INTERNATIONAL STANDARD ISO 16440 First edition 2016-10-15 Petroleum and natural gas industries — Pipeline transportation systems — Design, construction and maintenance of steel cased pipelines Industries du pétrole et du gaz naturel — Systèmes de transport par conduites — Conception, construction et maintenance de conduites en fourreau en acier Reference number ISO 16440:2016(E) © ISO 2016 ISO 16440:2016(E) COPYRIGHT PROTECTED DOCUMENT © ISO 2016, Published in Switzerland All rights reserved Unless otherwise specified, no part o f this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission Permission can be requested from either ISO at the address below or ISO’s member body in the country o f the requester ISO copyright o ffice Ch de Blandonnet • CP 401 CH-1214 Vernier, Geneva, Switzerland Tel +41 22 749 01 11 Fax +41 22 749 09 47 copyright@iso.org www.iso.org ii © ISO 2016 – All rights reserved ISO 16440:2016(E) Page Contents Foreword iv Introduction v Scope Normative references Terms and definitions Design Installation 4.1 4.2 4.3 4.4 4.5 General Carrier pipe design Casing design Electrical isolation Corrosion protection 5.1 5.2 5.3 General Handling and storage New casing 5.3.1 General 5.3.2 Carrier pipe installation 5.3.3 Casing end seals 5.3.4 Test leads 5 Inspection and monitoring 6.1 6.3 6.5 6.2 6.4 B ackfilling S p lit- s leeve typ e cas ing extens io ns and ins tallatio ns General f Monitoring of carrier pipe and casing Corrosiveness of the annular space I ntegrity ins p ectio n o carrier p ip e Leakage s urvey Maintenance and repair 7.1 General 7.2 Maintenance of vents and test leads 10 7.3 Clearing of shorted casings 10 7.4 Filling of casings 11 7.5 Removal of casings 11 Annex A (informative) Casing filling procedures for Dielectric Filler Materials 12 Annex B (informative) Examples of cathodic protection testing and monitoring techniques for carrier pipes and casings 15 (informative) Inspection tools for cased carrier pipe 30 Annex D (informative) Clearing a shorted casing 35 Annex E (informative) Removing and cutting a casing 37 Annex C Bibliography 39 © ISO 2016 – All rights reserved iii ISO 16440:2016(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies) The work o f preparing International Standards is normally carried out through ISO technical committees Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters o f electrotechnical standardization The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part In particular the different approval criteria needed for the di fferent types o f ISO documents should be noted This document was dra fted in accordance with the editorial rules of the ISO/IEC Directives, Part (see www.iso.org/directives) Attention is drawn to the possibility that some o f the elements o f this document may be the subject o f patent rights ISO shall not be held responsible for identi fying any or all such patent rights Details o f any patent rights identified during the development o f the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents) Any trade name used in this document is in formation given for the convenience o f users and does not constitute an endorsement For an explanation on the meaning o f ISO specific terms and expressions related to formity assessment, as well as information about ISO’s adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html The committee responsible for this document is ISO/TC 67, Materials, equipment and offshore structures for petroleum, petrochemical and natural gas industries, Subcommittee SC 2, Pipeline transportation systems iv © ISO 2016 – All rights reserved ISO 16440:2 016(E) Introduction Users of this document are advised that further or differing requirements might be needed for individual applications This document is not intended to inhibit a vendor from offering, or the purchaser from accepting, alternative equipment, or engineering solutions for the individual application This might b e p ar tic u la rly appl ic able where there i s i n novative or developi ng te ch nolo g y Where an a lternative i s o ffere d, it i s advi s able that the vendor identi fy any vari ation s © ISO 2016 – All rights reserved from th i s c ument a nd provide de tai l s v INTERNATIONAL STANDARD ISO 16440:2016(E) Petroleum and natural gas industries — Pipeline transportation systems — Design, construction and maintenance of steel cased pipelines Scope This c u ment s p e c i fie s i n s ta l l ation a nd re qu i rements , mai ntenance i nclud i ng o f s te el- c a s e d corro s ion pip el i ne s for pro te c tion, pip el i ne petroleum and natural gas industries in accordance with ISO 13623 NOTE for the de s ign, tran s p or tation fabric ation, s ys tem s in the Steel casings can be used for mechanical protection of pipelines at crossings, such as at roads and i l ways a nd the i n s ta l l atio n o f a c a s i n g at a h ighway, i l way, or o ther c ro s s i n g c a n b e re qu i re d b y the p er m itti ng agenc y or p ip el i ne o p erator NO TE T h i s c u ment e s no t i mp l y th