Petroleum Development Oman L.L.C.
Isolation of Process Equipment
Document ID
Document Type
Security
Discipline
Owner
Issue Date
Revision
PR-1076
Procedure
Unrestricted
Engineering and Operations
UOP –Functional Production Manager
May 2012
6.0
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this document may be disclosed to others or reproduced, stored in a retrieval system, or transmitted in
any form by any means (electronic, mechanical, reprographic recording or otherwise) without prior
written consent of the owner.
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i
Revision: 6.0
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Document Authorisation
Authorised For Issue May 2012
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ii Revision History
The following is a brief summary of the 4 most recent revisions to this document. Details of all
revisions prior to these are held on file by the issuing department.
Revision No.
Date
Author
Scope / Remarks
6.0
May-12
Robin Norman UOP6
Interim Amendments incorporated and
procedure aligned with Sour Isolation
Philosophy. See Addendum 10 for details
5.0
Oct-10
Robin Norman UOP6
Extensive changes. Refer to Addendum 7
for changes
4.0
Mar-10
Robin Norman UOP6
Re-issued. Refer to Addendum 6 for
changes
1.0
Sept 98
UOP/1
SI-26 rewritten to new format with minor
comments incorporated.
iii Related Business Processes
Code
Business Process (EPBM 4.0)
EP.71.02
Operate Wells and Facilities
iv Related Corporate Management Frame Work (CMF)
Documents
The related CMF Documents can be retrieved from the CMF Business Control Portal.
CP-115
Operate Surface Product Flow Assets CoP
Reference are included in Appendix 4
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TABLE OF CONTENTS
1
Introduction ............................................................................................................................ 7
1.1
Background ...................................................................................................................... 7
1.2
Purpose ............................................................................................................................ 7
1.3
Distribution / Target Audience .......................................................................................... 7
1.4
Changes to the Document................................................................................................ 7
1.5
Step-out Approval ............................................................................................................. 7
1.6
ALARP .............................................................................................................................. 7
2
Roles and Responsibilities ..................................................................................................... 8
3
Isolation of Process Equipment ........................................................................................... 10
3.1
Scope ............................................................................................................................. 10
3.2
Terminology.................................................................................................................... 10
3.2.1
Major Work .............................................................................................................. 10
Table 1 – Minimum Isolation Requirements ........................................................................... 11
3.2.2
Minor Work .............................................................................................................. 12
3.2.3
Battery Limits ........................................................................................................... 12
3.2.4
Baseline Isolation Standard ..................................................................................... 12
3.2.5
Boundary Isolation ................................................................................................... 12
3.2.6
Hydrocarbon Services.............................................................................................. 12
3.2.7
Hazardous Substance / Service............................................................................... 12
3.2.8
Non-Hazardous Service ........................................................................................... 12
3.2.9
H2S / Toxic System .................................................................................................. 13
3.3
Guidance Notes for Isolation .......................................................................................... 13
3.3.1
Issue of PTW to Permit Holder ................................................................................ 13
3.3.2
Positive Isolation of Equipment for Maintenance ..................................................... 13
3.3.3
Removal and Replacement of Relief Valves on ‘Live’ Systems .............................. 13
3.3.4
Isolation of Moving Machinery ................................................................................. 14
3.3.5
Isolation of Vessels .................................................................................................. 14
3.3.6
Isolation of Tanks..................................................................................................... 14
3.3.7
Isolation of Equipment Containing H2S .................................................................... 14
3.3.8
Use of Breathing Apparatus ..................................................................................... 15
3.3.9
Immobilising Devices ............................................................................................... 15
3.4
General Exceptions ........................................................................................................ 15
3.5
Precautionary Considerations for Isolation ..................................................................... 15
3.6
Typical Isolation and De-isolation Process ..................................................................... 17
Figure 1 – Process Equipment Isolation Process .................................................................. 17
Appendix 1 – Positive Isolation Arrangements ............................................................................ 20
Appendix 2 – Abbreviations ......................................................................................................... 25
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Appendix 3 – Tank Pressure / Vacuum Valve Changeout .......................................................... 26
Appendix 4 – Reference Material ................................................................................................ 30
Appendix 5 - User Feedback Page .............................................................................................. 31
Addendum 1 – Changes at Revision 2.1 ..................................................................................... 32
Addendum 2 – Changes at Revision 3 ........................................................................................ 33
Addendum 3 – Changes at Revision 3.1 ..................................................................................... 34
Addendum 4 – Changes at Revision 3.2 ..................................................................................... 35
Addendum 5 – Changes at Revision 3.3 ..................................................................................... 36
Addendum 6 – Changes at Revision 4.0 ..................................................................................... 37
Addendum 7 – Changes at Revision 5.0 ..................................................................................... 38
Addendum 8 – Interim Amendment May 2011 ............................................................................ 39
Addendum 9 – Interim Amendment September 2011 ................................................................. 40
Addendum 10 – Changes at Revision 6.0 ................................................................................... 41
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1
Introduction
1.1
Background
Revision: 6.0
Effective: May-12
Whenever process plant, equipment or systems require to be taken out of service for
major maintenance, repair or modification, then positive mechanical isolations shall be
provided between the process plant, equipment or system and any potential hazardous
energy source. Positive Mechanical Isolations requires the insertion of a spade / blind in
the line, or the removal of a spool (if required), ‘downstream’ of the last tight isolation
valve to physically isolate the potential ‘energy source.
IMPORTANT: A ‘double block and bleed’ arrangement on its own is not
considered ‘positive mechanical isolation without the insertion of a spade / blind.
1.2
Purpose
The purpose of this procedure is to provide a safe and consistent method for the
isolation of process equipment prior to and during maintenance / modification / repair.
1.3
Distribution / Target Audience
This procedure is intended for use Production Operations, Maintenance, Well Services,
EMC/ODC personnel and any other parties tasked with carrying out the work requiring
isolation on equipment and systems in PDO.
1.4
Changes to the Document
Responsibility for the upkeep of the Document shall be with the Functional Production
Team Leader UOP, the Owner. Changes to this document shall only be authorised and
approved by the Owner.
Users of the Document who identify inaccuracy or ambiguity can notify the Custodian or
his/her delegate and request changes be initiated. The Requests shall be forwarded to
the Custodian using the “User Feedback Page” provided in this Document.
The Document Owner and the Document Custodian should ensure review and reverification of this procedure every 3 years.
1.5
Step-out Approval
This procedure is mandatory and shall be complied with at all times. Should compliance
with the procedure be considered inappropriate or the intended activity cannot be
effectively completed or safely performed, then step out authorisation and approval must
be obtained in accordance with PR-1001e – Operations Procedure Temporary Variance
prior to any changes or activities associated with the procedure being carried out.
1.6
ALARP
ALARP is the acronym for ‘As Low As Reasonably Practicable’ which simplified means,
‘reducing the risk to a level at which the cost and effort (time and trouble) of further risk
reduction are grossly disproportionate to the risk reduction achieved’. Full Compliance
to PDO Standards and Procedures is a key element in achieving ALARP.
For more details refer to ALARP Definition
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Roles and Responsibilities
Production Coordinator
Responsible Supervisor
Production Operator and
Area Authority
Maintenance Personnel
Permit to Work Applicant
Page 8

To be accountable for the isolation(s) to be carried
out.

