Rig Equipment

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Well Engineering Distance Learning Package (The DLP)
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Petroleum Engineer: Mohd. Zouhry El-Helu.
E-Mail Address: peteng.mzhelu@gmail.com
1.1 Drilling Sites, Rigs, Derrick and Masts

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Before the drilling equipment can be set up the drilling site must be
prepared and transport arrangements finalised
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Onshore, civil engineering work will be required not only to construct
the drilling location and a camp, but usually also to build roads to
provide access for heavy vehicles. The requirements that both site
and roads have to meet depend greatly on the size of the rig and the
type of terrain in which the site is located e.g. desert, mountainous,
rocky ground, woods or inhabited areas.
Included in the Scope of Work of onshore site preparation is the
provision and supply of fresh water, which will be used, untreated, as
drill water and, treated, as potable water for the camp. Depending on

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local circumstances this may be obtained from a river, by damming a
stream or by drilling a water well. (In the latter case two wells would
normally be drilled since a failure of down-hole equipment in a single
well would have serious consequences.)
In areas where access is diffiult , or which would involve long travel
times by road, site preparation would also include the construction of
an airstrip or helipad.
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Offshore the drilling rig equipment will consist of fixed platforms or
mobile rigs (i.e. bottom-supported, jack-up and þoating units).
Transport to and from the drilling site will be by ship and/or
helicopter. Depending on local facilities civil engineering work may be
required to construct jetties, storage areas (including fuel storage)
and loading facilities.

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Offshore Operations are covered more fully in Section 7.
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In swamp areas a swamp-rig will have to be placed in position.
Approach channels and slots will have to be dredged out to the
required depth for this purpose. The most likely means of transport
to and from the rig is by water.
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This Topic deals with the normal requirements for an onshore drilling
site, which are :
 That it has adequate size.
 That the bearing capacity of the site is adequate e.g. it is able
to take the load of Heavy rigs and transport.

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 That it shall meet environmental and safety requirements, e.g.
that a separate campsite is provided and that there are at least
two distinct escape routes from the drilling location.
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The factors on which the dimension of a drilling site depends include:
 The type of derrick or mast; it must be possible to rig this up
on site.
 The layout of the drilling equipment.
 The size of the waste pit.
 The amount of storage space required for materials and
equipment, plus the manoeuvring area required by the
transport and handling equipment.
 The number (and type) of wells to be drilled on the site.
A drawing of a typical single-well location is shown in Figure 3.1.1.

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Figure 3.1.1: Layout of an onshore drilling site
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1.1.2.2.1 GENERAL
From the point of view of bearing capacity the drilling location
comprises two areas. One is the area which supports the drilling unit
substructure and probably also the motors, generators and mud
pumps. The other is the surrounding area which is used for the
handling and storage of materials and equipment, and the placement
of workshops, tanks etc. The latter area requires the same strength
as the access roads, but the former area has to have a much higher
bearing capacity to take the rig loads, and a special foundation is
normally used.
1.1.2.2.2 FOUNDATIONS
Foundations are required:

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 to provide a stable, level base for the rig-up, including the
mast erection.
 to support the derrick or mast under the most extreme
conditions of high hook loads and the maximum amount of
pipe racked in the derrick.
 to provide support for heavy vibrating equipment
The foundation must be level and sufficiently large and strong to
prevent the derrick or mast from tilting or the substructure from
distortion.
The type of foundation used depends on the safe bearing capacity
provided by the ground itself and on the length of time for which it
will be used.
A solid ledge of hard rock can have a safe bearing capacity of the
order of 2.5 - 10 MPa (50,000 - 200,000 psi). However, the bearing
capacity of the order of 2.5-10MPa (50,000-200,000 psi). However,

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the bearing capacity of fine loose sand or swampy ground is only of
the order of 0.1 - 0.2 MPa (2,000 - 4,000 psi) or less.
In circumstances where the sub-soil is relatively weak, and/or the
foundation has to remain in place for the life of a field, a concrete
foundation would be preferred. Its thickness would depend on the
type of ground. If the sub-soil consists of a very weak formation such
as soft clay it may even be necessary to drive piles to support the
foundation.
A common alternative on stronger ground is to use wooden mats. In
this case the soft top soil must be removed down to suitable firm
ground conditions. The hole made in this way is then filled with sand
and called the sand bed. The sand is watered or rolled to compact it
and finally the surface is levelled off before the foundation is
installed. Mats are made of three layers of 7.5 cm (3 inch) timbers

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nailed together crosswise (the total thickness is 22.5 cm or 9 inches)
as shown in Figure 3.1.2.
Figure 3.1.2: Wooden foundation plus sub-structure
A new development is to use Stelcon Mats. These are steel framed,
re-inforced concrete slabs approximately 4 feet square and 3 inches
thick with a lifting eye in the centre for easy positioning by a crane.
The advantage of this method is that it is less expensive than
permanent concrete or piling and the mats or slabs can be used

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again on another location. It is also easier to restore the site to its
original state.
1.1.2.2.3 THE CELLAR
At the point where the well will be drilled a cellar is constructed. This
will usually have concrete walls and þoor, although a fabricated steel
construction is sometimes used. The cellar is used to keep the
wellhead below ground level so that:
 If a high BOP stack is required it can be accomodated without
having to use an abnormally high sub-structure.
 During the production phase the Christmas tree is at a level
which can easily be reached.
 For workovers a low production hoist will hoist over the
wellhead

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Figure 3.1.3 is a diagram of a concrete foundation structure with
cellar construction.
In some areas cellars have been eliminated from sites used for
shallow and medium depth wells by the use of compact wellheads.
Figure 3.1.3: Cellar with concrete foundation

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1.1.2.3.1 DRAINAGE SYSTEMS
It is essential to prevent water and ground pollution and for this
reason it is important that no foreign matter should be allowed to
leave the site. The surface area of a location should be coated and
drained, and construction and maintenance of the site should be such
that all types of pollution e.g. oil and contaminated water are trapped
and not allowed to leave the working area.
In order to reduce the requirement for holding basins etc. it is
common practice to construct dual drainage systems. The larger
system will drain off rainwater falling on areas which are unlikely to
be contaminated - water from this system may normally be disposed
of without treatment. The othersystem will cover the areas in which
contamination is more likely to occur, i.e. under the drilling unit and

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in the vicinity of drilling fluid tanks and fuel storage tanks. After
skimming off any oil (see below) contaminated water will be either
recycled or stored in a waste pit until the end of operations, at which
time it will be disposed of. In some areas a double barrier is required
to retain contaminants on location.
1.1.2.3.2 OIL TRAP
Oil traps should be included in the site drainage systems at a point
before they enter the waste pit or leave the location.
In principle the oil trap consists of a partition which divides a basin
into two compartments (see Figure 3.1.4). The oil, whose density is
lower than that of water, will remain in the first compartment and the
water, free of oil, can be drained off. However, there must always be
some water in the basin to prevent the oil from being able to flow
under the partition into the second compartment.

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Figure 3.1.4: The principle of an oil trap
1.1.2.3.3 CAMP SITE
For safety reasons accommodation is not set up on the rig site.
Where only one well has to be drilled the camp site is about 150 -
300 m (500 - 1000 ft) away in an up-wind direction from the rig (the
prevailing wind direction in the area is used for this). A central camp
site is usually used in an area where several wells will have to be
drilled in one field.

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Hygiene and safety requirements are applicable to the camp site.
Waste-pits for garbage and cess pits must be constructed.
1.1.2.3.4 SITE AND ACCESS ROAD RE-INSTATEMENT
Before any work is done to either the rig- or camp-site and any
access roads, a survey should be carried out detailing the terrain, the
use of the soil, the position and condition of any man-made structure
or crops. Boundaries of plots, if existing, need to be precisely
recorded. It is recommended to take photographs (preferably in
colour) of everything to back up the information. This information is
necessary to re-instate the area to its original state after operations
have ceased and to avoid future company liability.

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Once the drilling site (including the anchors for the derrickman's
escape line and for the guy lines of portable and telescopic masts) is
ready, the rig equipment can be installed.
This Topic deals with selection criteria for a drilling rig and will list the
major components thereof.
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Ideally a drilling rig should be selected to suit a specific well, avoiding
the use of a rig which is either too large or too small. In practice
equipment suitable for drilling a range of wells economically is
chosen. The depth rating alone may not be decisive because wells in
different areas require emphasis on different rig functions.

