Hot Tapping - wahaoil.net

1 WOC LPWOC HSE1_91,,(16,..r On. cManual& EP DepartmentStandardsDOCUMENT NO: WOC-HSE-ST-0001 Section H003 Hot TappingREVISSUEPREPARED BYREVIEWED BYAPPROVED BYISSUE DATE0 Issued for Use!.1v/A 1 tel) (W. McIntoshWO ExecutiveVice PresidentOperationsJune 2009LP & EP Manager,i-ip,,. ,-- -ot, c41141-LP & EP DEPARTMENT HSE Standards ManualSection: H003 TITLEDOCUMENT NUMBERREVDATEPAGEHot TappingWOC-HSE-ST-00010 June 20092 of 12 PURPOSETo outline the practices required to safely perform a hot tap into a "live" line or equipmentwithout blinding or purging of WAHA worksites and facilitiesDEFINITIONHot Tapping is the technique of attaching a mechanical or welded branch fitting to piping orequipment in service, and creating an opening in that piping or equipment by drilling or cutting aportion of the piping or equipment within the attached fitting.)

2 Therefore, this work mainly coverswelding technique without a process stream shut down, as it is impractical to take the piping orequipment out of :It should be noted that Hot- Tapping is not be implemented as a means of convenience. A formal risk assessment shall be performed and Hot- Tapping should be done as a last resort. Thisinformation shall be documented and signed off by the Area Superintendent prior to Hot-Tappingtaking place. POTENTIAL HAZARDS welding burns and radiationfire and explosiontoxic welding vapors5. Hot Tapping is restricted to carbon steel piping systems. Plant systems are governedby rules established by ASME, , Chemical and Petroleum Piping Systems orgovernment regulation. Pipeline systems follow the requirements of API 1104, andAPI RP 2201 Procedures for Welding or Hot Tapping on Equipment in Service as ,, 4 OLP & EP DEPARTMENTHSE Standards ManualSection: H003 TITLEDOCUMENT NUMBERREVDATEPAGEHot TappingWOC-HSE-ST-00010 June 20093 of Before undertaking a hot tap, Form A, "Request to Proceed with a Hot Tap," mustbe completed and approved by the area Operations Manager and engineering.

3 Acopy of this form must be forwarded to Operations personnel responsible for thisarea for approval. This approval must be obtained before the hot tap is started. Itshould be noted that within this request to Hot Tap Pipeline form a Work Pack isincluded that contains all the relevant job details such as scope of work, normaloperating pressure and temperature, specific product in pipeline, pipeline flowvelocity, QA/QC procedures, P & Ids, plus hot tap engineering calculations. Inaddition to this a comprehensive risk assessment using a Job Safety Analysis (JSA)process must be carried out and attached with all the relevant potential hazardsidentified and the method of control to remove or mitigate these hazards are fullyunderstood by all Form B, "Hot Tap Check List," must be completed and signed off by the Company(WAHA) representative in charge of carrying out the hot tap.

4 This information shouldbe retained as QC documentation by the Operations Waha employees carry out hot Tapping operations, however, If a competentContractor carries out the hot tap, they shall have a Manual, which contains a SafeOperating Practice describing the procedure for operating hot tap equipment, QualityControl manual, Welding Procedure Specification for the materials to be welded, andWelder Certificate for the welder that will execute the hot tap. The welder shall bethoroughly familiar with the welding equipment and hot tap and welding procedures tobe Competent Company representatives including HSE representative must be presentduring execution of the hot Suitable fire extinguisher shall be The location to be hot tapped must have be identified and physically marked.).''.q 0,, 'LP & EP DEPARTMENTHSE Standards ManualSection: H003 TITLEDOCUMENT NUMBERREVDATEPAGEHot TappingWOC-HSE-ST-00010 June 20094 of All necessary gas and toxicity tests has been made to ensure a safe environmentthat is free from flammable Signs and barriers have been provided to isolate the job area from the public andunauthorized Appropriate personnel protective equipment shall be Written emergency procedures specific to the job are required in the event of procedure shall indicate isolation points and response by rescue and Prior to the hot tap, the inspector shall ensure the fittings, valves, gaskets andbolting, etc.

5 , are identified and meet all the required specifications for pressure,temperature and service The minimum pipe wall thickness for hot Tapping plant piping shall be mm (1/4") & mm (3/16") for pipelines. The base metal to be hot tapped shall be properlyinspected for adequate wall thickness and the absence of imperfections such aslaminations, hydrogen attack, or stress corrosion cracking. Imperfections, whichmight prevent a sound weld from being made, shall be evaluated by qualified The hot tap shall be at least 3" (7 cm) to a welded seam (including a longitudinalseam of welded piping), or 18" (46 cm) to a flange or threaded connection. Otherspacing distances must be reviewed and approved by Facilities If a hot tap is installed upstream of rotating equipment or control valves, strainers orother devices must be in place to prevent damage from metal 1, 1'40, cLP & EP DEPARTMENTHSE Standards ManualSection: H003 TITLEDOCUMENT NUMBERREVDATEPAGEHot TappingWOC-HSE-ST-00010 June 20095 of Welding electrodes shall be limited to the low hydrogen type & as specified in theWPS.