Approve methods for isolations.

Specifying frequency of isolation integrity checks (if
required).

Check isolations are in compliance with the
approved standard and procedure

Initiate variance procedure where proposed isolation
is out of compliance

Agree isolations with the Permit Applicant

Inspect the work site with Permit Applicant to identify
all hazards (mandatory for Class A permits)

Carrying out integrity checks of isolations

Authorises Permit to Work (PTW)

Perform or oversee the isolation and sign the
necessary Isolation Certificate (Mechanical /
Electrical)

Carryout isolations integrity checks and maintain the
isolation records

Maintain the Override Log

Carryout or oversee depressurisation, draining, gas
freeing and gas testing

Supervise the worksite

Witnessing isolations

Performing electrical, mechanical, rotating equipment
and major isolations associated with work being
undertaken

Requesting any changes to the approved isolation
from the Responsible Supervisor

Completing Section 1 of the Permit to Work
Certificate

Carryout site inspection and identification of hazards
with Responsible Supervisor

Agree the mechanical, electrical and instrument
overrides required to carry out the work with the
Responsible Supervisor

Produce Job Safety Plan and specific procedures
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Permit Holder
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
Conducting TRIC discussions and completing TRIC
with personnel carrying out the work

Ensure that any changes to work scope or conditions
are captured and implemented before work is
allowed to continue

Maintain safe working conditions and practices

Witness and / or apply isolations / overrides with
attendance of the Area Authority

Witness and / or remove isolations / overrides with
attendance of the Area Authority
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Isolation of Process Equipment
3.1
Scope
Revision: 6.0
Effective: May-12
This procedure covers the mandatory administration and mechanical isolation of
process equipment prior to maintenance or engineering work.
For major maintenance or engineering work the minimum requirement for process
equipment shall be;

shut down;

depressurised to atmospheric pressure;

drained and flushed (if required);

freed of flammable or toxic gases
Positive isolation shall be applied once the above have been completed between any
adjacent systems that may, or may not, remain live during the work.
3.2
Terminology
3.2.1
Major Work
Positive isolation shall be required for all Major Work. For the purpose of this procedure
major work will be considered as any intervention that results in spools or equipment
being removed from a process line (including non-hydrocarbons), Confined Space entry,
or Hot Work (including cold cutting) being carried out.
Examples:
Valve removal / replacement (including RV changeout);
Spool removal / replacement;
Equipment i.e. pump, changeout;
Vessels / tank inspections:
IMPORTANT NOTE: There may be exceptions to the above e.g. relief valves
changeout, and these shall be addressed on an individual basis after risk assessment.
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Table 1 – Minimum Isolation Requirements
System
System Description
Major Work
I
System in service, of ANSI
class 300# and below.
Positive isolation by a single proven
valve (Note1) and a swung spectacle
blind/spade or removable spool (Note 2).
For flashing liquids and toxic
see II below.
II
System in service, of ANSI
class 600# and above.
Double block
spade/blind.
and
bleed
plus
a
All systems containing toxic
fluids (Note 3).
Systems containing flashing
liquids above ANSI 300, (Note
4) i.e. ANSI 600 and above.
NOTE 1
Provided the line upstream of the required isolation is depressurised,
drained, flushed and hydrocarbon free then a single proven valve will provide sufficient
isolation for Major Work.
NOTE 2
A bleed connection should be installed between the valve and the
spade/blind for line sizes 6" and above. The purpose of the bleed is to establish that
positive isolation is achieved and to provide a means of draining or depressurising the
volume between the isolation valve and the spade/blind.
NOTE 3
For the purposes of this requirement, toxic in the case of H2S is defined
as more than 500 ppm H2S in the process stream.
NOTE 4
The definition of flashing liquids for the purposes of this Table is that
given for Cat. A fluids in Appendix B of the IP Code Part 15, section 1.6.7, table 1.2.
Page 11
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3.2.2
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Minor Work
Valved isolation shall be required for all Minor Work. For the purpose of this procedure
minor work will be considered as any intervention that does not require spools or
equipment being removed from a process line (including non-hydrocarbons), or where
there is no Hot Work.
Examples:




