Petroleum Development Oman L.L.C.
Document title:
CS & CRA Dead leg Management Procedure
Document ID
PR-2547
Document Type
Procedure
Security
Restricted
Discipline
Material, Corrosion, and Integrity
Owner
Issue Date
Version
UEC
30/06/2024
1.0
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
Document Authorisation
Document Owner
Document Custodian
Document Author
(CFDH)
NABHANI,TALAL UEC
Mukhaini, Ali UEC5
Date : 30-07-2024 4:16 PM
Date : 08-07-2024 8:25 AM
Hubaishi,
UEC57
Mohammed
Date : 27-06-2024 1:58 PM
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ii Revision History
The following is a brief summary of the most recent revisions to this document. Details of all
revisions prior to these are held on file by the issuing department.
Version No.
1.0
Date
30/06/2
024
Author
Mohammed, Al Hubaishi
UEC57
Scope / Remarks
Initial issue
iii Related Business Documents
Code
Business (EPBM 4.0)
iv Related Corporate Management System (CMS) Documents
The related CMS Documents can be retrieved from the Corporate Management System Portal
(CMS).
Code
CP-104
Doc title
Maintenance & Integrity Management – Code of practice
CP-208
Corrosion Management Code of Practice
SP-2328
Static Equipment Integrity Management
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TABLE OF CONTENTS
i
Document Authorisation ......................................................................................................... 3
ii
Revision History ..................................................................................................................... 4
iii
Related Business Documents ................................................................................................ 4
iv
Related Corporate Management System (CMS) Documents ................................................ 4
1
Introduction ............................................................................................................................ 6
1.1
Purpose ............................................................................................................................ 6
1.2
Background ...................................................................................................................... 6
1.3
Objective .......................................................................................................................... 6
1.4
Target Audience ............................................................................................................... 7
1.5
Review and Improvement ................................................................................................ 7
2
Scope ..................................................................................................................................... 8
3
Definition of dead legs ......................................................................................................... 10
3.1
Dead legs Management - Solutions ............................................................................... 11
3.1.1
Buried dead legs:.......................................................................................... 11
3.2
CS Dead legs Management – Procedure ...................................................................... 13
3.3
Risk assessment ............................................................................................................ 15
Appendix 1, dead leg examples .............................................................................................. 17
Appendix 2, Dead leg register ................................................................................................. 24
Appendix 3, Team members ................................................................................................... 26
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1 Introduction
Purpose
1.1
The purpose of this PR is to provide the assets and the projects with a systematic and a riskbased approach to effectively manage CS & CRA dead leg internal corrosion.
The aim of this PR is to eliminate and reduce the number of CS & CRA dead legs to the extent
possible and to effectively manage the dead legs threat for those which cannot be eliminated.
Background
1.2
For many years, PDO has been suffering from many leaks across its asset due to the aggressive
internal corrosion in CS & CRA Dead legs. The leaks associated with this threat has recently
increased as PDO asset aged and due to an increase in fluid corrosiveness. This has resulted in
unnecessary shutdowns, major production deferment and exposing people and asset to toxic &
dangerous environment.
Several solutions were implemented to manage the internal corrosion in the CS & CRA dead legs.
While some of these implemented solutions helped partially manage the internal corrosion in the
dead legs, the leaks due to dead leg internal corrosion did not stop as all the solutions
implemented has its own limitations.
Increasing inspection intervals is one of the mitigations implemented by PDO to help manage the
dead leg issue. However, Inspection is generally not a cost effective, long-term mitigation option
for highly corrosive dead legs where high corrosion rate can result in inspection intervals that are
too short to be practical or economical. Furthermore, the selection of the wrong inspection
technique or inspection location and extent can easily render the inspection ineffective. This is
especially critical where the dead leg is suffering from localized corrosion (i.e., pin holes)
The key causes of corrosion in dead legs are:
12345-
Microbial corrosion,
Under deposit corrosion and
Condensing CO2 corrosion
Acidic Sour Water Corrosion
A combination of the above
The forms of corrosion in dead legs can be either a general corrosion or Localized corrosion.
Appendix 1 provide typical example of dead legs in PDO.
