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Subchapter 14. Petroleum Safety Orders--Drilling and Production
Article 2. Definitions
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§6505. Definitions.

The following definitions shall apply in the application of these Orders.

Air Intake Shut-off Valve. A device located between the engine air filter and the intake manifold, designed to shut off the diesel engine's combustion air in the event engine runaway occurs.

Alteration (Pressure Vessel). An alteration is any change to the item described on the manufacturer's data report which affects the pressure containing capacity or the pressure vessel. Nonphysical (re-rating) such as an increase in the maximum allowable working pressure (internal or external) or design temperature or the addition at loading not considered in the original design, shall be considered an alteration. A reduction in the (minimum) design metal temperature such that additional mechanical tests are required shall also be considered an alteration.

Anchor, Deadline. A means of holding the deadline to the derrick or substructure.

Approved. As defined in the General Industry Safety Orders. Section 3206.

A.N.S.I. American National Standards Institute.

A.P.I. American Petroleum Institute.

A.S.M.E. American Society of Mechanical Engineers.

A.S.T.M. American Society for Testing Materials.

Authorized Person. A person assigned by an employer to perform or supervise the performance of a specific type duty or duties at the work site.

Auto Ignition Temperature. The minimum temperature to which a flammable or gas mixture in air must be heated in order to initiate self-sustained combustion.

Back-up Line. A length of wire rope used for holding the leverage arm or handle of a tong to prevent tong rotation.

Back-up Post. A post, column or stanchion to which a back-up line is secured.

Barrel. A liquid measure of 42 U. S. gallons (158.9 liters).

Bail. A cylindrical steel bar, similar to the handle or band of a bucket, only much larger, that supports the swivel and connects it to the hook. The links that attach the elevators to the hook may also be referred to as bails.

Bailer. A long cylindrical container, fitted with a valve at its lower end, used to remove water, sand, mud, or oil from a well.

Blind. A device such as metal plates inserted in flanged joints, blind flanges, and caps or plugs installed on the ends of pipe lines, used to prevent liquids, gases, or vapors from passing through a pipe line or nozzle. Valves are not blinds.

Blowout. An uncontrolled discharge of gas, liquid, or mixture of gases and liquids from a well to the atmosphere.

Blowout Preventer. A device attached to a casing head that allows the well to be sealed to confine the well fluid in the well bore.

Breaking Line. (Break-out Line, Make-up Line, Jerk Line, Snap Line). A wire rope or fiber rope or chain, one end of which is secured to a tong handle and the other end attached to or wound on a mechanical device to impart a pulling power on the tong leverage arm or handle.

Cathead. Unless referred to as “automatic” cathead, means a spool shaped metal mechanical device mounted on the end of a shaft on which a rope is wrapped. The rotating cathead imparts a pulling power to the rope that is wrapped on it.

Cathead, Automatic. A clutch operated metal mechanical device consisting of a wheel having a flanged or flat surfaced rim or a spool shaped drum mounted on a shaft to which the end of a wire or fiber rope or chain is attached. The rotating cathead imparts a pulling power to the line attached to it.

Catline. A rope, usually reeved on a crown block sheave in a derrick or mast, for the primary purpose of lifting and transferring materials from one place to another about the derrick or mast floor. A rotating cathead imparts the pulling power to the catline that is wrapped on it.

Catwalk (Derrick Walk or Mast Walk). A walkway extending from the derrick and/or mast to a point beyond the outer end of the drill pipe and casing storage rack at a well, the purpose of which is to facilitate the handling of such pipe between the rack and the derrick and/or mast.

Cellar. An excavation around the well head to provide space for equipment at the top of the well bore.

Circulating Hose (Bumper Hose). A hose for high pressure circulation between the high pressure side of the mud pump and the bottom of the standpipe.

Combustible Liquid. Any material which has a fluidity greater than that of 300 penetration asphalt when tested in accordance with American Society For Testing and Materials. Designation D5-86, Standard Test Method For Penetration of Bituminous Materials, pages 1-5, which is hereby incorporated by reference. Combustible liquids shall be subdivided as follows:

Class II liquids shall include those having flash points at or above 100oF (37.8oC) and below 140oF (60oC).

