US2167138A - Treatment of gas distribution systems - Google Patents

Description

July 25, 1939. B, w s 2,167,138.

TREATMENT OF GAS DISTRIBUTION SYSTEMS Filed Jan. 11, 1939 Patented July 25, 1939 TREATMENT OF GAS DISTRIBUTION SYSTEMS Duncan B. Williams, Glen Ridge, N. J., assignor to The United Gas Improvement Company, a corporation of Pennsylvania Application January 11, 1939, Serial No. 250,306

5 Claims.

This application is a continuation in part of my copending applications Serial Numbers 167,316 and 167,317, filed October 4, 1937, which in turn are continuations in part of an application copending therewith Serial Number 673,618 filed May 31, 1933, now Patent 2,094,691, dated October 5, 1937.

The invention pertains generally to the treatment of the-interiors of gas mains or other gas enclosures for the purpose of sealing joints or laying dust, or both.

The invention pertains more particularly to the use of glycerine, and glycerine mixtures for the treatment of the interiors of gas conduits.

Systems for the distribution of gas include conduits or mains which are usually laid underground, and which comprise sections of pipe joined together by means of welding, by means of packed joints, )or otherwise.

The welded joint is a more recent development and is used chiefly to join pipe sections of steel or iron, other than cast iron.

Older mains are usually made up of cast iron pipe sections joined by means of bell and spigot or other similar joints. These joints are frequently packed with hemp, jute, flax or other cellulosic material which in turn is backed up with lead or cement or other material in a well known manner.

The lead or cement seal is tight and effective in preventing gas leakage when first applied but soon loses this quality due to expansion and contraction of the main with change in temperature or for other reasons. When this happens the effectiveness of the joint in preventing gas leakage depends entirely upon the packing.

Manufactured gas for a long period of years has been produced for the most part locally, that is, in or near the points to be supplied. Until recently no special effort has been made to recover condensible materials from the gas prior to its delivery to the mains. As a consequence such gas is upon delivery to the mains more or less saturated with moisture and is generally referred to as being wet.

In the case of a wet gas the lower temperatures of the mains particularly during cold weather causes considerable condensation of water as well as of other material composed chiefly of hydrocarbons, the latter being referred to generally as drip oil. v

Since the joint packing, namely, hemp, jute, flax or other cellulosic material is exposed to the interior of the gas main, such packing is also exposedto the wet gas and any condensed water, 7

the latter accumulating and/or flowing along the bottom of the main.

As a result the packing absorbs moisture-and is swollen thereby asthe moisture penetrates the cells of the fibers of the packing, causing the packing to form a gas-tight'fit.

' Generally speaking, there are two types of cellulosic packing or yarn which have been used in joints of gas mains or other gas enclosures.

At the time of their insertion in the joint, packing materials may be classified as absorbent and non-absorbent in that the capacity of the former to absorb water has not been impaired by special treatment, whereas such capacity of the latter has been purposely removed such as by treatment P with tar.

These widely difierent types of packing may be referred to as untarred and tarred respectively, and have widely different characteristics in service.

For instance, the untarred type of packing is capable of absorbing water which in turn swells the packing.

Until recently, when high pressure distribution has come into more general practice, the bell and spigot or other joints packed with the untarred type of packing gave very little trouble since the gas generally contained suificient moisture to keep the packing saturated and, therefore, gas-tight.

In fact traps or drips were installed at low points in the mains to catch the condensed hydrocarbons (known collectively as drip oil) and condensed water vapor.

However, when the gas is compressed to a high pressure for long distance distribution usually in welded mains before being expanded to low pres- Y sure for local distribution, most of the water vapor (and some of the oils) are condensed out. There is then no longer suflicient water vapor in the gas when expanded to the low pressure to keep the fibrous packing in the packed joints in the low pressure mains moist. On the contrary, the gas is so dry that it rapidly draws out any absorbed moisture in the packing. When the packing dries out serious leaks occur.