1.3
Objective
The objective of this PR is to set the minimum requirements for managing CS & CRA dead legs
for the assets and the Projects. The PR has been developed based on a comprehensive review
of:
1- Available practices, solutions, resources, and references from PDO Various disciplines
2- Available international codes and practices
3- Available practices and codes of other operators in the region and internationally
The PR will clearly define:
1234-
The scope of the PR
The definition of dead leg
The solutions
The solutions implementation methodology
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1.4
Revision:
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Target Audience
All PDO users
1.5
Review and Improvement
This Procedure will have a validity of three years from date of issue. The review authority
will be within the head of inspection and integrity. Changes to this document shall only be
accepted upon obtaining approval from the custodian (Head of Materials and Integrity).
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2 Scope
The scope of this PR is applicable to:
1- All dead legs in CS systems (piping, pipeline, equipment nozzles), where the
dead legs are meeting all the criteria and definition in section 3.
2- All dead legs in CRA system (piping, pipeline, equipment nozzles), where the
dead legs are meeting all the criteria and definition in section 3.
a. This is only applicable to SS316L, DSS and Alloy 825
3- All asset (Operations) and all Projects (Design)
4- All instrumentation and small-bore piping
This PR doesn’t cover the following:
1- CRA (Mainly SDSS & alloy 625) and GRE Dead leg
a. Dead leg in GRE is not foreseen.
b. CRA (Mainly SDSS & alloy 625) material should be resistance to corrosion in
dead legs. However, in specific cases and under specific
conditions/environment, there materials may suffer from corrosion at dead
legs. For such cases, the material and corrosion engineer shall evaluate the
risk of corrosion in dead leg. The control measure, if required, shall be
indicated in the relevant asset/project documents (e.g., MSR, CMM…etc.)
2- Internally coated/lined dead leg (e.g., PCS-8, HDPE lined CS…etc.).
3- Anything not meeting the criteria or definition in section 3.
4- Mothballing of decommissioned equipment (Non-operational side)
a. This is the part that is not continuously exposed to the process fluid (i.e.,
isolated). In such cases, the same shall follow the required preservation
procedure.
5- Drain, vent, flare, and relief lines downstream of the “closed” valve.
a. This is the part that is not continuously expose to the process fluid (i.e.,
Intermittent operation).
b. It shall be designed as per SP-1126 requirements.
6- CS dead leg external corrosion
7- Drain/Vent Vertical upward liquid filled dead legs:
a. if the vertical upward dead leg has a pocket or horizontal section where
liquid can be stagnant then it shall be considered as dead leg and shall be
follow this PR requirements. The below sketches give further clarification of
what shall be considered as a dead leg in vertical upward liquid filled
sections.
b. In any new project vertical upward section shall be designed to avoid
corrosion due to dead legs
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This configuration shall not be considered as
a dead leg and shall not follow this
procedure requirements
Revision:
Effective:
The vertical upward line contains horizontal and
vertical downward section before the blind flange.
The same shall be considered as dead leg and shall
follow the requirements of this procedure.
8- No buried dead legs are allowed therefore buried systems are not included.
9- Instrumentation tubing
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3 Definition of dead legs
The General definition of dead leg is:
“A Components of a system that normally have little or no significant flow where it
can trap fluids at stagnant conditions during normal operating condition”.
Based on the review of resources and references available, it was obvious that there are
many ways to define and categorise dead legs. To avoid confusion and to standardize our
approach and for the purpose of this PR, Dead legs will be divided into two main categories:
I.
II.
Permanent/Physical (design) dead legs: Areas subject to long term stagnation
which have been built into the plant or have arisen from modifications over the
course of the life of the facility.
Operation dead legs: Location or sections of the plant that are stagnant due to
temporary changes, repairs, or other operational reasons.
Regardless of the classification, the issue remains the same across all type of dead legs.
