Gasoline and Petroleum Gas Tank Car Explosions
Summary of Several Recent Cases of Explosion in Cars Loaded with These Dangerous Substances— Rules for Unloading Such Cars Formulated by Bureau
IN last week’s issue appeared an analytical account by Colonel Dunn of the explosion at Memphis, Tenn., caused by the removal of the dome cover of a tank car containing casinghead gasoline without previously releasing the interior pressure and the consequent forcing of a column of liquid and gas into the air vertically to a height of one hundred feet. The double explosion which followed the settling of this vapor wrecked a block of dwellings, destroyed part of the Colyar-Reese plant, and caused the death of thirteen and injury to eighteen persons. The general comments which follow deal with the subject of gasoline and petroleum oil explosions in a more comprehensive manner.
The following is a brief statement showing previous accidents of this nature and general information concerning them: The Bureau’s records contain the following list of fires similar in character to that which occurred at Memphis, Tenn., on January 24th, involving a tank car of gasoline:
April 22, 1911—Liq. Petroleum Gas., St. Louis, Mo.; 8 killed; 7 injured; loss, $2,100. To secure sample, dome cap was unscrewed while tank car was under pressure. Vapor ignited by fire in watchman’s shanty 60 feet away. Car standing on siding of Bell Oil Co.
August 20, 1912—Casinghead Gasoline, Toledo, O.; 2 killed; 3 injured; loss, $1,000. G. A. T. X. Tank Car 4307, standing on the Sun Oil Company’s siding, caught fire when the dome cap was removed to sample contents. The vapor was driven by the wind in the direction of the boiler house, 150 feet distant, where ignition occurred.
March 14, 1915—Liq. Petroleum Gas., Ft. Worth, Tex.; 1 injured; loss, $1,060. Dome cap removed while tank was under pressure. Vapor ignited by lighted lantern 75 feet away.
September 27, 1915—Casinghead Gasoline, Ardmore, Okla.; 47 killed; 524 injured; loss, $645,502. (Total loss to date, for Ardmore, Okla., accident including personal injury claims, $1,054,246.00). I. N. T. X. Tank Car 8051 while standing on spur track near the Ardmore Station was noted giving off vapor and liquid through the safety valve indicating extreme internal pressure. An employee of the Ardmore Refinery to whom the car was consigned, removed the dome cover to relieve the pressure, which threw a column of liquid and vapor many feet into the air, and approximately one minute later an explosion occurred, due to the ignition of vapor, either by a switch lamp 215 feet distant or an open fire in an asphaltum plant 330 feet distant.
February 14, 1916—Gasoline, Cedar Rapids, Ia.; 1 killed. A tank car of gasoline had been partly unloaded by consignee on Saturday. On Monday morning, while preparing to complete the unloading, an employee of the consignee on removing the dome cap was blown some distance into the air and killed by the explosion of vapor in the tank. Ignition being due either to friction spark or static electricity.
February 6, 1917’—Casinghead Gasoline, El Paso Tex.; 2 injured; loss, $3,000. R. W. O. X. Tank Car 521 on consignee’s siding. Incompetent representative of carrier, sent to verify alleged shortage, removed dome cap while tank was under pressure. Gasoline and vapor shot into the air 25 or 30 feet, and were ignited by the fire in a stove in the consignee’s office nearby.
April 19, 1917—Gasoline, Omaha, Neb.; loss, $1,388. S. C. E. X. Tank Car 8326 at consignee’s plant. Dome cap removed and vapors carried 150 feet along the ground to tar kettle of another plant. Ignited vapors trailed back to tank.
May 18, 1017—Casinghead Gasoline, Gainesville, Tex.; 1 killed; 4 injured; loss, $36,170. G. R. C. X. Tank Car 1355 arrived at Gainesville with safety valves popping off and vapor escaping from plugged hole below the dome. The yardmaster, in order to relieve pressure, loosened dome cover, which blew off. Contents of tank spurted 20 feet into the air and vapors ignited from a switch light 70 feet distant.
November 13, 1917—Liq. Petroleum Gas., Bingham, Pa.; loss, $655. Shortly after a tank car had been coupled to on siding, liquid was noted bubbling from the dome. Before tank car could be isolated the dome cover blew off and gasoline spurted about 10 feet into the air. The vapor was doubtless ignited by a switch light 130 feet distant. Only about V/2 per cent, of vacant space was provided for outage, and undoubtedly the dome cover was improperly secured.
