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Other Hazards on the Drilling Site

Flammable and Combustible Liquids

Only approved containers and portable tanks should be used for storage and handling of flammable and combustible liquids. Approved safety cans should be used for the handling and use of flammable liquids in quantities greater than one gallon.


No persons (except those having necessary duties or those authorized by the employer) should be permitted within the vicinity of a job or operation where the atmosphere is known to be contaminated with hazardous concentrations of flammable vapors or gases.

Flammables, such as gasoline and naphtha should not be used as cleaning material due to their high flashpoints. Smoking or open flames should not be allowed within 75 feet of the handling of flammable liquids. Oxygen should not be stored or used in the vicinity of flammable liquids.

Any engine being refueled should be shut off during such refueling. An electrical bond should be maintained between containers when a flammable liquid is being transferred from one to the other. Dispensing nozzles and valves should be of the self-closing type.

Except for the fuel in the tanks of the operating equipment, no flammable fuel should be stored within 75 feet of a well bore. Drainage from any fuel storage should be in a direction away from the well and equipment. Spills should be immediately cleaned up. The area around all storage facilities should be maintained reasonably free of oil, grease, and other combustible materials.

Flammable and Combustible Liquids (Continued)

Fuel storage tanks should be protected by crash rails or guards to prevent physical damage unless by virtue of their location they have this protection. Adequate berms should be placed around storage tanks.

Electrical Safety


Working with electricity can be dangerous. Engineers, electricians, and other professionals work with electricity directly, including working on overhead lines, cable harnesses, and circuit assemblies. Others, such as office workers and sales people, work with electricity indirectly and may also be exposed to electrical hazards.

Electricity has long been recognized as a serious workplace hazard. OSHA's electrical standards are designed to protect employees exposed to dangers such as electric shock, electrocution, fires, and explosions. Electrical hazards are addressed in specific standards for the general industry, shipyard employment, and marine terminals.

The primary power source is normally one or more internal combustion engines. On larger, modern rigs, the engines providing power are frequently located at ground level, 100 or more feet from the derrick. This is to minimize the potential of fires caused by engines igniting gases that could escape from the well bore. On smaller rigs, the engines frequently are mounted immediately next to the derrick. The most common fuel used is diesel; but gasoline, natural gas, liquefied petroleum gas, and purchased electricity are also used. Typically, several hundred horsepower (HP) will be generated and used on a drilling rig, although a larger rig may produce more than 3,000 HP.

Electrical Safety (Continued)

The transmission is mechanical or electric. A mechanical transmission, which is more common in older rigs, utilizes a "compound" of clutches, chains and sprockets, belts and pulleys, and a number of driving and driven shafts. An electric transmission is more common in newer equipment.

Most exposures to hazards associated with the power generation and transmission system occur during maintenance, fueling, and lubrication. Inadequate or nonexistent equipment guards and ineffectual (or the lack of) lockout procedures for maintenance operations during continuous drilling increase the risk of physical injury. Other hazards include high voltages, and chemical injury to the eyes during fueling, fire, and explosion. The noise levels in power generation areas may be high, with the risk of hearing loss.

Electrical Hazard Zones: Areas of the drilling rig are classified into "electrical hazard zones" based on the operative potential of release and accumulation of flammable gases. Electrical equipment used in these zones must conform to OSHA regulations.

Grounding and Bonding: All temporary, 120-volt, single-phase, 15- to 20-ampere flexible electrical cords and receptacles must conform to OSHA grounding and bonding requirements by having a ground-fault circuit interrupter system or an assured equipment grounding program.

Lightning and Static Electricity

Each stationary and portable steel derrick and mast in use where flammable vapors or gases are present (or may escape to the atmosphere in sufficient quantity that the ignition would endanger the safety of employees) should be effectively grounded to a ground pipeline, well casing, or other equivalent source of grounding. Where not effectively grounded or bonded by contact or connection, provisions should be made to prevent the accumulation of a static electrical charge, which could create a source of ignition in the presence of flammable vapors or gases.

Conductors, used for bonding and grounding stationary equipment or conductors should be of copper wire no smaller than No. 8 American Wire Gauge. Bonding and grounding clamps or clips should be attached with secure and positive metal-to-metal contact.

Fire Safety


According to the Bureau of Labor Statistics' Census of Fatal Occupational Injuries Charts, 1992-2007, fires and explosions accounted for 3% of workplace fatalities in 2007. This page provides valuable reference materials for prevention of fire-related injuries in all workplaces.