Typical Dead legs examples are in Appendix 1
A section of the facility shall be considered as a dead leg and shall follow this PR
requirements if all the following criteria are met:
a) The material of construction is Bare CS, SS316L, DSS or Alloy 825
b) The fluid or the internal environment within the section is corrosive (e.g.,
containing H2S, CO2, O2, Sand, acids, presence of bacteria, corrosive
chemicals…etc.)
c) The section contains fluids that are at stagnant condition or with No significant
flow.
d) A section that operates intermittently (At a continuous stagnant condition for > 3
month)
• For the advance/early tie-in sections that meet all the dead leg criteria, an
inspection shall be done Annually. Other dead leg solutions shall not be
implemented unless the tie-in scope will remain in stagnant conditions for
more than 2 years.
e) Not self-draining
f) When the length is longer than 3 X pipe OD or 1.2 meter whichever is lesser
(applicable only to horizontal and downward vertical section)
• The length of the dead-leg is the distance measured from the outside
diameter of the header (or run) to the near end of the section containing the
stagnant fluids.
g) When the gas operating temperature is below the water dew point temperature
• This is mainly applicable to gas vent, drain and relief section connected to
a gas main line/equipment. The gas at the main line/equipment usually
operates at temperature above its water dew point but at the
vent/drain/relief lines, the gas temperature at the farthest point may drop
below the water dew point temperature causing condensation and water
accumulation at the horizontal section of the vent/drain/relief line. This is
especially of a concern when vent/drain/relief line are having the following
conditions:
- The length of the vent/drain/relief line up to the first valve is
sufficient to allow for the temperature of the gas to drop below its
water dew point temperature.
- The vent/drain/relief line up to the first valve is not insulated/heat
traced.
- The vent/drain/relief line has horizontal section or a pocket with
no slope or free draining and where liquid can accumulate.
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-
3.1
Revision:
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(Refer to the last example in appendix 1)
This is only a concern with water condensation and not with HC
condensation.
Dead legs Management - Solutions
Based on the review completed on the available resources and references, it was obvious that
the solutions available to manage dead legs are limited and common for both the assets and the
projects.
The different solutions identified can be classified into three groups.
1- Solutions that can Eliminate Dead legs issues:
a. Eliminate/remove dead leg from the system.
b. Redesign (changing orientation, reducing length…etc.)
c. Material upgrade (including internal coating)
2- Solutions that can Mitigate/control Dead legs issues.
a. Chemical injection (inhibitor and biocide)
b. Flushing & Draining
c. Insulation/heat tracing (applicable to gas system)
3- Solution to monitor dead legs:
a. Inspect and replace (reduced inspection interval)
Some of the solutions above will need to be combined with other solution to ensure its
effectiveness. For example, injecting corrosion inhibition shall be combined with inspection…etc.
The solution implementation will differ if the dead leg is in an asset (operation) or in a project as
some solutions can be easily implemented at the project phase but not at operation phase.
Dead legs identified as with a high and medium risk shall be
1- Prioritize first
2- Solutions that can eliminate dead legs, shall be implemented first. (Refer to a solution
prioritization tree below)
The following guidelines shall be considered when using the solution prioritization tree below:
1- For High-Risk dead leg, the asset/project shall implement Priority No.1 Solutions first.
Only if there are solid justifications, Priority No.2 solutions can be implemented, and the
same process shall be followed for the rest of the solutions. The justifications for going
to solutions other than priority No.1 shall be documented in the risk register and shall be
accepted and approved by Material & Corrosion TA2
2- For Medium-Risk dead leg, the asset/project shall implement Priority No.1 Solution
first. Only if there are solid justifications, Priority No.2 solution can be implemented. The
same process shall be followed for the rest of the solutions. The justifications for going
to solutions other than priority No.1 shall be documented in the risk register, but
Material & Corrosion TA2 approval is not required.
3- For low-risk dead legs, normal PDO dead leg inspection strategy (Priority 5 solution in
the solution prioritization tree below) shall be implemented in line with SP-2328
requirements.
3.1.1 Buried dead legs:
Dead leg in buried system shall be avoided and shall not be allowed. However, and only at
extreme cases, if dead leg in buried system exists, then it shall follow either solution Priority 1 ,2
or 3 only. Other solution priority for buried dead leg are not allowed.
