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Institution of Gas Engineers & Managers

Technical Report of 41

Technical Report

Barholing Investigation

Technical Report by

XXXXXXX

Sector Operations Manager

National Grid - Gas Distribution

Grade Application – Incorporated Member (IEng)

IGEM Approved Mentor – XXXXXX

Submission Date – 31st July 2007

Note: The basis of this report was created in 2001/2002 prior to National Grid merging with

Transco (Lattice Group). Therefore, the report considers Transco as the National gas

transporter and emergency service provider and any reference to Transco and its policy’s &

procedures was relevant at the time.



Technical Report Page

Contents

1. Executive Summary 5

2. Introduction 6

3. Barhole Tool Principles 7

(a) Basic Principles of the Barhole Tool 7

(b) Application of the Barhole Tool 8

4. Investigation & Research 10

(a) Legislation, Policies and Procedures 10

(b) Safeway Searcher Bar Literature 11

(c) Other Barholing Methods 12

(d) Barhole Operation (Transco) 12

(e) Observations of the Safeway Searcher Bar 14

(f) Barhole Related Injuries 14

(g) Consequences of an Injury 15

(h) Barhole Training and Competency Assessment 15

(i) Research Summary 16

5. Technical Investigation 17

(a) Safeway Searcher Bar Calculations 17

(b) Safeway Searcher Bar Calculation Summary 21

(c) FCO Calculations 22

(d) Analysis of calculations 23




6. Considering a Solution 24

(a) Brainstorm 24

(b) Conceptual Designs for Barholing 25

(c) Selected Option 26

(d) Modifying the Safeway Searcher Bar 26

(e) Technical Specification for Searcher Bars E8 27

(f) Modified Tool Specification & Theoretical Calculations 28

(g) What Difference Will the Modifications Make? 29

7. Model Fabrication 30

(a) Working Model 30

(b) Model Materials 30

(c) Model Summary 31

8. Design Phase 32

(a) Drafting 32

(b) Safeway Searcher Bar Component Materials 32

(c) Safeway Searcher Bar Costing 34

(d) Modified Tool Prototype Costing 34

9. Final Specification of the Modified Tool 36

10. Conclusion 37

(a) Emergency Services Searcher Bar (Modified Tool) 37

(b) Project Continuation 38

(c) Further Developments 39




11. Referencing & Bibliography 40

12. Acronyms 41

13. Declaration and Testimony 41

Appendices Ref

Gantt chart (a)

Diagrammatic representation of a reversible type Searcher Bar (b)

Highway construction layers (c)

Calculation sheet (d)

Conceptual design sketches (e)

Rough sketch (f)

First draft (g)

AutoCAD 3D, Solid Modelling (h)

AutoCAD Dimensions (i)

Operative user guide (j)



‘Barholing’ is a technique utilised in the gas distribution industry, which

enables effective location and classification of gas escapes emanating from

distribution mains and services generally operating up to 200kPa.

1. Executive Summary

The barholing technique is simple in that a mechanical tool operating in a pile

driving manner is operated by a single person to penetrate a small hole in the

desired location, enabling gas samples to be taken at sub ground level.

A number of injuries had occurred to operatives using the barhole tool. This

report considers the design and operation of the barhole tool utilised within

Transco and the method employed by the operatives to carry out this

essential function. It then considers if the operation of the existing tool could

be improved and therefore reduce the likelihood of injury.

This ‘Barholing Investigation’ was the basis of my HNC mechanical

engineering project. However, this report was written specifically for

submission as an IGEM technical report and is not the actual HNC

submission. This report is still relevant to the gas industry today.

The report looks at a number of facets including; policies & procedures,

technical investigation, conceptual designs and solutions and the construction

of a working model.



‘Barholing’ is a technique used in the gas distribution industry to aid the

location and classification of external gas escapes, where the gas is escaping

upstream of the consumer control valve. The basic principle is to penetrate a

small diameter hole into a footway or carriageway, enabling gas samples to

be taken within the pavement structure.

2. Introduction

The barhole tool is used by First Call Operatives (FCO’s) attending public

reported gas escapes, and ‘Escape, Locate & Repair’ teams (ELR teams)

investigating outside gas escapes.

A number of Lost Time Injuries (LTI’s) and Non-Lost Time Injuries (NLTI’s)

had occurred throughout the year 2001, due to barholing activity in my local

area within the Transco East Anglia region. Any injuries within the workplace

have serious safety, health & financial implications. Therefore, following a

discussion with my line manager, we agreed that I would investigate the

suitability of the existing barhole tool and the methods of use employed by the

FCO’s as part of my HNC Mechanical Engineering project.

I wrote a project brief and action plan and I carried out a feasibility study to

determine if the project was achievable within the timescales and resources

available to me. Having concluded to proceed with the project, I devised a

Gantt chart to manage the delivery of the project (appendix a), which included

timelines and key project milestones.



