maintenance strategy mba assignment - dave phelan

MAINTENANCE STRATEGY

COURSE ASSESSMENT 2

Student Name: Dave Phelan

Student Number: 7495538

Assignment Reference No. MSTR/July10/1

Date Submitted: 25/10/10

Question

Answer these questions in the form of an essay (2000 - 2500 words)

Figure 1 shows a manufacturing process and Figure 2 shows a batch chemical reactor unit within this process. Table 1 shows the life plan for the batch chemical reactor with an indication if the task can be done with the reactor on-line (i.e. working) during a plant shutdown or during a short gap in production between batches – which is called a production window. There is a separate Microsoft Excel spreadsheet which gives details of all of the closed maintenance jobs which have been carried out on this reactor unit. This is called “Worklist for MSTR Assignment2.xls”

a) Explain why you would regard this batch chemical reactor as a plant unit.

b) Explain your reasons for concluding that this unit is critical for production.

c) Extract any user requirements for this designated unit from the plant description. Are there any production ‘windows’?

d) Extract any corporate requirements for this unit from the plant description.

e) Extract any legislative requirements for this unit from the plant description.

f) Having described the requirements for this unit, comment on whether you believe any other of the tasks in Table 1 could be completed during a production window in addition to the visual inspection.

g) Comment on whether you think any maintenance tasks are missing

h) How do you think this maintenance strategy could be improved?

Answer: 2499 words (word limit 2000-2500)

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Table of Contents

Section 1 - Introduction ...........................................................................................3

Section 2 – Questions

2.1 Explain why you would regard this batch chemical reactor as a plant unit ......3-4

2.2 Explain your reasons for concluding that this unit is critical for production ......4-5

2.3 Extract any user requirements for this designated unit from the plant

description. Are there any production ‘windows’?...................................................5-7

2.4 Extract any corporate requirements for this unit from the plant description .....8-9

2.5 Extract any legislative requirements for this unit from the plant description .....8-9

2.6 Having described the requirements for this unit, comment on whether you

believe any other of the tasks in Table 1 could be completed during a production

window in addition to the visual inspection .............................................................8-9

2.7 Comment on whether you think any maintenance tasks are missing...............8-9

2.8 How do you think this maintenance strategy could be improved......................8-9

Section 3 – Conclusions ....................................................................................9-10

References .....................................................................................................................................................19

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1. Introduction

This short essay answers a list of specific questions that pertain to a bulk

pharmaceutical manufacturing process (Figure 1) that includes a batch

chemical reactor unit (Figure 2). These questions broadly cover a view of the

criticality of the reactor, consideration of legislative, corporate and user

requirements derived from the plant description, a view of possible

opportunities to expand maintenance activities during a production window,

and consideration of how the existing maintenance strategy could be

improved.

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Raw Material

StorageCentrifuges

CentrifugeFeed

Vessel

Batch Reactor

Unit

Figure 1: Manufacturing Process

88

T1TIC

LP Steam

CV1

V1

P1

M1

SV1

SV2

Raw Materials

Figure 2:

Batch Chemical Reactor

Condensate

Trap

2. Questions

2.1 Explain why you would regard this batch chemical reactor as a

plant unit

The reactor clearly forms an integral and substantive part of the

manufacturing process, itself comprising of a number of ‘sub-level’

plant assets (e.g. P1) and control loops (e.g. LP steam TI/TIC/CV1).

Moubray (1997, Appendix 1) provides guidance on how to develop a

plant asset register as a foundation to apply a maintenance

management strategy, in his case a reliability centred maintenance

(RCM) programme. The ultimate aim of such a programme is to

ensure that the physical assets targeted do what the user wants

them to do in their present operating context. A list of equipment,

vessels, buildings etc. forms the plant asset register and, Moubray

asserts, should be constructed as a hierarchy that makes it possible

to identify any system or any asset at any level of detail, down to

individual components.

Moubray recommends (1997 p.81) that the level at which RCM is

best applied in a hierarchy, known as the level of indenture, is that

which leads to a reasonably manageable number of possible events

that could cause a functional failure. Starting too low down in the

hierarchy will often lead to too many unhelpful complexities including

difficulties dealing with control loops that cross sub-system

boundaries and can lead to the same function being analysed

multiple times. Equally, starting at the top of the hierarchy may lead

to many failure modes being overlooked. Moubray states that

identification of the optimum level to apply RCM becomes intuitively

obvious with practice (Moubray: 1997,p.86).