In other words, as long as the main is used for distributing ordinary manufactured gas very little trouble with joint leakage is experienced, pro-' vided the packing is of the untarred type, or if of the tarred type that sufficient tar has been re-.

moved to render the fibres of the packing absorbent.

However, when the service is changed over to a manufactured gas of lower moisture content, or over to natural gas which is characterized by a.

very low moisture/content, or over to mixtures which are essentially dry, the packing dries out and shrinks sufficiently to cause the joint to become leaky.

While the useof'the tarred type of packing avoids the absorption of water in the first instance, and consequent drying and shrinking should the moisture content of the gas be lowered, nevertheless, the, tarred type of packing has not beenwholly successful. This is thought to be due in part to shrinkage in volume or cracking'of the tar due to drying or polymerization, and also in part to the necessity of swelling a packing in a joint to cause the packing to conform more exactly to the contour of the joint and to reduce voids between the fibers.

I as spindle oil, such expansion is only 14%.

To overcome these deficiencies in the tarr ed type of packing it has been proposed to force into the voids between the fibers a highly viscous liquidsuch as oil or glycerine under considerable pressure and to thus plug the leaks. However, even though such pressure is considerably greater 'than" that of the gas within the main, when such pressure is released, the viscous liquid will eventually be dislodged and the treatment must be repeated, In fact, it has been proposed to use the tendency of such liquids to dislodge as a substitute forgas or air in testin the leaking tendency of a joint.

While the packing as a whole may be said to absorb or to be moistened or impregnated with such liquids in the sense that such liquids enter between the fibers and thus function as fluid packings, the ind vidual fibers are incapable of taking up such liquids because the fibers themselves have been previously impregnated with Ample proof of non-absorption by the individual fibers lies in the fact that such liquids may function as testing med ums to determine the tendency of a joint to leak which would be impossible if glycerine were absorbedby the individual fibers since such absorption would cause the fibers to swell to tightly close the joint and make it impossible to transmit pressure therethrough.

Further proof of the absence of absorption by the individual fibers and consequent swelling lies in the fact that oil and glycerine are considered full equivalents for such treatment, whereas oil is wholly incapable of swelling untarred and therefora'absorbent fibers to more than a small fract on of the swelling caused by water or by glycerine.

or instance, the volume expansion of dry jute on saturation with water or with glycerine is 44% whereas with oil, even though non-viscous, such A swelling of substantially 44% isrequired to stop leaking. v

Another great disadvantage of the proposed treatment of tarred packing is that it is necessary to dig up the main at each joint each time the treatment is required. Q)

In order to successfully treat tarred packing it is necessary to cut or d ssolve out sufficient tar either before or during the treatment to render the packing fibres absorbent, and then cause the packing to swell as described and claimed in copending application, serial number 236,822, filed October 24, 1938 by John R. Skeen.

. Soap is sometimes applied to the untarred type of packing. Such treatment, however, does not prevent drying and shrinking.

A number of methods for correcting leaky joints have been proposed and used. For instance, the joints may be individually uncovered and surrounded with a rubber clamp. This method is effective in stopping leakage but is very troublesome and expensive. Also attempts have been 5 made to re-moisten the untarred type of packing by spraying oil or steam into the mains, this being known respectively as oil fogging and steam fogging. I Y

The oil commonly used for this purpose has 10 been drip oil condensed out of the gas during I compression or other mineral oil, such as petroleum oil. Neither type of oil causes any considerable swelling of the packing, and is, therefore, inefieetive inperrnanently sealing the joint. Con-' 15 sequently, this type of fogging must be continu-- ous. I Fogging with steam must also be continuous since when stopped the joints immediately dry out.

7 Referring now to the problem of dust, over a 20 period of years the water condensed from wet gas together with other constituents of the gas such as carbon dioxide, hydrogen sulfide, hydrocyanic acid, naphthalene, and so forth, have in 25 many instances, caused extensive corrosion of the interior walls of the mains. The products of corrosion have accumulated on the walls of the mains and, in many instances, large quantitles have become disconnected and have col- 3o lected along the bottom.