at uti l i z ation o f c a s i ngs i s m a ndato r y o r ne ce s s a r y NO TE This c u ment e s no t i mp l y th at c a s e d c ro s s i ngs , whe ther ele c tr ic a l l y i s o l ate d o r ele c tr ic a l l y s ho r te d , contrib ute to co rro s ion o f a c a rr ier pip e with i n a c a s e d c ro s s i ng H owe ver, c a s e d c ro s s i ngs c a n advers el y a ffe c t the i nte gr ity o f the c a rr ier pip e b y s h ield i n g c atho d ic p ro te c tion (C P) c u r rent to the c a r r ier pip e or re duc i ng the C P e ffe c tivene s s o n the c a r r ier p ip e i n the vic i n ity o f the c a s i n g T hei r u s e i s no t re com mende d u n le s s re qu i re d b y lo ad s ideratio n s , u n s tab le s oi l cond itio n s , o r when thei r u s e i s d ic tate d b y s ou nd engi ne er i n g prac tice s Normative references T he fol lowi ng c u ments are re ferre d to i n the tex t i n s uch a way th at s ome or a l l o f thei r content s titute s re qu i rements o f th i s c u ment For date d re ference s , on ly the e d ition cite d appl ie s For u ndate d re ference s , the late s t e d ition o f the re ference d c ument (i nclud i ng a ny amend ments) appl ie s ISO 15589-1, Petroleum, petrochemical and natural gas industries — Cathodic protection of pipeline systems — Part 1: On-land pipelines EN 12954, Cathodic protection of buried or immersed metallic structures — General principles and application for pipelines Terms and definitions For the pu r p o s e s o f th i s c u ment, the fol lowi ng term s and defi n ition s apply ISO and IEC maintain terminological databases for use in standardization at the following addresses: • IEC Electropedia: available at http://www.electropedia.org/ • ISO Online browsing platform: available at http://www.iso.org/obp 3.1 carrier pipe pip e that conveys the flu id N o te to entr y: N o te to entr y: T h i s ap p l ie s to b o th tra n s m i s s io n a nd d i s tr ibutio n p ipi n g 3.2 casing steel pipe installed around a carrier pipe for mechanical protection © ISO 2016 – All rights reserved ISO 16440:2016(E) 3.3 electrolyte me d ium i n wh ich ele c tric c u rrent i s tran s p or te d b y ion s 3.4 electrolytic contact ion ic contac t b e twe en the c arrier pip e and the c as i ng pip e th rough an ele c trolyte 3.5 end seal device installed over or within the end of a casing to keep water, deleterious materials and debris out of the casing or provide a water tight seal between the casing and the carrier pipe 3.6 holiday un i ntentiona l environment d i s conti nu ity in a pro te c tive co ati ng th at exp o s e s the b a re s te el s ur face to the for the 3.7 isolator spacer d iele c tric device de s igne d to ele c tric a l ly i s olate a c arrier pip e carrier pipe from a c as i ng and provide s upp or t 3.8 metallic short unintentional contact between two metallic structures 3.9 P/S potential pipe-to-electrolyte potential structure-to-electrolyte potential potential difference between the surface of a buried or submerged metallic structure (pipe or casing) and the ele c trolyte th at i s me as u re d with re s p e c t to a re ference ele c tro de i n contac t with the ele c trolyte 3.10 split sleeve ca s i ng i n s ta l le d i n s itu b y weld i ng two lve s o f the c as i ng to ge ther arou nd the c a rrier pip e 3.11 tunnel liner plate steel plate used when micro tunnelling, used to shore horizontal excavations in soft ground 3.12 C/S potential casing–to–electrolyte potential p o tentia l d i fference b e twe en the s u r face o f a burie d or s ubmerge d me ta l l ic c a s i ng a nd the ele c trolyte that i s me a s u re d with re s p e c t to a re ference ele c tro de i n contac t with the ele c trolyte Design 4.1 General The purpose of a casing is to provide additional mechanical protection to the carrier pipe A casing can f the location of a crossing a l s o b e re qu i re d by a p erm itti ng authority to a l low repl acement o a c a rrier pip e without exc avation s at © ISO 2016 – All rights reserved ISO 16440:2016(E) A carrier pipe within a casing is not designed to be cathodically protected It is designed to be electrically isolated from the casing with non-conducting spacers, or isolated i f the annulus o f the casing is filled with a dielectric filler material The carrier pipe is designed to be protected with a protective coating Steel casings shall not be cathodically protected by the pipeline’s dedicated CP system 4.2 Carrier pipe design The carrier pipe shall be coated for corrosion protection The application of an abrasion resistant coating over the corrosion coating should be considered NOTE See NACE/SP 0169 for details of abrasion resistant coatings NOTE See NACE/SP 0286 for details of isolation techniques The carrier pipe shall be supported inside the casing with isolating spacers and outside the casing to prevent sagging Sagging can lead to metallic contact between the casing and the carrier pipe and to carrier pipe stresses 4.3 Casing design Casing design shall be in accordance with the