February 12, 1918—Casinghead Gasoline, Atlanta, Ga.; 2 killed; 11 injured; loss, $5,500. C. O. S. X. Tank Car 1470 on side track. Consignee’s employee without carrier’s permission unscrewed dome cover to get sample of contents. Vapor ignited by open fire in a vulcanizing plant 3 feet from track.
December 31, 1918—Casinghead Gasoline, Leach, Ky.; 5 killed; 1 injured. U. T. L. X. Tank Car 24229 on shipper’s siding developed leak around dome cover due to buckling of gasket. Cover not removed account of interior pressure. Safety valve caps raised with iron bars, but pressure continued to escape from caps and around dome cover for two hours. Finally dome cover was removed and escaping vapor ignited. The flash extended to the porch of a house 200 feet away, killing 4 children and their mother. It is believed that ignition was caused by flame in kitchen stove of above house.
February 13, 1919—Casinghead Gasoline, Turner, W. Va.; 3 injured; loss, $17,591. U. T. L. X. Tank Car 1316 loaded shell full; dome did not allow sufficient outage. The material was loaded at 24° F. Temperature increased to 55° F. on the day of shipment internal pressure forced dome cover off when car was coupled on to other cars, dome cover having been insecurely held by about two threads. Vapor ignited by fire inside a carbon black plant 37 feet away.
June 1, 1919—Casinghead Gasoline, Wilsonburg, W. Va.; 1 injured; loss, $1,000. U. T. L. X. Tank Car 5112 returned for repairs to shipper’s nearest siding, on account of vapor escaping at safety valve and dome cover. The cover, which was defective, blew off and contents of tank overflowed into creek and was ignited by bonfire 1,500 feet down stream.
July 31, 1919—Casinghead Gasoline, W. Tulsa, Okla.; 1 killed; 18 injured; loss, $10,242. Consignee’s employee unscrewed dome cover while tank was under pressure. Dome cover blew off stripping threads. Car bore dome placards. Vapor ignited by flame from hand forge 205 feet distant.
February 23, 1920—Casinghead Gasoline, Griffin, Ga.; 4 injured; loss, $75,000. Consignee’s employees removed dome cover while tank was under pressure to obtain samples. Gas sprayed into the air and was ignited by fire in boiler plant 20 feet away. Dome of a tank of refinery gasoline was open at the time and its contents added to the fire.
In order to assist in the education of all concerned in the hazards attending the transportation and use of gasoline, the Bureau of Explosives issued on July 10, 1919, to shippers of gasoline, owners, lessees and builders of tank cars, a circular, M. C. L. No. 273. This circular, which may be obtained from the Bureau of Explosives, recommends that oil companies place specially qualified men in charge of operations. The serious results from the accidents mentioned above demonstrate that the unloading of a tank car containing casinghead gasoline, especially in thickly populated districts, is an operation that seriously affects the safety of the public. Men entrusted with this duty should be thoroughly qualified, and this qualification should be shown in some formal way, such as issuing to them a certificate of fitness for the work. This certificate should be issued only after careful verification of their knowledge and reliability.
Shippers of gasoline have objected to the comparisons of transportation hazards in M. C. L. No. 273 on the ground that the circular does not give due weight to the great difference in volume of explosives and gasoline shipped. It is true that in normal years the weight of gasoline shipped is probably over forty times as great as the weight of explosives, and that the average transportation losses per pound of explosives are not less than twice the average loss per pound of gasoline; but this large volume of gasoline that must be transported is the principal reason for the large losses. Our suffering is measured by total losses of life and property, and not by losses per unit of weight. It would be unwise, unfair and inaccurate, however, to use the comparisons in this circular for a general attack on gasoline. When handled or used under normal conditions it would not represent the hazards we are trying to reduce.
The Memphis accident brings forcible to our attention once more the general hazards of gasoline, and the danger involved in having large gasoline plants located so close to the main lines of railroads and to inhabited dwellings. The country is full of such hazards, and it is impossible now to eliminate them. The rules in B. C. L. No. 190 (which may be obtained upon application) were issued first by the United States Railroad Administration and were adopted and reissued by the American Railroad Association at its last annual meeting. These rules are designed to apply corrections as far as practicable to new installations of loading and unloading points. The rules were issued first in July, 1919, and revised in January, 1920. The records of the Bureau of Explosives show that Colvar, Reese & Co., Inc., at Memphis, built its storage tanks in the spring of 1920, after these rules became effective. This company in the first instance applied to the Illinois Central Railroad, whose main lines run along the western side of the plant, for side track service for unloading tank cars. After an investigation by the Bureau of Explosives, which showed that such facilities could not be provided at this point without violating the rules in B. C. L. No. 190, the application was refused by the Illinois Central Railroad. Subsequently, arrangements were made by Colyar, Reese & Co., Inc., for this service to be furnished by the Union Railway, which does not operate passenger trains.
