At the current level of drilling rig utilization, there is a tremendous investment in both new and old drilling equipment that is idle.
Preserving this investment for future use should be of a major concern to the drilling contractor. Equipment manufacturers have generally been aware of the need to provide means for protection of new equipment during rig-up and for ocean shipment. Many of these procedures can be used for storing an inactive rig. Although some cost is associated with the storage procedures recommended in this paper, it should be minimal when compared to the cost of repairs, down time and potential safety hazards when the rig gets a contract. In general, the stored rig needs to be protected from physical damage, theft and vandalism, and the elements. This paper will first address some general concepts relative to equipment storage and then give specific recommendations for individual equipment items.
Selection of a storage site for a rig is an important part of protecting the investment. Generally rigs are stacked in a yard or on location in the field. A fenced yard with restricted access provides the best physical protection and security. The stacking location, yard or field, should be well drained to prevent standing water from accumulating under the equipment. Timbers or support beams should be provided to keep all equipment from touching the ground. Supports must be high enough to prevent run-off from touching the equipment and allow good air circulation under the equipment.
Some thought should be given as to how the equipment will be located in the yard or on the location. Access should be provided for renewal of rust inhibitors and periodic inspection. Equipment should not be placed in areas of high vehicular traffic to minimize exposure to physical damage, dust and theft.
When asked, most equipment manufacturers will list inside storage as the preferred location. Although inside storage offers the best protection, available inside space is usually limited to small shop areas or inactive vehicle service bays. Where inside areas are available they should be used for electrical equipment, rubber products and items most subject to theft.
In most circumstances there will be little choice as to geographical location of the storage site. Certainly the dry climate of West Texas would be preferable to coastal areas as a storage location. If an extended storage period is anticipated relocation of equipment to a more favorable climate may be practical.
CLEANING OF EQUIPMENT
Prior to placing the equipment in storage it should be thoroughly cleaned. Mud and dirt will hold moisture causing accelerated corrosion. The use of steam cleaners is a common practice but should be limited to painted surfaces. If steam cleaning is used on non-painted surfaces, these should be thoroughly dried and protected with a corrosion inhibitor. Care must be exercised to avoid spraying steam and water into bearing housings and pivot bushings.
Lubricating oil sumps should be drained and cleaned with nonhazardous solvent. After cleaning, the sump should be either refilled or treated with a corrosion inhibitor per the equipment manufacturer recommendations.
Touch up painting should be done after the equipment is cleaned. Any loose paint and rust should be removed and surfaces thoroughly cleaned and dried prior to painting.
Condensation occurs when moisture laden air contacts machinery surfaces which are at or below the dew point temperature. Condensation can be prevented or minimized by removing the moisture from the air or by maintaining temperatures above the dew point.
The moisture content of air can be controlled by use of desiccants. This is generally practical only in the case of small equipment enclosures that are or can be made virtually air tight. Desiccant bags have limited moisture absorbing capacity and require periodic replacement to remain effective.
Maintaining equipment temperatures above the dew point can be practically accomplished in two ways. Equipment may be stored in a heated building or heaters may be placed inside equipment enclosures. The commonly used D.C. drilling motors are equipped with space heaters as are some electrical cabinets. Incandescent lamps may be installed as heat sources inside cabinets not fitted with heaters. Heaters should not be used inside oil sumps where flammable liquids or vapors are present unless the heater is specifically designed and is NEMA approved for hazardous environments.
For large machinery items such as draw works and mud pumps, it will normally not be practical to control moisture content of the air or temperature. In this case all internal components should be protected with corrosion inhibitors and a drain provided so that condensation that does occur can escape. Alternatively to providing a condensate drain, a level of oil may be left in the sump. The condensate will be trapped below the oil and not reabsorbed into the air in the housing.
Three types of corrosion inhibitors have been found to be useful in the storage of rig machinery. They are grease type inhibitors, dry film type inhibitors and volatile type inhibitors. All major oil companies and some chemical companies offer extensive lines of corrosion inhibitors. The author has not attempted to catalog all available products. For reference only, the names of products with which the author is personally familiar will be mentioned. The contractor is advised to contact his normal lubricant supplier for equivalent products.
Grease type inhibitors are useful for protecting internal non-painted surfaces of machinery and for protecting pivots and control linkages. The product is typically brushed on or applied with a grease gun. These products typically serve as a lubricating grease as well as a corrosion inhibitor.
Dry film type inhibitors are useful for protecting both internal and external non-painted surfaces. The product used should be compatible with lubricating oils to preclude the need for complete removal prior to start up. This product can be sprayed on hard to reach internal surfaces. Manufacturers recommended precautions against breathing vapors should be followed.
