Procedure For Pipeline De-Oiling [PDF]

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Procedure for De-oiling of 24’’x 44km San Barth to Nembe Pipeline



1.1



General



1.1.1



All work will be carried out in accordance with the Safety Procedure.



1.1.2



Before operations commence, the Pigging Engineer will perform a Toolbox talk with the Crew and Client/Site Rep on the technical and safety aspects of operations, highlighting as a minimum the following topics: •



Safety



•



Incident Reporting Process



•



Review of generic RA’s (job specific RA’s will be developed if required)



•



Operational pressures



•



Equipment layout



•



Duration of operations



•



Location of and setting of PRV



•



Housekeeping



•



Protection of Pipeline ends from contamination



•



Protection and storage of permanent system components



•



Noise



•



Any other ongoing operations



•



Impact on other activities



•



Any questions



1.1.3



The following procedure is common to all De Oiling operations regardless of the line being pigged or the type of pig being used. Details of which type of pigs, and number of pigs, will be determined during detailed engineering.



1.1.4



Raise Permit for flooding operations. Erect temporary barriers around work sites. Check communications between Control Cabin, Shift supervisor and Pump operator.



HSE



Name



Sign



Date



1.1.5



During the flooding of the pipelines, no personnel will be allowed in the vicinity of the system. Only essential personnel associated with the flooding operations shall be allowed within the immediate vicinity of the flooding equipment spread.



1.1.6



Before any direct work on a section or associated connection under pressure is permitted, the pressure will either be isolated with a double block or reduced to ambient.



1.1.7



All paperwork/checklists shall be signed before any work commences and a copy will be passed to the company representative onboard for review.



1.2



Instrumentation



1.2.1



The following instrumentation will be set up and used to monitor and record the parameters during Deoiling operations :-



Qty 2 2 2 2 2



Description Gauge Recorder Data Logger Pressure Recorder Flowmeter Stroke counter



Location Store Container Store Container Store Container Flooding Pump Chemical Pump



1.2.2



All instrumentation is to be calibrated within two months of mobilisation with the calibration certificate available on site.



1.2.3



Pressure Relief Valves will be calibrated immediately prior to mobilisation.



1.2.4



Pressure gauges and recorders will be chosen such that the pressure falls within 50% 90% of the range of the instrumentation.



1.3



Equipment Rig-Up and Function Testing



1.3.1



Raise Permit for rigging up and functioning testing. Erect temporary barriers around work sites. Check communications between Control Cabin, Shift supervisor and Pump operator.



HSE



Name



Sign



Date



1.3.2



On completion of rig up, the equipment will be function tested as below:-



1.3.3



Configure temporary valves as per the following Valve Status check list ref drawing . Valve ID



RISK



Description



Status



Check



Temporary Pumping Spread (ref drawing -DWG001) V1 V2 V3 V4 V5 V6 V7



Lift Pump Inlet Valve Lift Pump Outlet Valve Flooding Pump Inlet Valve Chemical Injection Pump Inlet Valve Flooding Pump Outlet Valve Chemical Injection Pump Outlet Valve Vent Valve



Closed Open Open Closed Closed Closed Closed



V8



Vent Valve



Closed



V9



PRV Isolation Valve



Closed



V10



Instrumentation Isolation Valve



Open



•



Pressure test temporary system to 1.1 x maximum flooding pressure.



•



Confirm pressure relief valve setting.



•



Pressure test instrument lines and check instrument readings.



•



Calibrate injection pumps and ascertain volume per stroke and number of strokes per minute required.



•



Run up pumps (including contingency) confirming operation of flowmeters.



•



Run up pumps and pump through downline to confirm achievable flowrates and pressures (confirm available horsepower)



1.3.4



Before operations commence the supervisor will ensure all hoses and fittings used are of the correct rating (this can be achieved through a combination of pre-mobilisation checks and random spot checks on site, however the responsibility for compliance lies with the test engineer).



1.3.5



Confirm function testing has been completed satisfactorily.



HSE



Name



Sign



Date



1.4



Flooding Operation and Connection Test Raise permit for downline deployment and flooding operations. Name



HSE



Sign



Date



1.4.1



The Field Engineer will brief all personnel in the ensuing operations and will detail the necessary safety precautions required as detailed in the risk assessments.



1.4.2



Preliminaries: •



Ensure the correct pigs are ready for loading /end fitting is connected to the



•



Ensure the temporary system has been function tested as per procedure



•



Ensure the correctly rated PRV’s are connected to the system



hoses



1.4.3



On approval from the Client Site Supervisor to commence deploying the pigs for de oiling activities.



1.4.4



Once the hose has been rigged up, connect the hose to the flooding equipment spread and commence flushing the hose with filtered, water.



1.4.5 Once a good flow of air free water is being discharged from the hose stop the flooding pump. 1.4.6



On completion of flooding, start the pressurizing pump and commence pressurizing against closed pig launcher valve.



1.4.7



Commence the routine pigging until the first pig has a free pass.



