Safety Talk 12

Preparation for overhauls

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Why discuss overhauls ?

• Briefings and discussions like this are essential:

• To maintain awareness of the risks, the controls, and the penalties of failure

• To learn the lessons from past accidents

• To add your local knowledge and experience to the Company’s procedures

An overhaul involves a considerableincrease in risk and requires careful planning.Accidents during overhauls continue to happen;frequency rates increase.

Workplace safety depends on people !

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What are the risks?• A big increase in activity

• Interactions between different jobs

• Shutdown and start up operations

• Higher risk work eg. heavy lifts

• Hazardous materials eg. pyrophorics

• Environmental risks eg. dirty effluent, sludge

• Difficult access, working at height, dropped objects• Workforce is mobile and unfamiliar with site details • A variety of contractors with different safety

management standards

• Specialist activities unfamiliar to site personnel

• Difficult and complex communications

• Can you add some ?

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Managing the risks

• Set up an overhaul management team

• Identify and assess the risks

Develop and apply the appropriate controls:

– plan the overhaul well in advance

– involve all the relevant people

– familiarisation of people – preparation of worksites and equipment

– communications

– materials purchasing / quality controls

– contractor controls

– procedures

– PPE, first aid, and emergency planning

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Overhaul Plan

• Develop overhaul plan

• Establish work requirements

• Purchasing and contracts

• Divide work into manageable parts

• HSE requirements

• Work schedules

• Integrated shutdown procedures

• Approval and acceptance procedures

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Detailed planning – Workplace input

• Teamwork - all departments to provide input to maintenance planners – work required– isolation requirements– other preparation work and temporary facilities – higher risk work / risk assessments / method

statements – waste handling and other environmental issues

• Establish a shutdown file for each unit / area

• Identification, tagging, blank lists, check lists

• Inspection and housekeeping checklists

• Preparation of tool box talk material

• Specific shutdown and equipment preparation procedures

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Site preparation

• Identification and demarcation of work areas / zones

• Tag valves, joints, spades etc.

• Scaffold where safe

• Supplement PPE, shower / eyebath, rescue facilities

• Position temporary equipment

• Check utility / service systems, surface drains

• Overhaul equipment must not obstruct operating areas prior to shutdown

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People preparation

• Keep an overhaul skills and experience database

• Define manpower criteria and influence selection (by contractor)

• Appoint permit controllers

• Carry out training and tool box talks, on topics like:

– overhaul activities and risks– equipment isolation

and preparation– cross training operations /

maintenance / HSE– relations with contractors– working at height / falling objects

• Plan staff cover eg. weekend work, shift / night work

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Communications

• Communications is the key to a successful, safe overhaul

• Adequate communications equipment eg. radios, telephones (booths) on site

• Key personnel carry radios, bleepers

• Systematic presence on site of BP representatives with radios

• Daily shutdown meetings at set time, mandatory attendees, standard record for immediate circulation

• Workforce communications

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Contractor induction

Requirements clearly defined (in booklet or on video)

• General rules including security

• Accident prevention

• Hazardous areas,work zones

• Work permit system

• Accident / incident reporting

• PPE

Joint site / contractor implementation

• Contractor focus on activity safety

• Site focus on oil industry / refinery safety

• Test presentations on an uninformed group

• Resource significant and may need to be contracted out

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Security

Area security• Log of people eg. by contractor

• Access controls to / from contractors offices and accommodation / camp

• Process unit (additional) access, temporary walkways or cross overs

Site security• Number, location

and control of gates

• Personal identification

• Matches and lighters

• Vehicle passes, parkingsite traffic safety, bussing

Health, hygiene,food, toilets etc

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Pre-shutdown facility inspection

• Adequate number and location of: isolation valves, spades, blanks, drains and vents, purge points, pump out connections, flushing facilities, lifting devices

• Plan temporary facilities needed for hoses, pumps, scaffolding, purge connections, lifting equipment etc.