Volatile type inhibitors give off vapors which form a chemical corrosion resistant barrier on metal surfaces. This type of inhibitor is useful in machinery having relatively air tight housings such as gear reducers, pumps and engines. This type of product is available in concentrate form or mixed into lubricating oil.
Several types of wrapping paper impregnated with volatile inhibitors are available. These are useful for wrapping spare parts or for wrapping machinery parts which would otherwise be difficult to protect.
When applying corrosion inhibitors the manufacturers recommended safety precautions must be followed. Most inhibitors are combustible and may form explosive vapors. The health aspects must be understood and personnel properly protected when applying these products.
It should go without saying that all access openings and inspection covers must be in place and secure. However, the author is continually amazed
to see very expensive equipment being internally exposed to dirt, rain and foreign objects when access covers are carelessly left off. Perhaps the most common example of this occurs when the draw-works input drive and rotary drive are broken for a rig move. Most machinery manufacturers provide either wood or metal covers for the draw-works and compound openings but they are seldom if ever used.
In preparing machinery for storage, all housing openings must be secured to prevent entry of dirt, water and foreign objects. In some areas animals and insects present additional hazards. Electrical equipment is particularly susceptab1e to rodent damage. Insects such as mud dobbers frequently plug vent holes and other small orifices. Housing openings which are left open for ventilation purposes must be securely screened to keep animals and insects out. Small orifices may be closed with plastic plugs.
Access covers that do not fit well due to damage in service should be caulked or closed with waterproof tape. Waterproof tape is also useful for closing breathers and as physical protection around shaft extensions. Shaft extensions should be coated with dry film type inhibitor prior to taping.
Equipment containing antifriction bearings should be stored in a manner which will allow the bearings to be rotated periodically. Condensation occurring in bearing housings can cause staining or etching of bearing raceways. This type of corrosion can lead to bearing failure and usually occurs at the roller or ball to raceway interface. Periodic rotation of bearings redistributes the grease in the bearing and moves the roller or ball to raceway interface. The recommended periods of rotation vary with equipment manufacturer from two weeks to six weeks.
COVERING WITH A TARPAULIN
As added protection against weather and sun, equipment stored outdoors can be covered with a plastic tarpaulin. Black plastic not less than six thousandths of an inch thick is recommended. Canvas or materials that will wet through at contact points must not be used. Contact points and sharp corners should be protected with wood blocking. This protects the plastic at corners and provides space for air circulation. The tarpaulin should be draped in a manner to avoid water collection. The tarpaulin should be well secured with cord or light rope to pre vent billowing in the wind.
An important part of any equipment storage program is periodic inspection to ensure the program is effective. A storage log should be kept on each machinery item with dates and results of each inspection recorded and corrective action noted. If periodic inspection indicates the inhibitors in use are marginally effective, then alternative products should be tried. Under typical outside storage conditions, most inhibitors will require renewal at least every six months.
SPECIFIC MACHINERY ITEMS
The general protection and storage concepts previously discussed can be applied to specific machinery according to the following recommendations:
A. Draw Works
- Drain all water from drum brakes and auxiliary brake. Remove drain plugs from drum brake flanges and rotate drum so that drains are on bottom.
- Disconnect air supply line and open drain valve on draw works and tank.
- Remove covers from all oil bath enclosures. Drain oil from draw works and clean out sump. Thoroughly spray coat all internal surfaces including all shafting and components and chains with grease type inhibitor or dry film type inhibitor. Rotate shafts by hand while spraying to insure complete coverage. Spray both sides of all chains.
- Grease all grease lubricated bearings. Rotate shafts and sprockets while greasing to distribute grease in bearings.
- Grease cover gaskets and seals and reinstall on housing.
- Grease all bushings and pivots in brake systems and any other linkages.
- Remove clutch guards and wrap friction clutch assemblies with paper impregnated with volatile type inhibitor followed by a layer of black plastic. Wrap in such a manner that clutch assembly may rotate freely. Replace clutch guards.
- Thoroughly spray coat all external unpainted surfaces with dry film type inhibitor.
- Wrap drillers control panel with paper impregnated with a volatile type inhibitor followed by a layer of black plastic.
- At six week intervals, rotate all shafts to redistribute grease in bearings.
- At six month intervals, inspect for corrosion and renew inhibitors as necessary.
B. Mud Pumps
- Drain oil from pump power end and from chain drive guards if so equipped. Replace drain plugs.
- Drain water from heat exchanger.
- Drain water from liner flush system and thoroughly wash out cradle area and flush water sump.
- Remove valves and valve springs, clean and dry, wrap in corrosion inhibiting paper and plastic. Store inside.
- Remove pistons and liners, clean and dry, wrap in corrosion inhibiting paper and plastic. Store inside.