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API Bulletin D10 "Procedure for Selecting Rotary Drilling Equipment"
should be used as reference.
1.1.3.1.1 CONSIDERATIONS WHICH INFLUENCE RIG
SELECTION
The following considerations inþuence the selection of a drilling rig:
 The mechanical rating and suitability for the range of wells in
the programme.
 The mobility and transportability of a land rig in the
circumstances of the operating area,
or
The operability of an offshore unit in the conditions of the
operating area
 The contract rate.

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And the following influence the selection of contractors who will be
given the opportunity to tender for the contract to supply one:
 Their HSE record
 Their QMS record (ISO 9002 certified ?)
 Their financial strength
 Their staff development record
 Their technical support structure
 Their familiarity with the area of operations
1.1.3.1.2 CHOOSING THE BEST RIG TO DRILL A PARTICULAR
WELL
The following factors should be taken into account when choosing
the best rig for a particular well:
 Anticipated formation pressures.
 Hole and casing programmes.

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 Preferred drill string size and weight(s) to be used.
 Hoisting requirements
 Hydraulic requirements.
 Rotary requirements.
 Auxiliary equipment required.
1.1.3.1.3 MOBILITY
A land rig has to be transportable in the conditions of the operating
area. Different types of environment in which they have to operate
include:
 developed country with good roads.
 desert.
 tundra.
 mountainous areas
 thick jungle, economically accessible only by air.

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A land rig will always be broken down into packages for transport,
the maximum size of the packages being constrained by :
 the type of vehicle that is available and usable over the route
 the obstructions that have to be negotiated (the main problem
usually being bridges - the load carrying capacity and/or the
clearance under them)
There is a wide range of specialised transport available to cope with
all types of conditions.
1.1.3.1.4 OFFSHORE OPERABILITY
Individual offshore drilling units have a relatively limited envelope in
which they can operate:
 Jack-ups are restricted as to water depth by the length of their
legs, they are also limited by the conditions of the sea bed.

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 Drill ships cannot operate in shallow water and are sensitive to
weather conditions. An advantage which they have over other
offshore units is that they have a very large storage capacity
and can thus operate autonomously for relatively long periods
 Semi-submersibles cannot operate in shallow water, but are
less sensitive to wind and swell than drill-ships
Offshore units are also occasionally constrained by the requirements
of the access to the operating area rather than by the operating area
itself. There may be shallow water to en route, or it may be
necessary to pass under a bridge, or even under a cable car system.
A well known problem for example is the bridge over the entrance to
Lake Maracaibo. It is too low to allow an offshore unit to pass under
it with the mast erected, which does not cause great difficulty. What
does make it expensive to move a jack-up in or out of the lake is that
the distance from the lake bed to the bridge is less than the usual

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length of jack-up legs, so a section of each leg has to be cut off and
then welded back on again (involving inspections and re-certifying
the structure).
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Figure 3.1.5 is a schematic diagram of a rotary drilling rig. The major
components of all drilling rigs are fundamentally the same and are as
follows:
 Derrick or mast and substructure.
 Hoisting equipment.
 Pipe-handling equipment.
 Prime movers and power transmissions.
 The drilling fluid system.
 Instrumentation.
 Well control equipment.

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Details of the composition of these major component groups are
shown in the table.
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Once the drilling site (including the anchors for the derrickman's
escape line and for the guy lines of portable and telescopic masts) is
ready, the rig equipment can be installed.
This Topic deals with selection criteria for a drilling rig and will list the
major components thereof.
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1.
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Ideally a drilling rig should be selected to suit a specific well, avoiding
the use of a rig which is either too large or too small. In practice
equipment suitable for drilling a range of wells economically is

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chosen. The depth rating alone may not be decisive because wells in
different areas require emphasis on different rig functions.
API Bulletin D10 "Procedure for Selecting Rotary Drilling Equipment"
should be used as reference.
1.1.4.1.1 CONSIDERATIONS WHICH INFLUENCE RIG
SELECTION
The following considerations inþuence the selection of a drilling rig:
 The mechanical rating and suitability for the range of wells in
the programme.
 The mobility and transportability of a land rig in the
circumstances of the operating area, or The operability of an
offshore unit in the conditions of the operating area
 The contract rate.

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And the following influence the selection of contractors who will be
given the opportunity to tender for the contract to supply one:
 Their HSE record
 Their QMS record (ISO 9002 certified ?)
 Their financial strength
 Their staff development record
 Their technical support structure
 Their familiarity with the area of operations
1.1.4.1.2 CHOOSING THE BEST RIG TO DRILL A PARTICULAR
WELL
The following factors should be taken into account when choosing
the best rig for a particular well:
 Anticipated formation pressures.
 Hole and casing programmes.

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 Preferred drill string size and weight(s) to be used.
 Hoisting requirements
 Hydraulic requirements.
 Rotary requirements.
 Auxiliary equipment required.
1.1.4.1.3 MOBILITY
A land rig has to be transportable in the conditions of the operating
area. Different types of environment in which they have to operate
include:
 developed country with good roads.
 desert.
 tundra.
 mountainous areas
 thick jungle, economically accessible only by air.

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A land rig will always be broken down into packages for transport,
the maximum size of the packages being constrained by :
 the type of vehicle that is available and usable over the route
 the obstructions that have to be negotiated (the main problem
usually being bridges - the load carrying capacity and/or the
clearance under them)
There is a wide range of specialised transport available to cope with
all types of conditions.
1.1.4.1.4 OFFSHORE OPERABILITY
Individual offshore drilling units have a relatively limited envelope in
which they can operate:
 Jack-ups are restricted as to water depth by the length of their
legs, they are also limited by the conditions of the sea bed.

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 Drill ships cannot operate in shallow water and are sensitive to
weather conditions. An advantage which they have over other
offshore units is that they have a very large storage capacity
and can thus operate autonomously for relatively long periods
 Semi-submersibles cannot operate in shallow water, but are
less sensitive to wind and swell than drill-ships
Offshore units are also occasionally constrained by the requirements
of the access to the operating area rather than by the operating area
itself. There may be shallow water to en route, or it may be
necessary to pass under a bridge, or even under a cable car system.
A well known problem for example is the bridge over the entrance to
Lake Maracaibo. It is too low to allow an offshore unit to pass under
it with the mast erected, which does not cause great difficulty. What
does make it expensive to move a jack-up in or out of the lake is that
the distance from the lake bed to the bridge is less than the usual

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length of jack-up legs, so a section of each leg has to be cut off and
then welded back on again (involving inspections and re-certifying
the structure).
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Figure 3.1.5 is a schematic diagram of a rotary drilling rig. The major
components of all drilling rigs are fundamentally the same and are as
follows:
 Derrick or mast and substructure.
 Hoisting equipment.
 Pipe-handling equipment.
 Prime movers and power transmissions.
 The drilling fluid system.
 Instrumentation.
 Well control equipment.

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Details of the composition of these major component groups are
shown in the table.

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Figure 3.1.5: Diagrammatic view of a drilling rig

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This Topic deals with:
 General information on derricks and masts
 Derricks
 Portable masts
 Telescopic masts
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1.1.5.1.1 PURPOSE
Derricks and masts have two functions. The primary function is to
support the crown block (ref. Section 3, Part 2 ). The secondary
function, which is not fulfilled by the masts used with lighter types of
well servicing rigs, is to provide support so that tubulars (drill-pipe,

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drill collars or tubing) can be stored vertically, or "racked", in
"stands" of three lengths. By doing this only one in every three
connections has to be unscrewed when pulling the pipe out of the
hole to change the bit or perform other work on the lower end of the
drill-pipe or tubing string, thus saving time.
1.1.5.1.2 SUBSTRUCTURES
Derricks and portable masts other than the telescopic type are
supported by a heavy steel substructure. The derrick transmits all the
vertical loads through four points at the lower ends of the legs, and
the purpose of the substructure is transmit these loads to the ground
via the relatively large area of the flanges of the basal I-beams. The
required bearing capacity of the ground is thus kept within
reasonable limits and less expensive foundations are required.

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The height of the substructure is chosen so that in combination with
the cellar depth it will accomodate below the derrick floor a BOP
stack appropriate to the rig
Telescopic masts are normally mounted on wheeled units and the
loads are supported by jacks. The bearing capacity is provided by
inserting plates or beams under the jacking units. Such masts are
only used for relatively light work, thus the vertical loads are not as
great as are experienced with derricks and the other type of mast.
1.1.5.1.3 CAPACITY
The ratings for all types of derricks and masts are specified by the
manufacturers in accordance with the standards given in API
Specification 4F "Drilling and well servicing structures". These include
a design factor of 50% for steel derricks when new. The ratings of
used equipment, however, should be reviewed regularly after
inspection by the manufacturer or insurance company surveyor.