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High/Medium Risk Dead legs
Priority 1
Eliminate/rem ove dead leg from the system
1- Remove unnecessary dead legs or low points that are not required for operation and that have no chance of being
utilized in the future
2- Pipe running on pipe ways, racks or trenches for supporting purposes shall be removed
3- Answering the following question may help determine if dead leg is required or not:
a. What is the purpose of the dead leg?
b. Is it required for operation? How frequently is it used or how frequent it will be used?
c. What benefit does it provide?
d. Is there an alternative piping system or configuration, which may be used in place of the dead leg?
Priority 2
Re-design dead legs
1- Re-design of dead legs to eliminate or minimize the conditions that lead to corrosion, fo r example:
a. Shortening the length of dead leg to be less than the length criteria
b. Add a block valve in close proximity to the main piping system to isolate the dead legs from the corrosive fluids. The
remining length of the dead leg section upstream of the block valve shall be less than the dead leg length criteria
c. change the orientation of the dead leg (e.g. for liquid filled dead leg make it vertical upward)
Priority 3
Material upgrade
1- Material Engineer shall advise the material selection
2- Internal coating/lining shall be considered. The maintenance and design life of the coating shall be considered when
selecting this option
3- Insulating kit might be required wherever CRA is used
4- Th e Nozzles and dead legs connected to the Nozzles of the Vessel, tank, heat exchanger or any equipment shall
follow the material of the equipment or it shall be of a higher material grade. This is applicable to instrumentations
tubes, taps, connections and nozzles
5- Material Upgrade shall include all items exposed to the stagnant fluid including valves, b lind flanges, spectacle
blinds...etc.
Priority 4
Priority 4
Priority 4
Chem ical injection
Flushing & Draining
Insulation/heat tracing
1- The dead leg shall be design with injection point
or injection system
2- Th e dead leg shall be design with drain system
to remove the stagnant liquid before chemical
injection
3- A design that prevent shutting down the facility
to carry out chemical injection is recommended .
3- Th e corrosion control engineer sh all advise type
of the chemicals and injection rate
4- Th e chemical injected shall not become
corrosive when accumulated and when at stagnant
condition
5- It is recommended to inject both inhibition and
biocide
6- Th e frequency of injection shall be advised by
corrosion control engineer
7- The dead leg shall be registered in CIMS and
shall follow PDO dead leg inspection strategy
1- The Dead leg shall be designed to
accommodate flushing, preferably without the
requirements of shutdown
2- Flushing shall be done on monthly basis for high
risk dead leg and every quarter for medium risk
dead legs
3- Flushing velocity shall be minimum 1.5-2 m/s or
higher to ensure removal of deposits from the
dead leg
4- Th e dead leg shall be registered in CIMS and it
shall follow PDO dead leg inspection strategy
5- Th e flushing frequency can be optimized based
on the inspection result and resultant corrosion
rate
6- Automatic self flushing is should be considered
1- Th is is mainly applicable to gas System vent and
relief section connected to gas main line operating
at temperature above its water dew points and
where the temperature of the gas at the vent or
relief line drop below its water dew p oint
temperature leading to water con densation and
accumulation at dead legs
2- Th e dead leg shall be registered in CIMS and it
shall follow PDO dead leg inspection strategy
Priority 5
Inspect and replace
1- Th is is PDO current dead leg inspection strategy (inspect every 3 years) as per SP -2328.
2- Th is shall not be considered as a mitigation or control measure. It helps determine metal loss and predict remaining
life in which replacement/repair can be then planned before leak.
3- This shall be considered for the dead leg with remaining life > 3 years
4- Dead leg with remaining life < 3 years shall not be considered for this solution and more robust solution shall be
implemented
5- The dead leg shall be registered in CIMS
6- Th e Inspection technique shall be identified for each dead leg and shall be clearly mentioned in the dead leg register.
a- Th e inspection technique shall b e recommended/reviewed by the integrity Engineer and NDE specialist
b- GA drawing, Isometric, actual photo of the dead leg, the dead leg configuration from 3D module shall be provided to
the Integrity Engineer and NDE specialist
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3.2
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CS Dead legs Management – Procedure
Two structured procedures are shown below indicating different steps that shall be followed by
the project or asset to manage CS dead legs.