Rules for Unloading Gasoline Cars
The following recommendations of precautions, referred to in the first installment of this article published in the issue of April 13, are issued by the Bureau of Explosives to railroads and shippers to be observed in the unloading of tank cars of inflammable liquids through bottom discharge valves. These rules are issued with the unanimous approval of the principal members of the petroleum industry as shown by communications transmitted to the Bureau of the American Petroleum Institute. In the bulletin containing these rules it is suggested that “Individual railroads should arrange at once for a wide distribution of these instructions among all their representatives whose duties bring them in touch with such unloading operations and suitable action should be taken to insure compliance herewith.”
- See that caution signs are placed between switch and first car on siding and left up until after car is unloaded and disconnected. Signs must be at least 12 x 15 inches in size and bear the words “STOP—Tank Car Connected” or “STOP—Men at Work,” the word “STOP” being in letters at least 4 inches high and the other words in letters at least 2 inches high. The letters must be white on a blue background. If siding is open at both ends signs must be placed at each end.
- Raise safety valve to see if there is any interior pressure in tank. Dome cover must not be removed while such pressure exists.
- Where pressure is found it must be reduced by cooling tank with water or relieved by raising and keeping safety valve open.
- After pressure is released break seal and remove dome cover as follows:
- Screw Type—Unscrew by placing bar between dome cover lug and knob.
- Hinged and Bolted Type—Loosen all nuts one complete turn and then sufficiently more to open up cover.
- Interior Manhole Hype — Carefully remove all dirt and cinders from around cover and then loosen screw in yoke.
- Move valve rod handle in dome back and forth a few times to see that outlet valve in bottom of tank is properly closed and seated. If valve apparatus is in proper adjustment the closed position of handle in contact with cam will indicate that the valve is closed.
- Replace dome cover but do not entirely close so that air may enter tank for venting as follows:
- Screio Type—Replace dome cover directly over dome opening, but do not engage the threads.
- Hinged and Bolted Type—Place a small wooden block under one edge of cover.
- Interior Manhole Type—Tighten up screw in yoke so that cover will be brought up within 1/2-inch of closed position.
- Start removal of valve cap with suitable wrench, having a pail in position to catch any liquid that may be in outlet nozzle. If large outlet is to be used, remove reducer, first loosening set screws. If valve cap or reducer does not unscrew easily, tap lightly with wooden mallet or wooden block in an upward direction. If leakage shows upon starting the removal of outlet valve cap, it should not be entirely removed but sufficient threads should be left engaged and sufficient time allowed to permit escape of any accumulation of liquid from the outlet chamber before taking cap entirely off. If leakage continues, further efforts should be made to seat the
- outlet valve as per rule 4. If this fails screw the valve cap back to tight position and unload tank through the dome.
- If it is found that the outlet chamber is blocked with frozen liquid, wrap with burlap or other rags and apply hot water or steam. Careful examination should be made to detect cracks in the outlet chamber. If a crack is found the tank should be unloaded through the dome. If no crack is found, proceed as directed in first section of this rule after the frozen liquid has been melted.
- Attach unloading connection securely to nozzle or reducer and raise outlet valve by turning valve rod handle in dome.
- When unloading through bottom outlet of cars equipped with interior manhole type of dome covers and in all cases where unloading is done through the dome opening (unless special dome covers are used, provided with safety vent opening and tight connection for discharge outlet), the dome openings must be protected against entrance of sparks or other sources of ignition of vapor by being covered and surrounded with wet burlap. This must be kept damp by replacements or the application of water as needed.
- Do not throw seals or other substances into the tank. Also care should be taken to avoid spilling any of the contents over car or tank.
- After tank is unloaded replace dome cover, valve cap and reducer securely.
- Inflammable placards and railroad defect cards must not be removed.
- Remove all shipping cards from the car and promptly notify railroad agent when car is empty.
- Tank cars must not be allowed to stand with unloading connections attached after unloading is completed and employes must be in charge throughout the period of unloading.
- If necessary to disconnect a tank car during unloading the outlet valve must first be closed and the outlet valve cap must be securely reapplied until unloading is resumed.
- Cover ground around connections with fresh dry sand or dirt frequently, especially if oil or gasoline has been spilled previously.
- Brakes should be set and wheels blocked on all cars unloaded on grade.
- All tools and implements used in connection with unloading should be kept free from dirt and grit.
Warning: Keep lights and fires away.