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Ratings given include:
 maximum hook load i.e. the maximum string weight including
the weight of the travelling block.
 maximum setback capacity i.e. the maximum weight of drill
pipe and drill collars that can be racked in the derrick or mast.
 maximum wind velocity with full setback.
 pitch and roll tolerances (for offshore applications).
 general depth rating for a given size and weight of drill pipe.
It is therefore essential to be familiar with the capacity of the derrick
or rig in use. The necessary information can be obtained from:
 the manufacturer's nameplate which gives "Mast and Derrick
Name Plate Information".
 substructure Name Plate Information.
 manufacturer's operating instructions.

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1.1.5.1.4 STRENGTH AND CAPACITY CONSIDERATIONS
The following strength and capacity factors should be taken into
account to prevent the derrick or mast being overloaded:
 Maximum anticipated casing load. (Although a rig may be rated
to drill to a certain depth, it may not be designed strong
enough to run casing heavier than drill pipe to that same
depth.)
 Anticipated wind load or other exceptional conditions e.g.
dynamic derrick foundations as on a drill ship.
 Substructure (base) setback capacity.
1.1.5.1.5 DERRICK AND MAST LOADS
During operation derricks and masts are subjected to vertical forces
arising from the load carried by the travelling block and hook and
horizontal forces arising from the pressure exerted by the wind.

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On a floating unit the derrick will be oscillating as the vessel rolls and
pitches which will result in the hook load having a lateral (relative to
the derrick) component. The movement of a floating vessel will also
generate inertial loads in the derrick, but the period is so long that
these will be insignificant relative to the other loads.
 Vertical forces
Figure 3.1.6 shows one possible arrangement of the drilling line, the
fast-line and the dead-line (the fast line and the dead line are the
names given respectively to the sections of the drilling line between
the crown and the draw-works and between the crown and the point
where the line is made fast on the substructure. The latter is known
as the dead line anchor). The arrangement shown would be
described as having six lines strung, because there are six segments
of line supporting the travelling block.

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Figure 3.1.6: Stringing arrangement of a drilling line
Ignoring friction, the tension in the line is
Where N = the number of lines strung.
Hook load = load on hook + weight of travelling block
It is important to note that because the ends of the drilling line are
attached at rig-floor level there are two more lines pulling down on
the crown block than there are pulling up on the travelling block. It
follows that:

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 Static derrick load
The static derrick load (ignoring the weight of the derrick plus crown
block) occurs when the block is not moving but is carrying the full
hook load.
Because there are no friction effects the fast line load and the dead
line load are both equal to the line tension and:
Derricks and masts are designed to a static load capacity for a
specified number of lines and with an established position for the
dead line anchor. Changing the number of lines strung or moving the
dead line anchor position will alter the static load capacity
considerably.

4
45
5
 Dynamic derrick load (crown load)
The dynamic derrick load is the load which occurs while running in or
pulling out a drill string or casing string. The derrick load is still the
sum of the hook load, the fast line load and the dead-line load, but in
this case friction plays a part - which is a combination of the bearing
friction of the sheaves and the internal friction within the line as it is
bent round the sheaves.
To balance frictional forces the tension in a line increases by a factor
"k" as it passes over each sheave. This assumes that the frictional
forces are directly proportional to the load on the sheave and that
the line wraps round 180° of the sheave. The latter is true for the
lines which pass round the sheaves in the travelling block and is
approximately true for the fast line and the dead line.

4
46
6
In drilling line calculations, allowance is made for the friction by
means of factors derived from the above-mentioned factor "k" and
the number of lines strung.
API RP 9B quotes a value of 1.04 for "k" for roller bearing sheaves,
which are the most common type. Substituting this figure in the
above equation and comparing the result with the static derrick load
indicates that the dynamic load on the derrick is insignificantly higher
than the static load. The increase due to friction varies from 1% with
only two lines strung (i.e. a single sheave travelling block) to 0.5%
with ten or twelve lines strung.

4
47
7
Note however, that the changes in fast line and dead line tensions
are far from insignificant. With ten lines strung the dynamic fast line
tension will be some 23% higher than the static line tension, and the
dynamic dead line tension will be 17% less. What is even more
significant is that if the weight indicator sensor is on the dead line,
which it usually is, the dynamic fast line tension with ten lines strung
will be almost 50% higher than the figure shown by the weight
indicator.
 Shock loads
As shock loads are difficult to calculate rigs are designed to twice
their rated strength (the design factor of 50% previously mentioned).
Shock loads occur when a string is picked up out of the slips and
there is acceleration of the string and when the brake is applied to
decelerate it. The tripping of a hydraulic or mechanical jar will induce

4
48
8
shock loads although most of the energy is transmitted to the stuck
pipe.
The harsh acceleration or deceleration of a heavy string can result in
large inertial forces developing which are capable of overloading the
derrick or mast. It is also possible that the block line or the string
could break in such circumstances. For this reason the inertial forces
should be reduced as far as possible when the rig is handling heavy
loads by braking and picking up the string with care.
 Wind load
The wind load on a derrick with a rack full of drill pipe results in
considerable transverse forces.
Derricks and masts are constructed in accordance with API Spec 4F
to comply with a maximum wind load specified for that particular rig.

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9
Most derricks and masts can withstand a wind load of 45 - 58 m/s
(100 - 130 mph) with the racks full of pipe.
1
1.
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5.
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2 D
DE
ER
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S
1.1.5.2.1 CONSTRUCTION OF THE STANDARD DERRICK
The so-called API standard derrick is shown in Figure 3.1.7. It
consists of four main legs of beams which are bolted together plus a
series of horizontal girts and diagonal cross bracing, also bolted. The
material is normally structural steel with a minimum yield of 224.4
N/mm2 (33,000 psi) and a hot-dipped galvanised surface finish. One
side of the derrick has a higher opening at the bottom than the other
sides; this is known as the V-door and is required in order to give
sufficient clearance to lift forty foot (12 m) lengths of pipe from the
pipe racks into the derrick.

5
50
0

5
51
1
Figure 3.1.7: A standard derrick
Some eighty feet above the derrick floor is the derrickman's platform,
called the "monkey board", where he has the equipment to handle
the upper ends of the stands of pipe and rack them neatly. This
consists of "fingers" hinged to a bar which is fastened across two legs
of the derrick. Figure 3.1.8 shows the details.

5
52
2
Figure 3.1.8: Racking equipment in derrick
At the top of the derrick is the crown block with the axle supported in
a structure called the water-table. Above the crown is one single
beam, called the gin-pole, which is used to support a pulley block
used solely to lift the crown into position.
This construction allows the standard derrick to be transported on
normal trucks and to be erected without heavy lifting equipment. A
specialist rig-building crew is used, who construct it from the bottom
up, with each successive layer lifted into place by a gin-pole
supported by cables attached to the previous layers. This is
illustrated in Figure 3.1.9. Since every component of a derrick is
designed to carry its share of the load any parts omitted, improperly
placed or needing to be forced into place may contribute to the
failure of the derrick. For this reason the nuts and bolts are tightened
only slightly more than finger tight (where safety permits) during the

5
53
3
initial construction. Once the entire structure has been erected all
nuts and bolts are then tightened to the required tension. This
method ensures a more even distribution of stresses.
Figure 3.1.9: Gin-pole for rig building

5
54
4
Unfortunately the name "gin-pole" has been given to two different
pieces of equipment related to the derrick - the connection is that
they are both temporary lifting devices.
1.1.5.2.2 DYNAMIC DERRICKS
Dynamic types of conventional derricks are primarily used on board
floating drilling rigs. They are much stronger than the API standard
derrick. Given that they rarely have to be dismantled they consist of
welded sections that are pinned together instead of being
constructed of individual bolted beams.
Field welding is not normally allowed on masts or derricks. Where
this is unavoidable high grade welding rods have to be used under
special procedures. During welding a representative of the
manufacturers will have to be present. It will then be necessary to
have the mast or derrick inspected by the certifying company.

5
55
5
1.1.5.2.3 APPLICATION
Conventional or standard derricks are used:
 where there are many wells on the same location: without
dismantling, the derrick is rolled to the next cellar.
 on small, tender supported platforms where there is insufficient
space to assemble a mast horizontally.
 in situations where mast sections cannot be transported.
 on very heavy duty rigs for deep wells where the inherently
stable layout of a standard derrick can be made stronger than
a portable mast and has more racking capacity.
Disadvantages of such derricks
 Specialist rig builders are required.
 Erection and dismantling is time consuming. (But time delays
can be avoided by "leap-frogging" two derricks.)