For all Projects, the full steps of the dead leg management exercise including (risk assessment)
shall be considered in the project Schedule and CTD. It is also recommended that for brown field
the below steps should start from BFD stage and for green field the same can start from the define
stage.
Project
Start
Step 1
Identify CS systems/sections/loops that are susceptible to corrosion due to CS dead legs
Responsible: Material Engineer
Instructions:
1- Any Systems not meeting the below two conditions shall not be considered:
a. Only CS/SS316L/DSS/Alloy 825 system/section/loop to be included (including inhibited
lines and dry gas system)
b. The process fluid shall be corrosive to the specified material at the dead legs
2- Internally coated or lined CS is excluded
3- A dead leg management section in MSR shall be added and making reference to this PR
Step 2
During Model review, identify dead legs and update the dead leg register
Responsible: Material engineer, Process engineer & Piping engineer
Instructions:
1- Prior to the Module review, a pre identification of the dead legs in the PEFS for the susceptible
corrosion loops (identified in step 1) shall be carried out by the 3D module design team.
2- Dead leg identification during module review shall not rely only on the pre-identified dead leg in
the PEFS, however the full susceptible corrosion loop shall be reviewed thoroughly for all dead legs
that otherwise not identified/captured in the PEFS
3- During the identification of the dead legs in the module review, all the identified dead legs shall
be verified to ensure it is meeting the below two criteria:
a. Meeting the length criteria
b. For Dry gas system, verify if the temperature can drop below the dew point at the
farthest point from the main line. The piping engineer shall provide the length of the vent/
drain/relief line from the main line up to the first valve and the Process engineer shall
calculate the water dew point temperature of the gas at the discharge line and shall
confirm if the temperature of the gas at the farthest point will drop below the water dew
point temperature or not.
4- For small scale project or FCP, where 3D module is not used then the dead leg verification shall
be conducted on 2D piping GAD desktop review
Step 4
Conduct risk assessment workshop to Rank the identified dead legs and identify the solutions
Responsible: Material engineer
Instructions:
1- Process, piping/static & TSE shall attend the workshop
2- Refer to Risk assessment Guideline in section 3.3 of this PR
3- Refer to Solution assignment guideline in section 3.1 of this PR
Step 5
Implement the agreed solution and update the dead leg register
Responsible: Material engineer
Instructions:
1- Once all Solutions are implemented and agreed, the risk register shall be updated (final version)
2- Dead legs that need to be inspected shall be shared with M&I team to be captured in CIMS as
dead leg. This include dead legs with combined solution where the inspection is part of the
solution.
3- Dead legs that need to be flushed or drained shall be captured in the POM and a Maintenance
plan shall be created in SAP for each dead leg requiring flushing or draining with the agreed
frequency as identified in the dead leg register.
4- If a modification is required as part of the identified solution then it shall follow PMOC process
5- If other modifications (not related to dead leg solutions) has resulted in additional dead legs then
the above steps shall be followed and the register shall be updated
Finish
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Start
Step 1
Identify CS systems/sections/loops that are susceptible to corrosion due to CS dead legs
Responsible: Corrosion Control Engineer
Instructions:
1- Both on plot and off plot corrosion loops shall be considered
1- Any Systems not meeting the below two conditions shall not be considered:
a. Only CS/SS316L/DSS/Alloy 825 system/section/loop to be included (including inhibited
lines and dry gas system)
b. The process fluid shall be corrosive to the specified material at the dead legs
3- Internally coated or lined CS is excluded
Step 2
Identify and Mark dead legs in the Isometrics for the identified systems in step 1
Responsible: Static Integrity & Pipeline Integrity Engineer
Instructions:
1- Dead leg in piping, pipeline and equipment shall be considered
2- Process engineer to help confirm if the identified dead legs are:
a. At stagnant conditions or operation frequency is > 3 months
b. Not self draining
3- The identified dead leg length to be confirmed in step 3
Step 3
Carry out site survey to Verify identified dead legs in step 2 and update the dead leg register
Responsible: Operation team
Instructions:
1- The main verification at this stage is to confirm if the dead legs identified in step 2 are;
a. meeting the length criteria
b. For Dry gas system, verify if the temperature can drop below the water dew point at
farthest point from the main line
2- A training shall be provided to the surveyor
3- Refer to appendix 3 for the dead leg register
Step 4
Conduct risk assessment workshop to Rank the identified dead legs and identify the solutions
Responsible: Static and Pipeline integrity engineer
Instructions:
1- Process, operation, TSE, corrosion control, Material shall attend the workshop
2- Refer to Risk assessment Guideline in section 3.3 of this PR
3- Solution assignment shall follow section 3.1
Step 5
Implement the agreed solution and update the dead leg register
Responsible: Static support OXO61
Instructions:
1- Once all Solutions are implemented and agreed, the risk register shall be updated
2- Risk register shall be kept as live document and it shall be updated continuously
3- Dead legs that need to be inspected shall be shared with Inspection team to be captured in CIMS
as a dead leg. This include dead legs with combined solution where the inspection is part of the
solution.
