composition and means for pings and run-oir of the additional material and returning' them to a receiver from which they are ,elevated to a position abovethe pipa-for re-use* "7".

as coating material.

In the drawing, there are shown section of f5 I coating ma-` pipe lll to be coated and thepipe chine mounted upon the pipe.

The coating machine includes a supporting frame work mounted upon rollers l2 which restV upon the top of the uncoated portion of the pipe.,`r

The machine includes also coating material, a nozzle I a hopper i3 for the spreading member or shoe of frusto-ccnical segments I5 including a series tion of the first layer, so as to allow some cooling the spreading member are spaced at a predeterillustrated by description a sectional view on line 2-2 of 1i 4 with suitable coni nections for delivering coating material from the hopper to the upper portion of the pipe I0, a.`

of rigid material, and a support I8 for the various parts of the spreadmined distance from the pipe it), as by means of pins or screw bolts il, the inner ends of which .rest against the pipe; by their setting, these pins control the space between the pipe and the edges of the spreading elements, thus determining the thickness of the coating which is left on the pipe after the shoe has passed the position of coat ing. t will be noted that the shoe or spreading member extends only around the lower part of the pipe. If desired, however, the spreading member may constitute a ring (not shown) extending completely around the pipe, in accordance with the conventional construction of spreaders that are sometimes used.

Disposed below the spreader member .is a receiver iii constituting a reservoir for collecting material which overflows from the sides of. the spreading member or otherwise passes downwardly. A tube in the form of pipe line is, opening at its lower end in the reservoir and connecting at its upper end with pump 2c, provides means ior returning the liquid from the reservoir to the hopper i3 above the pipe itl.

The present improvement comprises supplementary means for supplying additional coating material. These means include the tube` or pipe Ei for delivering the additional coating material, as from the reservoir i3 and through the spreading nozzle 22, to the upper side and mid-portion of the pipe. A drip pan or apron 23 extends on both sides of the position of application of the additional coating. This apron 23 receives the drippings and run-od` from the additional' coat ing and returns them, as illustrated, to the reserM voir id, so that they are combined with the material which is delivered through pipe i@ and pump 2@ to the upper part of the machine. Valve til disposed in the tube iii provides means for controlling the flow ci the coating composition through the tube.

The apron 23 is supported upon the trame work of the machine, as by braces il.

The pipe 25, which is shown only in part, pro vides an inlet ioradditional coating material as needed for the operation of the machine or an outlet from the reservoir i3.

A pipe coated by the machine described is shown in Fig. 3. The layer of coating material applied by nozzle id and spreader member ib is indicated at 25, whereas the additional coating flowed upon layer 28 is denoted by El.

Burner 28 is arranged to deliver a flame into a chamber dened by the metal member 2@ disposed below the burner and the bottom 3@ of the reservoir "it previously described.l This bot torn 3G is provided with an outlet Eil for the products of combustion which rise between an outer acordes to the pipe in substantially unheated condition.

Among such compositions that suitable those having the general properties stated andl that are commonly used in the coating' oi pipes to prevent corrosion, as forexample, the so-called pipe coating enamels. These enamels ordinarily have asphalt, tar, or pitch, as the base or major ingredient with the admiirture of a binder or iller material and suitably also a plasticizer.

The by-product tar from the manufacture ci illuminating gas or wood pitch are preferred as the base materials, because of thev relative toughness and other desirable properties of coating compositions including such tar or pitch.

As the iiller, there may be used any of those solid materials that are usual in pipe coating .enamels as for example, mica, slate powder, or

asbestos fines.

It a plasticizer is used, it is a material adapted to extend the range of fiowability of the base material, so that there is avoided a rather sudden change from a non-nowable almost solid material to a freelowing liquid. if asphalt is used the base, the addition of a plasticizer is not so important, because the asphalt alone softens gradually, over a wide range of temperature. With tar or pitch, on the other hand, the change from practically non-owable solid to a thin liquid is relatively sudden, so that the use of a plasticizer is important, to widen the tempera ture range during which the material is a viscous liquid. The plastclzer used is one of those that is conventional for the purpose.

The proportions oi materials, if any, added to the asphalt, tar, pitch, or like base may be varied in accordance with the consistency desired in the coating material and in accordance with usual practice.

The coating composition to be used is placed, either in the cold or preheated condition, upon themember d@ of the receiver at the bottom of the machine, or in preheated conditionn in reservoir is. The pump E@ is started and the burner 2S placed in operation.

Relative motion between the coating machine and pipe iii is initiated, longitudinally with re=1 spect to the pipe iii, the coating machine during this motion being supported upon the bare pipe by rollers i2 and others (not shown).

E@ The movement of the pipe with respect to the casing member 32 and an inner casing member .4

coating composition to be applied. The coating composition should be one that is iiowable as applied but adapted to be hardened quickly by` contact with the cold pipe iii. For this purpose there are used thermoplastic compositions that are applied in the heated or warmed condition 75 machine is to the right in Fig. l, ordinarily the pipe being supported in fixed position and the machine being pushed along the pipe.