Due to. the presence of relatively large quantitles of moisture, largely responsible for the corrosion in the first instance, the products of corrosion were maintained in a wet condition and 35 did not tend-to form dust in any appreciable quantity.

Therefore, until high pressure distribution came into practice, and while the use of natural gas or natural gas mixtures was less widespread, very little difflculty was experienced with the formation of dust in mains from the products of corrosion.

15 other words, as long as a main is used for distributing ordinary wet manufactured gas very little trouble with dust resulting from corrosion is experienced. However, when the service is changed over to a manufactured gas of low moisture content, or over to natural gas or natural gas mixtures wh ch moisture content, the moisture on and in the corrosion-products dries out and such products become a serious source of dust. I

The presence of considerable quantities of dust in the gas flowing through the mains of a distribution system is very undesirable because dust tends to clog up customer service connections, interferes with the proper operation oi. meters, and tends to clog up burners and pilot outlets.

Under extreme conditions corrosion may be so severe as to form a serious obstruction in the main itself by reducing its effective cross-sectional area such as by the accumulation of dust in piles in the main.

A number of methods of correcting dust troubles have been proposed and used.

For instance, excavations have been made at suitable spaced points along the main, say every 300 feet, the main severed at each excavation 7 and the accumulation removed mechanically.

This has been done by dragging a ball of chain back and forth through the disconnected section and increasing the size of the ball as more and more of the products of corrosion have been are characterized by very low 50 removed. In some instances a cutter has been substituted for the ball of chain.

In another method a compressor is conformed to function as a suction device for sucking air through the disconnected main section, and the dust is collected in a bag in a manner customary in the operation of the ordinary vacuum cleaner.

It will be appreciated that either of the foregoing methods of overcoming dust troubles is very expensive in view of the immense amount of labor involved. Furthermore, both methods put the main out of service during the treatment.

The use of steam for dust laying has the same disadvantage as when used for joint sealing, namely, that the deposited moisture dries out as soon as steaming is stopped. As far as I am aware the same also applies to the fogging of oil into the mains, since the oil which it has been necessary to use for successful fogging has had to be so light as to make it appreciably volatile. Furthermore, since the corrosion products comprise not only ordinary iron rust but also a variety of other compounds resulting from the action of hydrogen sulfide, hydrocyanic acid, naphthalene, and other corrosive substances, the problem of wetting down the dust, of wetting the main wall, and of thoroughly spreading a dust laying liquid becomes a major factor.

The swelhng of dry Jute caused by a number of liquids is set forth in Tables 1 to 3:

TABLE 1 Substance Swelling Percent Water 44 Glycerine 44 Ethylene glyco 44 Diethylene glycol 44 Monomethyl other of ethylene glycol 38 Monomethyl ether 01' diethylene glycol 44 TABLE 2 Substance Swellng Percent Monobutyl ether of ethylene glycoL 0 Monobutyl ether of diethylene glycoL. 0 Monophenyl ether ol' ethylene glycol... 0 Triethylene glycol 1 Monoethyl ether of triethylene glycol 2 Monomethyl amyl ether of ethylene glycol 4 Monoethyl ether of diethylene glycol l6 Monoethyl ether of ethylene glycol 10 TABLE 3 Substance Swelling Percent Mixed tar bases 0 Hermie 3 Quinoline h 4 Octylaldehyde 8 D 8 9 l 1 l3 l4 Benzaldehyde 0 Oleic acid l 3 0 0 4 0 13 Disintegrates Disintegretes Disintegrates It will be noted that only five substances have been found which swell dry jute to substantially the same extent as water. I

Substances suitable for dust laying embrace a somewhat larger field as more particularly set forth in my copending applications Serial Number 167,316 and Serial Number 208,729 filed Oct. 4, 1937 and May 18, 1938, respectively.