local, national, or industry requirements/standards The casing should be kept as short in length as possible to minimize the risk of electrical shorting over time due to soil stress and pipe movement The casing internal diameter shall be selected based on the nominal diameter of the carrier pipe, the thickness o f any abrasion resistant coating, such as concrete, duroplastic material, or epoxy polymer and the design of the isolators between carrier pipe and casing For individual carrier pipes with a nominal diameter of 200 mm (8.0 in) or greater, the outer diameter of the casing should be a minimum of 100 mm (4.0 in) larger than that of the carrier pipe or if installing parallel cable or conduits the casing should be a minimum of 300 mm larger than that of the carrier pipe For individual carrier pipes with a nominal diameter less than 200 mm (8.0 in), the diameter of the casing should be a minimum of 50 mm (2.0 in) larger than that of the carrier pipe Uncoated casing should be used Coated or non-conductive casing may be used i f the casing can be harmonized with the carrier pipe cathodic protection NOTE The use of coated or nonconductive casing pipe is not recommended due to potential shielding problems when cathodic protection is applied I f coated casings (either internally coated or externally coated or both) are used, external cathodic protection will not provide protection to the carrier pipe in the event that the annulus is filled with a conductive electrolyte I f vent pipes are required, then they should be installed on both ends of the casing Vent pipes should be positioned so that they are not directly over any isolation spacer or end seal I f concrete coated pipe is used and no isolating spacers are used, then the vent pipes should only be installed on the top of the casing The casing vent hole should be at least one-half the diameter of the vent pipe, with a minimum of 25 mm (1,0 in) The vent pipe should be a minimum of 50 mm (2.0 in) in diameter Vent pipes shall be designed to prevent intrusion of water and debris Casing end seals shall be installed to prevent ingress of water, deleterious material and debris Vent pipes are used for venting, monitoring the casing for carrier pipe leaks, filling the casing and as line markers NOTE NACE/SP 0200 gives guidance for design of end seals © ISO 2016 – All rights reserved ISO 16440:2016(E) 4.4 Electrical isolation Su fficient i s olators s l l b e de s igne d to prevent me ta l l ic contac t b e twe en the c arrier pip e and the casing, and to provide adequate support Isolators shall be designed to minimize coating damage The use of metallic components in isolation spacers should be avoided I s olators s l l b e s ele c te d to en s u re they h ave the me cha n ic a l s treng th re qui re d to with s tand the installation loads, considering all conditions including pipe weight, length of casing, conditions of weld b e ad s , defle c tion s i n the c a s i ng and o ther field cond ition s S ele c tion s hou ld fi rm the abi l ity o f the i s ol ators to provide ele c tric a l i s olation a fter i n s ta l l ation and to p o s ition the ca rrier pip e prop erly for end seal application/installation Test leads should be located (connected to the carrier pipe) on the carrier pipe at each end of the casing f installed in accordance with 5.3.4 Test leads to be installed after the carrier pipe is inserted in the casing Metallic shorts between the vent pipe, test leads and carrier pipe shall be prevented to p ermit veri fication o 4.5 metal lic is olation O ne tes t lead shal l b e required as a minimum Tes t leads to b e Corrosion protection C on s ideration may b e given to applyi ng c atho d ic pro te c tion to the c a s i ng as re qu i re d b y cond ition s or re gu l ation s C atho d ic pro te c tion de s ign sh a l l b e i n accordance with approve d i ndu s tr y s tandard s , s uch as ISO 15589-1 C on s ideration may b e given to plac i ng a h igh d iele c tric fi l ler or conduc tive grout i n the an nu la r s p ace or i nj e c ti ng a vap ou r phas e i n h ibitor Annex A give s gu idance on fi l l i ng and the fi l l i ng pro ce du re C atho d ic a l ly pro te c te d c a s i ngs us i ng the pip el i ne s de d ic ate d C P s ys tem may have a de tri menta l e ffe c t on the carrier pipe AC corrosion should be considered as a possible problem when the pipeline is located in an area of AC i n fluence Installation 5.1 General This Clause provides requirements for the installation of new cased pipeline crossings, casing extensions and new casing installation on existing pipelines 5.2 Handling and storage The carrier pipe and casing or tunnel liner plate shall be handled and stored in a manner that minimizes coating and pipe end damage Lifting shall be accomplished utilizing slings, wide belts, or appropriate end hooks If skids are utilized to support the carrier pipe or casing, padding material shall be used to prevent coating damage Skids shall be removed upon completion of the installation 5.3 New casing 5.3.1 General Cased