Effective: Oct-14
Petroleum Development Oman L.L.C.
Document Title: Gas Testing
Document ID / PR-1154Document Type / Procedure
Security / Unrestricted
Discipline / Engineering and Operations
Owner / UOP –Operations Function Team Leader
Issue Date / October 2014
Version / 4.1
Keywords: 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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i Document Authorisation
Authorised For Issue October 2010
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. / Author / Scope / Remarks4.1 / Oct-14 / Philip Hatherton UOP61 / Revision to incorporate minor amendments
Apr-11 / Robin Norman UOP6 / Added Section 1.6 ALARP
4.0 / Oct-10 / Robin Norman UOP6 / Major revision and update. Informative general text moved to Appendix. Section 2 dedicated to Roles and Responsibilities. Contents arranged to be more concise.
3.0 / May-07 / UEV/11 / Reformatted & Revised
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.
Refer to Appendix 6 for Reference Material
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 8
1.6 ALARP 8
2 Roles and Responsibilities 9
3 Gas Testing 10
3.1 Scope 10
3.2 Potential Hazards 10
3.2.1 Oxygen Enriched Atmosphere 10
3.2.2 Oxygen Depleted Atmosphere 10
3.2.3 Flammable or Explosive Atmosphere 10
3.2.4 Toxic Atmosphere 11
3.2.5 Hydrocarbon Enriched Atmosphere 11
3.3 Gas Test Requirements 11
3.3.1 Breaking Containment 11
3.3.2 Hot Work in a Process or Hydrocarbon Area 11
3.3.3 Gas Freeing and Purging 12
3.3.4 Confined Space Entry / Work within a Confined Space 12
3.3.5 Checking for Suspected Gas Leaks 12
3.3.6 Providing Clearance for Work Activities 12
3.3.7 Use of Diesel Engines in a Process / Hydrocarbon Area 12
3.3.8 Vehicle Entry to a Process / Hydrocarbon Area 12
3.4 Testing Instruments 12
3.4.1 Multigas Monitors 13
3.4.2 Explosimeter Monitors 13
3.4.3 Detector Tubes 13
3.5 Gas Tester 13
3.6 Pre-User Checks 13
3.7 Gas Testing Process 15
Appendix 1 – Atmospheric Testing 17
Appendix 2 – Oxygen Content Testing 18
Appendix 3 – Flammable Gas Testing 20
Appendix 4 - Toxic Gas Testing 22
Appendix 5 – Hydrocarbon Vapour Narcotic Effect 24
Appendix 5 – Abbreviations 25
Appendix 6 – Reference Material 26
Appendix 7 – User Feedback Page 27
1 Introduction
1.1 Background
The requirements of Gas testing are clearly described in PR-1172 – Permit to Work System Sections 3.5, 6.2.4 and 6.12. PDO Operations Staff and Contractors shall require to employ only personnel who have been trained and certified competent to perform gas tests and the procedure / methods that they use to carryout the tests shall be as prescribed by the course.
Gas testing is mandatory prior to work being undertaken in a process or hydrocarbon area that carries a risk to personnel or equipment from exposure to explosive, flammable, toxic or life threatening vapours. Gas testing shall also be required in any other area where the above risks are considered to exist which are covered by the PDO Permit to Work or a 3rd Party compliant system.
NOTE: Gas testing shall be carried-out on facilities where NORM or Mercury is identified or likely to be present. Specific procedures shall be used when testing for these risks.
1.2 Purpose
The purpose of this procedure is to present the high level requirements for gas testing and define the key hazards and methods of testing.
This procedure does not intend to duplicate methodology taught during the Gas Tester course or information contained in PR-1172 Permit to Work System.
1.3 Distribution / Target Audience
This procedure is intended to be referenced by PDO Operations and Engineering staff and Contractors undertaking work authorised by 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 re-verification 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 approval must be obtained in accordance with PR-1001e – Operations Procedure Temporary Variance.