Fig 1 Searcher bar being used by an FCO

3. Barhole Tool Principles

3 (a) Basic Principles of the Barhole Tool

The barhole tool is basically a bar, one end tapered to

penetrate the selected surface, the other end finished

with a boss head. The bar resides within a barrel,

which is electrically insulated (appendix b).

The principle of operation is that of a pile driving

action created by the barrel handle falling, which

forces the tapered end of the bar into the ground. To

achieve this, the barrel handle is raised to the top of

its stroke, and allowed to fall, thus the inside of the

barrel strikes the boss head causing the two

components to couple, transferring the energy to the

bar. As a result, the bar penetrates the surface, requiring the bar to be

withdrawn in a percussive manner, through lifting the barrel handle to the top

of its stroke causing the reverse side of the boss head to strike the base of the

barrel. The process is then repeated until the penetration depth is attained.



3 (b) Application of the Barhole Tool

Upon receipt of a reported gas escape, an FCO will attend the location and

ensure the safety of life and property, followed by a survey of the area with a

gas detection instrument.

When indications of gas are identified, barholing must be carried out as

detailed in Transco’s procedures. The FCO will first consult utility plans and

utilise a cable avoidance tool to mark the position of electrical cable and other

utilities plant.

The barhole tool is set to penetrate at a depth of 0.2m when barholing in the

footway. This ensures penetration into the sub layers (appendix c), whilst

considering the depths at which utility plant is expected in the footway. This

has the benefit of minimising the risk of injury through striking electric cables.

And fewer costs associated with repairs relating to underground plant

damage.

FCO’s are not permitted to barhole in the carriageway for two reasons:

Road surface can be very difficult to penetrate

Working in the road requires appropriate signing, lighting and guarding

as per the New Roads & Street Works Act (NRSWA), which is not

carried by the FCO

In circumstances where the FCO needs to barhole in the carriageway, an ELR

team would be called.



Following the appropriate gas samples being taken and recorded, the FCO

will either program the gas escape for monitoring and repair at a future date,

or, request the immediate assistance of an ELR team. The ELR team also use

the barhole tool but they frequently utilise a pneumatic rock drill to penetrate

hard surfaces, i.e. concrete reinforced carriageways.

An ELR team penetrate to a depth of 0.38m in the carriageway, again to

ensure penetration into the sub layers taking into consideration the depth at

which utility plant is expected. However, this report does not include a detailed

review of barholing in the carriageway.



4 (a) Legislation, Policies and Procedures

4. Investigation & Research

During my initial research I identified a number of documents relating to

barholing which are listed under ‘Procedures’ (Referencing & Bibliography -

section 11).

Considering that a number of operatives had been injured using the barhole

tool, I focussed on the salient points relating to the safe use of the tool.

o SBGI (Nov 1991) A Code of Practice for Barholing

Section 4.1 – ‘In no circumstances must undue force be used to drive

the searcher bar…’

Section 4.2.2 – ‘The use of rock drills of approved type is

recommended to penetrate the surface of roadways and footpaths

where the surface is exceptionally hard.’

o Transco (2001) Health Safety & Environment Book (Issue 5)

Section Barhole tool (use of) – ‘Assessment of the surface should be

taken prior to the use of the tool to reduce the risk of injury from

attempts to penetrate surfaces that are exceptionally hard’.

o Transco (1995) Field Procedures D2

Section 11 – ‘Do not use excessive force to drive in the searcher bar

and cease barholing if you feel any obstruction’.

o Transco (May 1998) Emergency Procedures EM71



P49 – ‘In no circumstances must undue force be used to drive the

searcher bar….’

o Transco (June 2001) Emergency Field Procedures EM72

Barholing (EM72/FS2/0601) - ‘Do not use excessive force to drive in the

searcher bar and cease barholing if you feel any obstruction’.

Note that the above documents have been superseded, but the principles

remain current today.

4 (b) Safeway Searcher Bar Literature

The barhole tool sourced by Transco was manufactured by ‘Peter Wood & Co

Ltd’. Their barhole tool, the ‘Safeway Searcher Bar’, was manufactured to

meet the Transco (Feb 1993) Technical Specification for Searcher Bars E8. I

contacted Peter Wood & Co Ltd and they sent me some literature regarding

their Searcher Bar, which included a sheet titled ‘‘How to use the impact

Searcher Bar’. Below is an extract from Peter Wood & Co Ltd How to use the

impact Searcher Bar;

‘Raise the barrel handle and force down so that the ‘top closure plug’ (inside

the handle) hits the ‘boss head’ of the spike (also inside the handle). The pile

driver action will drive the spike into the ground (soil, asphalt, or concrete –

concrete being the most difficult to penetrate’.



These instructions are fairly basic and do not consider the effect on the user

or provide any guidance on reducing the consequential impact on the user.