crossings are installed using various techniques including boring, directional drilling, tunnelling and open cutting NO TE Fi l l i n g o f the a n nu l a r s p ace b e twe en p er m itti ng agenc y when the b o rehole i s u n s tab le o r the casing fracke d a nd e xc avatio n is s o me ti me s re qu i re d by the o ut © ISO 2016 – All rights reserved ISO 16440:2016(E) B.4.2 Procedure This technique can be applied to a pipeline survey using an interrupter in the most influential cathodic protection rectifier unit The location o f the cycling rectifier selected should be su fficiently remote from the casing under test so that anode bed voltage gradients not influence the measurement Step Pipeline and casing potentials should be measured with the cathodic protection current applied Step Measurements made for step should be repeated at the same instant that the cathodic protection current is switched off B.4.3 Analysis If the ON and OFF potentials from the casing are close in magnitude to the ON and OFF potentials of the carrier pipe, the presence of a possible metallic short is indicated If water or soil is present in the casing, this test procedure does not give a conclusive result In such situations, additional testing techniques should be employed B.5 Casing depolarization test B.5.1 Purpose Isolation can be verified by discharging DC from the casing I f the two structures are not metallically connected, a significant potential di fference occurs between the casing and carrier pipe B.5.2 Procedure Step A temporary metallic structure (anode bed) should be constructed laterally to, and spaced an appropriate distance from, the carrier pipe and casing [a spacing o f 15 m (50 ft.) is usually an adequate distance] Steel rods driven into the earth or sheets o f aluminium foil in contact with the earth (usually placed in standing water) can provide an adequate temporary structure Step The negative terminal o f a variable DC power source should be connected to the temporary metallic structure Step The positive terminal of the same variable DC power source should be connected to the casing Step A reference electrode should be positioned over the carrier pipe near the casing end Step An appropriate DC voltmeter should be used to measure and record the carrier pipe and casing potentials Step A small increment o f current (0,1 A is a satis factory first increment o f current) should be discharged from the casing for a short period of time, such as one or two minutes Step The current should be interrupted, then the carrier pipe and casing instant-off potentials should be measured and recorded to determine the effect of the applied current; the increment of current should also be recorded Step Steps and should be repeated using additional increments of current (e.g 0,2 A, 0,3 A) A minimum of three different values of test current and measurement of the effects should be taken The amount of current required for an effective evaluation varies due to the size of the structure and condition of any coating present A maximum of 10 A should adequately develop significant potential shi fts 26 © ISO 2016 – All rights reserved ISO 16440:2016(E) B.5.3 Analysis B.5.3.1 Casing shorted If the casing is shorted, the casing-to-soil potential shifts in a positive direction The pipe-to-soil potential also shi fts in a positive direction, usually by about the same magnitude as the casing As subsequent steps are taken, the pipe-to-soil potential largely tracks the positively shi fting potentials o f the casing B.5.3.2 Casing clear I f there is no metallic short, the pipe-to-soil potential may shi ft in a positive direction by only a few millivolts, whereas there will be a dramatic shift in the casing-to-soil potential In some cases, the pipeto-soil potential may shi ft in a negative direction by a few millivolts If the casing potential shifts in a positive direction and the carrier pipe potential remains near normal, electrical isolation is indicated If the casing and pipeline potentials both shift in the positive direction, a shorted condition is indicated Tables B.1 and B.2 illustrate examples of values that indicate electrical isolation (casing clear), and Table B.3 illustrates example of values that indicate an electrically shorted condition (casing short) Table B.1 — Casing is clear (not shorted; example 1) V Initial Readings Step Step Step Step 6,0 18 45 65 A 0,25 0,68 1,0 1,8 P/S potential V −0,975 −0,974 −0,975 −0,981 −0,986 C/S potential V −0,850 −0,710 −0,505 −0,210 +0,0100 Potential difference V 0,125 0,264 0,470 0,771 0,996 Table B.2 — Casing is clear (not shorted; example 2) V Initial Readings Step Step Step Step A P/S potential 0,0860 0,258 0,413 0,566 −1,250 −1,139 −1,104 −1,060 −1,022 V 6,0 18 30 42 © ISO 2016 – All rights reserved C/S potential V −1,21 −0,700 −0,140 +0,240 +0,490 Potential difference V 0,040 0,439 0,964 1,300 1,512 27 ISO 16440:2016(E) Table B.3 — Casing is shorted V A P/S potential V C/S potential V Potential difference V Initial Readings −1,246 −1,242 0,004 