As a pre-cursor for major work;
Breaking flanges for draining of depressurised systems;
Insertion of blinds between flanges on depressurised systems;
Working on instrumentation lines.
NOTE: For Minor work the valve isolation will require to be appropriate to address the
risk i.e. double block and bleed for H2S or pressurised lines, and demonstrated tight.
3.2.3
Battery Limits
This term is often used loosely with the industry. The word battery is used to represent a
set of units. For the purpose of this procedure a battery limit is an agreed boundary
surrounding a processing unit or battery of units, along with related utilities and services.
Therefore the perimeter of a ‘Battery Limit’ can form a single boundary isolation or a
number of boundary isolations within the defined limit.
3.2.4
Baseline Isolation Standard
The Baseline Isolation Standard is the minimum acceptable standard of final isolation for
intrusive and non intrusive maintenance against live plant under normal circumstances
as per the HSE guidelines, (UK HSE Publication Issue 2006 ISBN 0-7176-6171-7 The
Safe Isolation of Plant and Equipment) This standard is based upon risk assessment.
The Baseline Isolation Standard shall be one of the following two isolation methods:
Positive Isolation: is the removal of a spool and fitting of blinds, or fitting of a spade or
spectacle blind to allow complete separation of the plant/ equipment to be worked on
from other parts of the system
Proved Isolation: is a valved isolation where effectiveness of the isolation can be
confirmed via vent/bleed points before breaking into the system, and for the duration of
the isolation
3.2.5
Boundary Isolation
An isolation at any location where the defined Baseline Isolation Standard is met.
3.2.6
Hydrocarbon Services
All systems containing hydrocarbons.
3.2.7
Hazardous Substance / Service
A substance or containing a substance which is able to cause harm or damage if loss of
containment occurs.
3.2.8
Non-Hazardous Service
Any service not classified as hazardous.
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3.2.9
Revision: 6.0
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H2S / Toxic System
High concentrations of H2S in the process fluid, requiring a high degree of protection
against leakage. For the purpose of this procedure an H2S / Toxic System is defined as
having >500ppm in the process stream.
3.3
Guidance Notes for Isolation
3.3.1
Issue of PTW to Permit Holder
The Area Authority shall not release the PTW to the Permit Holder (authorisation to
commence work) until all isolation processes have been completed and verified.
3.3.2
Positive Isolation of Equipment for Maintenance
A spade and blind check list, marked up copies of the As-Built drawings etc, shall be
made by the Permit Applicant and submitted with the PTW to ensure the correct spades
or blinds are closed during isolation and removed upon completion of the work.
NOTE: This spade list will be signed off by the Operator / Area Authority after isolation
and prior to equipment reinstatement after de-isolation.
The positive isolation shall be reviewed and approved by the Responsible Supervisor.
The Area Authority shall apply or oversee the positive isolation for every piece of
equipment identifying the connections that will be isolated, disconnected and tagged
before starting to open the equipment.
The Area Authority shall verify spade and blind positions with the list before the work is
commenced and after the work is completed. He will also supervise gas testing and gas
freeing / purging as required.
Locked Open / Locked Closed valves that are operated during isolation shall be
recorded on the Lock Open / Locked Closed Register.
Valves used as part of isolation shall be ‘tight’ when shut off. Where this cannot be
demonstrated the Production Coordinator shall be informed and a ‘variance’ raised in
accordance with PR-1001e – Operations Procedures Temporary Variance.
NOTE: Butterfly valves shall not to be considered as ‘tight shut-off’ valves.
3.3.3
Removal and Replacement of Relief Valves on ‘Live’ Systems
The permit applicant shall write a site specific procedure for the removal and
replacement of Relief Valve(s) and attach a Risk Assessment signed by the appropriate
authority. The procedure shall be reviewed and approved by the Responsible Supervisor
and shall be attached to the PTW.
PTW shall be in accordance with PR-1172 – Permit to Work Section 15.6
No authorisation for the work shall be given if:
Page 13

The system that the relief valve is protecting does not have 100% redundancy;

The relief valve does not have as a minimum a ‘double block and bleed’
arrangement upstream. This includes interlock systems;