Class IIIA liquids include those having flash points at or above 140oF (60oC) and below 200oF (93.4oC).

Class IIIB liquids shall include those having flash points at or above 200oF (93.4oC).

Confined Space. As defined in General Industry Safety Orders, Section 5156.

Contractor's Standby. A half hitch in a wire line secured by a wire line clamp(s).

Corrosive. A substance that causes visible destruction of, or irreversible alterations in, living tissue by chemical action at the site of contact.

Crown Block Assembly. An assembly of mechanical parts mounted on top of a derrick tower or mast, consisting of a framework to which a number of sheaves are fastened over which hoisting lines are reeved.

DBBS. Double block and bleeder system.

Dead Line. The line (which does not travel) from the crown block sheave to the anchor.

Dead Line Stabilizer. A device attached to the mast or derrick for restricting lateral movement of the dead line.

Derrick Crown Platform (Runaround, Water Table). A continuous platform that provides access to the crown block assembly and warning lights.

Derrick Ladder or Mast Ladder. Any fixed ladder providing access to any location in or on the derrick or mast.

Derrick. The tower component of a drilling or well servicing rig that supports the crown block assembly, traveling block and hoisting lines. Derricks and masts may be stationary structures normally requiring dismantling and disassembly when moved from location to location, or may be portable with the capability of being laid down and raised to and from ground level fully assembled.

Division. The Division of Occupational Safety and Health.

Drawworks. Any assembly of power transmission equipment and machine parts used in the rotary method of drilling or well servicing, for hoisting and lowering the drill pipe, casing, tubing and drilling tools used in a well.

Drilling. Includes redrilling and means digging a hole in earth formation with a power-driven drill bit for the purpose of exploring for or developing of oil or gas. Drilling includes those operations that are concerned with the completion of a well.

Drilling (Hoisting) Line. A wire line used in the main rig hoisting system.

Effective. Capable of performing with safety the particular function specified in the order.

Elevator. A metal mechanical device used in connection with and suspended from a traveling block or hoisting line, to hold pipe or sucker rods in suspension when being hoisted or lowered in a well.

Enclosed. As applied to mechanical guarding means that the moving parts are so guarded that physical contact by parts of the body is precluded as long as the guard remains in place. This does not prohibit the use of hinged, sliding, or otherwise removable doors or sections to permit inspection or lubrication.

Finger. A bar or structural steel shape which serves as a restraining support for pipe or other equipment racked in a derrick or mast.

Finger Board. A support for the finger. It may be a timber, metal bar, structural steel shape, or inside derrick platform secured in the derrick or mast.

Finger Brace. A bar or structural steel shape secured to the finger board or to the derrick or mast members to resist horizontal movement of the finger.

Flammable Liquid. A liquid having a flash point below 100oF., (37.8oC) and having a vapor pressure not exceeding 40 lb. per sq. in. (absolute) (176 kPa) at 100oF (37.8oC) and shall be known as Class I liquid. Class I Liquids shall be subdivided as follows:

Class IA shall include those having flash points below 73oF., (22.8oC.) and having a boiling point below 100oF., (37.8oC.).

Class IB shall include those having flash points below 73oF., (22.8oC.) and having a boiling point at or above 100oF., (37.8oC.).

Class IC shall include those having flash points at or above 73oF., (22.8oC.) and below 100oF., (37.8oC.).

Flare. The stack, pit, or device, or location where waste or excess flammable gases and vapors are burned in the atmosphere.

Gas. A fluid, such as air, that has neither independent shape nor volume, but tends to expand indefinitely.

Gas Free or Free of Gas. Free from harmful or hazardous concentrations of vapors, fumes and gases.

Gin Pole Mast. A single or double leg type mast supported in working position by either guys or one or more auxiliary legs, normally used for supporting crown block and traveling block. This definition includes tripods.

Girt. A cross-brace between the legs of a mast or derrick.

Good Engineering Practice. The use of mathematics, scientific formulae, manufacturer's data and/or experience by a qualified person to determine the elements of safety, such as stress values, strength of materials, overturning moments and factors of safety, of equipment and component parts.

Guarded. Shielded, fenced, enclosed or otherwise protected to prevent injury to employees.