The employer should develop a fire protection program to be followed throughout all phases of the operation. Appropriate firefighting equipment should be provided and access to the equipment maintained at all times.

At least four fire extinguishers having a minimum rating of 40 B:C should be conveniently located at the rig. Additional extinguishers should be provided for the doghouse, the cellar, the generator area, and any flammable storage areas.

Fire Safety (Continued)

Firefighting equipment should be periodically inspected and maintained in operating condition at all times. A record should be kept showing the date when fire extinguishers were last inspected, tested, or refilled. After any use, fire protection and firefighting equipment should be made serviceable and returned to its proper location.

Smoking, open flames, or spark-producing equipment should be prohibited in areas subject to contamination or accumulation of flammable liquids or gases. Areas for the prohibition of smoking and open flame should include all areas within 75 feet of the:

  • well head or shale shaker, whenever potentially hydrocarbon-bearing formations are exposed in the well
  • degasser while it is operating
  • fuel storage areas
  • no smoking

The following specific actions should be taken in areas where smoking and open flames are prohibited:

  • Striking matches anywhere should be prohibited.
  • Cigar/cigarette lighters and smoking materials should not be permitted.
  • "No Smoking" or "No Open Flame" signs should be conspicuously posted.

Fire Safety (Continued)


Exhaust pipes from internal combustion engines, located within feet of any well bore or in other nonsmoking areas, should be constructed and used so that any emission of flame or spark is suppressed.

Engine-driven light plants should be located at least 75 feet from the well bore unless properly protected to prevent them from becoming a source of ignition and should have an adequate overload safety device.

Welders' torch lighters of the spark type should be prohibited in areas where the atmosphere is contaminated by flammable vapors or gases or where sources of ignition are forbidden, unless sheathed or otherwise protected against accidental operation.

Employee heating devices involving the use of an open flame or exposed electrical element should not be allowed in any crew doghouse located on the derrick, mast floor, or within 75 feet of the well bore. Heaters should be safely located more than 75 feet from the well bore or have an explosion-proof design.

Flare Pits and Flare Lines

A flare pit contains a flare and is used for temporary storage of liquid hydrocarbons. These hydrocarbons are not burned, but are sent to the flare during equipment malfunction.


Flammable waste vapors or gases should be burned or controlled to prevent hazardous concentrations from reaching sources of ignition or otherwise endangering employees.

When a flare is used to burn flammable waste gases or vapors, the following precautions should be taken:

  • Flare pits should be lit from the upwind side. When there is no wind or when the wind direction is undetermined, no attempt should be made to light the pit unless the operator can position himself in an explosive-free area.
  • The use of hand-thrown rags or similar flaming objects should not be permitted.
  • Reliable and safe means of remote ignition should be provided when hydrocarbon gases are released to the air through flares.
  • Flares should be located in such a manner that unburned gases or vapors will be dispersed without creating a hazard to employees.
  • Means should be provided to prevent the prolonged escape of hazardous quantities of unburned gases or vapors from flare installations. Automatic warning devices are acceptable, provided they are tested at such regular intervals that their operation will be assured.
  • Where a flare has been extinguished, and the means of igniting the flare has failed, employees should not enter or be required to enter the involved area for the purpose of relighting, until tests have established that the area is free from flammable gases or vapors.
  • All combustible material should be cleared for a safe distance from the flare pit or end of the flare.

Exposure to Rotating Parts


Exposure to rotating parts on an oil rig is a daily occurrence. All rotating equipment parts have inherent dangers. Even slowly rotating equipment can grip material it contacts. Where there are protrusions, the potential for catching increases and the travelling motion of a rotating piece of equipment is a cause for yet greater vigilance.

In addition to rotating the drill string and bit, the rotary table provides for free vertical motion of the drill as the bit penetrates into the earth. Torque is transmitted from the rotary table to the drill by the kelly, which also conveys the drilling mud that is pumped into it through a swivel connector.

A typical drill string consists of 30-foot sections of drill pipe, male and female threaded, that weigh between 14 and 18 pounds/foot (500 pounds/joint). Several heavy, thick-walled joints of pipe, called drill collars, are made up in the drill stem, just above the bit, so the bit will penetrate into the formation being drilled. A single drill collar can weigh between 2,500 and 4,000 pounds (or more) depending on its diameter.

Employee exposure to rotating parts during drilling makes this operation one with a high potential for severe injuries, although the frequency of occurrence is low. The rotary table and kelly bushing are in nearly continuous motion and are not usually provided with any guarding mechanism. Contact with either is likely to cause slips, falls, and bruising accidents; also, there is a risk of being caught between stationary and rotating parts.