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
2 Roles and Responsibilities
All affected personnel shall read this procedure. If they do not understand something within the procedure they shall ask their line supervisor or The Operating Integrity Coordinator (Interior) to explain it. It is the line Supervisor’s Responsibility to ensure that all his subordinates have read and understood this procedure. When the procedure is read and understood they shall sign the Record of Procedure Understanding Form.Role / Responsibility
Permit Applicant / · Define the gas testing requirements for the work
· Prepare the Job Safety Plan and indicate the frequency of gas testing
· Complete the appropriate section for gas testing on the PTW
· Indicate the special gas detection equipment is required e.g. hydrocarbons in inert
Responsible Supervisor / · Agree requirements of gas testing with the Permit Applicant
· Authorises relaxation of rules for 1st Gas Test on Class A permits where appropriate
· Agree the Job HSE Plan
· Ensure all technicians under his supervision read and understand the procedures and sign the Record of Procedure Understanding Form
· Ensure that the Record of Procedure Understanding Form is correctly completed and retained in a central location within each area.
Area Authority / · Tick the gases to be tested for on PTW.
· Indicate how often the test shall be repeated on PTW.
· State if continuous monitoring for gas is required during the work.
· For Class A permits performs the 1st gas test each day, unless authorised by Responsible Supervisor that this can be carried out by Authorised Gas Tester
Authorised Gas Tester / · Comply with PR-1172 Permit to Work System regarding gas testing requirements and frequencies
· Performs all Gas testing for Class B permits
· Carryout ‘ad-hoc’ gas testing when required
· Enter gas test results and frequency of further tests on PTW and Confined Space Entry Certificate / Additional Gas Test sheet (if applicable),
NOTE: Authorised Gas tester to agree test results with area authority and enter into PTW.
Permit Holder / · Include gas testing requirements in the TRIC
· Agree gas test results
· Ensure compliance to gas testing requirements is adhered to
· Ensure correct type of gas detector is used for the gas testing activity
Maintenance Staff / · Comply with this procedure
· Ensure the procedures are read and understood and they sign the Record of Procedure Understanding Form
3 Gas Testing
3.1 Scope
The scope of this procedure shall cover;
- the hazards which gas testing shall address;
- the requirements for gas testing;
- typical testing instruments used;
- the gas tester and;
- pre-user checks
The procedure shall make reference where appropriate to material located in other documents and provide links to those documents where necessary.
3.2 Potential Hazards
Generally the potential hazards addressed by gas testing are;
· Oxygen enriched atmosphere
· Oxygen depleted atmosphere
· Flammable or explosive atmosphere
· Toxic atmosphere
· Hydrocarbon enriched atmosphere (narcotic effect)
Each of the above shall be addressed with a more detailed description in the Appendix.
3.2.1 Oxygen Enriched Atmosphere
Atmospheres containing more than 21.5 % vol. oxygen shall be treated as oxygen enriched. Generally oxygen enrichment does not occur often as the source of the extra oxygen shall have to be introduced. Oxygen enriched atmospheres when mixed with hydrocarbons can result in explosive mixtures quicker than would be the case with normal air (20.8%).
3.2.2 Oxygen Depleted Atmosphere
Atmospheres containing less that 20% vol. oxygen shall be treated as oxygen depleted. Such atmospheres can occur when gas freeing of purging has been carried out to remove hydrocarbons / toxics or air. The oxygen in the atmosphere shall have been normally replaced / diluted with an inert gas i.e. nitrogen.
3.2.3 Flammable or Explosive Atmosphere
Flammable or explosive atmospheres are those that contain mixtures when exposed to an ignition source will or may ignite and burn. Such atmospheres can be created when opening pipework or equipment that contains or has contained hydrocarbons.
3.2.4 Toxic Atmosphere
Toxic atmospheres are those that contain concentrations of vapours that shall cause injury or death to humans. Such atmospheres may have sufficient oxygen to support life and insufficient flammable concentrations to cause explosions or fire, but may contain sufficient concentrations of the toxic to harm personnel. An example would be H2S or mercury.