They also refer to penetrating through concrete, which is extremely

demanding on the user. However, Peter Wood & Co Ltd manufactured the

tool to the required Transco specification and was not responsible for training

Transco operatives. The training and assessment process was carried out

internally within Transco (refer to 4h).

4 (c) Other Barholing Methods

I found very little information outside of Transco relating to Barholing.

However, I did discover a company in Canada, ‘Heathus’ who produce a

‘plunger bar’. The plunger bar is designed for utility companies and is very

similar in principle to the Searcher Bar. However, it is designed to penetrate

soil only and therefore cannot be directly compared.

4 (d) Barhole Operation (Transco)

I visited 3 FCO’s at different locations to observe how they used the existing

barhole tool. My observations and discussion with the 3 FCO’s identified:

• The handle is not always raised to the maximum height

• There was a tendency to force the barhole tool in an attempt to

increase penetration



• The FCO’s received a degree of shock when forcing the tool as the

barrel handle strikes the boss head

• A throwing action was employed on occasion

• It was evident that there was a tendency to ‘hang on’ to the tool in an

attempt to force the bar into the ground. This could be likened to forcing

a power drill rather than letting the drill do the work.

I recorded basic information on how they used the tool in terms of the stroke,

height and any force they applied.

The data was recorded through observation and a stopwatch, so I took ten

sample times and I calculated the median value to prevent any distortion from

the average.

FCO FCO Height

Stroke used

Forced Tool?

Median Time from 10 samples

Peter Wilson 1.78m 0.45m Yes 0.255s Ricky Samuels 1.75m 0.74m Yes 0.3s

Richard Bayford 1.81m 0.6m Yes 0.275s



4 (e) Observations of the Safeway Searcher Bar

I noticed that the reversible adaptor that enables the depth to be changed

between 0.2m and 0.38m is not suitable for use in soft ground such as a lawn

or grass verge. This is because the adaptor diameter is only 0.009 m larger

than the bar. Thus, the adaptor enters the ground resulting in a depth greater

than 0.2m achieved. This is potentially dangerous as utilities plant can be

expected below this depth.

Fig 2 Reversible Adaptor below ground level resulting in a greater penetration depth

4 (f) Barhole Related Injuries

Richard Davies (Health, Safety & Environment Manager) arranged for me to

have copies of injury reports from the incident database within the Transco

East Anglia region. There were four injuries recorded, spanning a six-month

period in 2001. Three of the four injuries related to upper body injuries through

trying to penetrate tough ground.

Reversible Adaptor Ground level Bar



Extracts from the incident reports included:

• Jarred elbow and shoulder barholing in tarmac footpath and concrete

slabs.

• Whilst using barhole tool, I had difficulty penetrating footpath, on doing

this I aggravated my tennis elbow injuries.

• Jarred left shoulder and neck whilst barholing.

4 (g) Consequences of an Injury

The HSE have calculated that the average economic cost to an employer for a

serious or major injury in the construction industry is approximately £17000 -

£19000 (based on year 2000 prices). In addition, the average number of days

lost per injury in the skilled craft sector is 13.4 days.

(2000/2001) “Injury Costs” (http://www.hse.gov.uk/).

4 (h) Barhole Training and Competency Assessment

An approved training service provider carries out Barhole training on a three

yearly basis. Transco employed D32/33 assessor’s carry out a competency

assessment on an annual basis on every FCO. Having been trained in the use

of the barhole tool, I can confirm that I was trained to simply raise the barrel

handle and allow it to fall freely. I was advised not to force the tool. From my

observations of the FCO’s, there is evidence that the recommended method is

not always employed.



4 (i) Research Summary

Use of the barhole tool is covered by a comprehensive range of Legislation,

Policies and Procedures. All of which clearly state that the operative should

not apply undue or excessive force. However, the literature from Peter Wood

& Co Ltd refers to forcing the handle down and penetrating harder surfaces

such as concrete.

Having observed FCO’s using the barhole tool, it is clear the tool is not always

used as designed despite the training and annual competence assessment.

This is reinforced by the four injuries that occurred in a six month period.

Considering this equates to an average of 13.4 days per injury per person

based on HSE Injury data, the impact on both the operative and Transco is

extremely significant.

Appropriate use of the tool through training and assessment also needs to be

considered as the injuries may have been caused through behavioural issues.

The above considerations should seek to reduce the number of injuries and

the likelihood of an FCO being injured using the barhole tool.

Consideration needs to be given to the mechanical operation of the tool and

the potential for over penetration to occur due to the reversible adaptor.



5 (a) Safeway Searcher Bar Calculations

5. Technical Investigation

In order to understand the force generated in the bar I carried out a number of

theoretical calculations.

