Many Factors to Be Followed in Designing a Plant—Chlorine in Contact with Gasoline Is an Exceedingly Dangerous Hazard

ALTHOUGH the natural-gasoline industry has recently made great strides in reducing accidents, the industry remains a hazardous one, due to the very nature of the raw materials handled, the process of extracting gasoline from natural gas, and the products obtained, according to the United States Bureau of Mines, Department of Commerce. Since gasoline is extracted under pressure and gas and gasoline are highly inflammable, the risk of fire and explosion always attends the recovery of gasoline from natural gas. The serious explosions and fires that have occurred recently demonstrate the need of increased efforts to prevent recurrence of similar disasters.

Decreased height of towers, better design of stills, automatic regulator controls, and proper venting, have improved operating equipment and increased the safety of operation. Improvements in equipment and the introduction of new devices and methods have resulted also in the manufacture of better grades of gasoline than heretofore.

In designing a natural-gasoline plant the following factors bear directly upon its safe operation: Selection of the site; the plan of the plant and equipment with reference to the surface contour; arrangement of the hazardous equipment to reduce, so far as possible, the risk of fire; provision for future construction without congestion; adequate strength of all structures and equipment; and specifications for materials.

In so far as safety is concerned, the advantages offered by selecting a site with reference to topography call for considerable attention. An elevated location is superior to one that is perfectly level, because the buildings and equipment can be arranged so that gasoline or oil from a bad break or spill will flow away from the course of ignition and thus reduce perceptibly the danger of fire.

Judicious Arrangement of Equipment

The next important factor upon which the safety and success of a gasoline plant depend is judicious arrangement of equipment. Spacing equipment at minimum distances that will provide for economy in construction, safe and efficient operation, and the security of the men connected with operations are very important problems. Because of the variety of sites upon which gasoline plants are built and the various types of equipment used it is evident that a set of specifications for arrangement of equipment that will be best for every condition cannot be drafted. Nevertheless, there are certain fundamental considerations on the location of the more hazardous machinery and equipment which must be noted by the designer in making a layout of any installation. Systematic arrangement of the plant equipment facilitates the efficient use of fire-fighting equipment. Moreover, experience has shown that fires are more easily confined to small areas in properly designed plants.

To reduce the fire and explosion hazards of a plant to a minimum, a proper place must be provided for every combustible substance, safely removed from every source of ignition. This is acomplished by progressively arranging the sources of ignition and combustion so that the most dangerous is farthest removed or isolated from the most dangerous combustible, the next dangerous in a correspondingly closer relation and the least dangerous accordingly placed in the closest relation to each other.

Although some designers of gasoline plants still adhere to wood-frame construction for compressor buildings, the trend in design is toward all-steel fireproof buildings. The adoption of fireproof structures is a forward step in plant safety. A building of steel frame construction covered with corrugated-iron sheathing and with a contiguous row of steel sash around it, wide doors in front and back of each compressor unit or opposite the aisles between the units, and a monitor on the ridge which runs the entire length of the building is a type of construction that is commonly adopted in recent compressor-plant design.

The spacing and arrangement of the compressor units with reference to duplicate units and auxiliary equipment are details that affect safe operation. Wide passageways between machinery in motion greatly reduce the danger of accidents.

Few gasoline-plant managements fail to provide safeguards for compressors and auxiliary operating equipment. Moreover, nearly all states have mandatory regulations governing the safeguarding of moving machinery.

Pressure Equipment and Storage Tanks

The construction of absorbers, stills, accumulators and other pressure equipment is rather well defined and standardized. Both riveted and w’elded shells are in common use. Although poor welding and poor materials, coupled with poor design, have resulted in welding failures and disaster and have created a sentiment unfavorable to welded vessels, it is significant that successful welding is being accomplished in building this equipment.

To prevent excessive losses due to vaporization, it is general practice to store natural gasoline in tanks under a low pressure. In the mid-continent area nearly all of the product is shipped in tank cars, and a large storage capacity is therefore required at the plants. Experience has shown that storage should be provided for thirty days’ production to allow for irregularities in shipping. Horizontal tanks ten feet in diameter and forty feet long are the most commonly used and are undoubtedly the best storage for handling large quantities of gasoline. The tanks are designed to withstand an operating pressure of twenty to twenty-five pounds per square inch and are subjected to a hydrostatic test of fifty pounds per square inch.