5
56
6
1
1.
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1.
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5.
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3 P
PO
OR
RT
TA
AB
BL
LE
E M
MA
AS
ST
TS
S
Figure 3.1.10 shows a portable drilling mast in both vertical and
horizontal position.
Figure 3.1.10: Portable drilling mast
In principle portable masts are always raised by their own travelling
blocks and draw-works. The mast and engine substructure are
installed first, then the engines and drawworks. The drawworks and

5
57
7
engines are checked and prepared for running while the mast
sections are being pinned together. The lower mast section is
mounted by hinge-pins to two brackets on the substructure.
An "A" frame is set up on the substructure and the block line is
reeved so that the fast line runs over a sheave in this frame. The
mast is raised by the block line and a raising sling which run over
sheaves on the mast and the "A" frame. The procedure is illustrated
in Figure 3.1.11. Once the mast is vertical it is locked in position to
the "A" frame and is ready for use.

5
58
8
Figure 3.1.11 : Forces exerted while raising a mast
Considerable force is required to raise the mast from the horizontal
position. The horizontal distance between the centre of gravity and
the hinge point, and thus the torque required, is the greatest (Figure
3.1.12a). This makes great demands on the lifting equipment and
lifting must be carried out extremely slowly.

5
59
9
The further the mast is lifted the shorter the horizontal distance
between the centre of gravity and the hinge point and the force
required is correspondingly less (Figure 3.1.12b).
Once the mast is vertical its weight is supported by the hinge point.
Distance L = 0.
The mast will, however, fall slightly past the dead point. Therefore
only a small force will be needed to overcome the friction and lower
the mast past the dead point, a sandline, for example, can provide
this force. As soon as the mast has passed the vertical position it is
lowered by its own weight.
1
1.
.1
1.
.5
5.
.4
4 T
TE
EL
LE
ES
SC
CO
OP
PI
IC
C M
MA
AS
ST
T
Figure 3.1.12 shows a telescopic mast.

6
60
0

6
61
1
Figure 3.1.12: Ideco Rambler rig (H30)
Telescopic masts with their drawworks and engines are usually
mounted on trucks or trailers. The load should be borne by hydraulic
or mechanical jacks, not by the tyres, so that the mast is kept steady
and perpendicular. The jack feet are relatively small and, as large
surface pressures are likely to occur, especially during fishing jobs or
while casing is being run, wooden mats are usually laid to distribute
the load before the truck or trailer is moved to the site.
First the bottom section, containing the upper section, is raised by
two hydraulic cylinders to approximately 4 degrees past dead centre.
This tilt makes it possible for the travelling block to be positioned
slightly away from the mast, directly above the well once the erection
of the mast has been completed.

6
62
2
After the lower section has been raised and guyed the top section is
extended by the raising sling and rig hoisting equipment. Some
telescopic masts have a hydraulic cylinder to extend the top section.
Once in the highest position the top section is locked to the lower
section by the four pivot catches of the locking mechanism. The
lower section must be locked securely by bolts or clamps so that no
movement between the sections is possible.
Since the applied load is normally outside the base of a telescopic
mast it must be used with guy lines to provide stability (see figure
3.1.13). The thickness of the guy lines, the sequence and the tension
at which these are fastened depend on the size and the construction
of the mast. These values can be found in the instruction manual.
Reference may also be made to API 4E for guy line specifications.

6
63
3
Figure 3.1.13: Recommended guying pattern - general conditions
A = 4 crown to ground guys.
B = 2 crossed guys from racking board to ground.
C = 2 additional racking board to ground guys. Recommended with
strong winds or when pipe set back exceeds the rated racking
capacity.
D = 2 or 4 internal bottom section guys to ground or structure on
vehicle.

6
64
4
1
1.
.1
1.
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6 P
Po
ow
we
er
r r
re
eq
qu
ui
ir
re
em
me
en
nt
ts
s
The drilling engineers should be able to calculate the power required
for the drilling operations. This is necessary to select the most
economical rig for the job. Inefficient use of the engines affects the
daily costs which can be controlled by the driller. Remember
overloading means higher wear and higher fuel consumption. Most
diesel engines and gas turbines driving the rig achieve highest
efficiency at approximately 80 to 90% of their full load capacity. At
this point fuel consumption is most economical and there is no
overheating.
It is possible in both direct diesel drive systems and electric systems,
that more engines are run than would be necessary for the job on
hand. The driller must therefore also be able to calculate the rig

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5
power needed. This topic will cover power formulae and calculations
of power requirements.
The equations
1
1.
.1
1.
.6
6.
.1
1 P
PO
OW
WE
ER
R E
EQ
QU
UA
AT
TI
IO
ON
NS
S
It is necessary to be able to determine the prime mover and/or
generator power requirements for hoisting, rotary and pumping
equipment.
1.1.6.1.1 HOISTING POWER
Mechanical work = force x distance (i.e. weight x height)
The term 'powe' represents the work done per unit time
thus power = force x speed
In SI units

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6
In Oilfield units
1.1.6.1.2 ROTARY POWER
The torque applied to the drill string determines the power
requirements for rotary drilling.
Assuming that the torque, T, is applied by a force, F, at a distance r.

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67
7
1.1.6.1.3 RIG PUMP POWER
The circulating rate and the pressure losses in the system determine
the power requirements of the rig pumps.
or
or, if circulation rates are measured in U.S.gallons/min as is common
in U.S. based rigs:

6
68
8
1.1.6.1.4 ELECTRIC POWER
Electric power = voltage x current, i.e. watts = volts x amps
and the conversion factor for oilfield units is 1 HP = 746 watts
1.1.6.1.5 EFFICIENCIES
All systems are affected by losses, which have to be taken account of
when calculating power requirements:
 Mechanical efficiency
The percentage relation of mechanical power output to mechanical
power input (normally about 85 %).
 Hydraulic efficiency
The percentage relation of hydraulic horsepower output to
mechanical horsepower input. In some cases this may include
mechanical efficiency.

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 Volumetric efficiency
The percentage relation between the actual delivered capacity of a
pump and the calculated displacement of the pump (see Part 3.3).
 Transmission loss
The difference between output horsepower and input horsepower. It
may conveniently be expressed as percentage of input horsepower.
 Electrical loss
The energy converted to heat. The percentage of loss can be
influenced by the cable diameter, length and conduction coefficient.
When calculating power requirements the efficiency and losses must
be taken into account.

7
70
0
1
1.
.1
1.
.6
6.
.2
2 E
EX
XA
AM
MP
PL
LE
E C
CA
AL
LC
CU
UL
LA
AT
TI
IO
ON
N
Using the data given for two rigs, one using SI units and the other
using traditional oilfield units, calculate the power required for
tripping out the drill string while circulating.
1.1.6.2.1 HOOK POWER
For the rig using SI units
For the rig using oilfield units

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1
1.1.6.2.2 HYDRAULIC POWER
For the rig using SI units
For the rig using oilfield units
1.1.6.2.3 TOTAL POWER
The total power requirements are approximately 465 Kilowatts for the
rig using SI units and 577 HP for the rig using oilfield units.
1
1.
.1
1.
.7
7 S
Sa
af
fe
et
ty
y a
an
nd
d i
in
ns
sp
pe
ec
ct
ti
io
on
n
Safety is an essential aspect of good drilling practice. Ensuring that
the entire rig and all the equipment are in good condition can save
lives and money. Inspections while rigging-up/down and during use
are therefore extremely important

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2
1
1.
.1
1.
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7.
.1
1 C
CA
AU
US
SE
ES
S O
OF
F D
DE
ER
RR
RI
IC
CK
K A
AN
ND
D/
/O
OR
R M
MA
AS
ST
T
F
FA
AI
IL
LU
UR
RE
E
The following is a list of actions/conditions which could lead to a
derrick/mast failure:
 Unauthorised cutting and welding of structural members.
 Drilling holes in structural members.
 Bent and missing braces.
 Welding defects, cracks etc.
 Wear, elongation of bolt holes or pin holes.
 Bolts missing, not tight.
 Mast raising slings damaged/worn/improperly used.
 Safety latches not set.
 Worn or damaged sheaves on "A" frame.
 Corrosion, especially mast raising slings.
 Rig not level.