Hazardous Substance. One which is likely to cause injury by reason of being explosive, flammable, extremely flammable, poisonous, corrosive, oxidizing, irritant, or otherwise harmful.

High Line. A specially rigged rope used to convey pipe, drilling tools or other equipment from a derrick or mast to the derrick, catwalk or other location outside the derrick or mast.

Inside Derrick Platform. A fixed platform for workers inside the derrick.

Kelly. The square or other shaped steel pipe connecting the swivel to the drill pipe. The kelly moves through the rotary table and transmits torque to the drill string.

Kelly Bushing. A device fitted to the master bushing that transmits torque to the kelly.

Kelly Cock. A valve installed at one or both ends of the kelly that can be used to confine pressure inside the drill string.

Ladder Climbing Assist Device (Angel Lift). A device consisting of a length of wire rope reeved over a sheave, with one end attached to a counterweight and the other end attached to a belt that passes under a person's buttocks. As a person ascends or descends the mast ladder, the device acts as an assist by lightening the person's weight.

Ladder Offset Platform. A platform installed on the derrick or mast at points where the ladder is offset to provide access from one ladder section to an adjacent offset section.

Lanyard. A flexible line to secure a wearer of a safety belt or harness to a drop line, lifeline, or fixed anchorage.

Lease. Any property, irrespective of the legal title or possession, from which gas or oil is being produced or sought. A single lease may include adjacent properties under the same employer.

Loading and Unloading Platform. A platform giving access to the tops of tank cars, tank trucks and trailers and to overhead valves and pipes.

Mast. The tower component of a drilling or well servicing rig that supports the crown block assembly, travelling block and hoisting lines. Derricks and masts may be stationary structures normally requiring dismantling and disassembly when moved from location to location, or may be portable with the capability of being laid down and raised to and from ground level fully assembled.

Monkey Board (Tubing Board or Racking Board). The derrickman's working platform.

Mousehole. An opening through the rig floor, usually lined with pipe, into which a length of drill pipe is placed temporarily for later connection to the drill string.

Oil Saver. A device used in conjunction with a wire line in an oil or gas well to direct liquids and gases from such wells into desirable outlets.

Open Well Bore. A well open to the atmosphere during well drilling, work-over, maintenance, repair or abandonment operations.

Owner-User Inspection Agency. An owner or user of pressure vessels who maintains a regularly established inspection department whose organization and inspection procedures have been accepted by the Division.

Pressure Relief Device. A device for relieving pressure, such as a direct spring-loaded safety valve, rupture disk, or shear-pin set safety valve.

Pressure Vessel. A container, including cylinders, used for the storage or accumulation of any gas or liquid under pressure and as defined in the Unfired Pressure Vessel Safety Orders with the following exceptions:

(a) Those exceptions defined in Section 451 of the Unfired Pressure Vessel Safety Orders.

(b) Pressure vessels constructed entirely of pipe and fittings conforming to and in service as prescribed in the applicable ANSI code.

(c) High and low pressure gas holder covered by General Order No. 94-B of the Public Utility Commission of the State of California with revised Section 4a, effective November 12, 1970.

This definition is not intended to include boilers as defined in the Boiler and Fired Pressure Vessel Safety Orders, and pressure chambers that are integral parts of such devices as pumps, motors, engines, clothes presses, flatwork ironers, tire molds, etc., where the pressure-containing part is subjected to severe mechanical stresses.

Prime Mover. An engine or motor whose main function is to drive or operate other mechanical equipment.

Production Facility. Typically, an area where production wells, stock tanks, separators, lease automatic custody transfer (LACT) units and other production equipment are located.

Qualified Inspector. An inspector as defined in the Unfired Pressure Safety Orders, and who holds a valid certificate of competency issued by the Division.

Qualified Person. A person designated by the employer who by reason of training and experience has demonstrated the ability to safely perform his duties and, where required, is licensed in accordance with federal, state, or local laws and regulations.

Rathole. A hole in the rig floor lined with a casing that projects above the floor into which the kelly and swivel are placed when hoisting operations are in progress.

Remote Control. A wired or wireless equipment control device that operates the diesel engine's air intake shut-off valve from a distance.