4-Maintenance plan shall be created in SAP for each dead leg requiring flushing or draining with
agreed frequency identified in the dead leg register.
5- If asset modifications occurred in future and new dead legs were created the above steps shall
be repeated for the new dead legs
Finish
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Risk assessment
3.3
Risk assessment shall be conducted to identify the risk ranking of the identified dead leg.
The risk assessment will follow the guidelines given in shell MEC_RP_04-04.2_V1 with slight
modification to meet PDO requirements.
Likelihood
PCRD
minus
DCR =
>0.5
mm/y
Community
PCRD
minus
DCR =
0.25 0.5
mm/y
Environmental
PCRD
minus
DCR =
0.13 0.25
mm/y
Asset
0
Consequences
Health & Safety
Consequence Severity
The Risk assessment matrix is shown below:
PCRD
minus
DCR <
0.13
mm/y
No injury
or health
effect
No
damage
No effect
No effect
L
L
L
L
Slight
injury or
health
effect
Minor
injury or
health
effect
Major
injury or
health
effect
<100k
USD
Slight
effect
Slight
effect
L
L
M
M
100 -1M
USD
Minor
effect
Minor
effect
L
M
M
H
1M –
10M
USD
Moderate
effect
Moderate
effect
M
M
H
H
4
PTD or up
to 3
fatalities
10 100M
USD
Major
effect
Major
effect
M
H
H
H
5
More
than 3
fatalities
>100M
USD
Massive
effect
Massive
effect
M
H
H
H
1
2
3
Notes:
1- PCRD: Potential corrosion rate of dead leg
2- DCR: Design corrosion rate (unmitigated) of the main piping, pipeline, or equipment
(i.e., Hydrocor CR)
3- Other operational scenarios (e.g., high pressure, high temp, toxicity…etc.) shall be
considered during risk ranking assessment.
The PCRD shall be specified by the material and corrosion engineer it can be obtained from
1- Hydrocor simulation (creating a case with low water flow while keeping the other
parameters in the system as it is )
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2- Historical Corrosion rate in dead legs at the same asset
Using the historical corrosion rate obtained from actual inspection of dead legs or reported leaks
are the most recommended way to obtain the PCRD.
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Appendix 1, dead leg examples
Dead legs examples include, but not limited to,
1- Blanked (blinded) branches,
2- Lines with normally closed block valves,
3- Lines with one end blanked (blinded),
4- Pressurized dummy support legs,
5- Stagnant control valve bypass piping,
6- Spare pump piping,
7- Level bridles,
8- Pressure relieving device inlet and outlet header piping,
9- Pump trim bypass lines,
10- High-point vents,
11- Sample points,
12- Drains,
13- Bleeders,
14- Instrument connections and tapping.
15- Piping that is no longer in use but still connected to the process (Not isolated)
Examples from PDO assets are shown in the table below:
Example
Description
Vessel
Nozzle
connected to
NC valves
drain lines
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1-Vessle
vacuum truck
connection
(right piping)
2-Vessel
level Gauge
connection
(76-LG-601B)
Vertical line
connected to
NC valve but
with
Horizontal
section
Such case
might be
applicable to
gas line
where
condensation
can occur
and
accumulate
in the
horizontal
section
Printed 05/08/2024
Procedure
Printed copies are UNCONTROLLED.