Step 6,0 0,234 −1,211 −1,195 0,016 Step 18 0,594 −1,050 −0,980 0,070 Step 30 1,00 −0,796 −0,710 0,086 Step 45 1,20 −0,610 −0,540 0,070 Step 75 2,00 −0,135 −0,100 0,035 NOTE During this test, current is being discharged from the casing and this could result in creating an interference condition with other structures B.6 Use of pipe/cable locator The presence and location o f a pipe-to-casing metallic contact may also be approximated by following a low-power audio or radio signal (pipe locator trace) set between the carrier pipe and the casing The signal returns at the point o f contact, which should be verified from the opposite end B.7 Panhandle Eastern method B.7.1 Purpose The Panhandle Eastern method (developed in the 1950s by Panhandle Eastern Pipeline Company) involves determining whether the casing is electrically isolated or not by discharging DC current from the casing and comparing the electrolytically coupled response o f the carrier pipe I f the two structures are not metallically connected, a significant potential di fference occurs between the casing and the carrier pipe Because the casing is anodically polarized with respect to an independent ground, the casing-to-soil — C/S potential shi fts in a positive direction I f the carrier pipe and casing are metallically shorted, pipe-to-soil — P/S potential also shi fts in a positive direction, usually by about the same magnitude as the casing As additional current is applied to the system, the P/S potentials largely track the positive shifting potentials of the casing If the casing potential shifts in a positive direction and the carrier pipe potential remains near normal, electrical isolation is indicated For electrolytic coupling, no conclusion can be determined in many situations, so this test is not recommended for determination o f electrolytic connection between a casing and carrier pipe B.7.2 Procedure B.7.2.1 Access requirements Test access to the pipeline and casing is required, at least on one end of the casing Test access to the casing may consist o f one or more test leads or a casing vent Best results are obtained when available access includes two points of access to the casing so that current and voltage circuits can be established separately An isolated ground should be available for use as the cathode of the applied current circuit The pre ferred configuration o f this structure is perpendicular to the casing and at least 15,24 m (50 ft.) from the carrier pipe and casing at its nearest approach 28 © ISO 2016 – All rights reserved ISO 16440:2016(E) B.7.2.2 Resistance measurement Using a portable generator and rectifier, battery or other power source, establish a current measurement circuit, including an ammeter or voltmeter and shunt, between the isolated ground (negative/cathode side) and casing (positive/anode side) The source current output should be variable by means o f control rheostats or tap settings With no current applied, measure and record P/S and C/S “off” potentials, relative to a copper-copper sul fate re ference electrode positioned over the pipeline and just outside the casing With approximately 0,5 A o f applied current, obtain P/S and C/S “on” potential measurements, relative to a copper-copper sul fate re ference electrode positioned over the pipeline and just outside the casing Record all potentials and the magnitude of the test current Repeat steps B.7.2.2 and B.7.2.3 at applied currents of approximately 1,0 A and 2,0 A B.7.2.3 Interpretation of the pipe-to-casing reference For each level of applied current, calculate the pipe-to-casing resistance as follows: R (ohms) = [(P/S “o ff”) – (P/S “on”) – (C/S “o ff”) + (C/S “on”)]/ (Applied Current) NOTE milliamps All potentials are measured in millivolts (typically negative) and all currents are measured in The resistance value obtained from each set of measurements should be similar to others Resistance values o f 0,08 Ω or less typically indicate a metallic contact Resistance values greater than 0,08 Ω may indicate the presence o f an electrolytic path or e ffective isolation © ISO 2016 – All rights reserved 29 ISO 16440:2016(E) Annex C (informative) Inspection tools for cased carrier pipe C.1 General Table C.1 describes inspection techniques applicable to cased pipe 30 © ISO 2016 – All rights reserved © ISO 2016 – All rights reserved Table C.1 — Inspection tools for cased carrier pipe Name type DCVG Direct Current Voltage Gradient Electrical contact required Applicability Bare casing Carrier Casing Clear Metallic pipe short No No A A Identifies Description Comments Limitations Coated casing Electrolytic Clear A A Metallic short Electrolytic metallic path, in the coating of the carrier pipe near the edge of the casing AC Current Attenuation No No A A A 1 AC Voltage Gradient No No A A A A A A CIPS (no interruption) Electrical Potential Yes Yes A A A 2 There is a gradient the end of the Possible to casings denote have holiday a possible detected and there is no metallic or metallic short electrolytic path between the casing and