Circulating Fluid Systems

Drilling fluid, or "mud," is typically a mixture of water and bentonite (an absorbent, gel-forming clay) and sometimes oil or other components. It has four primary functions: cooling, lubricating, and cleaning the bit; removing the cuttings; providing hydrostatic pressure to prevent entry of formation fluids into the well bore; and reducing the risk of hazardous blowouts.

Mud pumps force the mud up a standpipe and through the flexible kelly hose to the swivel, where it enters the drill string via the kelly and eventually emerges at the bit in the well bore. Cuttings carried by the drilling fluid are taken for analysis to determine the composition of the stratum being drilled.

Typical hazards associated with working on or around components of circulating fluid systems are various:

  • Chemical: Mixing of the mud exposes workers to airborne respirable dust and chemical splashes.
  • Falls: Tanks in which mud is mechanically stirred are hazardous when unguarded.
  • Electrical: Effective lockout procedures may not be followed during tank maintenance operations.
  • Slips and trips: Walking surfaces nearby may be slippery, especially in wet or icy weather.
  • High pressure: Pressure surges causing line rupture are an occasional hazard.

Hand and Power Tools

Hand and power tools are a common part of our everyday lives and are present in nearly every industry. These tools help us to easily perform tasks that otherwise would be difficult or impossible. However, these simple tools can be hazardous and have the potential for causing severe injuries when used or maintained improperly.

Special attention toward hand and power tool safety is necessary in order to reduce or eliminate these hazards. Hand and power tool hazards are addressed in specific standards for the general industry, shipyard employment, marine terminals, longshoring, and the construction industry.


On February 15, 2002, a 31-year old male rig hand/welder was fatally injured when he was pulled upward and entangled in the rotating drive shaft between the chain case and the rotary table in the substructure of the oilrig derrick. The victim had previously removed a non-working light from the rig substructure and taken it to the doghouse, a general-purpose room that is a combination tool shed, meeting room, office, and communications center.

The replacement light was a 2-foot, 2-bulb fluorescent light with a 6-8 foot long cord. To attach the light to the rig substructure beam, he stood on either the hydraulic winches that lift the drill pipe, or the winch mounting brackets, or both. The winches/mounting brackets were located about 3½ feet above the rotary drive box for the chain case drive unit. By standing on the winches/mounting brackets, it placed him approximately 3 feet below and to the right of the rotating drive shaft. The 2-foot long drive shaft was approximately 8 inches in diameter, was located approximately 4-6 inches below the rig floor deck and was rotating at least 70 rpm.

The rig was not shut down or locked out during the removal of the defective light or when placing the replacement light. The event was unwitnessed, so it is unknown how the victim became entangled in the drive shaft. A co-worker heard a thumping sound and observed the victim spinning with the drive shaft. The co-worker shut down the rig and emergency services were called. The victim was pronounced dead at the scene.


  • Employers should ensure that workers follow established lockout/tagout procedures for control of hazardous energy prior to service and maintenance of equipment.
  • Employers should train workers to recognize potential workplace hazards and participate actively in workplace safety.
  • Company management should consider developing a joint health and safety committee.
  • The company should develop a written disciplinary procedure for safety and health policy violations.
  • Oilrig manufacturers should consider engineering a guard to provide worker protection from rotating drive shafts when working in the derrick substructure.


A huge pillar of black smoke enveloped the Venezuelan town of Puerto La Cruz in August 2013 after a bolt of lightning set fire to one of the country's largest oil refineries. The explosion forced residents to evacuate the immediate area. Below is some raw video of the explosion:


Before beginning this quiz, we highly recommend you review the module material. This quiz is designed to allow you to self-check your comprehension of the module content, but only focuses on key concepts and ideas.

Read each question carefully. Select the best answer, even if more than one answer seems possible. When done, click on the "Get Quiz Answers" button. If you do not answer all the questions, you will receive an error message.

Good luck!

1. Only approved safety cans should be used for the handling and use of flammable liquids in quantities greater than _____.

2. An electrical bond should be maintained between containers when a flammable liquid is being _____.

3. Except for the fuel in the tanks of the operating equipment, no flammable fuel should be stored within _____ of a well bore.

4. All temporary, 120-volt, single-phase, 15- to 20-ampere flexible electrical cords and receptacles on the drilling rig must have a ground-fault circuit interrupter system or _____.

5. All of the following specific actions should be followed in areas on a rig where smoking and open flames are prohibited, except _____.

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