Page 18
Petroleum Development Oman LLC
Revision:
Effective:
Pipe with
blind flange
Horizontal
dead leg
(spool with
blind flange)
Printed 05/08/2024
Procedure
Printed copies are UNCONTROLLED.
Page 19
Petroleum Development Oman LLC
Revision:1.0
Effective:30/06/2024
Vertical
downward
blind flanged
dead leg
A section of
pipeline with
blind end
Printed 05/08/2024
Procedure
Printed copies are UNCONTROLLED.
Page 20
Petroleum Development Oman LLC
Revision:
Effective:
Vertical
downward
pipe section
connected to
NC valve
Instrument
connections/t
ap piping.
Printed 05/08/2024
Procedure
Printed copies are UNCONTROLLED.
Page 21
Petroleum Development Oman LLC
Revision:1.0
Effective:30/06/2024
Typical dead
legs in
pipeline
receiver/laun
cher lines
Bypass line
Printed 05/08/2024
Procedure
Printed copies are UNCONTROLLED.
Page 22
Petroleum Development Oman LLC
Revision:
Effective:
This is an
example of
drain line
connected to
main gas line
where the
temperature
of the gas
dropped
below its dew
point (53
degC)
Causing
condensation
and
accumulation
of sour water
at the
horizontal
section which
had
eventually led
to a pin hole
leak
Printed 05/08/2024
Procedure
Printed copies are UNCONTROLLED.
Page 23
Appendix 2, Dead leg register
CS dead leg register shall follow below formatting. Asset/project team may develop their own dead leg register format, but it shall contain the below minimum requirements.
Asset/Project name:
CS Dead Leg Register
No.
PEFS/ISO No.
Parent
system
TAG
number
Service
Dead leg
Classification
Orientation
Length
diameters
description
Risk Ranking
Solution Identified
Solution identified remark
1
2
3
4
5
6
7
8
9
10
Definitions:
123456-
PEFS/ISO No: It is the number of the PEFS or Isometric drawing containing the dead leg.
Parent system Tag number: It is the number of the system (piping, pipeline, or equipment) containing the dead leg.
Service: It is the type of fluids overseen by the parent system (i.e., Multiphase, gas, oil, water…etc.)
Dead leg classification: Permanent/Physical (design) or operation dead legs
Orientation: Horizontal, vertical downward. Vertical upward with horizontal section…etc.
Length: It is the length of the dead leg section
Action Owner
Due date
Solution implementation status
Petroleum Development Oman LLC
Revision:
Effective:
7- Diameters: The ID of the dead leg
8- Description: Dead leg description to give clear understanding of the dead leg configuration such as: off take line from main line to drain valve or vacuum truck
connection or instrument connection or blinded section …. etc.
9- Risk ranking: High, medium, or low based on risk assessment as per section 3.3
10- Solution identified: it is the solution agreed as per section 3.1.
11- Solution identified requirements: any requirements applicable to the identified solution (e.g., flushing frequency, chemicals dosage rate, inspection
frequency…etc.)
12- Solution implementation status: The status of the solution implementation
Printed 05/08/2024
Procedure
Printed copies are UNCONTROLLED.
Page 25
Appendix 3, Team members
The below individuals were part of the creation of this dead leg procedure:
Team
Name & ref. indicator
South Static support
Hakmani, Mohamed OSO61
North Static support
Saifi, Ahmed ONO61QAS
Gas Static support
GB Static support
Suleiman, Barwani GGO61
Martinez Blanchard, Oscar GGO61
Hosni, Mazin OSGO61
Shahid, Adnan OSO7T
Operation team (Amal)
Rajula, Gangadher OSO222T
Fazari, Mohamed OSOT1
Mechanical Static/Piping
Abri, Muhanna UEMS9
Sankaranarayanan, Ramalingam UEP1
Process
Al Lamki, Said OSO23N
Gustaman, Frieza OSO23
Al Hosni, Hamad OSO23T
Material, corrosion, and Integrity
Al Khouly, Shadha UEC411S
Kharusi, Amjad UEFM14