6 In order to eliminate the occurrence of burn-through, the following steps shallbe followed: The first weld pass less than 1/4" ( mm) thick shall be made with 3/32" ( ) or smaller diameter welding electrode. The subsequent weld passes be made with 1/8" ( mm) diameter weldingelectrode, or smaller if the metal wall thickness does not exceed 1/2" ( ). The larger diameter electrodes may be used for metal wall thicknessgreater than 1/2" ( mm). Welding on compressed air lines under pressure is not allowed. No Hot- Tapping shall take place on piping systems known to have a vapor/airor vapor/oxygen content as the heat from welding may cause a vapor mixtureto enter the flammable range. Hot Tapping stress relieved piping systems is not allowed. Under specialcircumstances, approval to hot tap a stress relieve system may be granted byWAHA management provided job specific welding procedures have beendeveloped.

7 When the metal wall thickness is greater then what code will allow withouthaving stress relieving performed, Facilities Engineering shall be contacted soas a thorough engineering evaluation may be performed. Max thickness formost piping systems is 19mm (3/4") without PWHT Cooling period shall be included between the completion of the full-encirclement fillet weld and the completion of nondestructive testing. Thecooling period after welding and before testing provides for the assessment ofany delayed hydrogen-induced cracking. The length of time for the coolingLP & EP DEPARTMENTHSE Standards ManualSection: H003 - .:- , *h4 oft GO fly'TITLEDOCUMENT NUMBERREVDATEPAGEHot TappingWOC-HSE-ST-00010 June 20096 of 12period should be evaluated for each hot tap and approved by Engineering andthe Chief Inspector. Unless specifically authorized by specialized procedures or following anengineering evaluation, hot Tapping is not permitted on in-service lines orequipment with cladding, or with glass, lead, refractory, plastic, or strip linings.

8 Overheating of liquids and burn-through conditions during the welding of abranch connection for a Hot-Tap is less likely when flow is too high of flow velocity increases the weld cooling rate and the riskof cracking. Therefore, it is desirable to provide minimum level of flow ifpossible. Minimum of flow velocity in a gas line shall be maintainedto provide sufficient heat transfer. A maximum flow velocity does not appearcritical within the limits of practicability in a gas line. In liquid lines, therecommended flow velocity range is Maximum Operating Pressure During Hot In order to avoid the occurrence of burn-through during hot Tapping , the operatingpressure in the pipeline shall be maintained at pressures not exceeding its criticallevel by considering that the Heat Affected Zone (HAZ) reduces the strength of The MAOP can be calculated using the related ASME formulas ( for plantpiping, for liquid lines and for gas lines) with considering correctionfactors as described below.

9 The base metal wall thickness (t) should be reduced by the depth of to there are no data available yet for the depth of HAZ, it isrecommended to consider as 60% of wall thickness for plant piping, and 30%for cross country pipelines either gas or liquid laboratory test/ experiment showed that depth of HAZ is about mm( ") for the following welding parameters: base metal of 8" ,LP & EP DEPARTMENTHSE Standards ManualSection: ,)et",, .._---,,,4 ori TITLEDOCUMENT NUMBERREVDATEPAGEHot TappingWOC-HSE-ST-00010 June 20097 of API 5L and a plate of 9 mm thick, ASTM-572 , mm AWS E-7018, DCRP, 70 150 Amperes, and 20 35 The specified minimum yield strength of base metal should be determinedbased on the LMT (log mean temperature) as calculated below,LMT = (T2 T1)/ Ln T2/T1 Where, T1 is the temperature of fluid in the pipeline/piping.

10 T2 is thetemperature of metal at HAZ, assumed 750 deg Nondestructive Prior to welding, the hot tap location shall be verified for thickness and checked forlaminations and other defects using ultrasonic examination After completion of welding, the final weld shall be visually examined and subjectedto magnetic particle or dye penetrant All Hot Tap connections will be subjected to a hydro test prior to the cutting out of REFERENCESAPI Publication 2201 API RP 74i:-ItIl rn ' n- q 'ti-OIL CO LP & EP DEPARTMENTHSE Standards ManualSection: H003 TITLEDOCUMENT NUMBERREVDATEPAGEHot TappingWOC-HSE-ST-00010 June 20098 of 12 Form A - Request to Hot Tap PipelineDate of Request:WAHA QC #Purpose of Hot Tap:Length of cooling period:Location:Description of run pipe:Pipeline No.:MOP during hot tap (calculated):PsigOperating Pressure :PsigFProduct in pipeline:Pipeline Velocity:Ft/secondDescription of branch pipe:Hot Tap Contractor- Procedures Manual :Welding Contractor- Quality Control Manual- Welder MIGAS CertifiedWPS#Work Pack CompleteJSA DoneApproved :Operations ManagerApproved by: EngineeringApproved by: QC , e, -its iii.