Peter Wood & Co Searcher Bar dimensions

Component Dimension Reversible Plug diameter 0.025m length 0.23m weight 0.65kg (including thread guard & grub

screw) Bar diameter 0.016m length 1.315 m (including boss head) weight 2.15kg Insulated Handle length 0.95m weight 6kg

Below, is a schematic diagram of the Searcher Bar in the open and closed

position. Due to the design of the reversible plug, the raised height of 2.21m

can only be achieved with the tool in the 0.2m setting. Where the 0.38m depth

is selected, the raised height is reduced to 2.04m.

2.21m 1.37m

Closed

Open Fig 3 Schematic diagram of a Searcher Bar



My calculations assume the Searcher Bar is operated in the following method;

keep bar tip in contact with the ground and raise the handle to its maximum

height in the 0.2m depth setting. Allow the handle to fall freely with the

operative offering no resistance.

During impact, it is assumed that the impact force between the handle and bar

is much greater than the resisting force offered by the ground and the effects

of gravity. Therefore, the latter forces may be neglected during impact. Thus,

there is no significant external force acting on the handle and bar. Friction

between the bar and handle has also been neglected.

It is also assumed that there is no rebound, thus, the two systems couple at

impact. Hence, the collision is inelastic and some Kinetic Energy will be lost to

the system.

Acceleration due to gravity (g) = 9.81m/s²

Striking velocity calculation (V1 )

V1 = √ (2gh)

V1 = √ (2 x 9.81 x [2.21 – 1.37])

V1 = 4.06m/s

v1

Penetration

Fig 4 Velocity diagram

h

v

R

Symbol Key V velocity m mass g gravity h height K.E. Kinetic Energy P.E. Potential Energy



Common velocity of coupled system after impact

mT V = m1 V1

8.8 V = 6.65 x 4.06

V = 3.07m/s

Kinetic energy of system after impact

Kinetic Energy = ½ mT V2

K.E. = ½ 8.8 x 3.072

K.E.= 41.47 Joules

I have assumed a constant penetration of 0.01m per stroke to provide

comparative calculations regardless of the material being penetrated.

Loss of potential energy in descending 0.01m

Lost P.E. = mT g distance

= 8.8 x 9.81 x 0.01

= 0.86328 J

Therefore, the work done by the handle and bar = K.E. + loss of P.E.

= 41.47 + 0.86328

= 42.33 J

So the resisting force, R = Work done / distance

= 42.33 / 0.01

= 4.233kN

Masses of the components m1 = 6.65kg (handle & reversible plug)

m2 = 2.15kg (bar)

m T = 8.8kg (total weight)



Newton’s third law of motion states that; ‘To every action there is an equal and

opposite reaction’. Therefore, the resisting force equals the force in the bar.

Thus, the force in the bar = 4.233kN

To check the accuracy of my calculations I used linear motion.

Initial velocity (u) u = 0

Final velocity (v) V = 3.07m/s (after impact)

Distance travelled (s) s = 0.01m

Acceleration (a) a = ?

V2 = u2 + 2 a s

3.072 = 2 x a x 0.01

a = 471.245m/s2

F = m a

F = 8.8 x 471.245

F = 4.147kN

Note: this force does not take potential energy into consideration.

K.E / distance = 41.47 / 0.01 = 4.147kN

Thus, the force is 4.147 kN and with the lost Potential Energy included, the

force is 4.233kN.



Calculation Summary – 0.2m depth setting

Measure Result Striking velocity 4.06m/s Common velocity 3.07m/s K.E after impact 41.47J Loss of Potential Energy 0.86328J Work done by system 42.33J Resisting Force / Force in bar 4.233kN

Note: The calculations are displayed on one sheet in appendix d. This set of

calculations is used a number of times.

I repeated the calculations (appendix d), for the tool being used in the same

way but in the 0.38m setting to enable theoretical comparisons to be made.


5 (b) Safeway Searcher Bar Calculation Summary

So it can be seen that the force in the bar is reduced from 4.233kN to 3.39kN

when comparing utilisation of the tool in the 0.2m and 0.38m setting.

The 20% reduction occurs due to the reversible adaptor (which acts as the

‘stop’ in the 0.2m setting) being inserted inside the handle. The boss head at

the top of the bar strikes the reversible adaptor, resulting in a 0.17m shorter

stroke. This reduces the velocity of the tool before impact, thus a lower impact

force is generated.



5 (c) FCO Calculations

Considering my theoretical calculations, I applied the same process to my

observations of the three FCO’s; refer to 4(d) for values used.

FCO - Peter Wilson

As Peter forced the tool, we can no longer use gravity for the acceleration.

Therefore, I applied linear motion and the median time and stroke Peter used.

s = u t + ½ a t2

0.45 = ½ a x 0.2552

a = 13.84m/s2

Calculation Summary


So, it can be seen that although Peter exerted his own force on the barhole

tool, the reduction in stroke resulted in a lower striking velocity and

subsequently a lower force in the bar. In fact Peter is exerting more energy

and is therefore at risk of injuring himself.