1.5



Flooding Operations



1.5.1



During flooding operations the following forms must be filled in:



•



Pigging/Flushing Report



•



Chemical Dosing Report



•



Daily Operations Log



•



Pig Launch/Receive Register



•



Gauge Plate Report



1.5.2



Engage flooding pump and launch pig 1, taking a note of the time of pig launch.



1.5.3



Increase flowrate to approx. TBC m3/min and continue pumping until TBC m3 (TBC linear metres) of untreated filtered water has been pumped.



1.5.4



On pumping TBC m3 disengage the flooding pump and record the following:



•



Time



•



Time of pig launch



•



Volume of water pumped / flowrate



•



Pressure



1.5.5



Request Supervisor to the launcher valves as listed. OPEN valve TBC and CLOSED valve TBC.



1.5.6



Zero or note flowmeter reading prior to launch of pig 2.



1.5.7



Upon receiving confirmation the valves have been functioned, engage the flooding pump and launch Pig No. 2, taking a note of the time of the pig launch.



1.5.8



Increase flowrate to approx. TBC m3/min and continue pumping until TBC m3 (TBC linear metres) of untreated filtered seawater has been pumped.



1.5.9



On pumping TBC m3 disengage the flooding pump and record the following:



•



Time



•



Time of pig launch



•



Volume of water pumped / flowrate



•



Pressure



1.5.10 Request Supervisor to check the launcher valves as listed. OPEN valve TBC and CLOSED valve TBC. 1.5.11 Zero or note flowmeter reading prior to launch of pig 3. 1.5.12 Upon receiving confirmation the valves have been functioned, engage the flooding pump and launch Pig No. 3, taking a note of the time of the pig launch. 1.5.13 Increase flowrate and maintain between TBC - TBC m3/min (pigging velocity TBC – TBC m/s) 1.5.14 On confirmation the pig has been launched start the chemical injection pumps and inject the following chemicals at the required ppm •



Chemical 1



TBC ppm



•



Chemical 2



TBC ppm



1.5.15 After a line volume less the volume of the slugs between the pigs (TBC m3) has been pumped behind the final pig the first pig of the train should be in the receiver. An indication of the receipt of the pigs may be seen on the pressure chart i.e. a pressure spike as the pig blocks the discharge port. 1.5.16 Continue pumping until 120% line volume (TBC m3) has been pumped behind the last pig in the train. Confirm 120% of line volume has been pumped and inform the client Name



HSE



Sign



Date



1.5.17 Disengage the flooding pump and isolate. 1.5.18 Chemical injection pumps will also be stopped and isolated.



1.5.19 During flooding operations the following operations will be recorded at 15-minute intervals: •



Time



•



Volume pumped (m3)/ flowrate (m3/min)



•



Pressure



•



Chemical injection volumes



•



Pigging speed/Velocity



1.5.20 JESCO to function OPEN temporary vent valve to ensure PIPELINE is at ambient pressure. 1.5.24 Request to Close the flooding hose from the pig launcher. 1.5.25 On confirmation the line has been disconnected, de-isolate the flooding pump and commence flushing through the downline with a minimum one line of the hose using filtered swamp water to remove the residual chemicals. 1.5.26 On completion of flushing the pipeline engage the flooding pump and isolate. Allow the pump unit to cool down prior to shutting down. 1.5.27 Disconnect the hose from the temporary equipment 5.5.28. Flooding operations are now complete. 5.5.29. At the receiver end the supervisor shall present to client for acceptance and signature. If signatory authority is not present complete deviation to procedure request to this effect and gain signature from client site representative, or other witness.



Contingency – Stuck Pig General



If a pig(or pigs) is(are) believed to be stuck in the pipeline, check the pig inventory, the pig launch/receive register and the operational logs to ensure the pig(s) are in the pipeline. Client representatives shall be informed in case of any abnormalities regarding pig run and shall be updated accordingly.



Stuck Pig During Flooding



In the event of a pig becoming stuck in the pipeline whilst pigging with filtered seawater, increase the pump output to give an increase in pigging pressure. If the pressure reaches 30 barg and the pig has not moved try to shock the pig into moving by following the steps below.



•



Close pipeline outlet valve for 5 minutes.



•



Open the discharge valve fully to produce a high differential pressure over the pig in an attempt to shock it into moving.



•



These steps shall be cycled through until it is evident that there is no longer any pig movement



If this process does not produce movement of the pig, then shut down the pump and depressurise the pipeline to atmospheric pressure. Discussions shall take place with all parties on the viability of the vessel transiting to the receiving end of the pipeline and attempting to move the pigs in the reverse direction. NOTE: This shall only be possible if the pigs are Bi-Directional pigs.



If the conclusion of the discussions is to transit to the receiver then the downline shall be recovered and the launcher valves left in a status to allow for pigs to travel in the reverse direction.



On arrival at the receiver pigging operations shall continue in the reverse direction.



In the event that pumping from either end of the pipeline fails to move the pig train a decision shall be made as to whether a contingency foam pig,(if available), shall be introduced in the



flowline in an attempt to move the pig train forward in the original direction or alternatively a more suitable recovery plan shall be formulated and agreed with all parties concerned.