A number of dust laying liquids are set forth in Table 4.

TABLE 4 I a High boiling alcohols and/or ethers Glycerine Ethylene glycol Diethylene glycol Monomethyl ether of ethylene glycol Monomethyl ether of diethylene glycol Monobutyl ether of ethylene glycol Monobutyl ether of diethylene glycol Monophenyl ether of ethylene glycol Triethylene glycol Monoethyl ether of triethylene glycol Monomethyl amyl ether of ethylene glycol Monoethyl ether of diethylene glycol Monoethyl ether of ethylene glycol Octyl alcohol Lauryl alcohol Cetyl alcohol Propylene glycol Dipropylene glycol Organic oils Sulfonated corn oil Sulfonated cottonseed oil Sulfonated palm oil Turkey red oil Sulfonated cocoanut oil Sulfonated castor oil Sulfonated sperm oil Sulfonated cod liver oil- Sulfonated soy been 011 Sulfonated olive oil Sulfonated mineral oil Sulfonated peanut oil I have found that glycerine (glycerol) when admixed with a viscosity reducing agent is ideally suited for treating the interior of a gas conduit for the'purpose of laying dust and for swelling cellulosic fibre joint packing when such packing is present, provided the fibres of such packing have not been rendered Wholly non-absorbent such as by the application of tar.

Viscosity reduced glycerine is excellently adapted as a dust laying agent and when absorbed by the individual fibres of the packing,

the joints thus treated remain effective in preventing gas leakage.

Glycerine has the important advantage that it is substantially non-volatile. As a result, the treatment is of a substantially permanent character.

Furthermore, it is substantially inert in gas conduit environment and particularly with respect to the various types of natural and artificial gases which are now used; these gases have substantially no afilnity for glycerine.

Moreover, it is a very hygroscopic liquid having a strong ailinity for water vapor, and thus tends to increase rather than decrease in mass on exposure to moisture.

Pure glycerine, while efiective, is too highly viscous in undiluted form for practicable use. It is not only difficult to handle in pure form, the flow being at an extremely low rate, but also .its

which it is absorbed by the packing are extremely low.

However, when once in place, it is highly effec- 5 -tive for both dust laying and joint sealing pur- The flowing, wetting and climbing properties of glycerine may be improved upon dilution with a wide variety of substances.

When joint scaling is involved, I prefer to em- Dloy as a diluent at least in large part, one or more of the other substances listed in Table 1, all of which are of lower viscosity and have a comparable swelling action.

On the other hand, when the problem is primarily one of dust laying, I prefer to employ as a diluent at least in large part, one or more of the other liquids listed in Table 4 which as will be noted includes the liquids of Table 1.

These liquids for the most part are mutually miscible with glycerine and all are soluble in water. Should any combination of liquids prove to be incompletely miscible, water or any other suitable substance may be added as a common solvent, or an emulsifying agent might be added to form an emulsion, if desired.

The presence of moisture at the time of treatment will assist rather than resist wetting of the main wall, of the corrosion products, and of the packing. In this connection, it is to be obmrved that liquids of the prior art such as "drip oil" or petroleum oil" are non-hygroscopic in character and are characterized by being completely nonmiscible with water. Since it,is a well recognized fact that when a solid is contacted by two immiscible liquids one of the liquids will wet the solid to the exclusion of the other, and since this phenomenon has been shown to apply particularly to mineral oil and water, it will be seen that thorough and complete distribution of mineral oil is not possible in the presence of even a trace of water. It will be recognized that the surfaces ,of corrosion products in the mains may become sufficiently dry to cause serious dust troubles without the entire mass losing its water content. Therefore, the importance of this prop- .erty in my treating liquids cannot be overestimated.

Accordingly, water may be employed to assist in the wetting and spreading of the treating liquid such asby first wetting with water, for instance by steaming, followed by application of the treating liquid, or water may be added to the treating liquid or otherwise employed in the treatment.