I repeated this exercise with the 2 other FCO’s.

FCO Acceleration Force in bar Peter Wilson 13.84m/s2 3.559kN

Ricky Samuels 16.44m/s2 6.267kN Richard Bayford 15.87m/s2 4.931kN

It can be seen that the method of operation can make a vast difference with a

75% variation in force calculated between Peter and Ricky.

5 (d) Analysis of calculations

FCO Stroke (m)

Striking Velocity (m/s)

Common Velocity (m/s) Force (kN)

Peter Wilson 0.45 3.53 2.67 3.559 Ricky Samuels 0.74 4.93 3.73 6.267

Richard Bayford 0.6 4.36 3.3 4.931

Freefall

0.2m setting 0.84 4.06 3.07 4.233 0.38m setting 0.67 3.63 2.74 3.39

My calculations suggest that exerting force on the tool does not necessarily

mean more force in the bar at impact. It can be seen that Peter Wilson

produced considerably less force, which is due to the shorter stroke he

adopted. Simply raising the handle to the top of its stroke, and allowing the

handle to freefall would have produced more force.

Ricky Samuels was able to exceed the force obtainable via freefall alone. By

adopting a longer stroke than Peter and forcing the tool an increase of almost

50% can be seen.

It is clear from my observations that the longer the stroke, and the greater the

velocity, the resultant force is greater.



6 (a) Brainstorm

6. Considering a Solution

Reflecting on the outcome of my research and calculations, I brainstormed a

list of points that should be considered:

• Used by a single operative

• Health and safety implications on using the tool (reduce injuries)

• Operative competency training

• Portable tool and ability to safely store on vehicle

• Weight of tool

• Materials used in construction to ensure tool is robust

• Capable of penetrating tar-macadam and dense bitumen macadam

• Used in gaseous atmospheres

• Insulated to prevent electric shock (cable strike)

• Limit depth penetration (prevent over penetration)

• Conforms to Legislation, Policies, Procedures and Standards

• Use of the tool in the 0.38m setting results in less force in the bar, yet

the material to be penetrated is more substantial

• Operatives are able to comply with relevant Legislation, Policies and

Procedures

• Generate a greater force within the bar, without the operative ‘forcing’

the tool



6 (b) Conceptual Designs for Barholing

I then drafted a number of concepts (appendix e) and I have detailed the

advantages & disadvantages of each in the table below.

Design Number Design Type Advantages Disadvantages

1 Tripod

• User not in contact with tool at point of impact

• Stroke is very short - Low velocity at impact

• Ratchet mechanism needed to raise weight

• Bulky • Awkward to handle and

store

2 Hydraulic Barhole Tool

• Hydraulic fluid cushions the impact for the user

• Potential for oil to leak • Higher maintenance costs • More complex to

manufacture

3 Spring Loaded Handles

• Impact is cushioned for user by spring loaded handles

• Not suitable for short or tall people

• Tool could rebound • Awkward to store on

vehicle • Relies on the user firmly

holding the tool to work

4 Incorporated Spring

• Impact is cushioned by spring loaded

• Tool could rebound on impact

• Relies on the user firmly holding the tool to work

5 Modified Existing Tool

• Increased length creating a longer stroke

• Increased weight to increase the velocity before impact

• No reversible adaptor

• Only able to penetrate to 200mm depth

• Existing racking in vehicle needs to be longer

• Slightly more cumbersome due to weight and length



6 (c) Selected Option

During my feasibility study I identified a number of constraints, the main

issues being the timeline of the project, the time available for me to work on

the project and no financial budget. Given the limited scope of resources, it

would not be feasible to develop a new concept. Therefore, considering my

investigation and research I selected design number 5.

6 (d) Modifying the Safeway Searcher Bar

I decided to modify the tool as detailed in the table below, within the scope of

the E8 document.

Modification Advantage Increased length (longer stroke of 1m)

E8 / Design 4.5 - Transco will consider variations above 0.66m

Increased velocity of bar

Increased weight (10kg) E8 / Design 4.15 - 10kg is the maximum permissible weight

Greater mass will create more force

No reversible adaptor

E8 / Design 4.3 - Permissible to limit depth to one setting

Minimise the risk of damaging underground plant

New adaptor or guide has bigger diameter to prevent over penetration E8 / Design 4.3 – Requirement to limit depth of penetration


0.2m depth penetration only

E8 / Design 4.3 - Permissible to limit depth to one setting




The disadvantage of my modifications is that the Searcher Bar would only

penetrate to 0.2m depth. However, the modified tool is being designed for

FCO’s who do not require the use of 0.38m penetration. Considering there are

approximately 2500 FCO’s in Transco, it is entirely feasible to produce a

Searcher Bar specifically for their use. This will also eliminate the significant

safety issue of over penetration.