- Thoroughly clean and dry fluid end and coat internal surfaces with grease type or dry film type inhibitor. Plug all fluid end openings with plastic or wood plugs.
- Remove access covers on power end and chain drive guard. Spray internal surfaces and components with volatile type inhibitor. Use approximately 15% of the crankcase or guard volume. Grease access cover gaskets and reinstall. Remove breather and plug opening.
- Coat all external unpainted surfaces with grease type or dry film type inhibitor.
- At six week intervals, rotate pump two revolutions. Recoat extension rods with inhibitor.
- At six month intervals, drain volatile inhibitor and replace. Inspect external surfaces and renew inhibitors as necessary.
- Thoroughly clean exterior of swivel. Fabricate rack for storing swivel in vertical position.
- Remove wash-pipe and packing assembly. Thoroughly clean and dry all components and coat with grease base inhibitor. Install upper Wash-pipe ring nut on swivel stem for use as a turning device. Wrap remaining parts from wash-pipe assembly in corrosion resistant paper and plastic. Store inside.
- Thoroughly grease bail pins and upper and lower oil seals.
- Drain oil from swivel. Refill with oil containing rust and oxidation inhibitors. Fill swivel completely full of oil.
- Remove breather/dipstick assembly and plug opening with a pipeplug.
- Install thread protector on sub or in stem. Plug gooseneck openings and upper end of stem with plastic or wood plugs.
- Spray all unpainted surfaces with dry film type inhibitor.
- Store swivel inside if possible or cover with black plastic.
- At six week intervals, rotate swivel stem two revolutions.
- At six month intervals, inspect for corrosion and renew inhibitor as necessary.
D. Rotary Table
- Thoroughly clean exterior of rotary and remove turntable bushings.
- Drain oil from rotary. If any sign of mud or water is fount in oil, remove top cover and turntable and thoroughly clean out rotary. Pack turntable labyrinth seal grooves full of grease before reassembling rotary.
- Thoroughly grease pinion bearings and labyrinth seal.
- Fill rotary sump with volatile type inhibitor. Use about 15% of rotary housing volume.
- Spray all unpainted surfaces including turntable bushings with dry film type inhibitor.
- At six week intervals, rotate turntable two revolutions.
- At six month intervals, replace volatile inhibitor in rotary sump and inspect for any corrosion. Renew dry film inhibitor as necessary.
E. Rotary Drive Transmission
- Thoroughly clean exterior of transmission.
- Drain oil from transmission. If any sign of mud or water in transmission is observed, remove access covers and thoroughly clean out the transmission.
- Spray volatile type inhibitor into transmission, use about 15% of housing volume. Remove breather and plug opening.
- Spray external unpainted surfaces with dry film type inhibitor.
- At six week intervals, rotate transmission input shaft two revolutions ~ each gear.
- At six month intervals, renew volatile type inhibitor and inspect for corrosion. Renew dry film inhibitor as necessary.
- Disconnect air supply and open drain valve on air tank.
- Remove access covers and drain oil from sump. Thoroughly clean out sump and housing
- Thoroughly spray coat all internal surfaces including shafting and components and chains with grease type inhibitor or dry film type inhibitor. Rotate shafts by hand while spraying to insure complete coverage. Spray both inside and outside of chain.
- Grease all grease lubricated bearings. Rotate shafts and sprockets while greasing to insure good distribution in bearings.
- Grease cover gaskets and reinstall.
- Remove clutch guards and wrap friction clutch assemblies in corrosion inhibiting paper and black plastic. Wrap in such a manner that clutch assembly may rotate freely. Replace clutch guards.
- At six week intervals, rotate all shafts two revolutions.
- At six month intervals, inspect for corrosion and renew inhibitors as necessary.
Engines require preservation for storage which is beyond the scope of this article. The engine manufacturers publish extensive procedures for storage of engines. These procedures should be carefully followed.
H. Torgue Converters
- Clean filters and fill sump with rust inhibiting oil. Operate converter for short run-in period to distribute inhibitor on internal parts.
- Thoroughly clean external surfaces and coat unpainted surfaces with dry film type
- At three month intervals, rotate output shaft drive bell two revolutions. Inspect for corrosion and renew external inhibitor as necessary.
- Annually drain and refill sump with rust inhibiting oil followed by short run-in.
J. DC Motors and Generators
- Thoroughly clean motor or generator and coat external unpainted surfaces with dry film type inhibitor.
- Remove brushes from their holders and clamp under spring clips.
- Cover vent areas with waterproof tape or rein stall the rodent guard plates.
- Megger the machine and record the results.
- Connect power to the AC space heater in the machine.