Statistics show that inadequately and improperly installed illumination causes or helps to cause approximately eighteen per cent of industrial accidents. Improper lighting also impairs vision and decreases efficiency. At gasoline plants safety in a large measure depends upon good illumination.

When free chlorine combines with certain hydrocarbons in gasoline, hydrogen is liberated with explosive violence, especially in the presence of sunlight. To be safe, therefore, it is ncessary that the most rigid precautions and safety provisions be incorporated in the design of hypochlorite treating plants, so that there is no possibility of gasoline coming in contact with the free chlorine used in the process.

Care Required in Choosing; Fire-Fighting Equipment

To provide adequate protection against fire, too great stress cannot be placed upon the need of considering firefighting equipment as a part of the operating equipment and the importance of installing it before the gas is turned into the plant. To accomplish this end, individual plant conditions and hazards must be studied with the view to making the installation of a size and nature compatible with the requirements of the particular hazard. A careful study of conditions results in equipment being properly centralized and distributed, which greatly speeds up fire fighting.

Safety in natural-gasoline plants involves much more than the mechanics of the plant itself. After plants have been constructed according to the best design and have been provided with adequate fire-fighting equipment only a part of the work of accident prevention has been completed. The principal problem in the operation of plants deals largely with the human element. The selection of men who are careful to take charge of operations and proper instruction of the personnel in safe methods of operation are probably of greater importance in preventing accidents than any other single factors. Incorporating safety in the design of equipment and safeguarding mechanical hazards in compressor and absorption plants are comparatively simple matters, but the education of the men to recognize and guard against the inherent risks, whether small or great, requires consistent and persistent effort. Most accidents can be avoided by exercising ordinary skill and prudence, provided the men are thoroughly acquainted with the causes of accidents and the hazards of their occupation.

Importance of Periodic Inspection

Satisfactory and safe operation of natural-gasoline plants is obtained only by adhering strictly to a routine periodic inspection at regular intervals and by keeping an accurate log of operations, such as temperatures, pressures, fuel consumption, gas output, shutdowns, repairs, and any abnormal operating conditions.

Under the most favorable conditions the extraction of gasoline from natural gas is full of hazards, and it is exceedingly important that plants be designed and operated under the supervision of competent and careful engineers and foremen who fully realize their responsibility for the safety of the men and who are able to secure their full ocoperation. The men, in return, should realize the moral significance of thoughtfulness and attention in order that the safeguards which experience has provided are not nullified. A knowledge of the plant and the causes of accidents enables operators to anticipate in some measure the possibility of such accidents and to exercise a greater control over their occurrence.

In this industry accident prevention is inseparably related to fire prevention. Although every accident hazard is not necesasrily a fire hazard, every fire hazard is an accident hazard.





To What Extent Fire Protection is Needed in Such Apparatus—Protective Measures Used in Eight Systems

TO what extent is fire protection necessary in electrical apparatus? What apparatus needs the most protection? What measures are used now? What is the best form? What determines the expenditure warranted?

These are questions that every electrical engineer has to answer at one time or another. To secure a cross-section of the opinion on this subject eight prominent engineers were consulted.

As one engineer says:

“The best fire protection practice indoors is to install oil-insulated transformers and regulators in fireproof rooms, which can be closed in times of trouble and protected by some kind of a gas system similar to the so-called ‘lux’ system. In the case of large, expensive rotating apparatus, such as turbo-generators, frequency-changer sets and synchronous condensers, that have their frames built tight enough so that the air dampers can be closed in emergency, they should be protected either by perforated water pipes installed inside the frames or by some non-inflammable gas, such as the ‘lux’ system. My preference is for gas.”

Extent to Which Protection Is Necessary

One engineer says that all major apparatus should be fully protected, as damage by fire is usually expensive and also causes interruptions to service. This statement is qualified by three other engineers, one of whom says the extent of protection depends on the probable cost of repairs and the risk and seriousness of interruptions to service. Careful analysis should be made in each case, warns another engineer, in order that use of fire-fighting equipment may not prove more hazardous than the fire. Hazards to other equipment must also be taken into account.

In studying the need for fire protection, points out still another engineer, two classes of damage must be considered —direct and indirect. Apparatus which is very expensive, which is unusually susceptible to fire damage or which individually is very essential to service should be protected from fire danger. Consideration should also be given to the probability of any fire damaging other important equipment provided that the congregation of susceptible apparatus is extensive or of large aggregate value, or provided that service is endangered.