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After consideration of the factors outlined above and in conjunction

with personal experience and intuition, the author believes that the

batch chemical reactor should be regarded as a plant unit and should

be captured as such within the plant asset register.

2.2 Explain your reasons for concluding that this unit is critical for

production

In any maintenance programme resources will be finite, therefore a

quantitative analysis of business impact should be carried out to

identify the equipment which has the biggest impact on safety and

plant throughput (Wheelhouse: 2010, p.38).

Kelly (2006: p.170) agrees that it is important to rank the identified

plant unit according to its impact on production and safety. He bases

such rankings on the consequences of unit failure multiplied by the

likelihood of unit failure (see Figure 3).

Criticality

Ranking

Consequential

Production Impact

Consequential Safety

Impact

Level 1 (high)

criticality

Failure causes an

immediate and high

production loss

Failure causes an

immediate and high-

risk safety hazard

Level X (low)

criticality

Failure causes no

immediate or potential

production loss

Failure causes no

safety hazard

FIGURE 3 – TYPICAL CRITICALITY RANKING OF PLANT UNITS BASED

ON FAILURE CONSEQUENCES

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Here, in terms of operating context the primary function of the

manufacturing process is to produce 13,000 te/year of a bulk

pharmaceutical product. At the next level down in the plant asset

register hierarchy, the primary function of the batch reactor is to

produce 18 tonne of product within the required specification every

10 hours. This equates to 7,222 hours of operation at 1.8 tonne/hour

production rate, which, after allowing for the 16-hour annual

shutdown, requires that the reactor is available to run for 82.6% of

the year. This means that there is 17.4%, or 1525 hours per year of

spare reactor capacity.

From the process description provided there is no built-in redundancy

(i.e. no spare reactor). It is also stated that the centrifuges are the

process bottleneck. Therefore, if an unplanned reactor breakdown

occurs it wouldn’t necessarily immediately impact production.

However, a significant amount of reactor downtime may compromise

the primary function of the manufacturing process. The centrifuge

feed vessel will provide some buffer capacity to safeguard against

reactor breakdowns and keep the centrifuges supplied with feed. The

amount of buffer capacity available will determine the maximum

duration of reactor outage that can be tolerated before plant

throughput is adversely impacted. On the other hand, a breakdown

on the centrifuges will immediately impact plant throughput.

The author concludes that the reactor unit is clearly critical for

production, but it is logical that in a production criticality ranking list

the centrifuges might be ranked higher, perhaps as a Level 1,

whereas the reactor unit might be ranked slightly lower as a Level 2.

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2.3 Extract any user requirements for this designated unit from the

plant description. Are there any production ‘windows’?

A user specification requirement (USR) is defined as a description of

what the user wants from a unit or system that he believes will deliver

a business advantage. The USR should include details of the

functionality required of the unit/system, capacities, processing

details etc. Functional requirements usually specify what the system

is to accomplish rather than how it is to be accomplished.

Here, based on information included within the process description,

the USR for the reactor unit includes:-

The reactor must be capable of receiving 18 tonne of raw

materials from storage (details not specified although pumped

fill perhaps via P3 is likely to be required to minimise batch

cycle time).

The reactor must be sized to produce an 18 tonne batch of

product with a batch cycle time of 10 hours that meets the

required product specification.

The reactor must be constructed from materials that are

compatible with the chemicals/products used (i.e. no adverse

affect on product quality or safety), plus capable to withstand

the temperatures and pressures required for the process. It is

stated that the reaction materials are benign and do not pose

a corrosion concern. The author postulates that a glass-lined

vessel is required because it has a smooth, anti-stick surface,

is easy to clean, and does not introduce impurities to the

process materials.

The pipe-work must be fabricated from stainless steel.

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The reactor must be agitated and jacketed with a LP steam

supply to the jacket.

The reactor must be capable of being sealed to fully contain

its contents throughout the reaction.

The reactor must be fitted with a temperature control system

that has the capability to control the reactor contents through

a defined temperature/time profile with a high temperature

alarm at 125°C. Additionally, the control system must be

configured to protect the glass lined vessel from being

damaged by thermal shock.