While except in the case of water which is relatively inexpensive and is present under certain conditions, I prefer to use viscosity reducing substances of low volatility and having at least some properties in common with glycerine, nevertheless, materials such as the lower monohydroxy alcohols, for instance ethyl alcohol, and other volatile liquids which are good solvents are not to be excluded since they may be,used as solvents for glycerine or glycerine mixtures to facilitate its applicationto the conduit walls, to the products of corrosion, and to the fibres of the packing.

If desired, other substances may be added, for instance, substances to enhance tar penetration as described and claimed in the above mentioned copending applicationby John R. Skeen.

Generally speaking, any of the foregoing viscosity reducing agents will enhance the flowing,

; wetting and climbing properties of glycerine, and

the mixture retains the superior qualities of glycerine for main treating purposes.

The viscosity in centipoises of various liquids at C. is shown in the following table.

It is advisable to reduce the viscosity of glycerine to at least 85 centipoises at 20 (2., and preferably for all around main treating p rp ses to at least 50 centipoises at 20 C. Glycerine solutions having viscosities at 20 C. of 44 centipoises and centipoisesrespectively, have been employed with unusual success.

To reduce the viscosity of glycerine to a desired point, a sumcient quantity of a lower viscosity material or materials are, of course, added.

' For purposes of estimation and roughly speaking, when mixing two liquids having diflerent viscosities, the resulting mixture will have. a vialcosity which will be roughly what would be ex-; pected from the percentage composition. For instance, if a liquid having a viscosity of 40 centipoises at 20 C. is mixed half and half with a liquid having a viscosity of 20 centipoises at 20 C., the mixture at 20 C. will, roughly speaking, have a viscosity of 30 centipoises.

The viscosity may then be adjusted to the desired point, for instance, by adding either more of the less viscous or more of the more viscous material.

It is to be understood, however, that the exact viscosity is not of importance, it being merely necessary to have the final treating liquid of a sumciently' low viscosity for practicable main treating purposes.

The treating liquid maybe applied to the interior surface of a pipe section and/or to the packing in a joint in any desired manner.

If the main is already in service, sections of the main may be blocked off by means of infiated bags or other means, and the sections then completely filled with the liquidafter'which the liquid can be drawn off and re-used.

0n the other hand, the liquid may be sprayed into the gas by the fogging procedure earlier mentioned so that the packing and/or dust sources absorb the liquid from the gas stream or, in other words, so that the liquid is deposited from the gas stream onto the packing and/or onto the sources of dust. I

In another-method of application the liquid is introduced into the main at high points and allowed to run by gravity to low points where the excess can be drawn nif. An examination of mains treated in this manner shows that my compositions have greatly improved climbing properties.

Another method comprises inserting a long length of hose into the main with a spray at its end, or with a plurality of sprays distributed along its length, and pumping the treating liquid into the hose while withdrawing the hose either continuously or intermittently or otherwise, or while the hose remains stationary. V

In the last three methods of application service on the line need not be interrupted. The packing becomes saturated with thecomposition and dust Turn 5 Substance centipoises I Glyccrinc can. no Dicthylcnc glycol 38. 00

Ethylene gly 21. 0 Monornethyl ether of dicthylcnc glyco 6. (I) Monomethyl ether of ethylene glycol. 1. Ethyl alcohol (95%) l. 41

sources become coated with the. treating liquid. The wetting quality of the treatingliquid causes it to spread, climb and wet exposedsurfaces; The wetting of finely divided material causes it to be bound together in a mass which prevents it from A description is by way of illustration and that rising in a dust regardless of the velocity of the gas traveling through the main. The clogging of mains, meters, regulators and appliances is thus efiectively prevented.

A typical gas main is illustrated in the drawing in which:

Figure 1 is a side elevation, partly in-section, illustrating a gas main; and

Figure 2 is a cross-section on line 22 of Figure 1.