The relief valve is connected to a live vent and flare system that cannot be
isolated by one ‘demonstrated’ tight valve
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3.3.4
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Isolation of Moving Machinery
Moving machinery is defined here as any equipment using external motive force such as
electricity, air, steam or hydraulic fluid.
The electrical, air, steam, hydraulic or other source of energy to the moving machinery,
both flow and return circuits, shall be isolated from the drive unit and the drive unit
secured immobile before work commences.
Isolation of moving machinery from process fluids shall be accomplished by tight valves
and spades or blinds on the equipment side of inlet and outlet lines in order that
maintenance may be carried out while the surrounding facilities remain live. Where H2S
is present in the process stream double block and bleed and swung blind is the
minimum mandatory requirement.
Machinery brakes and brake locks are to be applied and the clutch (if applicable) is to be
disengaged.
3.3.5
Isolation of Vessels
Spades / blinds shall be installed on the downstream side of the inlet block valve
and the upstream side of the outlet block valve. Where practical these spades /
blinds should be mounted directly on the flange. Where H2S is present in the
process stream double block and bleed and swung blind is the minimum
mandatory requirement. Non-compliance shall be in accordance with PR-1001e
– Operations Procedure Temporary Variance.
NOTE: Refer to Table 1 for recommendations regarding isolation requirements.
3.3.6
Isolation of Tanks
Blinds / spades shall be inserted on the tank side of all inlet and outlet block valves.
These shall be placed as close to the tank as possible. This also applies to blanket /
purge gas lines, tank-balancing lines, and vent lines to flare headers and water draw-off
lines.
The cathodic protection electrical connections should be isolated to prevent any
possibility of a spark occurring.
Drain sumps should be routed to a closed drain header, collection tank or suitable open
pit (refer to PR-1073 Section.
3.3.7
Isolation of Equipment Containing H2S
Reference PR-1078 - Hydrogen Sulphide Management Procedure for classifications of
H2S risk.
For isolations on equipment containing H2S a double block and bleed system and swung
blind is the minimum mandatory requirement. Variance to this requirement shall be in
accordance with PR-1001e – Operations Procedure Temporary Variance.
For double block and bleed systems used on H2S service the bleed shall be hard-piped
to a safe disposal location to ensure that it does not create a hazard. Acceptable
disposal routes are to a remote vent or to a plant closed drain system. When using
closed drains systems checks shall be made to ensure that reverse flow does not occur
in the system.
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3.3.8
Use of Breathing Apparatus
It is mandatory to wear positive pressure breathing apparatus when breaking flanges
and opening equipment containing toxics. This shall be clearly stated under ‘Work
Description’ on the Work Permit.
Adequate isolation and purging shall be proven by a direct measurement (using gas
detector) for both hydrocarbons and the toxic component concerned (usually H 2S).
Further work such as opening the equipment for inspection will be carried out wearing a
personal H2S monitor and escape set. Refer to PR-1148 Entry into a Confined Space for
conditions allowing entry into a confined space.
3.3.9
Immobilising Devices
There are a number of proprietary devices used in the industry for immobilisation,
however PDO has standardised with ‘pro-lock’ securing device.
3.4
General Exceptions
Any proprietary insertion or extraction device e.g. Welker/ COSASCO retrievable
probes, Daniel Orifice Carriers etc, used on ‘sweet systems’ up to, and inclusive of,
900# rating shall be allowed by exception to the isolation requirements of this procedure.
NOTE: This exception shall be allowed provided the design of the fittings is not modified
or changed and that regular maintenance and inspection is carried out.
3.5
Precautionary Considerations for Isolation
1)
The main hazard when working on equipment that has been isolated from live
plant is that positive isolation from a source of energy or hazardous fluid / gas
may be overlooked or the isolation compromised, and the source then released
with serious consequences.
2)
Positive isolation of equipment shall be accomplished to provide the safest
environment to carry out any Major Work on that equipment to reduce risk of
injury to personnel, damage to the Company's assets or the environment.
3)
Production Supervisors and Operators shall ensure that the integrity of
isolations be maintained for the entire period of any work being carried out. The
isolation(s) and the EPI register shall be included in the shift change handover.
Long-term positive isolation shall be audited
conducted at 3-6 monthly intervals.
Page 15
as part of the Level 2 Audit
4)
ALL isolation work shall be carried out under the Permit to Work system.
5)
Hazards shall be identified, detailed and controlled by proper use of the Permit
to Work system.
6)
All work shall be authorised by the Production Supervisor or his delegated
representative.
7)
The method of positive isolation shall be in accordance with this procedure and
SP-1125 – Specification for the Isolation of Process Equipment.
8)
The use of ‘home made’ spades require the explicit approval of the TA for Static
equipment.
9)
All approved blinds that are fitted shall have all of their bolts set to correct torque
in accordance with SP-2020 Flange Connections Bolt Torquing and Tensioning.
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10)
Revision: 6.0
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Actuated valves shall only be used as part of the positive isolation if the fail safe
condition is closed and all motive power to the valve has been physically
disconnected from the actuator.
WARNING: Reliance on switches shall not be acceptable under any
circumstances.
11)
Double block and bleed arrangements provide positive isolation when used in
conjunction with spades or blinds.
Where the insertion of spades and blinds in conjunction with double block and
bleed is considered impractical i.e. not possible to break containment or suitable
spading and blinding locations not available, the use of the double block and
bleed may be authorised by the Production Coordinator provided a variance is
raised in accordance PR-1001e – Operations Procedures Temporary Variance.
For minor work, such as replacing a faulty instrument on a vessel a single
‘demonstrated’ tight valve may be allowed if authorised by the Production
Coordinator. For toxic and high pressure applications double block and bleed
shall be considered a minimum requirement. Where the piping and valve
arrangement of process equipment does not allow this to be met a variance
shall be raised in accordance with PR-1001e – Operations Procedures
Temporary Variance. In addition the work shall be completed during a working
shift, all valves employed for isolation shall be ‘demonstrated tight’ and the work
site shall not be left unattended while the work is in progress.
For work of longer duration or where fittings and accessories remain removed
for an appreciable period, e.g. overnight or longer, spades or blinds shall be
employed to provide positive isolation.
12)
For long term 1 isolations where a piece of equipment, or a system, is taken out
of service for a considerable period, e.g. months, yet the adjacent plant remains
live, it is essential that proper records are kept. (e.g. spade / blind / valve
checklist) and a record kept of the status of the isolation and its continuing
integrity. This should be carried out on an Extended Period Isolation and verified
regularly.
Such isolations shall be audited and checked for integrity at a frequency defined
by the Production Coordinator.
13)
All process isolations shall be recorded on the Process Isolation Wall.
14)
All electrical isolations must be done in accordance with SP-1108 - Electrical
Safety Operational Procedures.
The most important rule for isolation of equipment is ‘Stick to the Procedures’. For
guidance, the schematic diagrams in Appendix 1 should be used for reference to typical
isolation arrangements.
1
Depending on the type of long term isolation ‘moth balling’ may be considered.
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3.6
Typical Isolation and De-isolation Process
Typical Isolation and De-isolation Process
Permit Applicant
Responsible
Supervisor
Area Authority
Permit Holder
Operations
Manager /Delivery
Team Leader
Production
Coordinator
PREPARE THE PTW
AND DEFINE THE
POSITIVE ISOLATION
REQUIREMENTS
REVIEW PTW WITH
PERMIT APPLICANT AND
AGREE POSITIVE
ISOLATION
REQUIREMENTS
YES
DO ISOLATIONS
COMPLY TO
PR-1076?
NO
RAISE VARIANCE (STEPOUT) IN ACCORDANCE
WITH PR-1001E
REVIEW VARIANCE &
RAM
REVIEW VARIANCE,
RAM & AUTHORISE
NO
VARIANCE
AUTHORISED?
YES
RECEIVE PERMIT FROM
PA / RESP. SUPRV.
SUBMIT FOR
AUTHORISE THE PTW
VALIDATION
PERFORM / OVERSEE
POSITIVE ISOLATION AS
DEFINED ON
MECHANICAL ISOLATION
CERTIFICATE AND SIGN
VALIDATE PTW AND
AUTHORISE PERMIT
HOLDER TO START
WORK
CARRYOUT PERIODIC
CARRYOUT PERIODIC
SITE INSPECTIONS TO
SITE INSPECTIONS TO
ENSURE POSITVE
ENSURE POSITVE
ISOLATION AS DEFINED
ISOLATION AS DEFINED
BY
PTW
BY
UNDERTAKE WORK IN
ACCORDANCE WITH
PTW
PTW
ON COMPLETION OF
WORK DE-ISOLATE.
CHECK THAT DEISOLATION AGAINST
MECHANICAL ISOLATION
CERTIFICATE / MARKED
UP
PEFS
CLOSE-OUT PTW
Figure 1 – Process Equipment Isolation Process
The following process shall be followed to isolate and de-isolate process equipment
prior to and on completion of maintenance / repair / modification work.
Page 17
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1.