The reactor contents must be transferrable through an

automated discharge valve at the base of the reactor to the

centrifuge feed vessel via a pump.

Production Windows

Production window is defined as a short gap in production between

batches, during which it may be possible to carry out asset

maintenance tasks.

Here, the life plan for the batch reactor unit (ref table 1) indicates that

the only activity that could be undertaken during a production window

is the weekly visual check on the reactor coupling which takes 5

minutes to carry out.

The author suggests that there may be additional production

windows if the overall batch cycle is considered. The batch cycle time

may be defined as from “reactor-empty to reactor-empty”. This

equates to the time taken to fill the empty reactor with raw materials

(fill step) + the 10 hour temperature profile time (reaction step) + the

time taken to transfer the entire contents of the reactor to the

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centrifuge feed tank (empty step). As the fill and empty steps have

not been defined it is not possible to specify the batch cycle time

precisely. However, intuitively the author suggests that some

maintenance activities could be carried out on specific items during

the fill step (e.g. steam trap), during the reaction step (e.g. P1) or

during the empty step (e.g. CV1). The buffer capacity in the

centrifuge feed tank will also effectively create a production window.

2.4 Extract any corporate requirements for this unit from the plant

description

Corporate requirements include: the need to license the

pharmaceutical product by the FDA and British Pharmaceutical

Society; the need for all production and maintenance activities to

comply with Good Manufacturing Practice (GMP); the registration of

the manufacturing process to the quality standard ISO9002; the need

for all company activities to conform to the environmental standard

ISO14000; the need for maintenance activities to comply with the

company permit-to-work system; in line with company guidelines the

reactor must be maintained to achieve a 25 year life and gearboxes

maintained to achieve a 15 year life; the facility must be kept well-

painted, clean and tidy for possible visits from pharmaceutical

inspectors at any time or visits from key customers.

2.5 Extract any legislative requirements for this unit from the plant

description

The reactor and the reactor jacket are rated as a pressure vessel and

a registered steam receiver respectively and are therefore subject to

the Pressure System Safety Regulations (PSSR) 2000 (Lloyds

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British: 2010). The aim of PSSR 2000 is to prevent serious injury

from the hazard of stored energy as a result of the failure of a

pressure system or one of its component parts.

The Regulations require users to:

establish the safe operating limits of the plant

have a suitable written scheme drawn up or certified by a

competent person for the examination at appropriate intervals

of:

- pressure vessels

-all safety devices

-any pipework which is potentially dangerous

A reactor failure may result in an immediate and high risk safety

hazard, therefore the reactor unit should be rated as safety critical

(see Figure 3). The reactor and jacket must both be fitted with a

certified safety relief valve.

2.6 Having described the requirements for this unit, comment on

whether you believe any other of the tasks in Table 1 could be

completed during a production window in addition to the visual

inspection

The author believes that in view of the frequency and duration of the

specified tasks in Table 1, that a production window is effectively

created by the buffer capacity in the centrifuge feed tank, and that

there is 17.4% or 1525 hours/year of spare reactor capacity, that all

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tasks included within Table 1 and all secondary tasks if required

could be undertaken during a production window.

2.7 Comment on whether you think any maintenance tasks are

missing

Maintenance tasks on the reactor system that the author believes are

probably missing include:

The integrity of the glass lining on the reactor could be compromised

either due to mechanical damage resulting from impact, or by thermal

shock caused by heating or cooling the vessel too quickly. A typical

maintenance checklist for glass-lined equipment should include:

visual inspection of the lining; spark testing for signs of glass-lining

failure; glass-thickness readings; inspection of tantalum repair plugs

and patches, if installed; vessel nozzle connections; and vessel

jacket connections (Goliath: 2007). The inspection frequency may

range from once every two years to continuous testing depending on

the severity of service or if damage is suspected.

Performance monitoring of the agitator motor and drive (i.e. establish

baseline amps being pulled by the agitator motor then instruct

operator to check periodically, say 1 / week).

Performance monitoring of the pump motor and drive (i.e. check

delivery performance versus pump curve; establish baseline amps

being pulled by the pump motor then instruct operator to check

periodically, say 1 / week).

Visual check on reactor seals – perhaps consider changing out

periodically prior to failure.

Visual check on pipe-work flanges and joints for leaks, say daily, and

consider changing out gaskets periodically prior to failure.