the carrier pipe Holidays, Coating holiday which may be a indication near Metallic or between carrier pipe and casing For uncoated (bare) casings, a survey should be done over the casing to determine if it has an electrolytic contact or metallic short Signal HVAC power lines attenuates at a or changes in contact alignment near a rectifier 31 ISO 16440:2016(E) Compares each end of casing Measurement in dB/ft Metallic or Measure dB Coating HVAC power lines electrolytic path signal Strength anomaly tool, between carrier and direction Reliable pipe and casing at each end of detection of the casing electrolytic contact Metallic or Comparison of On Survey Telluric Currents, electrolytic path “on” P/S and Utilize a AC and DC stray between carrier C/S readings criterion current HVAC pipe and casings Preliminary considerations A preliminary check With Complementary screening tool coated casings, tool there can be a problem with electrolyte in the casing or electrolytic path current flow at Name type CIPS (interrupted) Electrical Potential Comparing P/S and C/S shifts Carrier pipe/Cable locator Radio Signal Electrical contact required Applicability Bare casing Carrier Casing Clear Metallic pipe short Identifies Description Comments Limitations Coated casing Electrolytic Clear Yes Yes A A A Yes Yes A A A Metallic short Electrolytic 2 2 © ISO 2016 – All rights reserved Metallic or Compare P/S and C/S shift magnitude between the Carrier pipe and Same direction Casing and similar magnitude suggest metallic contact Same direction but reduced C/S shift suggest electrolytic path C/S shift small or opposite indicates clear Metallic or Signal between electrolytic path carrier pipe and between the casing is traced carrier pipe and to point of casing metallic contact and returns (no appreciable signal outside casing) or signal reduction within casing may indicate electrolytic path Clear casing results in strong endwise signal outside casing along carrier pipe Electrolytic Path Telluric Currents, AC and DC stray current HVAC considerations HVAC power lines Cannot determine i f it is electrolytic contact or metallic short for bare casing Can determine if it is clear for bare casing ISO 16440:2016(E) 32 Table C.1 (continued) © ISO 2016 – All rights reserved Table C.1 (continued) Name type Panhandle Eastern “B” Reverse Current Applied to Casing for P/S and C/S Comparison Electrical contact required Applicability Bare casing Carrier Casing Clear Metallic pipe short Yes Yes U A Identifies Description Comments Limitations Coated casing Electrolytic Clear U U Metallic short Electrolytic U C o n fi r m ati o n of suspected pipe-casing metallic contact Reverse current applied to and Telluric need to be casing to f Current produce anode coated casings consideration polarization f where the C/S and P/S metallic short casings shifts from contain an Cannot determine levels to the difference applied current between clear and are used to calculate approximate pipe-to-casing resistance with , Ω m ay adj u s te d S tr ay D C C u r re nts or O n l y de te c ts i e le c tr o l y te e l e c tro l y ti c va lue s < , Ω co n fi r m i n g a Internal Resistance Electrical Resistance Yes Yes U A U U A U e l e c tro l y tic Isolation Checker/Tester Typ e : C a s i n g- P ip e C ap ac i ta nc e Yes Yes U A U U A U Resistance of path external to casing should be considered S tr ay D C C u r re nt consideration tool Can determine C o mp le me nta r y me ta l l ic s ho r t o n l y E le c tr o l y tic r a n ge not established tool Can determine metallic shorts C o mp le me nta r y only 33 ISO 16440:2016(E) metallic contact Pipe-casing Measured metallic or resistance equated to path contact down casing and back along carrier pipe to calculate distance to contact Pipe-to casing Uses isolation metallic contact checker to indicate clear or shorted condition based on pipe-to-casing capacitance Name type Four Wire Drop Test Current Flow Direction and Magnitude Temporary Intentional Metallic short Electrical Potential Comparing P/S and C/S shifts Electrical contact required Applicability Bare casing Carrier Casing Clear Metallic pipe short Identifies Description Limitations Access over top of casing required Not typically used Coated casing Electrolytic Clear Yes Yes U A U U Yes Yes A A U A Metallic short Electrolytic U U A U Pipe-to casing Using current metallic contact span testing to indicate the presence and location of contact of the carrier pipe to the casing Confirmation o f Compare P/S suspected and C.S metallic contact potential or shifts with temporary metallic short between carrier pipe and casing in place and removed No change indicates contact of similar resistance already existed © ISO 2016 – All rights reserved NOTE Contact to pipeline is required at the location o f signal transmitter set-up but not in the vicinity o f the casing NOTE Contact to pipeline is not necessary in the immediate vicinity o f the casing A – Acceptable This method should yield reliable results to identi fy metallic short or electrolytic