/ Petroleum Development Oman LLC / Revision:6.0
Effective:May-12

Petroleum Development Oman L.L.C.

Isolation of Process Equipment

Document ID / PR-1076
Document Type / Procedure
Security / Unrestricted
Discipline / Engineering and Operations
Owner / UOP –Functional Production Manager
Issue Date / May 2012
Revision / 6.0

This document is the property of Petroleum Development Oman, LLC. Neither the whole nor any part of 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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iDocument Authorisation

Authorised For IssueMay 2012

iiRevision 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 NormanUOP6 / Interim Amendments incorporated and procedure aligned with Sour Isolation Philosophy. See Addendum 10 for details
5.0 / Oct-10 / Robin NormanUOP6 / Extensive changes. Refer to Addendum 7for changes
4.0 / Mar-10 / Robin NormanUOP6 / Re-issued. Refer to Addendum 6 for changes
1.0 / Sept 98 / UOP/1 / SI-26 rewritten to new format with minor comments incorporated.

iiiRelated Business Processes

Code / Business Process (EPBM 4.0)
EP.71.02 / Operate Wells and Facilities

ivRelated 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

TABLE OF CONTENTS

1Introduction......

1.1Background......

1.2Purpose......

1.3Distribution / Target Audience......

1.4Changes to the Document......

1.5Step-out Approval......

1.6ALARP......

2Roles and Responsibilities......

3Isolation of Process Equipment......

3.1Scope......

3.2Terminology......

3.2.1Major Work......

Table 1 – Minimum Isolation Requirements......

3.2.2Minor Work......

3.2.3Battery Limits......

3.2.4Baseline Isolation Standard......

3.2.5Boundary Isolation......

3.2.6Hydrocarbon Services......

3.2.7Hazardous Substance / Service......

3.2.8Non-Hazardous Service......

3.2.9H2S / Toxic System......

3.3Guidance Notes for Isolation......

3.3.1Issue of PTW to Permit Holder......

3.3.2Positive Isolation of Equipment for Maintenance......

3.3.3Removal and Replacement of Relief Valves on ‘Live’ Systems......

3.3.4Isolation of Moving Machinery......

3.3.5Isolation of Vessels......

3.3.6Isolation of Tanks......

3.3.7Isolation of Equipment Containing H2S......

3.3.8Use of Breathing Apparatus......

3.3.9Immobilising Devices......

3.4General Exceptions......

3.5Precautionary Considerations for Isolation......

3.6Typical Isolation and De-isolation Process......

Figure 1 – Process Equipment Isolation Process......

Appendix 1 – Positive Isolation Arrangements

Appendix 2 – Abbreviations

Appendix 3 – Tank Pressure / Vacuum Valve Changeout

Appendix 4 – Reference Material

Appendix 5 - User Feedback Page

Addendum 1 – Changes at Revision 2.1

Addendum 2 – Changes at Revision 3

Addendum 3 – Changes at Revision 3.1

Addendum 4 – Changes at Revision 3.2

Addendum 5 – Changes at Revision 3.3

Addendum 6 – Changes at Revision 4.0

Addendum 7 – Changes at Revision 5.0

Addendum 8 – Interim Amendment May 2011

Addendum 9 – Interim Amendment September 2011

Addendum 10 – Changes at Revision 6.0

1Introduction

1.1Background

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.

1.2Purpose

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.

1.3Distribution / 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.

1.4Changes 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 ensurereviewandre-verificationofthisprocedureevery3years.

1.5Step-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.

1.6ALARP

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

2Roles and Responsibilities

Production Coordinator /
  • To be accountable for the isolation(s) to be carried out.
  • Approve methods for isolations.
  • Specifying frequency of isolation integrity checks (if required).

Responsible Supervisor /
  • 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)

Production Operator and Area Authority /
  • 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

Maintenance Personnel /
  • 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

Permit to Work Applicant /
  • 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

Permit Holder /
  • 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

3Isolation of Process Equipment

3.1Scope

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 forprocess 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 abovehave been completed between any adjacent systems that may, or may not, remain live during the work.

3.2Terminology

3.2.1Major Work

Positive isolation shall berequired 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.

Table 1 –Minimum Isolation Requirements

System / System Description / Major Work
I / System in service, of ANSI class 300# and below.
For flashing liquids and toxic see II below. / Positive isolation by a single proven valve (Note1) and a swung spectacle blind/spade or removable spool (Note 2).

II / System in service, of ANSI class 600# and above.
All systems containing toxic fluids (Note 3).
Systems containing flashing liquids above ANSI 300, (Note 4) i.e. ANSI 600 and above. / Double block and bleed plus a spade/blind.

NOTE 1Provided 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 2A 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 3For the purposes of this requirement, toxic in the case of H2S is defined as more than 500 ppm H2S in the process stream.

NOTE 4The 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.

3.2.2Minor 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.

3.2.3Battery 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.

3.2.4Baseline 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

3.2.5Boundary Isolation

An isolation at any location where the defined Baseline Isolation Standard is met.

3.2.6Hydrocarbon Services

All systems containing hydrocarbons.

3.2.7Hazardous Substance / Service

A substance or containing a substance which is able to cause harm or damage if loss of containment occurs.

3.2.8Non-Hazardous Service

Any service not classified as hazardous.

3.2.9H2S / 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.

3.3Guidance Notes for Isolation

3.3.1Issue 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.

3.3.2Positive 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 shallapply 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 Authorityshall 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 consideredas ‘tight shut-off’ valves.

3.3.3Removal 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:

  • 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

3.3.4Isolation 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 minimummandatory requirement.

Machinery brakes and brake locks are to be applied and the clutch (if applicable) is to be disengaged.

3.3.5Isolation 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 minimummandatory requirement.Non-compliance shall be in accordance with PR-1001e – Operations Procedure Temporary Variance.

NOTE: Refer to Table 1 for recommendations regarding isolation requirements.

3.3.6Isolation 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.

3.3.7Isolation 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 minimummandatory 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.

3.3.8Use of Breathing Apparatus

It is mandatory to wear positive pressure breathing apparatus when breaking flanges and opening equipment containing toxics. This shallbe 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 H2S). 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.

3.3.9Immobilising Devices

There are a number of proprietary devices used in the industry for immobilisation, however PDO has standardised with ‘pro-lock’ securing device.

3.4General 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.

3.5Precautionary 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.