Revision: 6.0
Effective: May-12
The Permit Applicant Shall complete the relevant sections of the PTW certificate
and define the isolation requirements on an As Built drawing (PEFS).
The marked up As Built drawing and the PTW shall be submitted to the Responsible
Supervisor.
2.
The Responsible Supervisor shall review and discuss the PTW and isolation
requirements with the Permit Applicant. The positive isolation proposed on the
marked up As-Built drawing shall comply to this procedure and SP-1125 –
Specification for the Isolation of Process Equipment. Where compliance has been
demonstrated the PTW shall be authorised by the Responsible Supervisor.
3.
Isolations that do not comply with this procedure shall require to have a variance
raised against them in accordance with PR-1001e – Operations Procedures
Temporary Variance. The Production Supervisor and the Permit Applicant shall
agree the minimum isolation that can be used to address the risks. The Risk
Assessment and the variance shall be reviewed, endorsed and authorised by the
DTL and Operations Manager before further work can be planned.
4.
The authorised PTW with the marked up As Built drawing shall be handed to the
Permit Holder who shall give them to the Area Authority.
The Area Authority shall complete the Mechanical Isolation Certificate from the
approved positive isolation on the As Built drawing. isolation2 as detailed on the
Mechanical / Electrical Isolation Certificate authorised by the responsible Supervisor.
IMPORTANT NOTE: No PTW shall be validated by Area Authority until the required
isolation process is completed.
Mechanical isolations that are to be put in place shall be listed on the Mechanical
Isolation Certificate or Mechanical Isolation Continuation Sheet and attached to the
PTW. These certificates shall be used to verify that all mechanical isolations have
been removed.
NOTE: Electrical and Safeguarding Instrumentation isolations are recorded on
separate Certificates and Forms and are attached to the PTW accordingly..
Positive isolation shall require having spades or blinds / spectacle blinds placed into
the lines. This shall involve breaking pipework at flanges and shall be recorded in a
specific procedure / method study for the work.
All precautions and safety points shall be recorded in the Safety Plan before any
breaks are made to the system / equipment integrity
5.
The Area Authority shall witness all gas freeing and gas testing operations.
The work required to be undertaken can be progressed as soon as the isolation has
been established, checked and the PTW is issued.
The Area Authority shall validate the PTW and hand it to the Permit Holder to
undertake the work.
6.
If the equipment is required to be test run this should be carried out under a ‘DeIsolation for Test (DFT) procedure’ using the reverse side of the Mechanical and / or
Electrical Isolation Certificates
All isolated valves, spades, blinds etc, shall be tagged with the “3 Part Tag”. The 2 nd part of the
tag shall be attached to the PTW and the 3rd part of the tag shall be placed on the PTW board.
The valve spade etc, should be secured with ‘pro-lock’ fittings.
2
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7.
Revision: 6.0
Effective: May-12
Depending on the length that the isolations will be applied, integrity checks shall be
defined. The integrity checks shall be carried out by the Area Authority and
Production Supervisor who will ensure that the isolations are correct and intact.
The positive isolation shall be checked before the PTW is revalidated.
Any violations shall be reported to Production Coordinator and a fountain
Incident raised. The work will be stopped until an investigation has been
carried out.
3
8.
On completion of all works, commissioning and testing the process equipment can
be de-isolated3. The de-isolation should be checked off against the Mechanical
Isolation Certificate and the marked up As-Built drawings.
9.
When the de-isolation is completed by the Area Authority the PTW can be closed
out by the Permit Holder.
This includes de-spading and re-instating blinds / spectacle blinds into their operating positions.
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Appendix 1 – Positive Isolation Arrangements
TANK ISOLATION (SOUR SERVICE)
TO FLARE
HEADER
BLANKET GAS
LO
LO
BALANCE LINE
OIL OUTLET
OIL INLET
WATER OUTLET
Breakout
Spool
NC
NC
NC
CLOSED DRAIN
HEADER
Normal Operation
TO FLARE
HEADER
BLANKET GAS
LC
LC
WARNING. The ‘Blind’ on the tank vent line to Flare can only be
swung if the station / facility is Shutdown or an isolation valve
is provided on the line upstream of the spade location.
BALANCE LINE
OIL OUTLET
LC
LC
Flange
Blinded
LC
LC
OIL INLET
WATER OUTLET
LO
NOTE. The Bleed Valve
will be locked open to
relieve any pressure build
up to the closed drains.
Provision should be made
to provide a means of
monitoring the bleed line
from the ‘double block
and bleed’
LC
Breakout
Spool
Removed
LC
LC
LC
LO
SPADE
Isolated
Page 20
PR-1076 - Isolation of Process Equipment
CLOSED DRAIN
HEADER
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VENT & FLARE HEADER
Header
TO FLARE
LO
LO
Vessel 2
Vessel 1
Vessel 3
Normal Operation
Header
TO FLARE
WARNING: In this case ‘blinds’ can
only be swung if the Vessel
connected to the flare line is
shutdown, isolated and
depressurised.
LC
LC
Where relief lines combine then all
associated vessels and equipment
shall require to be shutdown, isolated
and depressurised.
Vessel 2
Vessel 1
Vessel 3
Isolated
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NC
Vent & Flare System
or Atmosphere at
Safe Location
Vent & Flare System
or Atmosphere at
Safe Location
PG
PIG LAUNCHER
Vent & Flare System
or Atmosphere at
Safe Location
Vent & Flare System
or Atmosphere at
Safe Location
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NC
Pig Indicator
PG
PG
NC
Pig Indicator
INLET OR
OUTLET
NC
NC
NC
NC
NC
NO
DRAINS
SYSTEM
(Balance Line)
NC
NC
FROM / TO
MAIN LINE
NC
WARNING. Where a
Pressure Safety Relief valve
is provided on the Launcher
that is tied into a Vent and
Flare System then a full
Shutdown is required
unless isolation is provided
upstream of the Relief Valve
Vent & Flare System
or Atmosphere at
Safe Location
Vent & Flare System
or Atmosphere at
Safe Location
Vent & Flare System
or Atmosphere at
Safe Location
Vent & Flare System
or Atmosphere at
Safe Location
Normal Operation
LC
NC
Pig Indicator
LC
Pig Indicator
INLET OR
OUTLET
LC
LC
NC
LC
LC
LC
NO
DRAINS
SYSTEM
(Balance Line)
C
LC
LC
Isolation
Page 22
FROM / TO
MAIN LINE
LC
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VESSEL (SOUR SERVICES)
To Vent / Flare
Blowdown
to Flare
LO
LO
Gas
Outlet
Inlet
H
LG
NC
LA
LG
L
NC
Closed Drains
NC
NC
NC
NC
NC
Liquid
Outlet
NC
NC
To Closed Drains
Header
Normal Operation
To Vent / Flare
WARNING. The ‘Blinds’ on the
Pressure Safety Relief and Blowdown
lines can only be swung if the vent
and flare systems are shutdown or
isolation valves are provided
upstream of the Relief and Blowdown
valves.
LC
Blowdown
to Flare
LC
LC
Gas
Outlet
LC
Inlet
H
LG
LO
LA
LG
L
LO
Closed Drains
NOTE. The Bleed Valve
will be locked open to
relieve any pressure build
up to the closed drains.
Provision should be made
to provide a means of
monitoring the bleed line
from the ‘double block
and bleed’
NC
NC
NC
NC
NC
Liquid
Outlet
NC
NC
SPADE
To Closed Drains
Header
Isolation
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Casing Vent to
Safe Area
CENTRIFUGAL PUMP
Pump Discharge
NC
Pump Suction
PG
PG
Vent/Local/
Atmos Flare
Motor
Seal Drain Pot
NC
NC
Drain/Local Drain
Collection Tank
NC
To Closed Drains
Header
Normal Operation
Casing Vent to
Safe Area
CENTRIFUGAL PUMP
Pump Discharge
LC
NO
Pump Suction
LC
PG
Electric motor
isolated at the
main breaker
PG
NC
Vent/Local/
Atmos Flare
Motor
Seal Drain Pot
NC
NC
NC
Drain/Local Drain
Collection Tank
NC
To Closed Drains
Header
Isolation
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Appendix 2 – Abbreviations
The following abbreviations are used in this Procedure.
ANSI
CDFP
American National Standards Institute
Corporate Discipline Focal Point
CFDH
Corporate Functional Discipline Head
DFT
De-isolated for Test
EPI
Extended Period Isolation
ESOP
Electrical Safety Operational Procedures
LC
Locked Closed
LO
Locked Open
NC
Normally Closed
NO
Normally Open
PEFS
Process Engineering Flow Schematic
PDO
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PR
Procedure
PTW
Permit to Work
PVV
Pressure Vacuum Valve
RAM
Risk Assessment Matrix
TRIC
Toolbox Talk Risk Identification Card
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Appendix 3 – Tank Pressure / Vacuum Valve Changeout
1.
Mandatory Requirements
-
Inventory in the tank shall be reduced to low low level
-
If a second tank is available production shall be lined up to this tank. If second tank
is not available production shall be diverted around the tank
WARNING: In single tank operation if production cannot be diverted from the tank
then the activity shall not be allowed to proceed. Similarly, if a spare valve is not
available, the activity shall not proceed.
2.
in accordance with PR-1076 – Isolation of
-
Tank must be isolated on the inlet
Process Equipment
-
Pressure in the tank shall be vented to atmospheric via the flare / vent line or via an
atmospheric vent to a safe area
-
Operations or work in the vicinity of the tank shall be suspended for the duration of
the changeout
-
Work shall be undertaken in accordance with PR-1172 – Permit to Work System
-
The minimum number of personnel required to undertake the work safely shall be
employed on or around the tank
-
A TRIC discussion shall be conducted prior to any work being commenced and the
TRIC completed and attached to the PTW
-
If an unsafe operation is observed or monitored then work must be stopped
immediately and the area made safe
Precautions to be Observed
Gas Testing