6 (e) Technical Specification for Searcher Bars E8

E8 provides detail on the required specification for Searcher Bars used for

barholing operations, including dimensions, materials and performance. I have

listed below a number of the key points within E8 that will affect any design

modifications to the Searcher Bar.

• Shall incorporate means to limit penetration to 200mm and/or 380mm

• Minimum stroke of 560mm. Maximum stroke shall normally be 660mm

but Transco may consider variations

• Electrical insulation shall not be less than 600mm. No slip allowed

between insulation and handle

• Outside diameter shall not exceed 65mm

• The weight of the handle shall not be less than 4.5kg and the overall

weight of the equipment shall not be greater than 10kg



6 (f) Modified Tool Specification & Theoretical Calculations

I drafted a rough sketch (appendix f) and considered the components

required.

Bar - Existing Safeway Searcher Bar can be utilised, thus saving costs.

Handle - New length to give a maximum stroke of 1m.

• Length 1.115m

• Diameters

o Barrel int 0.033m , ext 0.041m , Insulation 0.0065m

• Weight approx 7.04kg (based on Safeway Searcher Bar assuming

same materials used and weight is uniform 6kg / 0.95 = 6.3158kg/m x

1.115m = 7.04kg)

Guide - The guide is smaller than the existing reversible adaptor, although

greater in diameter to prevent over penetration.

• Diameters

o Ext 0.05m , thread 0.033m , bar securing screw 0.008m

• Weight approx 0.75kg



Based on previous theoretical calculations as shown in appendix d, I

calculated the force in the bar considering the modified components.


6 (g) What Difference Will the Modifications Make?

The theoretical calculations show that the force achieved is higher than that of

Ricky Samuels, who exerted his own force on the tool. The proposed modified

tool is able to achieve that level of force through gravity alone, producing 44%

more force than the Safeway Searcher Bar.

Operation Stroke (m)

Striking Velocity

(m/s)

Common Velocity

(m/s)

Kinetic Energy (Joules)

Force (kN)

FCO (Ricky Samuels) 0.74 4.93 3.73 61.22 6.267

Safeway Searcher Bar – 0.2m depth

(Freefall) 0.84 4.06 3.07 41.47 4.233

Modified Tool (Freefall) 1 4.43 3.544 62.8 6.378



7 (a) Working Model

7. Model Fabrication

After creating a first draft of the tool on graph paper (appendix g), I drafted the

model tool in AutoCAD 2000 using solid modelling techniques. This gave

three-dimensional views and assisted with the production of the working

model.

The model was constructed from materials that were readily available in the

machine shop, such as steel and brass.

Dimensions are approximately 1/3 size in length, and diameters are

approximately ½ size. Components produced included: bar (inc boss head),

barrel, end plug, guide, and bar securing screw.

7 (b) Model Materials

Barrel: The barrel is made from steel and is drilled out to accept the bar. Its

external diameter is 0.020m and it is internally threaded at both ends.

End plug: The end plug is externally threaded and acts as the top striking

face. It is constructed from the same material as the barrel, although it is not

drilled out.

Bar (inc boss head): The bar was constructed from solid steel and has a tip of

45°. The top end of the bar is threaded to accept the boss head. The bar is

0.008m and the boss head is 0.010m, which is drilled and tapped to connect

to the bar.



The striking face of the boss head has a radiused edge to prevent the head

from being ‘mushroomed’, ensuring the boss head does not interfere with the

inside of the barrel.

Guide: The guide is made from steel and has an external thread. When

screwed into the bottom of the barrel it is flush with the whole barrel. The

oversized section diameter is 0.030m and demonstrates the ‘fixed stop’ to

prevent over penetration. It is also drilled to allow the bar securing screw to

pass through the cross sectional area to the bar. The guide was then

quenched in oil to give a finished look (oil blackening).

Bar securing screw: The bar securing screw is made from brass because it is

a softer metal and therefore will not damage the bar. The screw head is

considerably oversized, as it is a functional part of the model and prevents the

bar from sliding which is a safety feature, even when considering a model.

The head of the screw has been knurled to provide a greater grip when

tightening the screw.

7 (c) Model Summary

The model serves as a good depiction of the modified tool and it fully

demonstrates the principle of operation. I was not able to electrically insulate

the barrel handle as I did not have sufficient resources. However, this does

not detract from the principle of operation.



8 (a) Drafting

8. Design Phase of the Modified Tool

I drafted the modified tool in AutoCAD 2000 using solid modelling techniques

in a 3D environment (appendix h). I also drafted the components of the tool to

define the specific measurements (appendix i).