contact U – Unacceptable This method does not yield reliable results – Capability exists but protocol and procedures have not been validated – Indeterminate Data that is not available to establish effectiveness Comments Carrier pipe Long casing vents, and casing test i f used, may distort wires offer results Can only better results determine metallic shorts ISO 16440:2016(E) 34 Table C.1 (continued) ISO 16440:2016(E) Annex D (informative) Clearing a shorted casing Clearing a shorted casing normally involves excavating one or both ends o f the casing, exposing a length o f carrier pipe, examining the ends o f the casing, possibly li fting the carrier pipe and restoring the casing spacers and end seals All work performed in attempting to clear a shorted casing should include a work plan documenting what is required for personal sa fety, public sa fety, pipeline excavation, moving and li fting procedures, ditch sa fety and any requirements from local or national codes and permits that apply The first step in clearing a shorted casing is to research the method o f construction, materials used for the casing, spacers, end seals, etc., alignment sheets, records and any history about the cased crossing Doing this research and determining how it was installed can highlight the area of the casing that is shorted due to the materials used and/or the construction methods shorted and can veri fy the location o f the metallic short or can determine that the casing was installed The second step is to analyse the corrosion records, any in-line inspection (ILI) in formation and any previous attempts to clear the metallic short The ILI data might locate the metallic short if it is a data cannot determine the location of the metallic short, then the casing could be sitting on collapsed spacers and can be shorted at multiple locations “hard” metallic contact Knowing where the metallic short is located simplifies the process I f the ILI The third step is to prepare for the attempt to clear the casing by procuring casing spacers, end seals and shims, vent pipe material, test station material and carrier pipe coating Having all the materials available is important as most casing clearing projects are time critical with need to avoid delays, and the work should be per formed sa fely and e fficiently The fourth step is to excavate the casing end(s) to locate or clear the metallic short Using the work plan to ensure it is a sa fe project, the casing should be excavated and several meters (feet) exposed Normally several meters (feet) are exposed to expose the vent pipe and to have su fficient casing length exposed in case it should be cut off and trimmed to provide adequate area for working The carrier pipe hundred meters (feet) if it is determined that the carrier pipe requires to be moved Once the carrier also should be excavated and initially stripped back several meters (feet) to start and possibly several pipe is excavated and the casing end exposed, the existing end seal(s) (i f any) should be removed, and the annular space between the carrier pipe and casing examined Any broken/damaged casing spacers should be removed Spots where casing and carrier pipe are touching should be evaluated to determine whether they are the indicated shorts NOTE When the carrier pipe is excavated it can move (rise) on its own depending on the installation methods and sometimes clear the metallic short on its own The fi fth step is to clear the metallic short I f the metallic short is at the end o f the casing and adequate space is available, the casing can be cold cut and trimmed back to eliminate the casing to carrier pipe contact Once this is done and the metallic short cleared, the coating should be repaired then a casing spacer or shim should be installed between the casing and carrier to keep the casing from shorting out again An end seal should be installed and test leads and vent pipes as necessary If the casing cannot be trimmed back to clear the metallic short, then the carrier pipe should be moved/lifted in accordance with the work plan to attempt to clear the metallic short This can be accomplished using air bags, Jacks, excavation equipment, cranes or other methods that allow the carrier pipe to move in accordance with the work plan and not have any point loads on the carrier pipe If this is accomplished and the metallic short clears, than the coating should be repaired and a spacer(s) © ISO 2016 – All rights reserved 35 ISO 6440: 01 6(E) or shim should be installed between the casing and carrier to keep the casing from shorting out again E nd s e a l s , te s t le ad s and vent pip e s shou ld b e i n s ta l le d a s ne ce s s ar y If these attempts fail and the metallic short is determined to be not at the ends, then consideration should be given to removing the entire carrier pipe and replacing the crossing with a new carrier pipe If loading requires a casing then remove the casing and replace with a split sleeve 36 © ISO 2016 – All rights reserved ISO 16440:2016(E) Annex E (informative) Removing