Gas testing shall be carried out in accordance with PR-1154 Gas Testing
Procedure. All gas tests shall be undertaken by authorised gas testers as
required by PR-1172 Permit to Work System.
Breathing Apparatus

Breathing apparatus supplied from an external air source shall be required.
Breathing apparatus may be Self Contained Breathing Apparatus (SCBA), a
positive pressure hood supplied from an external air source or a combination of
the two.

Prior to use the charges in the air cylinders must be checked and it shall be
ensured that sufficient supplies, including reserves, are available to complete
the work.
Fire Fighting Equipment

Fire services shall be requested to be on station for the duration of the work. If
this is not feasible then a competent fire fighting team shall be employed to man
fixed firefighting equipment for the duration of the work.

Fixed and portable fire equipment shall be provided both on the tank roof and at
the work site to enable a fire to be contained.
Safety Harnesses and Man Basket
Page 26

Safety harnesses and safety ropes shall be provided and issued to the working
party prior to deployment on the tank roof.

Secure anchor points for the harnesses shall be identified and marked prior to
personnel moving to the tank roof.
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
3.
Revision: 6.0
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A man basket (intrinsically safe) shall be provided with rated lifting strops to
evacuate causalities from the tank top in emergency.
Preparation for Undertaking the Work
Permit to Work

The Permit Applicant and Responsible Supervisor shall comply with PR-1172
Permit to Work System and carryout a site inspection.

The Permit Applicant shall prepare an HSE Job Plan and a Rescue Plan which
shall be attached to the PTW.

A marked-up Process and Engineering Flow Scheme shall be completed to
indicate all isolations.
Tools and Spares

A new gasket, bolts, nuts and washers shall be procured for the PVV and
bagged ready for use.

Spanners and a suitable torque wrench for removing and replacing bolting.

Scrappers and brass wire brushes for cleaning and preparing the flange joint.
Solvents for cleaning (WD40) may be used provided they are suitable for the
application. Absorbent cloths for cleaning the area and mopping small spills.

All tools for the work shall be bagged and a check list provided to enable
accounting to be carried out on completion of work.

The replacement PVV shall be checked to ensure it is correct for the application
and has been tested accordingly. The flanges of the replacement PVV shall be
protected prior to lifting to the tank top.
Safety Equipment

The SCBA’s and air lines for the positive pressure hoods will require to be
carried or lifted to the tank top.

Personnel working on the tank top shall be issued with Emergency Escape
Hoods for evacuation.
Lifting Equipment

A suitably rated (25ton) with sufficient jib extension will be located, preferably up
wind of the operation, on site. Suitably rated slings shall be provided to lift the
old and replacement PVV during changeout.
NOTE: Gas monitoring shall be carried out before starting the crane and
continuously throughout the operation when the crane engine is running.
Permitry

If the tank is in H2S sour service all personnel involved in the operation shall
have an in date H2S certificate.

Personnel using breathing apparatus (SCBA) must be certificated.