The final drawings included a number of small changes that were identified

whilst producing the model;

• When the guide is inserted into the barrel in now finishes flush

• The top closure plug is threaded and is not secured using an

interference fit

• The hole through the guide for the bar is 0.0163m. This is because a

small gap is required to prevent a vacuum forming in the barrel, thus

preventing the bar from moving

8 (b) Safeway Searcher Bar Component Materials

The materials used by Peter Wood & Co Ltd to produce the Safeway

Searcher Bar were adequate and meet the specification of E8. The materials

have been seen to demonstrate the withstanding of ‘in-service’ treatment,

assuming the tool is used appropriately.

Bar: The bar is constructed from nickel-chrome-molybdenum steel, which is

often used for gears in automobiles and machines, where resistance to shock

and fatigue is important.



The bar tip is hardened to 55-60 HRC, which provides immense wear and

impact resistance. The top face of the boss head (striking face) is heat treated

to 35-40 HRC, again to provide impact resistance.

Steel grade – 817M40 (T) (EN24T) Standard - BS 970

Barrel: The barrel is made from steel and is a cold drawn seamless tube.

Standard - BS 2T 68:1980 (Specification for cold drawn 18/10 chromium-

nickel corrosion-resisting steel tube (niobium stabilized: 800 MPa) (weldable)

Guide & Top Closure Plug: Constructed from nickel-chromium-molybdenum

steel and the striking face’s are heat treated to 35-40 HRC.

Steel – 070M55 (T) (EN9) Standard – BS 970

Bar securing screw: I have decided to use brass for my bar securing screw, as

it is a very soft metal. If a hard metal is used it could damage the bar and

therefore, affect the operation of the tool.

Standard - BS 768:1958 (Specification for slotted grub screws)

Insulation: The insulation is made from natural rubber as it has high tensile

strength, good resistance to abrasion, tear and fatigue, excellent electrical

properties and low temperature performance.

The rubber is extruded onto the barrel and has a 6.5mm covering. The

insulation must be able to withstand current leakage testing (as per E8).

Standard - BS 3054:1959 (Specification for fireman's axe with rubber

insulated handle)



8 (c) Safeway Searcher Bar Costing

The existing complete Safeway Searcher Bar costs £73.00 excluding VAT.

Individual components are priced as follows (all exclude VAT):

• Bar £15.83

• Reversible adaptor £10.40

• Insulated handle £53.50

• Thread guard £2.89

• Thumb screws £0.28

8 (d) Modified Tool Prototype Costing

In order to produce a full size prototype I would need to purchase the following

minimum materials (all prices exclude VAT and carriage), as detailed in the

table below:

Component Material Size Sourced from Cost

Bar Nickel-chrome-molybdenum

steel

0.04m Dia 2m length

Abrapulman www.pulmans.co.uk £22.00

Guide & Top closure

plug

Nickel-chrome-molybdenum

steel

0.050m Dia 1m length

Abrapulman www.pulmans.co.uk £18.00

Bar securing

screw

Brass Rod 0.021m Dia 0.5m length

RS Components (www.rswww.com) £16.85

Barrel

Cold drawn seamless steel

tube

Dia 0.040 - 0.045m 2m

length

21st Century Steels

Approx £25-30

Rubber insulation

Rubber N/A

Essential Equipment Limited (www.essentialequi

pment.co.uk)

POA

http://www.rswww.com/�

http://www.essentialequipment.co.uk/�




In addition to the material costs I would need to consider the following costs:

• Machine shop

• Further heat treatment of the metals

• Rubber extrusion and bonding

• Wasted material due to minimum order quantity

Obviously building a prototype would be very expensive and would cost 4 to 5

times the £73.00 quoted by Peter Wood & Co Ltd for their complete tool. Peter

Wood & Co Ltd is clearly able to offer such low costs by mass-producing their

Searcher Bar (Transco have bought over 4000 Searcher Bars and they also

sell their tool to water utility industry, landfill companies and local authorities).

As previously identified, I did not have the resources to build and test a full

prototype.



9. Final Specification of the Modified Tool

My modified tool, the ‘Emergency Services Searcher Bar’ is designed

specifically for the 2500 First Call Operatives employed by Transco. The

Searcher Bar has a fixed depth of 0.2m and is suitable for penetrating a range

of surfaces including:

o Soil

o Tarmacadam

o Dense bitumen tarmacadam

o Clay

o Rubble/Hardcore

Note: The Searcher Bar is not designed for penetrating concrete.

Technical Specification

Part Specification Weight kg Bar Manufactured from nickel-chrome-

molybdenum steel Bar tip is hardened to 55-60 HRC Boss head striking face, hardened to 35-40 HRC

2.15kg

Barrel Cold drawn seamless steel tube

Combined 7.79kg

Guide & Top Closure Plug

Manufactured from nickel-chrome-molybdenum steel Striking face, hardened to 35-40 HRC

Bar Securing Screw

Manufactured from brass

Insulation Rubber insulation 6.5mm thick

Total Weight (theoretical) - refer to 6 (f)

9.94kg



10 (a) Emergency Services Searcher Bar (Modified Tool)

10. Conclusion

The ‘Emergency Services Searcher Bar’ produces over 44% more force than

the Peter Wood & Co Ltd Safeway Searcher Bar. The increase in force has

been achieved by increasing the striking velocity and therefore the combined

velocity of the handle and bar as it penetrates the surface. This has been

attained through increasing the weight from 8.8kg to 9.94kg and the length of

the stroke from 0.8m to 1m, an increase of 13% and 25% respectively.