In the drawing the gas main I is shown with a joint comprising bell II and spigot l2 fitting within said bell and spaced therefrom. In the space between the bell and the spigot is an absorbent packing l3 and a seal M of lead or other suitable material for holding the packing in place. The treating liquid N as illustrated is being run through the main by gravity. It contacts the bottom of the main and any deposits accumulated thereon. It also contacts the packing at space l6 which space is left between the spigot and the shoulder of the bell to provide for expansion and contraction due to temperature changes. The packing absorbs the liquid at l6 and the liquid tends to climb and be carried up in the packing by capillary action as shown by the outer group of arrows in Figure 2 to the uppermost portions thereof. Glycerine causes the packing to swell to substantially the same extent as water. The treating liquid also tends to climb up the metal walls of the main as illustrated by the inner group of arrows in Figure 2 to coat dust sources in addition to those along the bottom of the main.

The bulk of the treating liquid, of course, remains in the main only during the time that its flow from the point of introduction to the point of removal which usually is the nearest drip.

Any other means for applying the treating liquid to the packing and/or to the interior of the conduit may be employed. For instance, in the case of large diameter mains the level of the liquid 15 may be raised or may be made to fill the entire main if desired, or the spray or fogging methods may be employed.

In the case of a welded main, or mains having joints packed with materials other than untarred cellulosic fibre packing, the treatment becomes primarily one of dust laying.

While the invention has been described in connection with gas conduits, it is to be understood that it is applicable to any part of a gas distribution system wherein similar problems may arise. It is also to be understood that the various agents referred to herein may be used either in the pure or commercially pure form, or in any other suitable from including the commercial and crude forms.

It is, of course, understood that dust sources in a gas conduit might be accumulations of corrosion products or dust within the main, or the main wall or any portion thereof whether corroded or not at the time of treatment.

It is to be understood that the above particular changes, omissions, additions, substitutions, and/or. modifications, might be made within the scope of-=-the claims without departing from the spirit of the invention.

I claim:

1. A method of treating the interior of a gas conduit which comprises applying to the interior of said conduit a liquid comprising glycerine having admixed therewith a viscosity reducing agent.

2. A method for treating the interior of a gas conduit to lay dust which comprises applying to dust sources in the interior of said conduit a liquid mixture comprising glycerine and a viscosity reducingagent for said glycerine.

3. A method of treating the interior of a gas conduit to reduce gas leakage through a point thereof, said joint being packed with cellulosic fibre packing such as jute which is exposed to the interior of said conduit, and the fibres of which have not been rendered wholly non-absorbent to the treating liquid such as by a coating of tar, comprising applying from the interior of said conduit to at least a portion of said packing exposed thereto a liquid substance which contacts by capillary action non-exposed fibres of said packing and penetrates fibre cells to cause swelling of said packing, said liquid substance comprising glycerine and a quantity of a viscosity reducing agent suflicient to reduce the viscosity 'of said glycerine to at least 85 centipoises at C.

4. A method of treating the interior of a gas conduit which comprises applying to the interior of said conduit a liquid comprising glycerine and a quantity of a viscosity reducing agent sufficient to reduce the viscosity of said glycerine to at least 85 centipoises at 20 C.

5. A method of treating the interior of a gas conduit to reduce gas leakage through a joint thereof, said joint being packed with cellulosic fiber packing such as jute which is exposed to the 7 interior of said conduit, and the fibers of which have not been rendered wholly non-absorbent to the treating liquid such as by a coating of tar, comprising applying from the interior of said conduit to at least a portion of said packingexposed thereto a liquid substance capable of contacting by capillary action non-exposed fibers of said packing and of penetrating fiber cells to cause swelling of said packing, said liquid substance comprising glycerine and a quantity of a viscosity. reducing agent sufiicient to reduce the viscosity of said glycerine to at least centipoises at 20 C., said viscosity reducing agent comprising at least one of a group consisting of ethylene glycol, and water.

DUNCAN B. WILLIAMS.

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