SCBA or positive pressure hoods shall require to be worn by all personnel
working on the tank top while the operation of changing out the PVV is being
carried out.
Preliminary Work Prior to Removal / Replacement
a) Close inlet isolation valve and inlet ESD valve (if provided) to the tank that is to
be worked on.
b) Divert the flow to second tank (if available) by opening inlet isolation valve on
the receiving tank.
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c) Reduce the level in the tank to be worked on to low low level. Overriding of
safety critical alarms and trips shall be in accordance with PR-1001c –
temporary Overriding of Safeguarding Systems
d) Complete manual isolation of oil and drain outlet by closing the isolation valves on
the tank to be worked on. Record the valves and positions on the PEFS. Update
‘Locked Open / Lock Closed’ register for any normally Locked Open / Locked
Closed valves that are used. Refer to PR-1086 - Locked Valve Control
Requirements.
e) Isolate the blanket gas line (if provided) on the tank to be worked on.
f)
Blow down / vent the residual gas inside the tank to be worked on to via the flare
/ vent line or atmospheric vent line, to atmospheric.
NOTE: Use suitable sited pressure gauge on the tank to confirm condition.
g) PTW validated by the Area Authority
h) Hand-over the isolated tank to maintenance team.
4.
Removal and Replacement
a) Bring lifting crane on site adhering by all precautions of the PTW. Position the
crane up-wind of the work site if possible.
NOTE: All lifts involving the crane shall be in accordance with the lifting plan
attached to the PTW.
b) Bring Canter on site adhering by all precautions of the PTW. Position the Canter
adjacent to the tank and within safe lifting range of the crane.
c) Make ready the replacement PVV for lifting on the back of the Canter.
d) Position the air line breathing apparatus trolley adjacent the tank. Check all
connectors and check face mask operation.
NOTE: This should be undertaken by the personnel who will require wearing the
equipment. Check the correct operation of the face mask.
e) Using the crane lift the SCBA, air hose(s) and tools to the tank top location.
f)
Lift replacement PVV and blind flange to the tank top location.
g) The Area Authority wearing a SCBA shall carry out gas testing.
NOTE: The results of the gas testing shall dictate whether personnel will require to wear
SCBA or positive pressure hoods to perform preparatory work. Continuous gas testing
shall be carried out while preparatory work is being undertaken. Clean the threads on
the bolts securing the PVV. Apply solvent cleaner if required.
h) Unbolt using the appropriate spanners.
WARNING: As the tank will still contain hydrocarbons this operation and the
operation of re-bolting on completion will constitute ‘hot-bolting’ and will
require the Approval of the Production Coordinator in accordance with SP2020 - Flange Connections Bolt Torquing and Tensioning Section 10.
i)
Attach lifting strop to the PVV. Attach to crane hook in readiness of lift.
At this point a further gas test should be carried out and positive pressure hoods worn
by all personnel in the direct vicinity of the work. All other personnel should be moved
away from the PVV. A rescuer in a SCBA shall be made ready while the PVV is not in
place. For added safety all work should be undertaken if possible up wind of the
opening.
j)
Page 28
Un-bolt the PVV flange and carefully lift from the tank skin. Move to a suitable
laydown on the tank top.
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k) Prepare the replacement PVV for lifting.
l)
Clean and prepare the flange for fitting of the new gasket. Fit new gasket.
m) Lift the replacement PVV into position, ensuring that the gasket is not damaged.
NOTE: If the replacement of the PVV is halted due to damage of misalignment that
shall cause delay, a flange can be fitted providing it is fitted with a low range
pressure gauge to monitor a pressure build up. In conjunction with the pressure
gauge, a tee piece with a valved vent facility should be fitted, with the vent to a safe
area or flare system so that any pressure build up due to temperature change can
be vented safely (See Illustration below). A documented risk assessment shall be
carried out if this method is employed. The risk assessment shall ensure that regular
monitoring of the pressure gauge and venting is carried out by operations for the
duration that this flange is in place.
n) Replace the bolting and torque down to specified torque. See Warning following
Step i).
o) Carryout a gas test around the completed job to ensure tightness. Repeat the
gas test at intervals as working pressure is established and when the tank is at
normal operating pressure.
p) Check and confirm all tools are accounted for. Lift and remove old PVV from the
tank top to the Canter.
q) Carefully lift all remaining equipment from the tank top and secure the site.
r)
Page 29
Hand the tank back to Operations personnel to de-isolate and commission.
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Appendix 4 – Reference Material
PDO Documents
Code of Practice
CP-115 - Operate Surface Product Flow Assets
Specification
SP-1108 - Electrical Safety Operating Procedures
SP-1125 - Isolation of Process Equipment Specification
SP-2020 - Flange Connections Bolt Torquing and Tensioning
Procedure
PR-1001e – Operations Procedure Temporary Variance
PR-1073 - Gas freeing and Purging of Process Equipment (excluding tanks)
PR-1077 - Preparation of Tanks and Vessels for Internal Work
PR-1086 - Locked Valve and Spectacle Blind Control
PR-1148 - Entry into a Confined Space
PR-1154 - Gas Testing Procedure
PR-1172 - Permit to Work
Guideline
GU-256 - Static Equipment Inspection Guidelines
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Appendix 5 - User Feedback Page
PR-1076 – Isolation of Process Equipment User Feedback Page
Any user who identifies an inaccuracy, error or ambiguity is requested to notify
the custodian so that appropriate action can be taken. The user is requested
to return this page fully completed, indicating precisely the amendment(s)
recommended.
Name:
Ref ID
Page Ref:
To:
Date:
Brief Description of Change Required and Reasons
UOP7
Custodian of Document
Page 31
Date:
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Addendum 1 – Changes at Revision 2.1
Page No.
Changes / Additions
8
Section 1.8 – Changed to “This procedure is mandatory and shall be complied with
at all times. Should compliance with the procedure be considered inappropriate or
the intended activity cannot be effectively completed or safely performed, then step
out authorisation and approval must be obtained in accordance with PR-1001e –
Operations Procedure Temporary Variance (supported by Risk Assessment), prior
to any changes or activities associated with the procedure being carried out”.
9
Section 2.2 - Swim Lane Step 8 – Changed ‘flowline’ to ‘equipment’
10
Step 7 2nd para changed to “All isolations that are to be put in place shall be listed
either on the PTW, on the Mechanical Isolation Certificate or Mechanical Isolation
Continuation Sheet. If the latter two are used these shall be attached to the PTW.
These certificates require to be verified when the isolations are removed.”
10
Step 8 1st para added after production Supervisor “and the person who is deemed
competent to perform the isolation”
Footnote added
10
Step 9 2nd para changed to “Any violations shall be reported to Production
Coordinator and a fountain Incident raised. The work will be stopped until an
investigation has been carried out.”
11
Section 2.3 Step 7 – Production Coordinator changed to Production Supervisor
12
Section 2.3 Step 13 Last Sentence “In this event, the procedure to be followed will
be clearly illustrated and a ‘step out’ raised supported by a Risk Assessment in
accordance with PR-1001e – Operations Procedures Temporary Variance.”
12
Section 2.3 Step 14 1st para added to end “This should be carried out on an
Extended Period Isolation and verified regularly.”
13
Removed Note 2 ” For the purposes of this requirement, toxic in the case of
H2S is defined as more than 500ppm H2S in the process stream.”
15
Section 2.4.6 “Toxic” changed to “Sour”
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Addendum 2 – Changes at Revision 3
Page No.
Changes / Additions
6
Section 1.1 following added