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3
 Location not perfectly level.
 Poor drainage.
 Incorrect guy line tension.
 Poor condition of guy lines.
 Sudden overload, shock loads.
 Abuse during transport.
 The use of look-alike spare parts.
1
1.
.1
1.
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7.
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2 G
GE
EN
NE
ER
RA
AL
L C
CO
OM
MM
ME
EN
NT
TS
S
1.1.7.2.1 CONSTRUCTION
The construction of derricks and masts is such that each section
contributes to the correct distribution of the forces and loads which
occur. Any damage to, or modification of, structural members (such
as cutting or drilling holes in them) will weaken these so that they no
longer contribute adequately to the distribution of the loads.

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4
Figure 3.1.14: A dynamometer
The cause of bent or distorted sections can often be traced back to
inexpert dismantling, transportation, swinging of the block or
unauthorised attachments.
1.1.7.2.2 VIBRATIONS
Drilling derricks are subjected to considerable vibration which may
occasionally loosen certain bolts and nuts so that the strength of the
derrick is seriously impaired. Elongation of bolt holes or cracked
weldings can also result.

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5
1.1.7.2.3 GUYING
The guy lines ensure the stability of telescopic masts. Inspection of
the correct tension of the guy lines using a dynamometer is therefore
essential.
1
1.
.1
1.
.7
7.
.3
3 I
IN
NS
SP
PE
EC
CT
TI
IO
ON
N R
RE
EP
PO
OR
RT
T
A regular report of visual field inspection of derricks or masts and
substructures has to be prepared by the drilling contractor. A special
field inspection report form should be used. The form is a joint
publication by the American Petroleum Institute and the International
Association of Drilling Contractors and should be available in the
office and on the rig.
1.1.7.3.1 PURPOSE AND SCOPE OF INSPECTION
The report form and inspection procedure was developed as a guide
for making and reporting Þeld inspections in a thorough and uniform

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6
manner and has been approved by the API (APl RP 4G:
Recommended Practice for Maintenance and Use of Drilling and Well
Servicing Structures - Appendix A.) The procedure is intended for use
by operating personnel. More detailed and critical inspections may be
scheduled periodically, or ordered to supplement a program of these
inspections, if masts or derricks are used in the upper range of their
load limits, or if structures may have been subjected to critical
conditions which could affect safe performance.
1.1.7.3.2 MARKING DAMAGE
At the time of inspection, damaged sections or equipment must be
clearly and visibly marked so that needed repairs may be made.
When repairs have been made, the visible markings should be
removed by painting over them. It is also necessary for the inspector
to insert "None" when no damage markings are needed, as this is his
indication that the item has passed inspection. It is recommended

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7
that inspection be made with assistance of manufacturer's assembly
drawing(s) and operating instructions.
1.2 Rotary and Hoisting Equipment, Including Wire Ropes
1
1.
.2
2.
.1
1 I
In
nt
tr
ro
od
du
uc
ct
ti
io
on
n
This Part will explain the use of rotary and hoisting equipment
including wire ropes and, in particular, the block line.

7
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8
Rotary, kelly and swivel work together to turn the drill string and the
bit when making a hole.
The hoisting system of rigs consists of:
 the drawworks.
 auxiliary brake.
 travelling block.
 hook.
 links and elevators.
 wire rope (block line).
 deadline anchor.
When diesel mechanical drive is used both the drawworks and rotary
are driven by the same engines via a transmission. On diesel-electric
driven rigs, the rotary and drawworks have their own independent
motors.

7
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9
1
1.
.2
2.
.2
2 R
Ro
ot
ta
ar
ry
y e
eq
qu
ui
ip
pm
me
en
nt
t
The subjects dealt with in this topic are:
 Rotary table
 Master bushing
 Kelly bushing and Kelly
 Swivel
 Slips
 Rotary tong
1
1.
.2
2.
.2
2.
.1
1 T
TH
HE
E R
RO
OT
TA
AR
RY
Y T
TA
AB
BL
LE
E
 FUNCTION
The rotary has a double function:
To rotate clockwise or anti-clockwise, and to apply torque to the drill
string and anything attached to it.

8
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0
When the pipe is being pulled from or run into the wellbore, the
rotary supports the string on slips during those intervals in which the
pipe is not suspended from the hook. At such moments it carries the
weight of the entire string.
 COMPOSITION
The rotary table rests on reinforced beams in the rig floor so that the
high drilling loads are transferred to the sub-structure see Figure
3.2.1.

8
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1
Figure 3.2.1: Rotary table with split master bushing
The rotary has a cast or reinforced steel base which acts as a
foundation to provide the strength and stability required for such a
massive machine. Oil reservoirs for oil-bath lubrication are an integral
part of the base.
The turntable can rotate in the base using a heavy ball bearing and a
ring gear shrunk over the turntable. The ring gear is driven by a
pinion and a pinion shaft with roller bearings and seals. A detachable
sprocket is connected to the pinion shaft (for diesel mechanical drive)
or, when an electric motor is used, a coupling is mounted on this
shaft. Special seals are fitted to prevent the oil from leaking or being
contaminated by mud.
The ring gear and pinion have spiral teething which allows the table
to work as smoothly as possible. The great advantage of this type of
construction is that the table does not jerk and is less noisy.

8
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2
Every rotary table is equipped with a locking device allowing the
driller to lock it while making up and breaking out the bit or hold the
table when drilling with a mud motor. This lock should not be used to
replace the back-up tong when making up or breaking out
connections on a round trip as the combination of a torque and a
bending moment could result in the pipe strength being exceeded. If
the string has insufficient weight the pipe could also turn in the slips.
The turntable has an opening in the centre, cylindrical at the bottom
and square at the top. The master bushing is fitted into this specially
shaped recess.
1
1.
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2.
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2.
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2 M
MA
AS
ST
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ER
R B
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US
SH
HI
IN
NG
G
 FUNCTION
The master bushing fits into the turntable and makes it possible to:

8
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3
 drive the kelly bushing (see Subtopic 2.2.3), which in turn
drives the kelly
 accomodate the slips when the pipe is suspended in the slips.
Master bushings are used in rotary tables:
 to match the inside diameter of the rotary to the pipe passing
through it.
As the bushing is a loose and replaceable insert it automatically acts
as a wear sleeve.
 CONSTRUCTION
Master bushings can be constructed in two ways:
 Split: Made in two halves with a taper for the slips machined
into them (Figure 3.2.1).

8
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4
 Solid: Made as a single piece with the taper for the slips. Loose
inserts or bowls are used to reduce the inside diameter of the
master bushing to accommodate a range of pipe and slip sizes
(Figure 3.2.2). The inserts themselves can be split, solid or
hinged.
Figure 3.2.2: Solid master bushing with bowl

8
85
5
Figure 3.2.3: Square drive and pin drive for master bushing and kelly
bushing
1
1.
.2
2.
.2
2.
.3
3 K
KE
EL
LL
LY
Y B
BU
US
SH
HI
IN
NG
G A
AN
ND
D K
KE
EL
LL
LY
Y
1.2.2.3.1 KELLY BUSHING
The kelly bushing can be engaged with the master bushing by a
square drive or 4-pin drive (Figure 3.2.4). It is equipped with rollers
that permit the kelly to move freely upwards or downwards when the
rotary is turning or when it is stationary.

8
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6
Figure 3.2.4: Kelly bushings
Kellies can be square or hexagonal. When the kelly is square the kelly
bushing is fitted with four plane rollers. When a hexagonal kelly is
used the kelly bushing contains two plane rollers and two 120° V-
rollers (Figure 3.2.5).

8
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7
Figure 3.2.5: One-roller kelly bushing for hexagonal kelly
It is recommended to fit a non-rotating guard over the kelly drive
bushing to prevent incidents
To pass the kelly bushing over one of the upsets of the kelly, the
rollers must first be removed and are then replaced.
The rollers rotate and are adjustable to keep the play between kelly
and rollers to a minimum, preventing vibration on the rotary and drill
string and reducing wear on the kelly.

8
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8
There is also a two-roller type kelly bushing (Figure 3.2.6). This has
two rollers per kelly flat, one above the other, mounted in a roller
assembly block. The flat roller assembly type is for square kellies and
the tapered roller assembly type is for hexagonal kellies.
Figure 3.2.6: Two-roller kelly bushing
The kelly bushing is closed off at the top by a cover. This cover and
the roller blocks have to be removed before the kelly bushing can be
installed around the kelly. The kelly bushing rollers can be adjusted

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9
for kelly and roller wear by removing or adding shims below the
tapered roller assembly blocks.
One advantage of two-roller kelly bushing is an improved kelly guide
and therefore reduced vibration and wear. This applies only when the
kelly has not been bent by careless use or transport.
1.2.2.3.2 KELLY
The kelly, which is square or hexagonal, transmits or absorbs torque
to or from the drilling string while carrying all the tensile load. It also
directs drilling fluid into the string under high pressure. It is therefore
the most heavily loaded component of the drill string.