During this movement and the operation of the machine as described, the coating material is delivered by nozzle ill to the pipe and allowed. to now downwardly around the pipe and into the shoe l5 including the spreader elements. The shoe soon becomes lled with the composition and spreads it over the lower portion ot the pipe.

The heated coating composition so applied is cooled by the contact with the pipe the relative motion between the machine pipe proceeds.

The line 2l delivers additional coating material to the pipe, by nozzle 22. No spreading member is necessary here, the additional coating com position under the influence of surface tension and gravity spreading over the layer .drst applied, the excess of the tional composition appearing as run ofi or dr. and being colm lected in the apron 23 below the pipe ld.

The apron delivers falling on the apron to the reservoir it. The run ofi and drip-n pings trom both the first second coat accidentally by other means.

` ing operations are returned from the reservoir through the pipe I9 tothe pump 20, for re-use.

' 'After the application of the second coating, the coated pipe is ready for use. The coated pipe may be wrapped, however, with felt as by means of a conventional Vpipe wrapping machine (not shown), if the wrapping is desired.

with means similar to the nozzle I4 and spread- A ing member i5.

In applying the iirst and usually the only layer p of coating material, the thickness of coating is controlled as stated by the spacing pins Il. As the machine moves along thev pipe, these pins bear upon the pipe. The spreading elementsfollowing these pins tends to closeup and heal the grooves which are necessarily formed in the coating layer by the pins. This closing up and healing of the grooves is not always completely effective. i v

Furthermore, other irregularities or striations are present in the layer of coating material. Most important are holidays These take the formof pin-holes, due, for instance, to the initial inclusion and subsequent breaking of air bubbles or to thin spots in the coating introduced Since these holidays ordinarily require hand retouching of theA coating, a ring electrode has been used to' detectL the positions of them. Thus, a ring electrode is moved over the coated pipe, at a predetermined spacing from the pipe, the metal of the pipe and the electrode beingmaintained at a very high potential diierence. Indicating means, such as a light, signal the position of dielectric weakness and consequent arcing between the electrode and the metal of the pipe.

When the additional coating material is applied by tube 2i, this material quickly wets and spreads over the iirst coating which has then become somewhat hardened by partial cooling, as the position of application of the initial layer and the additional material are spaced at substantial distances apart and there is an appreciable though short interval of time .between the moments of application of coating material at the two positions. The additional coating material flows into or over the holidays, closes the grooves, and spreads as a relatively smooth coating over lthe exterior of the layer iirst applied.

The result is a pipe coating that contains relatively few `if any holidays and that is satisfactorily thick and of desirably smooth exterior.

means including a source of supply of the coating composition and a tube connected with the source oi supply, the tube opening above the midportion of thesaid pipe at a part thereof subsequent to the position of application oi the sai layer, so that the coating composition is delivere by the said tube upon the layer rst applied immediately after said iirst layer hardens 'to cling to the pipe, ilows downwardly therearound, and forms a smoothing coat over the said layer. v

2. In apipe coating machine comprising means for applying a layer oi heated thermoplastic iiowable coating composition to a pipe, a spreading member for distributing the applied composition over the'lower portion of the pipe and means for causing relative motion between the said machine and pipe, longitudinally with respect to the pipe, the improvement comprising supplementary means for applying additional heated coating composition over the layer rst applied, the said supplementary means including a source of supply of the heated coating composition and a tube connected with the source of supply and' opening above the mid-portion of the said pipe, at a part thereof subsequent to the position of emergence of the pipe from the action of the spreadingY member. so that the coating composition is delivered by the said tube upon the layer first applied, immediately after said first layer hardens to cling to the pipe, iiows downwardly therearound, and forms a smoothing coat over the said layer. l

3. A pipe coating machine comprising means for applying a iiowable thermoplastic coating composition as a layer around a cold pipe, means for supporting the machine upon the pipe in such manner as to make the machine movable lengthwise of the pipe, means for delivering additional coating composition of the kind described upon the upper part of the layer of composition rst applied immediately after said iirst layer Yhardens to cling to the pipe, so that the additional coating composition flows downwardly around the said layer, a catch member disposed below the pipe and extending on both sides of the position of dripping of the applied additional composition, means for returning the collected drippings to a receiver, and means for returning the col- ,lected material from the receiver to a position above the pipe, for application to the pipe.

4. A machine as described in claim 3 including means for heating the coating compositionto be applied to the pipe, the position of application of the additional coating being spaced a substantial distance from they position of application of the original layer, so that there is cooling It will be understood that the details given are for causing relative motion between the said machine and pipe, longitudinally with respect to the pipe, and supplementary means for applying additional coating composition over and directly upon that rst applied, the said supplementary of the layer by the cold pipe and attendant hardening of the coating composition before the additional composition is applied.

5. A machine as described in claim 3 including spreading means acting upon the said layer of coating material first applied, Aso as to spread the said composition over the lower portion at least of thepipe, the means for applying additional coating composition including a tube delivering the additional composition through a spreading nozzle upon the pipe to be coated so that the additional composition flows downwardly around the said layer and to the said catch member for collecting drippings.

, ALVIN W. NEAL.

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