- Preferably store inside or if stored outside cover with black plastic.
- At three month intervals, rotate shaft two revolutions (one month interval if stored outdoors), inspect for corrosion and renew inhibitor if necessary. Megger machine and record results. A decrease in insulation resistance indicates storage conditions are inadequate.
K. SCR System
- Install 200 watt incandescent lamp in each cubicle to act as a space heater to retard condensation.
- Store inside if uninstalled system or keep SCR house tightly closed to keep out dust and moisture.
L. AC Motors
- Thoroughly clean motor and lubricate bearings.
- Store inside if possible or wrap in black plastic.
- Megger motor and record results.
- Some larger AC motors have space heater, if motor is so equipped connect to power source.
- At six week intervals, rotate shaft two revolutions. Megger motor and record results. A decrease in insulation resistance indicates storage conditions are inadequate.
M. Mast and Substructure
- Support each component so that it is not in contact with the ground. Ensure support is stable and there is no danger of rocking or tipping. Avoid stacking components on top of each other.
- Thoroughly clean all components and coat all unpainted surfaces including pins and bolts with dry film type inhibitor.
- Thoroughly grease all sheaves and pivots.
- Lubricate all wire lines and store inside.
- At six week intervals, rotate all sheaves, inspect for corrosion and renew inhibitors as necessary.
N. Wire Line Anchor
- Thoroughly clean and coat unpainted surfaces with dry film type inhibitor.
- Thoroughly grease pivot.
- At three month intervals, inspect for corrosion and renew inhibitor as necessary. Rock drum on pivot to insure it is free.
- Thoroughly clean hook. Construct rack for storage in vertical position.
- Insure hook ;5 full of oil and thoroughly grease all pivots and latches. Spray coat with dry film type inhibitor.
- At six week intervals, inspect for corrosion and renew inhibitor as necessary.
P. Links, Elevators, Spiders, Slips, Bushings
- Thoroughly clean and grease any pivots or moving parts. Spray coat with dry film type inhibitor.
- At six week intervals, inspect for corrosion and renew inhibitor as necessary.
Q Mud Separator, Desander, Desilter, Mud Agitator
- Thoroughly clean and dry.
- Protect AC motors per above.
- Remove rubber components (belts, shock mounts, gaskets, desander and desilter cones) wrap in black plastic and store in cool, dry, dark inside place.
- Fill gear reducers to top with oil and replace vent plug with solid plug.
- Thoroughly grease bearings and spray coat with dry film type inhibitor.
- At one month intervals, rotate all shafts two revolutions, inspect for corrosion and renew inhibitors as necessary.
R Pulsation Dampener
- Bleed off charge from bladder.
- Thoroughly clean and dry. If unmounted, coat flange with grease type inhibitor.
- Wrap in black plastic.
S Kelli Cocks and Inside BOP
- Thoroughly clean and dry.
- Thoroughly grease lubricate moving parts. Apply grease type inhibitor to box and pin and install thread protectors. Store kelly cocks in full open position.
- At two month intervals, inspect for corrosion and operate kelly cocks closed and full open.
T. Mud System Valves
- Thoroughly flush out lines and valves.
- Thoroughly grease valves and leave in full open position.
- At two month intervals operate valves closed and full open. Regrease as necessary and inspect for corrosion.
U. Air Compressors
- Thoroughly clean compressor. Remove inlet filter, wrap in plastic and store inside.
- Pour one-half pint of compressor lubricating oil into compressor inlet and plug inlet. (Some compressor manufacturers may recommend use of volatile type inhibitor in compressor, consult manufacturer of your compressor for additional recommendations.) Cover compressor with black plastic.
- At six week intervals, inspect for corrosion and rotate compressor two revolutions.
V. BOP and BOP Control System
The BOP and BOP Control System require preservation for storage which is beyond the scope of this paper. The manufacturers of this equipment publish recommendations which should be obtained and followed.
RETURNING MACHINERY TO SERVICE
At the end of the storage period, several steps will be necessary to prepare the machinery for use:
- Clean off any dust or dirt that may have accumulated during storage.
- Remove corrosion inhibitors using a nonhazardous solvent.
- Remove protective covers and wrapping and thoroughly inspect for corrosion or physical damage that may have occurred during storage.
- Be sure to replace breathers or vent plugs that may have been removed for storage.
- Drain sumps and install fresh lubricants per manufacturers recommendation.
- Rotate shafts by hand and be sure all linkages are free and operational.
- Follow manufacturers recommendations for start-up of new equipment if instructions for removal from storage are not provided.
- Operate machinery under no load or reduced load for first two hours of operation and carefully check for correct functioning.
- Closely monitor operation of equipment for first few days in full service to insure correct functioning.