and cutting a casing E.1 Removing process Removing a casing normally involves excavating a section o f, or all o f, the casing and then removing that section of casing All work performed in attempting to remove a casing should include a work plan documenting what is required for personal sa fety, public sa fety, pipeline excavation, moving and li fting procedures, ditch sa fety and any local or national codes and permits that apply Step 1: — Per form any Close Interval Potential Survey (CIS), Direct Current Voltage Gradient Survey (DCVG), Pipeline Current mapping (PCM), Alternating Current Voltage Gradient Survey (ACVG) and intentional metallic short prior to starting the excavation — Take a P/S potential reading and a C/S potential reading on each end of the casing before starting the excavation Step 2: — Excavate carrier pipe to 30 cm (12 in) below casing bottom, support as necessary — Examine casing ends to see if carrier pipe is centred — Remove any end seals — Confirm that the casing is not wax filled or filled with any other type o f casing filler material — Document amount o f water in casing, i f any — Sample water for MIC, microbial influenced corrosion — Document the pH o f the medium (i f any) inside the casing — Install shims to hold carrier pipe away from casing Step 3: — Cut casing off with longitudinal cuts 180° apart taking care not to damage the carrier pipe — Align cuts with largest gap between carrier pipe and casing — Make a girth cut every 245 cm (8 ft.) to 305 cm (10 ft.) — Once the half section is removed, cut the second half section using increasing gaps between the carrier and the casing — Remove sections of casing — Remove any spacers © ISO 2016 – All rights reserved 37 ISO 16440:2016(E) Step 4: — Document type o f end seal and spacers, as well as dimension between spacers — Document any mud or debris in annulus — Document soil environment (pH, resistivity) — Clean off existing coating on carrier pipe Step 5: — Abrasive blast carrier pipe to allow inspection — Perform a direct examination of the carrier pipe — Take a P/S on both ends of the excavation opening once the casing is removed Step 6: — Clean and recoat carrier pipe — Take a P/S potential reading and a C/S potential reading after the carrier pipe is covered E.2 Cutting process Cold cutting is the preferred method of casing removal Acetylene torch cutting, grinding with abrasive disc, or saw with a diamond blade may be used, taking precautions as described below If torch cut: a) look for signs of damaging the coating on the carrier pipe; b) use a hammer to break any slag holding casing sections together If grinding: a) use a side grinder to make the first pass cut, removing 70 % to 90 % o f the metal; b) use a die grinder to finish the cut The operator should pay close attention to the area being cut, looking for signs o f complete cut o f the casing without getting into the coating of the carrier pipe NOTE 38 Coated casings make use o f a diamond blade di fficult as it coats the sur face, reducing e ffectiveness © ISO 2016 – All rights reserved ISO 16440:2016(E) Bibliography [1] ISO 13623, Petroleum and natural gas industries — Pipeline tran sportation system s [2] ISO 13847, Petroleum and natural gas industries — Pipeline tran sportation system s — Welding of pipelines [3] ASTM D937, 1) Standard Test Method for Cone Penetration of Petrolatum [4] ASTM D938, Standard Test Method for Congealing Point of Petroleum Waxes, Including Petrolatum [5] EN 15257, C a t h o d i c p r o t e c t i o n — C o m p e t e n c e l e v e l s a n d c e r t i f i c a t i o n o f c a t h o d i c p r o t e c t i o n personnel [6] NACE/SP 0169, 2) Control ofExternal Corrosion on Underground or Submerged Metallic Piping Systems [7] NACE/SP 0200, Steel cased Pipeline Practices [8] NACE/SP 0286, Electrical Isolation of Cathodically Protected Pipelines [9] NACE/SP 0274, High-Voltage Electrical In spection of Pipeline Coatings [10] NACE/SP 0490, [11] μ m ( t o Holiday Detection of Fusion-Bonded Epoxy External Pipeline Coatings of 250 to m i l s ) Regulation (EC) No 1272/2008 o f the European Parliament and o f the Council o f 16 December 2008 on classification, labelling and packaging o f substances and mixtures, amending and [12] repealing Directives 67/548/EEC and 1999/45/EC, and amending Regulation (EC) No 1907/2006 J ohnston V Road Casing Electrical Contact Characterization American Gas Association Distribution Conference, 1983 Cleveland, OH: American Gas Association (AGA), 1983 [13] NACE Publication 10A192 (latest revision), “State-of-the-Art Report on Steel Cased Pipeline ” Houston, TX: NACE P e abody A.W Control of Pipeline Corrosion NACE, Houston, TX, 2001 Practices [14] 1) American Society for Testing and Materials, 100 Harbour Drive, West Conshohocken, PA 19428-2959, USA 2) National Association of Corrosion Engineers, 1440 South Creek Drive, Houston, Texas 77084-4906 USA © ISO 2016 – All rights reserved 39 ISO 6440: 01 6(E) I C S 7 ; 0 Price based on 39 pages © ISO 2016 – All rights reserved