9
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0
 Standard sizes
Figure 3.2.7: Square and hexagonal kellies
Length overall (L):
 12.19 m (40 ft) for 9.14 m (30 ft) length singles.
 16.46 m (54 ft) for 9.14 m (30 ft) singles in offshore use (due
to ship's heave).
 16.46 m (54 ft) for 12.19 m (40 ft) length singles.
Dimensions across the flats (nominal size: DFL):

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1
 63.5 mm (2-1/2") square only.
 76.2 mm (3") square or hexagonal.
 88.9 mm (3-1/2") square or hexagonal.
 152.4 mm (6") hexagonal only.
 Loading and strength considerations
Square kellies are normally forged (pressed or rolled in shape when
the metal is red hot) over the drive section, whereas hexagonal
kellies are machined (excess material removed) from round bar
stock.

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2
Figure 3.2.8: Cross section through square and hexagonal kellies
The upsets are kept relatively long so that the kelly can be re-
threaded if top or bottom threads are damaged.
If kellies with the same outside diameter (max. diameter) are
compared, it will be apparent that the hexagonal kelly with a similar
bore has a substantially stronger drive section (See Figure 3.2.8).
Under similar loading conditions the hexagonal design is subject to
lower stress levels and therefore has a longer service life. In addition,
the machined flats have a greater resistance to wear than the forged
surfaces.

9
93
3
This is why the hexagonal kelly is generally preferred; but the life of
the drive section of either type is greatly influenced by the fit of the
drive bushing. It is therefore extremely important that frequent
adjustments of the rollers should be made to remove slack. This is
the driller's responsibility.
 Connections:
 Top: LH thread (box).
 Bottom: RH thread (pin).
 Material:
Fully heat-treated chrome molybdenum steel, 4145 hardness range,
Brinel 285-341 or Rockwell C 30-50.
Refer to API RP7G for kelly strength specifications.

9
94
4
1
1.
.2
2.
.2
2.
.4
4 K
KE
EL
LL
LY
Y A
AC
CC
CE
ES
SS
SO
OR
RI
IE
ES
S
 Kelly cocks
These provide protection against flow from
the drill pipe and isolate the swivel
washpipe packing and rotary hose from
high pressure:
 Above Kelly: Flapper type, bulbous
(Omsco, TIW, Shaffer). Manually
operated.
 Below kelly: Flush joint. Manually
operated ball valve (Hydril). Used to
shut off drill pipe pressure so that
kelly can be disconnected. Figure 3.2.9 : Kelly and
connections

9
95
5
 Kelly saver sub
This is made up to the kelly
bottom connection and provided with a rubber protector.
The sub is replaced when the downward facing pin of the saver sub
becomes worn after making repeated connections, preserving the
actual kelly connections and keeping the pin which mates with the
drill pipe in good condition. The thread must be inspected frequently
by the driller because replacing the sub too late could result in
excessive damage to pipe connections and therefore also in high
costs.
Special scabbards are used when moving the kelly from one location
to another to prevent the kelly being bent during transport. The
scabbard also serves as a kelly hole on the rig floor and is usually
called the rat hole.

9
96
6
If a bent kelly is used, this could result in:
 severe vibrations.
 rubbing and extra wear on the drill pipe tool joints and inside
of the wellhead/BOP stack.
 extra alternative bending stresses in the upper part of the
string
extra wear of kelly and master bushing.
1
1.
.2
2.
.2
2.
.5
5 S
SW
WI
IV
VE
EL
L
FUNCTION
The swivel is suspended from the hook and travelling block and
forms the top of the drill stem and permits this to rotate freely. It
also provides a connection for the rotary hose and a passage for the
flow of drilling fluid into the drill string.

9
97
7
CONSTRUCTION
The swivel (Figure 3.2.10) is made up of a stationary and a rotating
part and has to support the entire string weight during drilling. The
material of gooseneck and washpipe assembly needs to have high
resistance to the abrasive action of the drilling fluid which passes the
swivel at high speed.
Figure 3.2.10: National (Ideal) swivel

9
98
8
The rotating part turns over the main axial bearing which is mounted
in an oil-filled housing. The fluid-tight connection between the
stationary part of the swivel and the rotating part is called the
washpipe assembly. The seal unit is the most vulnerable part of the
swivel. Greasing the seals and checking the quantity of oil in the
body daily is very important. If there is any leakage, the washpipe
assembly has to be replaced as soon as possible by the driller. A
spare washpipe assembly should always be at hand.
1
1.
.2
2.
.2
2.
.6
6 S
SL
LI
IP
PS
S
FUNCTION
Slips are wedge-shaped segments with special dies inserted on the
inside, which support the pipe when suspended in the rotary
bushings.

9
99
9
Drill pipe and tubing slips consist of three body segments (Figure
3.2.11). The slips for drill collars and casing, however, are made up
of a large number of segments (Figure 3.2.12).
Figure 3.2.11: Drill pipe slips Figure 3.2.12: Casing slips
DESIGN
The wedging action of the slips in the master bushing converts the
downward force of the weight of the string into a much increased
lateral or transverse force on the pipe. See Figure 3.2.13. If friction is
disregarded it could be compared to a load suspended from a
spreader bar hanging on two slings which have an angle with horizon

1
10
00
0
equal to that of the angle of the slips (). The resultant compression
force in the spreader bar is equal to P/(2 tan ).
The heavy weight of long casing strings and the relatively thin pipe
wall make it important that the slips provide full circumferential grip
for even load distribution.
The slip angle commonly used is 9°27'45". Disregarding friction, a
string weight of 445 kN (100,000 lbs) would result in a compression
load on the pipe in the slips of 1,334 kN (300,000 lbs), equal to
29,552 kPa (4,286 psi) collapse pressure on a 127.0 mm x 29.02
kg/m (5" x 19.5 lb/ft) drill pipe in 35.6 cm (14") long slips having full
circumferential grip over the total length. The rated collapse pressure
of E pipe is 68,950 kPa (10,000 psi). There is more information on
this subject in Section C (slip crushing) of the Well Engineers
Notebook.

1
10
01
1
Slips have concave replaceable inserts called dies, designed for
specific sizes of pipe, to provide full circumferential gripping action.
Figure 3.2.13: Wedging action
PROPER SLIP USAGE
Some important points have to be taken into account when handling
slips:
 Check that the slips are the right size for the pipe, including
the inserts.

1
10
02
2
 Make sure that the inserts are sharp.
 Check that all the inserts grip the pipe.
 Make sure that the outside of the slips is clean and well
greased.
 Check that the taper of the slips is not damaged and matches
that of the master bushings in the rotary table.
 Make sure that the master bushing fits without play in the
rotary.
 Make sure that all slip handles are present and securely
fastened
It is extremely bad practice to:
 use the slips to stop the downward movement of the drill pipe.
 let the slips ride on the pipe while pulling out of the hole.
 catch the tool joint box with the slips.

1
10
03
3
Refer to the IADC Drilling Manual (Section B) for further information
about handling slips.
A spider is often used in the rotary instead of hand slips while
running casing. The spider will be discussed in Subtopic 2.4.3.
1
1.
.2
2.
.2
2.
.7
7 R
RO
OT
TA
AR
RY
Y T
TO
ON
NG
G
FUNCTION
The rotary tong is not part of the lifting equipment. It is however an
important tool in the running in and pulling out of most of the pipes
being used in the well. Its function is to tighten the screwed
connections in the drill string and casing to the recommended torque
and to break these connections when required.

1
10
04
4
Figure 3.2.14: Manual tong
COMPOSITION
A drawing of the tong is shown in Figure 3.2.15. It is made up of a
tong arm to which the jaws are attached with hinge pins. The whole
tong assembly is suspended by wireline from a point in the derrick
such that it hangs close to where it is applied to the pipe. The
suspending line runs over a sheave with a counterweight attached to
the other end. This allows the tong to be moved vertically to the
correct height for the tool joint or collar. The tong operator swings
the tong against the collar closing the jaws. When a force is applied

1
10
05
5
to the free end of the arm the jaws grip the pipe with dies.
Increasing the force on the arm increases the gripping action of the
jaws on the pipe preventing the tong from slipping over the tool
joint. Extension pieces of different length can be inserted to adapt
the jaws to different sizes tool joint or collar. Dies are made of
hardened steel having ribs on one side. They fit into dove-tail
grooves in the jaws and are held in place by split pins. It is important
that the ribs are kept clean allowing them to "bite" into the material
of the joint or collar.
Figure 3.2.15: Manual tong assembly
A tension meter is often installed at the end of the tong arm to which
the tong line is attached. The dial of the read-out of the tension

1
10
06
6
meter is normally calibrated in a torque scale. It is therefore
important to check whether the read-out is the correct one for the
length of the tong arm.
DEVELOPMENT
Making up and breaking out pipe manually is a time consuming
operation. To speed this up hydraulically or pneumatically driven
tongs, called power tongs, have been developed. The jaws, carrying
the dies, have been set in a semi-circular frame which, after the lock
in the housing has been closed, is driven by a motor to rotate the
pipe. A tension meter is normally installed on the back-up wire to
enable accurate torquing up of the connections (the tension sensor
can be seen hanging from the power tong depicted in Figure 3.2.16).