• Prepare / update spade / blank lists

• Prove / clear (low pressure) drainage systems

• Report substandard facilities forrepair or modification

• Special requirements eg. draining water from systems containing light ends

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Decommissioning

• Experienced operators must be present – adjust membership of shift teams

• Specific detailed procedure

• Depressure eg. to fuel gas system, then to flare

• Displace gas with inert gas or steam before admitting air

• Identify ‘live’ and ‘dead’ systems

• Take precautions against specific hazards / toxic materials

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Venting and draining

• Use temporary piping to drain to closed system

• Allow material to cool before draining

• Drain through permanently installed drain points

• Remove water, clear blocked drains, low points drained

• Minimise quantities of oil drained to the sewer

• Beware of the fire / explosion hazard

• Pumping out

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• Insert blinds, swing spades, remove spool-pieces etc. per isolation plan

• Segregation of equipment into manageable parts

• Prime movers must be positively isolated before work is allowed to commence

• A lockout / tagout system must be used to ensure isolation remains intact

Mechanical isolation

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Lock-out and tag-out

• A lock-out device is a lock and key used in combination with a multi-clasp or chain

• It prevents unauthorised operation of an isolation valve or switch

• A tag-out device is a warning tag or notice attached to a valve or switch forbidding operation

• Tag-outs can be used in combination with lock-outs, but are normally used where locks are impractical (Note: specific rules apply in some countries)

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Blind list

• Record of installation and removal of blinds

• List should contain identification details ie. area, plant, equipment, location, line number etc.

• List is attached to work permits

• Tags are used to identify blind positions and are often installed prior to work

• Note that blanks, blinds and spectacle spades must be clearly identified and not confused with spacers or rings

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Minimum potential energy

• Electrical systems should be earthed and condensers /capacitors discharged

Moving parts must be at a position of minimum potential energy so that no subsequentmovement can occur.

For example:

• Fin-fan blades should be anchored to prevent them turning due to natural convection

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Risks of venting to atmosphere

• Hydrocarbon vapours tend tosettle in low places

• Can persist for extendedperiods at ground level

• Flammable concentrations may persist for several hundreds of metres, where they may find a source of ignition

• Formation of a toxic cloud may be possible

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Precautions when venting to atmosphere

• Point and velocity of release should be as high as possible

• Use of steam or inert gas to disperse and dilute the vented materials below flammable and toxic levels

• Warning must be given (downwind)

• Plan action to be taken if a dangerous situation develops

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Steam purging

Light hydrocarbons are vapourised and heavier materials will flow more freely.

Precautions:

• Avoid overpressuring equipment if the steam supply pressure is greater than the design pressure

• Avoid damaging heat sensitive components, such as instrumentation

• Avoid creating a vacuum when steaming is stopped

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Closed steaming

Closed steaming with no outlet to the atmosphere eg. steaming of a column to the overhead condensers.

• More environmentally friendly

• Greater risk of forming a vacuum when steaming is stopped

Precautions:

• Equipment must immediately be opened to atmosphere on shut down, or fuel gas introduced on start-up

• At a sufficient rate to prevent pulling a vacuum

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Open steaming

Open steaming with steam vented directly to atmosphere together with remaining process material.

Precautions:

• Vents should be high, and well away from work areas and sources of ignition

• Route condensate to a dirty (process) drain

• Monitor compliance with environmental consents

• Provide adequate condensate drains to prevent liquid build up, with retention of process materials

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Water flushing and filling

• Water is heavier than hydrocarbons and equipment foundations may not support a vessel full of water

• Water may not remove all traces of hydrocarbons

• In cold climates, ice plugs may be formed at low points

• Residual pockets of water are hazardous on contact with hot oil

• Environmental risks with disposal

• Precautions:– check capability of foundations– remove final traces of water by draining

at low points or blowing with air (hazardous)

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Risks of inert gas

• Asphyxiation

• Overpressuring equipment eg. using bottled nitrogen

• Overchilling and embrittlement eg. using bottled CO2

• Inert gas may not totally gas free equipment

– if flammable materials are left behind in oily deposits and sludges

– if oxygen levels are not reduced sufficiently in presence of low energy combustible gases eg. hydrogen or H2S

• Corrosion eg. wet CO2

• Contamination eg. with process material

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Precautions with inert gas

• Oxygen testing per entry permit system

• Only specialist contractors are permitted to work in an inert atmosphere (and they must be closely monitored)

• Venting of inert gas rich mixtures must be carried out well away from personnel