“Approved ‘Variances’ that have been Risk Assessed shall be added when
appropriate in the Appendices of this procedure to enable infrequent activities that
can not meet compliance to this procedure to be undertaken. These approved
variances shall be added and Operations notified by circular.
IMPORTANT: The Approved Variances are for the activities stated. Other
instances where compliance can not be met shall still require the completion of a
Temporary Variance in accordance with PR-1001e – Operations Procedure
Temporary Variance”
7
Section 1.6 removed and the Abbreviations added to Appendix 2
7
Roles and Responsibilities – Permit Holder added “pausing the work at regular
intervals to check if any aspect (affecting safe working) of the work has changed”
9
Footnote added “All” and “blinds”
10
Step 10 added “If the equipment is required to be test run this should be carried
out under a ‘De-isolation for Test (DFT) procedure’ using the reverse side of the
mechanical Isolation Certificate”
Appendix 3 - Tank Pressure / Vacuum Valve Changeout procedure added
User Feedback Page moved to Appendix 4
23
Appendix 3 Tank Pressure Vacuum Valve Changeout
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Addendum 3 – Changes at Revision 3.1
Page No.
Changes / Additions
10
Step 10 – Last para changed
“If the equipment is required to be test run this should be carried out under a ‘De-Isolation
for Test (DFT) procedure’ using the reverse side of the Mechanical and / or Electrical
Isolation Certificates”
13
Added under Section 2.4.2 - Isolation of Equipment for Maintenance
“Locked Open / Locked Closed valves that are operated during isolation shall be
recorded on the Lock Open / Locked Closed Register.”
14.
Added Section 2.4.8 – Immobilising Devices
23
Appendix 3 Tank Pressure Vacuum Valve Changeout
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Addendum 4 – Changes at Revision 3.2
Page No.
Changes / Additions
22
Step 1 WARNING – “Similarly, if a spare valve is not available, the activity should
not proceed.” added
24-25
Step 4 after (n)
NOTE: If the replacement of the PVV is halted due to damage of misalignment that will
cause delay, a flange can be fitted providing it is fitted with a low range pressure gauge to
monitor a pressure build up. In conjunction with the pressure gauge, a tee piece with a
valved vent facility should be fitted, with the vent to a safe area or flare system so that
any pressure build up due to temperature change can be vented safely (See Illustration
below). A documented risk assessment shall be carried out if this method is employed.
The risk assessment shall ensure that regular monitoring of the pressure gauge and
venting is carried out by operations for the duration that this flange is in place.
Page 35
PR-1076 - Isolation of Process Equipment
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Addendum 5 – Changes at Revision 3.3
Page No.
Changes / Additions
4
Related Corporate Management Frame Work (CMF) Documents
Added SP-2020 to Reference Documents
Appendix 3 - Tank Pressure / Vacuum Valve Changeout – 4 Removal and Replacement
added / reworded:
23
i)
Unbolt using the appropriate spanners.
WARNING: As the tank will still contain hydrocarbons the operation of rebolting on completion will constitute ‘hot-bolting’ and will require the
Approval of the Production Coordinator in accordance with SP-2020 Flange Connections Bolt Torquing and Tensioning Section 10.
s)
Page 36
Replace the bolting and torque down to specified torque. See Warning following
Step i).
PR-1076 - Isolation of Process Equipment
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Addendum 6 – Changes at Revision 4.0
Page No.
Changes / Additions
6
Section 2.2 – Step 6
“Isolations that have been classified ‘major’ shall require having spades or blinds /
spectacle blinds placed into the lines strategically to provide positive isolation. This shall
involve breaking pipework at flanges and should be covered in a specific procedure /
method study for the work and will require an isolation to do the work.”
Section 2.2 – Step 6
6
“All isolations that are to be put in place shall be listed on the Mechanical Isolation
Certificate or Mechanical Isolation Continuation Sheet and attached to the PTW. These
certificates require to be verified when the isolations are removed.”
13
Changed wording of 2.4.2 1st para ‘The permit applicant shall apply a process isolation
for every piece of equipment to be isolated from live plant describing the connections that
will be isolated, disconnected and tagged before starting to open the equipment. The
isolation shall be reviewed by the Area Authority, approved by the Responsible
Supervisor and attached to the PTW.’
13
Added new Sub-Section 2.4.3 – Removal and Replacement of Relief Valves on ‘Live’
Systems.
All following Sub-Sections renumbered.
15
Section 2.4.9
“There are a number of proprietary devices used in the industry for immobilisation,
however PDO has standardised with ‘pro-lock’ securing device”
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Addendum 7 – Changes at Revision 5.0
Page No.
Changes / Additions
6
Section 1.1 – Introduction
Reduced the content to make it concise and remove any source of ambiguity.
Section 1.3 – Distribution and Target Audience
6
Added ‘Well Services, EMC and ODC’
Section 2 – Roles and Responsibilities
8
Made additions and changes to Production Coordinator, Production Supervisor, Operator
and Area Authority, and Permit Holder
Removed the word ‘Procedure’ from Section 3 heading
10
Revised extensively the whole section and re-organised the order.
Inclusion of more specific text to cover H2S operations
Typical Isolation and De-isolation Process moved to Section 3.4. Process flow chart
revised
18
Appendix 1 all illustrations revised to show isolation requirement updates.
24
Appendix 3 – Changes made to enhance safety when undertaking the procedure.
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Addendum 8 – Interim Amendment May 2011
Page No.
Changes / Additions
13
Added Section 3.3 General Exceptions
“Any proprietary insertion or extraction device e.g. Welker/ COSASCO retrievable
probes, Daniel Orifice Carriers etc, used on ‘sweet systems’ up to, and inclusive of,
900# rating shall be allowed exception to the isolation requirements of this procedure.
NOTE: This exception shall be allowed provided the design of the fittings is not
modified or changed and that regular maintenance and inspection is carried out.”
Page 39
PR-1076 - Isolation of Process Equipment
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Addendum 9 – Interim Amendment September 2011
Page No.
Changes / Additions
10 & 11
Added Section 3.1.1 Major Work & 3.1.2 Minor Work
Positive isolation shall be required for all Major Work. For the purpose of this
procedure major work will be considered as any intervention that results in spools or
equipment being removed from a process line (including non-hydrocarbons), Confined
Space entry, or Hot Work (including cold cutting) being carried out.
Examples:
 Valve removal / replacement (including RV changeout);
 Spool removal / replacement;
 Equipment i.e. pump, changeout;
 Vessels / tank inspections:
IMPORTANT NOTE: There may be exceptions to the above e.g. relief valves
changeout, and these shall be addressed on an individual basis after risk assessment.
Valved isolation shall be required for all Minor Work. For the purpose of this
procedure minor work will be considered as any intervention that does not require
spools or equipment being removed from a process line (including non-hydrocarbons),
or where there no Hot Work.
Examples:

As a re-cusor for major work;

Breaking flanges for draining of depressurised systems;

Insertion of blinds between flanges on depressurised systems;

Working on instrumentation lines.
NOTE: For Minor work the valve isolation will require to be appropriate to address the
risk i.e. double block and bleed for H2S or pressurised lines, and demonstrated tight.
Page 40
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Revision: 6.0
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Addendum 10 – Changes at Revision 6.0
Page No.
Changes / Additions
Added Section 3.2 Terminology. All subsequent Sections renumbered accordingly.
Revised Table 1 – Minimum Isolation Requirements in line with Sour Projects Isolation
Philosophy
Page 41
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