1
10
07
7
Figure 3.2.16: Hydraulic casing tong
Initially these tongs were only used for the running of casing, but
from these tongs new machines were developed capable of spinning
in drill pipe and making up the tool joint to the required torque
afterwards. This tool is usually set up to work together with power
slips. Both tools are operated by remote control from the driller's
position.

1
10
08
8
Figure 3.2.17: Iron roughneck
The spinning and torquing tool is called an "Iron Roughneck" (see
Figure 3.2.17). An Iron Roughneck is made up of a pipe spinning
tool, a power tong and a back-up tong. The function of the last tong
is to grip the bottom part of the joint and prevent it from rotation
when the power tong is applying the make-up or break-out torque.
Iron roughnecks are expensive tools and could suffer break-downs as
a result of incorrect or rough handling by the drill crew. They need to

1
10
09
9
be positioned exactly in line with the pipe to allow slips and tongs to
grip the pipe and tool joint or collar first time. If set-up and operated
correctly they save time, but more importantly they improve the
safety on the rig floor by performing the dangerous work of the tong
men.
1
1.
.2
2.
.3
3 H
Ho
oi
is
st
ti
in
ng
g e
eq
qu
ui
ip
pm
me
en
nt
t
The entire hoisting installation comprising draw-works, drum and
brakes is shown schematically in Figure 3.2.18.

1
11
10
0
Figure 3.2.18 : Rotary rig hoisting system
Factors to be considered when a hoisting system is designed or
chosen are:
 the maximum required hoisting load.
 the maximum speed at which loads can be pulled.

1
11
11
1
 the strength of the line.
 the maximum speed at which an empty block can be raised.
All these factors are strongly related to the:
 power and rpm of the motor.
 transmission.
 drum diameter. These factors, together with the number of
lines strung in the system, determine the hook load and the
speed at which it can be handled.
1
1.
.2
2.
.3
3.
.1
1 D
DR
RA
AW
W-
-W
WO
OR
RK
KS
S
Figure 3.2.19 is a picture of a draw-works with an auxiliary electro-
dynamic brake. The drive can be either diesel mechanical or diesel
electrical.
Shafts with sprockets and chains provide the internal drive
transmission. A gear wheel is connected to the main drive for

1
11
12
2
reversing. Shifting the sprocket to one side will engage a jaw clutch
and this makes forward movement possible. A toothed clutch on the
jack shaft is used to shift into low or second gear. Drum, rotary, sand
reel and cat head are all clutch activated. The arrangement of a
typical unit is shown in Figure 3.2.20.
Figure 3.2.19: Draw-works

1
11
13
3
Figure 3.2.20: Shaft diagram of a draw-works

1
11
14
4
Figures 3.2.19 & 20 show a twin drum draw-works. The upper (and
rear-most) drum is to accomodate a sand-line. The latter are not
often used in Shell operations due to the high incident rate
associated with such use.
1
1.
.2
2.
.3
3.
.2
2 D
DR
RU
UM
M
The drum is an important part of a hoisting system. The size depends
on the height of the derrick or mast. Its surface should be grooved so
that spooling is controlled and the wire is not deformed. A wedge-
shaped guide against the inside of the flange together with turnback
rollers on a bracket above the drum eases the line over for its return
wrap. The flanges are wide to accommodate the mechanical brake
bands (Figure 3.2.21).

1
11
15
5
Figure 3.2.21: Drum with flanges
On most drums manufactured nowadays one-step (called parallel) or
two-step (called counter-balance) grooving is used as shown in
Figure 3.2.22. These patterns prevent line build-up at the cross-over
points (places where one line crosses over a previous wrap).
In two-step grooving the grooves are divided into two sections where
the grooves run parallel to the drum flanges and two sections where
the grooves run spirally. The line spooling is guided by these grooves
which prevents the drum getting out of balance and reduces line
whip between drum and crown block when spooling at high speed.

1
11
16
6
One-step grooved drums are suitable for two or three layers of line
only. Counter-balanced or two-step grooved drums with only half the
angle of pitch give good spooling with many more layers of lines. The
spooling is faster with less line scrubbing and whip.
Figure 3.2.22: The extended length of a grooved drum
1
1.
.2
2.
.3
3.
.3
3 B
BR
RA
AK
KE
ES
S
Brakes can be divided into:

1
11
17
7
main brakes; these are the mechanical brakes on the drum flanges or
a hydraulic/mechanical disc brake system.
auxiliary brakes; these can be either hydrodynamic, electrodynamic
or magnetic particle brakes.
1.2.3.3.1 MAIN BRAKES
The main brake of a drilling rig is the mechanical band brake or the
hydraulic/ mechanical disk brake system. As the name implies, the
primary method of stopping the draw-works drum is by use of the
main brake. It is therefore essential that the driller is familiar with its
operation, adjustment and maintenance.
 Band brakes
The brake assembly consists basically of two flexible steel lined bands
that fit around the drum flanges. Each drum band is anchored on one
side while the other side is free to move. The brake lever is attached

1
11
18
8
to the free side by means of a lever shaft. When the brake is applied,
the bands clamp around the drum flanges and the drum is halted by
friction. This friction generates considerable heat so most drum
flanges are provided with a water-cooling system.
Figure 3.2.23: Band brakes with brake adjustment

1
11
19
9
The brake bands are lined with brake blocks which improve the
friction and allow redressing of the brake bands. These are made of
bonded asbestos fibre interwoven with copper wire and are shaped
to fit the contours of the brake flanges. Brakes without asbestos fibre
are under development. Countersunk brass bolts are used to connect
the brake blocks to the brake bands to avoid damaging the wear-
resistant rims on the brake flanges.
Figure 3.2.24: Schematic illustration of relative pressures
applied on the different segments of the brake flang
Operation

1
12
20
0
When the brake is applied, the segment nearest to the live end (i.e.
the brake handle) comes into contact with the brake flange first with
a pressure dependent on the force applied to the handle. This starts
to take up the load. Friction then brings the second segment into
contact with an increased tension and therefore increased pressure
and frictional force. This braking action goes round the flange with
ever increasing values of tension and friction until it reaches a
maximum at the dead end. A relatively light pressure on the handle
can thus provide a very high braking torque. The brakes are said to
be self-energising when lowering the load.
Capacity
The braking capacity of band brakes depends on:
 the diameter of the drum flange.
 the width of the drum flange and band.

1
12
21
1
 the angle of wrap of the band around the drum flange (this
should be at least 270°).
Equaliser
Normally each brake has to take half the load and for this purpose
the heavy adjustable hold-down bolts are connected to an equalising
yoke which ensures that each brake band will bear an equal amount
of tension. The hinge of this equalising yoke is bolted to the frame of
the draw-works. If one brake band fails, the equaliser switches the
full load to the other band.
It is important that both the adjustment and the condition of the
brake bands should be checked regularly. In normal circumstances
the wear of blocks and rims is checked according to schedule during
rig downtime. The API values for allowable wear on rims apply and
they can be found in API Spec. 7 section 18.