3.2.5 Hydrocarbon Enriched Atmosphere
Hydrocarbon enriched atmospheres are those where the concentrations of hydrocarbon vapours are sufficient to induce a narcotic effect on personnel inside the atmosphere.
3.3 Gas Test Requirements
PR-1172 – Permit to Work System Section 3.5 shall be referenced to determine the frequency of gas testing and the specific work it is required for.
In general gas testing is required for the following types of work;
· Breaking containment
· Hot work in a process or hydrocarbon area
· Gas freeing and purging
· Confined space entry / work within a confined space
· Checking for suspected gas leaks
· Providing clearance for work activities
· Use of diesel engines in a process / hydrocarbon area
· Vehicle entry to a process / hydrocarbon area
3.3.1 Breaking Containment
Gas testing shall be required when containment is broken on any system containing hydrocarbon or toxic liquids / solids / vapours. Appropriate PPE and safety equipment i.e. SCBA, masks, face visors etc, shall be worn as necessary.
The type of gas tested for shall be indicated on the PTW by the Area Authority in addition to the frequency of testing. Types of gas can include one or all of the following;
· Hydrocarbons
· H2S
· Mercury (refer to PR-1515 – Onsite mercury Management)
· NORM (refer to SP-1170 - HSE Specification - Naturally Occurring Radioactive Materials (NORM)
3.3.2 Hot Work in a Process or Hydrocarbon Area
Hot work carried out in an area where hydrocarbons are present or can be present must be preceded by a gas test of the work site and adjacent areas to address the risk of fire and explosion caused by concentrations within the Lower Explosive Limits.
The gas test shall be primarily for hydrocarbons and carried out in accordance with PR-1172 – Permit to Work System Section 3.5 and 6.2.4
3.3.3 Gas Freeing and Purging
Gas freeing of pipework and equipment shall be carried out prior to work being undertaken on hydrocarbon or toxic system. The normal medium for gas freeing is an inert, nitrogen or water.
Gas testing of the pipework or equipment shall be carried out in accordance with PR-1172 – Permit to Work System Section 3.5 and PR-1073 – Gas Freeing, Purging and Leak Testing of Process Equipment.
During gas freeing processes using nitrogen the gas testing shall be to detect hydrocarbons in an inert and requires the appropriate testing equipment to be used.
3.3.4 Confined Space Entry / Work within a Confined Space
Spaces or vessels requiring entry by personnel to inspect or carryout work shall require to be tested prior to and during the work.
Gas testing shall be undertaken in accordance with PR-1172 – Permit to Work System Section 3.5 and PR-1148 - Entry into a Confined Space Procedure
Confined space gas testing shall be to determine whether the atmosphere within the space can safely support life. Tests shall be for oxygen content and hydrocarbons / toxics.
3.3.5 Checking for Suspected Gas Leaks
Small gas leaks in and around pipework and equipment may be detected using portable gas testing equipment.
3.3.6 Providing Clearance for Work Activities
Work activities in hazardous area shall require that the atmosphere at the work site and in the surrounding areas is safe before permission is given to carryout the work activity.
3.3.7 Use of Diesel Engines in a Process / Hydrocarbon Area
The use of internal combustion engines (diesel driven) within a process or hydrocarbon area shall be subject to authorisation and require gas testing in accordance with PR-1172 – Permit to Work System Section 3.5.
Diesel driven plant i.e. mobile cranes, air compressors etc, shall be subject to continuous gas monitoring while in use. The units shall also be subject to a gas test prior to starting.
The gas test shall primarily be to check for hydrocarbons.
3.3.8 Vehicle Entry to a Process / Hydrocarbon Area
Vehicles shall only be allowed into a process area if covered by a PTW. A PTW is not required for a hazardous area but gas testing is mandatory for both.