Repair (Pressure Vessel). A repair is any work necessary to restore a pressure vessel to a safe operating condition, provided there is no deviation from the original design. Examples of repair include:

1. Weld repair or replacement of pressure retaining parts or attachments that have failed in a weld or in the base material;

2. Addition of welded attachments to pressure parts;

3. Replacement of pressure retaining parts identical or equivalent to those existing on the pressure vessel and described in the original ASME Manufacturer's Data Report;

4. Replacement or addition of a nozzle where reinforcement is not required to be considered by the code under which the vessel was constructed;

5. The addition of a nozzle where reinforcement is a considertaion provided the nozzle is identical or equivalent to the one in the original design and located in a similar part of the vessel;

6. Repairs of base material by weld overlay;

7. Repair or replacement of a pressure part with an ASME Code accepted material that has a nominal chemical composition and strength equivalent to the original material and is suitable for the intended service.

Reservoir. A roofed excavation for the storage of petroleum liquids.

Rod-Wheel Wrench. A spoked, circular metal wheel which when secured onto the sucker/polished rod is used to manually apply torque to the rod string.

Rotary Hose. (Kelly Hose). Length or section of hose between the swivel and the top of the standpipe.

Runaway. A condition affecting diesel engines, where the engine overspeeds out of control, as a result of the introduction of airborne flammable gas or vapor via the air intake causing the engine to accelerate to progressively higher and higher revolutions per minute beyond the normal operating range to a point where the engine becomes damaged due to mechanical failure.

Samson Post. The main upright post or column that supports the walking beam.

Secured. The device or object referred to is so anchored that it will not become accidentally detached, displaced or removed under normal use or foreseen circumstances.

Slips. The wedge-shaped pieces of metal with gripping elements used to prevent pipe from slipping down the well bore.

Source of Ignition. Any flame, arc, spark, or heat capable of igniting flammable liquids, gases or vapors.

Stabbing Board. A readily movable platform used in the derrick or on a mast which workmen stand on to perform work of a temporary nature and not normally performed from a fixed inside derrick platform or monkey board, or a fixed working platform on a mast.

Standpipe. A vertical pipe which joins the rotary hose to the circulating system.

Static Electricity. The type of electrical charge resulting from the separation of materials, friction or similar causes.

Stationary Internal Combustion Engine. An engine that is permanently attached to a fixed foundation.

Sump. A pit or excavation, for holding liquids.

Tank. A receptacle (covered or uncovered) of 60 gallons (227.1 liters) or greater capacity. Unless referred to in these Orders as “stationary,” the above definition shall include such receptacle when used on tank cars, tank vehicles or skids.

Traveling Block. Two or more steel plates and other metal parts assembled into a framework within which are mounted one or more sheaves on which the hoisting line is reeved in connection with the sheaves on the crown block. The traveling block travels between the derrick or mast floor and the crown block.

Traveling Block Hook. A hook or equivalent device suspended from the traveling block and from which the elevator links, swivel bail or other equipment is attached.

Valve. A device for regulating or controlling the flow of material by means of a movable part or parts which open or close a passage.

Wall, Diversion. A wall made of concrete, earthwork or other noncombustible material, built for the purpose of protecting employees by diverting the flow of hazardous substances.

Wall, Retaining (Dike). A wall made of concrete, earthwork, or other noncombustible material, built for the purpose of protecting employees by confining hazardous substances.

Well Servicing. Remedial or maintenance work performed within the well casing on any well, other than a drilling well.

Note: Authority cited: Section 142.3, Labor Code. Reference: Section 142.3, Labor Code.


1. Amendment filed 7-20-59; effective thirtieth day thereafter (Register 59, No. 12).

2. Amendment of section and Note filed 5-8-95; operative 6-7-95 (Register 95, No. 19).

3. Amendment of definition of “Owner-User Inspection Agency” filed 6-26-2006; operative 7-26-2006 (Register 2006, No. 26).

4. New definitions of “Air Intake Shut-off Valve,” “Open Well Bore,” “Prime Mover,” “Remote Control” and “Runaway” and amendment of definition of “Pressure Vessel” filed 10-31-2012; operative 11-30-2012 (Register 2012, No. 44).

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