1
12
22
2
 Disc brakes
The disk brake system consists of three major components:
 The discs.
 The capillar assembly.
 The ydraulic system.
(1) The disks.
The system uses two hard faced discs with an internal water jacket
either side of the main drum. Depending on the draw-works size the
disc thickness will vary from two to three inches. Disc diameter is
normally four to five inches larger than with brake bands.
(2) The calliper assembly.
Depending on the size of the draw-works there are four or six brake
calliper assemblies (two or three on each disc). Each assembly

1
12
23
3
consists of two brake pad assemblies (one on either side of the disc)
and an operating cylinder mounted in the middle on top of the disc.
The operating cylinder will move the brake pads at the end of the
calliper arm onto the disc if hydraulic pressure is applied to the
cylinder.
In addition to the hydraulically actuated callipers, each disc brake
system includes two spring-set, hydraulically released callipers.
During normal operation hydraulic pressure keeps the springs
compressed. However, in the event of complete loss of hydraulic
pressure, electrical failure, or by operation of a manual valve, the
springs extend and set the brake. These emergency callipers also
serve as parking brake when the rig is idle for short periods of time.
(3) The hydraulic system.
In a typical installation the draw-works has its own hydraulic unit
with two pumps, a fluid reservoir and accumulator bottles. The

1
12
24
4
pumps are normally working independently (one electrically and one
air operated), and are set to maintain 2,000 psi (13,800 kPa) with a
relief valve set at 2,250 psi (15,500 kPa). The two primary
accumulators, isolated from each other by check valves, supply
pressure to the two main valves at the driller's brake handle. The
braking system is a dual system; the pressures to the two sides are
completely independent. Either side of the system is capable of
holding the maximum rated hook load.
Since it is a hydraulically operated system the brake can be controlled
from positions remote from the traditional driller's position without
the need for complicated mechanical systems.
Operation
The operation of a disk brake is identical to that of a band brake; a
lever is manipulated to operate the brake. The more hydraulic
pressure is applied the faster the brake is applied and the stronger

1
12
25
5
the braking force. The difference with a brake band is that the
braking action is applied evenly over the disc and is therefore more
direct.
Advantages of a disk brake are:
 significant noise reduction
 less downtime on change out of brake pads (non-asbestos
type)
 greater holding power because of less fade than a band brake
 no brake handle "kick-back" caused by dragging brake bands
 ease of remote control and use of advanced controls
1.2.3.3.2 AUXILIARY BRAKES
Auxiliary brakes are used to control the descent rate of the travelling
block carrying a heavy load.
They serve to:

1
12
26
6
 ensure that the load comes down slowly and smoothly.
 reduce the wear of the mechanical brakes.
 take shock loads and weight off the friction brake.
 help to stop the travelling block before setting the slips.
Auxiliary brakes should be engaged at all times to prevent
accidentally dropping the string plus travelling block. Even so, care
must always be taken not to lower the block too rapidly in case the
auxiliary brake fails and the load has to be stopped by the main
brakes only.
 Hydromatic brake
The hydromatic brake consists of a stator (C) with fixed blades (F) in
which a rotor (A) with blades (E) can turn - refer to Figure 3.2.25.

1
12
27
7
Figure 3.2.25: Hydromatic brake
This brake's operation is based on the internal friction of fluid,
normally water, which is sheared by the moving rotor. The
mechanical energy from the shaft is converted into hydrodynamic
energy. Because the blades in the stator do not transfer energy, all
the hydrodynamic energy is converted into heat.
The amount of mechanical energy that can be absorbed depends on:
 the velocity of the rotor (see Figure 3.2.29).

1
12
28
8
 the quantity of water in the unit.
Therefore: the higher the water level in the stator and the higher the
speed of the rotor, the greater the amount of friction that will be
generated and the stronger the braking action.
To adjust the power of the hydromatic brake the driller has to adjust
the water level in the brake by opening a valve in the cooling system.
Various cooling systems are used (see Figure 3.2.26):
 Overflow or open system, if sufficient fresh water is available.
 Cooling tower or closed system, where the hot water flows
over cooling trays and collects in a tank.
An overrunning clutch, a clutch which engages in one direction but
which does not engage in the other, is used between the drum shaft
and the hydromatic brake. As soon as the travelling block is lowered

1
12
29
9
the clutch engages, "locks up" and turns the brake rotor. The clutch
is automatically disengaged while lifting the block.
Figure 3.2.26: Cooling systems for hydromatic brake

1
13
30
0
 Electro-dynamic or Eddy current brake
General
Unlike "water brakes", the eddy current brake develops exceptionally
high braking torque at both very low and high rotational speeds.
When used within the rated capacity, the brake will slow the string
enough to set the slips without the use of the draw-works friction
brake.
Problems associated with overrunning clutches are also eliminated.
Due to its design the braking force is produced without the use of
any frictional braking device, slip ring or other wearing element.

1
13
31
1
Figure 3.2.27: Eddy-current brake
The brake consists of a steel drum which is rotated through a
magnetic field produced by concentric electromagnets mounted
inside the drum. By varying the amount of current supplied to these
stationary electromagnets, the resistance exerted by eddy currents
generated in the rotating drum can be controlled, thereby controlling
the braking force. Because a large brake requires only about 20 kW,
power is easily supplied by standard AC plants.

1
13
32
2
Principles of operation
The electromagnetic field is excited by DC power from the driller's
control. The strength of the field varies with the current flowing
through the coil. Magnetic lines of force (emanating from the poles
when the field is excited) cross the air gap and pass into the drum.
When the drum is rotated (by the draw-works attached) through this
stationary field, emfs (electro-magnetic forces) are induced,
producing a current flow in the drum. These eddy currents vary
directly with the lines of force cut by the rotating drum and inversely
with the resistance of the drum so that the polarity of the magnetic
fields in the drum is opposite to that of the stationary poles. The
resulting mutual attraction creates the braking force and torque
developed in the brake. Therefore, mechanical energy is converted to
electrical energy and this in turn is converted to heat energy without
frictional rubbing elements that wear and have to be replaced.

1
13
33
3
The housing is water cooled to remove the heat.
Advantages
 High braking torque at low rotational speeds.
 Slips set without friction brake.
 No overrunning clutch.
 No belts, slip rings, bands or other wearing devices.
 Continual dead weight and heavy shock loads taken off friction
brake.
 Magnetic particle brake (MPW brake)
Figure 3.2.28 is a cross-section of a magnetic particle brake. This
brake consists of a housing containing coils, a rotor and a certain
quantity of iron powder. Magnetic barriers and magnetic seals
prevent the magnetic field, created when the coils are energised,
from scattering.

1
13
34
4
When the coils are energised a magnetic field is created around them
and the iron particles are also magnetised and begin to "lump"
together and form one mass with each other, the housing and the
rotor.

1
13
35
5

1
13
36
6
Figure 3.2.28: Cross-section of MPW brake
Unlike the eddy current brake, there is now contact between the
rotor and housing via the compacted magnetic iron powder. The
rotor in the MPW brake does not need to rotate to supply the
required brake torque.
The braking force can be increased or reduced by regulating the
power supplied to the coil. The brake torque can reach very high
values in this type of brake. Water cooling removes the heat
generated.
1.2.3.3.3 COMPARISON OF THE VARIOUS TYPES OF BRAKE
In conclusion, Figure 3.2.29 shows the speed/torque characteristics
of draw-works brakes.

1
13
37
7
Figure 3.2.29: Speed/torque characteristics of draw-works brakes

1
13
38
8
 Friction brakes may have very high static friction, the dynamic
friction is limited.
 Hydraulic or hydromatic brakes and eddy current brakes have
no brake torque when the rotor is not turning. The torque
increases as the speed increases. Eddy current brakes achieve
their maximum torque at lower rotating rates than hydromatic
brakes.
 Magnetic particle brakes can supply a very high torque
independent of the rotating rate and, like the friction brakes,
are able to hold the load.
1
1.
.2
2.
.4
4 H
Ho
oi
is
st
ti
in
ng
g a
ac
cc
ce
es
ss
so
or
ri
ie
es
s
Now that the draw-works, drums and the various types of brake have
been dealt with, the other components of the hoisting equipment will

1
13
39
9
be explained. These are the blocks and the hook, top drive drilling
systems, elevators and automatic pipe handling.
1
1.
.2
2.
.4
4.
.1
1 B
BL
LO
OC
CK
KS
S A
AN
ND
D H
HO
OO
OK
K
A block is an assembly of large pulleys or sheaves mounted on a
common shaft.
1.2.4.1.1 SHEAVES
 Diameter
The sheaves in drilling rigs have a large diameter, often 1.5m (60")
or more, to reduce fatigue in wire ropes and increase the endurance
of the cable. The diameter depends on the size of the wire rope
used.

1
14
40
0
Figure 3.2.30: Sheave
The sheave diameter is important because wear on the line is
caused mainly by bending the line around the sheave (see Figure
3.2.31). When the large-diameter lines are constantly flexed over
sheaves in the blocks, the friction of the wire against wire and strand

1
14
41
1
against strand becomes severe. The smaller the sheave (and the
larger the number of sheaves), the greater the wear.
Figure 3.2.31: Bending wire rope during hoisting
 Groove
The grooves in the sheaves have a depth of 1.5 times the cable
diameter to guide the block line; 120¼ of the cable circumference is
usually supported by the groove (see Figure 3.2.32).

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