The substantial increase in force will enable operatives to successfully barhole

without the need to exert their own force on the barrel handle. Therefore, the

potential of injuries resulting is greatly reduced.

Withdrawal of the Searcher Bar can be carried out in the same way, with no

additional effort required from the operative. This is due to the removal of the

reversible adaptor. Thus, the withdrawal stroke is not affected by the

increased stroke. Removal of the reversible adaptor also eliminates the

potential for over penetration which is a significant safety issue.

In addition, to address the behavioural factors, I produced an operative user

guide to reinforce and promote safe practices when using the tool (appendix

j). This is particularly important as the benefits gained through modifying the

tool would be lost if the tool is not correctly used.



10 (b) Project Continuation

During the project I recorded a number of factors that would require

consideration if the project was continued;

• The effects of friction between the barrel and bar. Could a different

material reduce any friction? Or is it insignificant?

• Incorporating a self-lubricating bush into the guide, thus no oiling of the

bar required.

• Carry out extensive field trials using sophisticated equipment to

accurately measure levels of force in the bar.

• Carry out extensive field trials to determine any shock received by the

operative.

• Consider the effects of altering the angle of the tip of the bar.

• Consider the effects on the force if the handle and bar don’t couple at

impact, i.e. rebound rates and variations on different surfaces

• Investigate my conceptual ideas (appendix e)

• Investigate the tool being used in the 0.38m setting in the carriageway

• Consider the Hand Arm Vibration Syndrome (HAVS) regulations

introduced during 2005



10 (c) Further Developments

If I was given the opportunity to develop my modified tool proposal further,

taking into account the budgetary constraints, I would have looked to form a

partnership between Transco & Peter Wood & Co. Considering their

knowledge in this field and the resources available to them, it would present a

minimal risk strategy for both parties. Should the collaboration be successful,

Transco will benefit through reduced associated injuries, with Peter Wood &

Co benefiting through enhancing their product, which they can then sell to

Transco and other organisations.



In research and the writing of this project, I referred to the following

information sources:

11. Referencing & Bibliography

Books Timings, R.L (1990) Engineering Materials Vol 2, Harlow: Longman Hannah, J & Hillier, M.J (1995) Applied Mechanics (3rd edition), Harlow: Pearson Bolton, W (1999) Higher Engineering Science, Oxford:Newnes Lock, D (2000) Project Management (7th edition), Aldershot:Gower Procedures SBGI (Nov 1991) A Code of Practice for Barholing Transco (Feb 1993) Technical Specification for Searcher Bars E8 Transco (1995) Field Procedures D2 Transco (May 1998) Emergency Procedures EM71 Transco (2001) Health Safety & Environment Book (Issue 5) Transco (June 2001) Emergency Field Procedures EM72 HSE (2000) Avoiding Danger from Underground Services HSG47 Literature Peter Wood & Co Ltd Safeway Searcher bar Peter Wood & Co Ltd How to use the impact Searcher Bar Transco (1996) Classifier Training Material Internet http://www.heathus.com/ Gas Consultants (Houston & Canada) http://www.bsonline.techindex.co.uk/ British Standards online http://www.pulmans.co.uk Abrampulman Material stockists http://www.specialiststeels.co.uk Steel stockists http://rswww.com/ RS Components http://www.essentialequipment.co.uk/ Rubber extrusion & bonding http://www.hse.gov.uk/ Injury Statisitics Company Intranet Transco Lattice Acknowledgements I would like to formally acknowledge XXXXX & XXXXX from Harlow College

for their assistance with the production of the working model.

http://www.heathus.com/�

http://www.pulmans.co.uk/�

http://www.specialiststeels.co.uk/�

http://rswww.com/�




Acronym

12. Acronyms

Description FCO First Call Operative ELR Escape, Locate & Repair LTI Lost Time Injuries

NLTI Non Lost Time Injuries HSE Health & Safety Executive HNC Higher National Certificate IGEM Institution of Gas Engineers & Managers

D32/33 NVQ Skills Assessor

13. Declaration and Testimony

I certify that I have read the Technical Report written by XXXXX and confirm

that to the best of my knowledge it is true and accurate.

Name: ___________________________________________________

Signed: __________________________________________________

Professional qualifications: ___________________________________

Relationship to candidate: ____________________________________

Date: ____________________________________________________

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