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Visual check of condition of lagging on the reactor jacket, steam and

condensate pipe-work.

Check calibration of thermocouple and the performance of the

temperature control loop. Replace conductive fluid in the temperature

pocket periodically (say every 6 months).

Thickness test pipe-work (establish baseline then check, say

annually).

From the completed work-list spreadsheet for the reactor system

there have been 10 reactive/breakdown tasks, of which 50% are

repeat failures that pertain to the following two issues :

Centrifuge P2 mechanical seal replacement:

- on 18/01/1997 (took 3hrs to complete v 2hrs standard)

- again on 29/03/99 (4hrs actual v 2hrs standard)

- and again on 18/05/99 (2hrs actual v 2hrs standard)

Recalibration of reactor T1 temperature sensor

- on 01/09/98 (took 3hrs to complete v 2hrs standard)

- and again on 17/04/01 (2hrs actual v 2hrs standard)

It is proposed that T1 be recalibrated annually and that P2 is visually

checked for condition and signs of leakage, say weekly.

2.8 How do you think this maintenance strategy could be

improved?

The author believes that the existing maintenance strategy appears

to be quite reasonable as the data provided in the completed work-list

indicates that there are a relatively very few breakdown maintenance

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tasks compared with preventive tasks (i.e. 2.9%). However, it is

asserted that improvements could be achieved by applying the RCM

approach referenced earlier including a rigorous failure mode and

effects analysis (FMEA). Use should be made of the equipment

history and known failure modes, plus the missing tasks itemised

earlier in Question 2.7.

The FMEA approach seeks to identify the failure modes that are

reasonably likely to cause each functional failure, and to ascertain the

failure effects associated with each failure mode (Moubray: 1997,

p.53). This should be developed by a cross functional team that

includes an operator, fitter, electrical/instrument technician and

chemical engineer who ideally know the facility and process well, and

have been trained to identify root causes in connection with the

analysis of failures. Their combined knowledge and skills coupled

with expert advice from vendors where needed should lead to the

creation of an effective preventive maintenance programme designed

to avoid expensive unplanned breakdowns that could otherwise

impact safety or production.

The author also strongly advocates the application of total productive

maintenance – TPM (Plant Maintenance Resource Center: 2010).

Some elements of this already exist (e.g. operator first line

maintenance routines). Further improvement could be derived from

better use of data, KPIs, visual management and industry

benchmarking. Operators could also be trained to carry out basic

preventive maintenance routines. Application of a structured

methodology to effectively manage the workplace, such as 5S, is also

advocated as this creates genuine plant ownership amongst the plant

team and sets high standards that the team members themselves

strive to maintain and improve upon.

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3. Conclusions

An analysis of the process description for a bulk pharmaceutical

manufacturing process was carried out to identify the key elements of the

USR and maintenance strategy for one of its major component parts, namely

the batch chemical reactor unit (BCRU).

It was concluded that it is appropriate to consider the BCRU as a plant unit

within a plant asset register hierarchy, and that it is critical to safety and

production within the operating context of the manufacturing process. A

number of tasks thought to be missing from the existing maintenance

programme were itemised and recommendations were provided to improve

the maintenance strategy, principally through the use of FMEA as a core

feature of RCM.

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References

Goliath (01 July 2007); Business Knowledge On Demand – Maintenance and repair of glass-lined equipment: a customized inspection and maintenance program will minimize operational and performance problems, http://goliath.ecnext.com/coms2/gi_0199-6800697/Maintenance-and-repair-of-glass.html

Lloyds British (2010): http://www.lloydsbritishtesting.co.uk/legislation3.php

Kelly, Anthony (2006): Strategic Maintenance Planning, Butterworth-Heinemann

Moubray, John (1997): Reliability-centred Maintenance, Industrial Press Inc New York

Plant Maintenance Resource Center (2010): An Introduction to Total ProductiveMaintenance (TPM), http://www.plant-maintenance.com/articles/tpm_intro.shtml

Wheelhouse, Paul (2010), Maintenance Strategy Study Guide, Manchester Business School MBA

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http://www.plant-maintenance.com/articles/tpm_intro.shtml

http://goliath.ecnext.com/coms2/gi_0199-6800697/Maintenance-and-repair-of-glass.html

http://goliath.ecnext.com/coms2/gi_0199-6800697/Maintenance-and-repair-of-glass.html

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