Apparatus That Needs Most Protection

Modern station buildings are fireproof and usually the only apparatus which would cause a fire of any magnitude is that containing oil, points out one engineer. Therefore, protection is needed primarily for oil-filled equipment such as transformers, regulators and oil circuit breakers. Small fires may result in insulation failures on wires, he adds, and machine windings sometimes cause fires within the equipment, but these are not very extensive. Two engineers insist there is no choice, if the apparatus contains oil or considerable fibrous insulation which will burn. Still another declares that air-cooled synchronous machinery of large capacity, connected to circuits in which high-voltage transients may originate, demands protection most. Aside from emphasizing the need of protection against fires from equipment containing considerable oil, the other engineers consulted call attention to the need of protecting rotating equipment such as generators, synchronous condensers and motor generators.

Protective Measures Used in Eight Systems

Methods of guarding against fires and limiting damage differ. Among precautions taken by the eight companies consulted are: Steam, water or CO2 connections with manual or automatic control; recirculating ventilating air continuously or temporarily; fire-resistive cells or group compartments; isolation by separation outdoors; crushed rock or cinders to absorb oil and quench fire outdoors; use of “foamite,” “pyrene,” carbon tetrachloride, sand.

Not all these precautions are necessarily used by each company. For example, one company reports use of steam connections to generators, two water connections, three COt connections, one recirculation of air, fire resistive cells and outdoor isolation (although others are known to use these methods), one crushed rock, three “foamite,” one “pyrene,” two carbon tetrachloride, one CO2 portable extinguisher, two sand, two unidentified portable equipment. One of the companies declares that “foamite” is probably the most effective for oil fires, and that small fires, such as switchboard wiring, are extinguished by carbon tetrachloride or carbon dioxide. CO2 gas is injected by one company into inclosed machinery, compartments or individual pieces of apparatus.

Opinions on Best Fire Protection

Again opinions vary, CO2 connections being favored by two, where air is confined; recirculation of ventilating medium by two, fire-resistive cells or rooms by four (although others infer this method), outdoor isolation by two, crushed rock by one, “foamite” by three, “pyrene” by one, carbon tetrachloride by one, portable COs extinguishers by two, sand by one and unidentified portable extinguishers by two. “Foamite” is recommended by one for oil fires, and for outdoor fires by another.

Protection of oil circuit breakers will be influenced by the amount of equipment involved, the amount of oil in use, the segregation of oil tanks, tightness of inclosures, complications due to piping and automatic equipment.

Although only one engineer pointed it out, others doubtless agree, by their practices, that providing differential relay protection on generators and transformers is a protection against fires of the preventive rather than remedial character.

Expenditure Warranted

Experience is too limited to serve as the determining factor in deciding upon fire protection, declares one engineer, because of rapid changes in design of electrical apparatus. It is the consensus of opinion that the expenditure for fire protection must be decided in each individual case by the risk involved, the cost of the equipment and the cost of interrupted service. However, one engineer claims that expensive fire-protective equipment does not appear warranted, and that portable fire apparatus in proportion to the fire hazard is relatively inexpensive.

Considered more in detail, says one engineer, the problem involves determination of

  1. Money value of apparatus Involved.
  2. Importance of service rendered by apparatus involved.
  3. Probability of Incidence of fire.
  4. Probability of spread of fire.
  5. Probable physical damage.
  6. Probable hazard to human life.
  7. Cost of insurance to reimburse monetary loss.

As one engineer points out, insurance of continuity of service might in individual cases justify an expenditure for fire equipment in excess of the material protected. Much of the information contained in this article is taken from the Electrical World.

Marietta, O., May Buy Apparatus—Marietta, Ohio, is considering the purchase of additional apparatus so that it may render better service to outside communities. On several occasions Marietta has been called upon for aid from outside areas.

Delphos, O., Receives Apparatus—Delphos, Ohio, has received apparatus purchased for the protection of rural property. The pump has a capacity of 500-gallons and has been approved by the Ohio Inspection Bureau.

Willow Springs Gave Away Truck—But—Two years ago officials of the village of Willow Springs, Ill., gave away an old piece of apparatus because it was considered to be too old for fire duty. The apparatus was given to local Boy Scouts. Recently there was a fire at which it was necessary to form a bucket brigade, but the building was destroyed at a $50,000 loss. Now the village is seeking new apparatus, even though it may be as antiquated as the unit given away.