• Check design pressure and fit reducer and relief valves

• Control rate of inserting to control temperature

• To inert a space containing hydrogen or H2S, the oxygen

content must be reduced below 1% volume

• Purge by pressuring / depressuring, introducing the inert gas at one end and venting at the other (piston effect)

• Disconnect immediately after use / when empty

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Air purging

• Air is used to purge storage tanks, but the gas / air mixture will have to pass through the flammable range

• So this method must not be used where sources of ignition may be present eg. pyrophorics

• Blow air in, rather than sucking out a gas / air mixture, as air movers can generate sparks if damaged

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Air blowing

• Air blowing is sometimes used to dry equipment or blow residual material from pipelines

• Open ends should be screened off and a roped off area established to prevent high velocity debris from injuring people or damaging equipment

• A ‘target’ should be positioned in direct line with the open end

• A hazard of introducing air is that equipment may not have been designed for plant air pressure

• Also, air could find its way into low pressure gas or flare systems, possibly creating an explosive mixture

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Standing under nitrogen ?

Two maintenance men were removing a large man way from a

distillation column standing under nitrogen. One of the men was overcome by N2 and

slumped over the man way entrance. Luckily the other man pulled him

clear and both fell onto the platform grid.

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Wrong pump

The supply had actually

been transferred to another

switchhouse, and the pumps

had never been adequately

labelled

To check that he was working on the correct pump, a fitter pushed

the local start button. On completion it was discovered that the incorrect

isolator had been locked off, and the pump being worked on was live,

but in the tripped condition.

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Wrong valve

Clear identification of ‘live’ and ‘dead’ systems is

essential. Equipment in the vicinity which must not be

touched should be tagged and secured.

During an overhaul, a subcontractor opened a valve body located in a live fuel gas line beyond

(but near to) a battery limit. The refinery lost its fuel gas main pressure. Luckily the hydrogen rich gas

escaped without ignition.

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A fire, started by external welding work, occurred inside the overhead line of a column undergoing major overhaul. The smoke spread quickly, fatally trapping 2 operators

who were in the column.

Fatal interaction

Before a space is declared ‘gas free’, it must be

free of materials which could produce flammable

or toxic vapors on heating

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An LPG H2S Absorber was being prepared for overhaul. The LPG had

supposedly been evaporated to flare, and the remaining liquid in the column drained to surface drain. After a period of steaming, hot condensate was drained from the column base. Two manhole

covers, each weighing 90 kgs. were blown off, one to a height of at least 5 metres to

clear a handrail before landing on an adjacent platform.

Erupting drains

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A storage sphere which was full of water collapsed during leg repairs. A cloud of LPG vapour formed and ignited.

Luckily injuries were not serious.

Heavy water

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Crane hits scaffold

A contractor's lorrywith an on-board crane drove

off with the crane jib / arm not fully retracted. This struck the bottom of

a scaffold suspended from an overhead pipetrack. Luckily the

two men working there werenot injured.

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A fitter was opening a flange on a line which had not been

drained. There was a release of naphtha which flashed and the

fitter was fatally burned.

Premature work

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An air driven winch wasbeing used to transport equipment to

various levels of a 90 ft high column. Toassist the descent of the winch hook, a 56 lb static measuring weight was used as ballast. The handle of the weight failed and it fell to

ground level, landing within the ropedoff area of the winch drive.

There were no injuries.

Winch incident

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During steam outof a column, light ends

flowed with the hot condensate into the open sewer system, and

then flashed, engulfing thecolumn in flames.

Fire during steam-out

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Optional quiz1. What are the main risks during overhauls ? (6)

2. List key aspects of the Overhaul Plan (5)

3. What specific input can you provide to the planning process ? (5)

4. What pre-overhaul site preparation work can be done in your area ? (5)

5. What pre-shutdown inspections / checks do you carry out ? (5)

6. What precautions should be taken when venting and draining ? (6)

7. What precautions should be taken when steaming out ? (6)

8. What controls can be used to avoid confusion over which equipment is to be worked on ? (4)

9. What are the hazards of air ? (4)

10. What are the hazards associated with inert gas ? (4)

11. Give examples from this Safety Talk of accidents during overhauls (5)

12. Give 2 more examples from your experience (2)